Owned a 2011 Z06, second owner, purchased at 14K miles, never modified from stock. Wiggle tested at 30K miles, exhaust guides out of spec, heads replaced under GM warranty with GM LS7 heads (due to factory warranty). Had those heads checked gain at 38.8K miles just prior to GM powertrain warranty expiring at 5 years, intake guides were out of spec. A second set of GM warranty GM heads were installed. However, both sets of replacement heads were of the same lot (2013), so expected intakes to prematurely wear. As predicted, had heads checked at 48XXX miles, intakes worn, replaced with aftermarket heads on GMPP warranty. Replaced that Z06 with 2011 Carbon Edition Z06 in Oct 2021, 6.6K miles, all original and stock. Had OEM heads replaced with aftermarket heads to be proactive. Checked guides on OEM heads and intakes were out of spec at only 6.6K miles.
Well dang it that is very concerning all round! What the hell?? What are we to believe then?? I’m concerned my 2014 Z28 will spit valves any day. Constant concern.
This video was mostly BUNK! I've seen hundreds of out of spec LS7 valves/valve guides, they range from every model year GM made the LS7 (including in the Z/28)... ALL THE YEARS POTENTIALLY HAVE THIS ISSUE!!! It's more rare to not see a stock LS7 without at least one valve close to being, or being completely out of spec. Mileage isn't a huge flag either, I've seen them loose with under 10k miles. This doesn't mean they will grenade at any moment (it's a fairly low percentage that totally nuke), but the point is every LS7 is suspect and an eye needs to be kept on them to make sure they don't get to the point of excessive wear. Please do not listen to the BS GM is spewing that it was only a few cars and only 2006!
What about LS3? I have one in my Holden Commodore SS paired to a T56... is there anything to worry about? (Mime still has the machined roller rockers not the cast ones btw)
@@GregoryShtevensh the ls3 is the most bulletproof out of the entire LS series. The only thing on them are the stock rocker arm needle bearings (all ls engines) if installing a high lift aftermarket cam.
Very strong opinion. I have found that folks with a strong opinion are often not 100% accurate. Get the heads replaced by a reputable company, AHP comes to mind. Get a mild cam and you are set. I did that and dyno numbers were 550.18 HP and 503 lbft torque.
If you are going to modify your LS7, I highly recommend Katech Performance in Detroit. They've been working with these engines from the beginning. Worked with GM to develop it, and built all of them for Corvette Racing ( Pratt and Miller). They know and address all the pitfalls of this engine.
@@toddhartmayer8327 which is pretty sad. And I don’t understand what this guy (original commenter) is saying either. Why would I go to a place that HELPED ruin the engine, to help fix it? 🤣
@@toddhartmayer8327 which is pretty sad. And I don’t understand what this guy (original commenter) is saying either. Why would I go to a place that HELPED ruin the engine, to help fix it? 🤣
Completely stock 06 Z06 with 30k miles dropped a valve without warning cruising on the freeway. Cost me the motor and oil system. 20k mistake thanks GM. This issue is very real. I high recommend anyone with an ls7 get there heads done.
Nice vid, however you forgot to mention!The LS7'S use relatively high lift camshafts. Premature valve train failures can be caused by high lift cams that cause long rocker arm travel. Long rocker travel causes lateral force on the valve stem when the valve is open. This lateral force wears out valve guides. Which causes valve and guide tolerance to go out of spec. GM even had a service bulletin with a valve stem "wiggle test". GM also acknowledged that several batches of valve stems were installed incorrectly at the wrong "angle". Valve issues are widely documented. Race Proven Motorsports to this day continues to find bad valve guides in LS7 Camaro's.
Ya he missed a lot of stuff, like how high rpms are needed when holding a gear thru corners, going thru traps on a drag strip, etc... You know the kinda things you buy a Z06 for. My guess is he is either really stupid, or trying to cover GM's ass over a well known well documented problem GM doesn't want to admit to. I laughed when he said you don't need high rpm's and not to over rev your engine. You CAN'T over rev a engine with stock tuning, the ECU will not allow it....
@Milo Jones I'm a fan of roller rockers. Also, just wanted to ask, are those duration numbers @.050 or advertised duration? Cuz if that's .050, good God that's gotta be a rowdy camshaft, especially at 111 lsa 😂. Unless the LS7 manages high duration well and those numbers are kind of normal for it. I know it is set up for high lift, so the 684/683 doesn't shock me.
@Milo Jones That's badass, man. And I agree on the rollers. I kinda think GM should have just used rollers to begin with. The thing has just about .6" of lift from the factory, and it's a nice, expensive engine. Just use rollers GM! Of course, GM has been pretty famous about cheaping out on rocker arms. Needle bearings with open trunions that scatter the needles everywhere comes to mind. But that is really, really good info about the swipe pattern with the rollers. I'm an Fbody guy, but of course one day would like to buy an ls7 car, probably a c6 Z06.
This video is another example of why I love this channel. Lyle lays it out with words everyone can understand and gives us the knowledge we need when making that huge decision to buy a Corvette. And this is coming from a former Corvette owner, five different ones over a 12 year history. Love the channel, Lyle.
This is BS. The issue was NOT fixed after 2006.The official GM bulletin specifically states the 08-11 cars which is also incorrect. Of course the GM engineer is going to say there was no issues but the truth is, its very much a real problem that still exists today. Please do your research before buying one of these cars even if its STOCK.
Totally agree from experience too!! Dropped a valve on a 2007 1st gear pull w a customer while tuning him, (stock limiter). Needless to say, destroyed the engine. I typically love your content, but this was complete bs on the airflow and tuning aspect affecting guide wear. The whole stock engine lives is bs, related to the valve guide wear issue. I’m a GM tuner and Mechanical Engineer from the automotive industry, I can back up my info too. I do generally agree w everything else that was said.
completely agree 💯. The only leg they have to stand on is that there are little to no issues with stock LS7 engines. Nobody leaves an LS7 completely stock! This is the most common form of manipulative statistics! Find a C6 Z06 without an intake or headers, and I'll show you a garage queen. Even when completely stock, and just well driven as designed, you'll have the same valve issues as they ALWAYS have eventually. Still a great platform if you're willing to spend the time and money necessary to make it perform and be reliable.
I owned my 2007 Z06 for 10 years and no engine problems (thankfully). However, I was well aware of the potential for a catastrophic engine failure. But I did have the clutch replaced under warranty due to something the dealer tech called an overcenter condition. In real world terms what this meant was the clutch pedal stuck to the floor and wouldn’t release until I backed off the accelerator. Even though a gm engineer told me the single disc clutch could handle the LS7 torque, I never believed it. It should have been built with the dual disc clutch like in the ZR1.
Lyle, Sorry I missed you at Carlisle, love your videos and this one in particular. I have a 2013 427 convertible with a little over 30,000 miles. I have read all of the dread on the forums, so I have changed the oil and filter every 5,000 miles or year whichever comes first. I also send the oil off to be analyzed and the reports have come back clean each time. I plan on keeping this car and enjoying the drive. Keep up the good work. Wish your shop was close to me, need a good shop in Eastern Va.
Now here is a smart owner. Don't believe all the BS GM is spewing. You don't hear of ANY of these problems with the LS1, LS2, LS3, LS4, LS6, LSA, or LS9. There was, is, and are reasons for cause and effect.....
Is 5 000 miles not standard oil change interval? If, with Covid, one could put that many on in a year. I went to once a spring change the last couple of years. I would think spring is better than fall to get out any winter moisture in oil? Yes/No?
I'm currently planning on buying my first Corvette. Your videos have been so helpful with learning about these cars, especially the C5 z06 which I've got my eye on. Thanks for sharing the knowledge!
get a c6 from 2008 to 2013 with the Ls3 is just is powerful is the Z06 , or if u really want a Zo6 get a c7 Zo6 if u really want some power,,, I have my 2008 with Ls3 537HP and I don't have to worry about a dam head, or valve ,, I even install a Zr1 widebody fenders and bumper too, it looks a lot better than a Zo6 C6 ,,,
Thanks for the video. But you were given wrong information. I own a C6 Z06 with an LS7, so I have researched it extensively. The titanium intake valves are chromium nitride coated from Del West (OEM valve) for guide compatibility. This is a good thing, but you got it wrong. The hollow stem sodium filled exhaust valves were supplied by the lowest bidder and the wall thickness is not consistent. Some will be as thin as .011". ALL the LS7 heads (not just 2006) had issues with the guides not being concentric with the seats. This was poor quality machine work done at a GM supplier facility in Canada. Combine these factors and the engine experiences excessive valve guide wear. When the wear gets to a point the thin wall exhaust valve stem breaks dropping the stainless-steel head into the chamber. The hypereutectic alum piston then hits the valve head and the result is catastrophic. Please add an addendum to this video to correct the information.
I have also seen cutaways of the GM exhaust valve. The stem material is NOT made with a consitent wall thickness, one side could be .030" then 180* its like .010" thick That valve is a POS!
After scrolling thru these comments, I STRONGLY URGE any of you who own an LS7 to join LS1 Tech, and/or the Corvette Forum. There are Engineers on BOTH forums who are just as smart, or smarter than Koerner, who do not have to answer to anyone higher up at GM, who will give you the flat out truth about what Koerner tried to bury. Coincidentally, the LS7 has been discontinued. Most people who have, or do own an LS7 (that hasn't blown!) absolutely love them. Now, if a product is extremely popular, and is profitable, why would a manufacturer discontinue it? GM still sells the original small block Chevy V8. They haven't ever stopped making it, since the Fall of 1954-68 consecutive years!!!
@@jamesw.6931 Exactly my point! They are popular, and they're profitable. The LS7 is also popular, so we're left with the "profitable" portion. There's only one reason they aren't profitable, and I think it's due to warranty claims.....
Great information, but..... I had a completely stock, 2008 Z06 that I purchased with 1,400 miles. At 19,xxx miles it dropped an intake valve and cratered the engine. It had not been tuned. It had not been to the track for a single mile. It was absolutely bone stock. So, while this is great information and likely applies to most people, just be aware that it does not apply to all. The likelihood that you will have a catastrophic engine failure may be small, but it is no small deal if you happen to be the one it happens to. Especially if you are out of warranty age-wise at the time the failure happens.
Asking a GM representative about failures is about like asking a kid if he stole a piece of candy. You might get the truth. How many times have I called the manufacture of a part and heard, "We've never seen that problem before". Sure..often I knew of others with the same problem that had called the same manufacturer. It's a CYA. While I don't know how legitimate the LS7 issue is, they don't seem to be as reliable as say a LS6.
@@P71ScrewHead there are debates as to what the LS7 block can handle stock versus sleeved. Titanium rods have been used in forced induction applications before, notably the LS9 with their rods sourced from Austria.
@@jamesw.6931 Unfortunately, the LS7 rods do have issues even at stock power levels. They changed from Mahle to Pankl due to some of these issues. Titanium is super cool, but the cost of a single titanium rod covers an entire set of powdered metal rods in the LT4
Great stuff, recently purchased a 07 . No more mid life crisis. Awesome beast, I am an ex state trooper, could never catch a Vette lol. Subbed and shared .Kudos..
ANDY, ON THE SERMON AMOUNT CHRIST SAID "DO UNTO OTHERS AS YOU YOU WANT DONE UNTO YOURSELF". OBVIOUSLY YOU'RE DOING THE SAME THING WITH YOUR CAR THAT ALL THE OTHER PEOPLE DID. THAT YOU GAVE TICKETS TO. AM I CORRECT ABOUT THIS?
I've had three C6 Zo6s 07,08,09 about 50,000 mi driven combined and never dropped a valve, I was very aware of the valve drop issue, it never happened to me. I still have the 09 and am thinking about heads and cam. Best of luck to every other LS7 owner out there.
I just bought my first 06 z06, 75k miles. After buying it I read that they spontaneously combust every 5-10k miles so I’m debating on whether to check my guides or just just bury my head in the sand and have a backup plan if the ls7 does decide to shit the bed.
Never had a problem with my ls_7 it was a 2008 zo6. Autocrosses it for 3 Years bought it 27k sold it with 56k. Between 2 drivers it won 14 of 16 races. I also personally ran about 100 to 125 quarter miles runs in the 4 years I owed it. I ran cold air intake and hypertech programer. At different times. I also very early on I reduced the rev limiter. 6500. Ran like a rolex watch. Never missed a beat. Miss everything but the arrest me red color. Just 2 cents.
I also have a 2008 Z06. Ran the thing hard on the streets all the time. Bought it at 36K miles. Never had it tested for the heads. Just enjoyed it. Like you should. Tuned it and added aftermarket parts. At 52K miles finally upgraded the heads and cam and went right back to beating on it and enjoying it. Mines also red
@@joem1382 mine is a 07 but with a 09 service engine since I blew the original spraying a big shot lol. The 09 engine has now 70k miles and running strong.
Wish I had, ha. I enjoyed my 2002 electron blue Z06 straight away 177 per hour tunnel vision for $55,000.00. Had 5 other vets various degrees lol. 3 C7s not impressed with Bowling Green. C6 felt kind of slippery. I probably will go back C5 when the dollar adjusts my way lol.
For ultimate performance, saying "shift 1000 rpm below redline" really doesn't work. You ARE losing performance. OTOH, for a street car which is not in serious competition, it makes perfect sense most of the time. Few if any street drivers need ultimate performance. If you drive any hi-po engine right up to its limits, it will need more maintenance, repair and will probably succumb earlier. That's the nature of the beasts.
I have a confirmed valve drop 26k miles and absolutely no aftermarket parts. Stock exhaust, air intake ect. I’d like to know why mine dropped then and if 7000 rpm is to much maybe redline should have been lower from factory
Yep, should have just said "ls7's have weak valve springs stock. Dont buy a car that isn't bone stock, unless it has aftermarket head work or heads in general." instead we get this scotty kilmer spiel about how the engineers know better than you and it's just a bunch of mansplaining. Dislike from me. Gl with your vettes, wouldnt bring em here.
@@fry.master the issue with LS7 valve drops are not with the valve springs. It was related to the valve guides. The broken valve spring issue dropping valves is with the LS6.
Am second owner of a stock 08 C6 50K miles with the original run flats. Once I learned about the "guide" issue I had Able Chevy put the caliper on to check tolerance. For piece of mind I allowed them to change heads for about 2500.00 ish. Driving the car home I could easily hear how much less rattley the new heads were. I know it's antedotal evidence but it was VERY obvious. I'm from a race car family been driving cars/karts for 50 years now. I fully restored my GT-1 car... I know sounds car motors make. I think what I did was the right thing for me
I’ve had two ls7s both of them failed both of them completely 100% stock. Absolutely no modifications, not even a custom tune. First one failed due to exhaust valve failure, second one spun a crank bearing. I really think it is a problematic engine. I didn’t have any problems like this with my previous ls2 and ls3.
Hey Lyle! It was great meeting you at Carlisle before you left. Just got my C4 safely back to Arizona now. Thanks for your advice, and glad you enjoyed the show!
my 2007 c6 zo6 had catastrophic valve failure on three valves, at 42k. completely stock. Fortunately the extended warranty paid for two brand new sets of heads however at 84k, (42k on the new heads)...guess what the valve train is ready for replacement. So out with the factory heads in with a custom set... ls7 uses a 1.8 rocker arm ratio that puts a lot of side load on the guides themselves, if you get new guides, get bronze but also research longer guides to assist with the additional side load stress
The head problems persist in every year Z06. This is not even debatable at this point. I know 3 individuals personally that have had dropped values. Failure on stock engines due to the valves is well well documented. Sorry...
Yea... This guy post me when he said just don't hit redline. Like are you for real right now? If your engine can't handle 7k rpm maybe don't put the redone there... The truth is LS motors can rev higher then 7k just not with stock components.
Such bad information. It is a known fact that ALL YEARS OF LS7 have valve guide issues, even on bone stock, lower mileage cars. Too many forum members have dropped valves. There isn't an issue with '06 heads and that wasn't even the year GM claimed was bad. And he didn't even mention things like: - Rocker issues on the '07 - Rod bearing issues on the '12-13 when GM changed materials (though most of those have been corrected unless you found an ultra low mileage example) - Coating on the connecting rods wearing away. Intake valves aren't the only source of titantium in your oil analysis As a former LS7 owner, I left for a reason. I (fortunately) came out unscathed and profited a bit on the car, but many others aren't as lucky as I was.
Brass valve guides?! I think you meant to say bronze. I repair cylinder heads professionally. The guide problems affect all LS7 engines. There may have been some machining problems at one point, but the bigger issue is the nitride coating on the titanium intake valve eating up the powdered metal oem guide. There are various fixes, including a heat treated powdered metal guide, and manganese bronze guides. I have redone several sets of LS7 heads for local Chevrolet dealers that were trying to service customers, and didn't want to wait to get parts from GM. I used manganese guides in those, with very good results. No further problems, some in service 9 years now. It would have been better to use a valve seat compatible with a titanium valve, and forego the coated valves, but I guess GM found that cost prohibitive.
Well your’s is the most interesting reply here, thank you and yes he did say brass. I’m impressed you’ve had such success with your fix techniques. How do we got hold of you??
@@540chevhell9 To be clear, I am not here to solicit business. If anyone has questions you can message me, I am happy to try to help or point you in the right direction.
117,000 miles on mine so far. Bone stock engine. Even the air filter is the stock AC Delco Donaldson Power Core. Was very diligent during break in period, swapped the oil/filter at 1100 miles. LS7 continues to be a gem of an engine for me. A very interesting article in Corvette Action Center by Hib Hiberson "The Ruthless Pursuit of Power' states (if I'm remembering correctly) Feb 2011, GM asked or required Linimar Manufacturing (they machined the heads) to do a 100% inspection on them instead of spot inspections. And the valve guide issue was largely 2008-2010. My engine was built in 2012 for the 2013 model year.
One note: The C5-R and C6-R both used a 7.0L not a 5.5L. That was background on how the LS7 came to be. The 5.5L in the race car didn’t come along until 2010 when the team moved from GT1 to the GT2 class. The class restrictions limited displacement to 5.5L.
Great video Lyle thanks I learned a lot I still have my C5 and love it but I always enjoy your videos thank you for posting great presentation of valuable information
Lyle, you've helped me tremendously concerning this issue. Now I can continue in my search for one of these with more confidence and knowledge. You're the man!!
Thanks for the LS7 information my question is l know the LS3 is a slightly different design than a LS7 the LS3 has a smaller bore 3.62 crankshaft and different heads and slightly less compression I've seen these engines run reliability and dependable for a fairly long time that rev to 7200rpm with a BTR EPS camshaft with 228 intake duration and 240 exhaust duration with good maintenance and surpass the LS7 505 horsepower rating by 55-65 horsepower with no ill effects while being streetable with a broad powerband from 2000-7200rpm just wondering why these engines modified seem to be perfectly fine while the LS7 is so much more finicky l could be wrong but l prefer the LS3 shorter stroke crankshaft of 3.62 over the 4.00 stroker crankshaft of the LS7 have a 2011 Camaro SS with a new GM performance LS3 495 horsepower that runs on E85 with many upgrades since December 2021 and so far I'm very happy with the performance and reliability of this engine
Gloria, I totally agree that the LS3 is an excellent platform for tuning and adding power. From what Paul told me, the LS7 isn't a good platform for those same things due to its design and the materials used. Lyle
What I've learned from getting involved with tuning the 96 C-4 with Jets DST is GM bogs these cars down with extreme knock tables and timing retard along with torque management in the ECM. Reducing some of these extreme measures they use for EPA, driveability and protection will greatly enhance performance as long as you know what you're doing. Tuning the stock 96 C-4 coupe with one of the tuner programs for the LT-1, I used JET, completely changed and enhanced performance. Slightly more horsepower but allot more torque over stock. I can only imagine what you can do to a C-5, C-6 and C-7 just by tuning them without bolt ons.
If you want to really have fun with a C4, replace the GM Injection with a Holley Sniper or anything else, even a Holley 750 double pumper carburetor. Put in a roller cam at 1970 LT1 specifications for street driveablilty. I also put in an MSD Distributor. My son has never lost street racing my old C-4 auto cross car when I put in my 1970 LT1 with the Doug Nash 4+3. scary fun
Head’s, Cam’s E85 an a tune is good for 640 reliable WHP. Mind you the transmission! If you behave and play like a nice boy all you theoretically need is a solid clutch combination and you should be good. Now! If you’re going to be banging that stick late at night with criminal intent! I would politely suggest you throw some axels in there for good measure. And again! We still playing nice here. Now if you really want to be naughty, and play with some oxygen supplementation… consider some good gears. A stock bottom end can live its entire existence @750hp, of course this is entirely dependent you your lvl of maturity.
You know it’s the weirdest thing, just as one of my pistons melted and the engine sucked two valves, my rear tires had gone completely bald down to the steel. I tell ya they were smoking somethin fierce.
Agreed! I learned a lot more about the LS7 issues from a GM insider who laid out far more facts about the weak points of an otherwise awesome engine. GM has it's story, as detailed in this video, but the truth is that doing the heads is necessary and encouraged. Lyle
I have a 2006 Z06 with 101,000 miles on it. I shift at 5800-6000. The engine has so much torque that there is no reason to rev past that. (only has had oil changes--still has the factor spark plugs-new clutch at 98,000)
I'm sorry,but if putting a cold air package,or a set of headers on an engine,can bring about an engine failure,I would have to say there is a problem with that engine,and your GM friend is just covering his ass!If it can't handle those minor additions,I wouldn't trust it to last very long even i stock condition.
Lyle, I appreciate your U tube videos & respect your knowledge but the LS7 had (has) valve guide issues through the 2013 model year...even the Z28 LS7 Camaros had ( have) this issue. Corvette Forum has many posts about the later model year LS7 cars suffering catastrophic engine issues. I own an LS7 Corvette & love the power the car has but this issue is always in the back of my head. This issue is real & it follows all model years
It's a $2-$3k job. Peace of mind goes a long way. When I bought my '08 Z06, I had it in the budget right away. It is BS that this affects only modded cars.
@@jrobles1019 And you just chose to believe the propoganda Lyle chose to believe FROM Chevrolet ?? Also...the new painting process the used in the late 80's had zero issues, the owners neglected to properly maintain the finish !
Not to sure if this is true , I’ve hade a few machinist tell me that gm had the LS7 heads machined by a second party and they made the valve guids to lose , witch made the valve go side to side when the valve closed eventually beating the valves to death and eventually braking the head off the valve.
I have a 2013 427 and no issues with 30k miles. Didn’t have any issues with my previous Z06 either with 44K miles. In 2011 GM improved the valves and created more allowable tolerances for improved reliability. They learned that from the C6R race-car in 2010. Good luck.
The valve guide bushing bores were mismachined off center. Enough for the engine to run and run powerfully, but it wore out the valve stems prematurely causing the valve head to snap off. Remove valve guides, press new unfinished guides in and machine shop final machines the valve stem bores in spec.
the story line here from GM just doesn't jive. Its the same one we've ALL heard before. Just look at all the comments here and around the Corvette forums of 100% bone STOCK cars dropping valves. These are limited production motors, not like there is 100K of them out there on the streets. Guys that have modded and upgraded their heads are probably at LESS risk, not MORE.
I have a bone stock 2007 Z06 corvette I purchased new and the engine dropped the valves in one cylinder at 44,000 miles. The failure caused the rod to punch a hole in the block which totally ruined the engine. I purchased a new complete engine from a local chevy dealer for $10,900. dollars and another $4,500.00 to install the new engine. The corvette presently sits in my heated garage with only 500 miles on the new LS-7 engine. I am now concerned about the quality of the engine which was purchased about 2021 and therefore do not drive it. It sits along side of my new 2023 corvette stingray collecting dust. It will serve as a collector vehicle. I got no help from chevy at all.
I trust his words. This is very useful info and normally I wouldn't care about info like this but since I own a 2007 c6 it was helpful watching. On a side note, this guy is legit, if anyone happens to read this comment or watch this video and has been thinking about buying stuff from their shop I would 100% recommend it. I've bought a harmonic balancer from them and it was shipped in less than three days, these guys work fast😂. Great video!
Thank you for for the information. This gives me some peace of mind with my bone stock 2011 Z06 with 6k miles on it. The chances of a valve drop appear to be very low due to the low mileage, being bone stock, and being a later year C6.
I own a 2007 ZO6 with corsa intake and corsa exhaust, from original owner Installed sometime before 37000 km when I bought it. It has 55000 km now and GM said my car was not effected by the valve guide issue. Pulled the heads off myself, and they are perfect, just like GM said they would be. It doesn't make sense that GM would say some are bad, and some aren't, if that wasn't the case. So, IMHO I think if GM says yours aren't effected then they aren't. If GM says they are bad then you better get that fixed. I have never tracked my car, but I do drive it hard. I mean red line all the time, almost every time I take it out, after the oil temp is up. I think giving it too much gas at low RPM is very hard on these engines. If I do ever track it I will definitely get the oil tank with the goiter attachment since mine came without. Super fun car!!! Highly recommend!
We have a fairly large LS scene here, all the go to guys say the valves have issues no matter what. That's all I really need to know. Additionally, a lot of us want to mod the car. Especially an LS7 given the appeal of making over 600 wheel, NA. Shouldn't have to worry about mods wiping a motor, when done correctly and with a tune. Just my opinion.
Right? To me it almost sounds like this motor wants to be modified to rectify the issue with the heads. Like getting good heads and a good tune would actually be better for it than leaving it stock. Like those guys with the early 6th gen Camaros that got sick of the torque converter problems and just went and got a stall put in. No more torque converter issues lol
Meh. I have an LS7 making 650hp. Heads/cam, FBO, SBE LS7. Been on the same motor. No issues. I learned the hard way, hot rodding ain’t cheap. I was once young and broke and couldn’t afford to do things right. Went through motors. Now, much older, different position in life I’ve learned. Quality parts, and it’s all in the TUNE. Car is on nitrous as well. I remember going to TX2K and running my car damn near all night, still was able to drive home after 8-10 spray passes. Hot rodding can be reliable, from my experience but there’s a triangle. Cheap, reliable, fast. You can only choose two. If you are not going to spend the money on the right, parts, tuning, safety measures, etc. Keep it stock.
Interesting to read all the negative comments. I bought a new ‘07 ZO6, and had all the forum negatives all around me. To save myself the possible $20K to $25K expense of a destroyed engine, I went to a local Chevrolet dealer and said I wanted the heads replaced. The work was done under warranty, new heads, but the old valves, springs, etc. The engine never gave me a bit of trouble, it was not modded, and maintenance was done by the book. Unfortunately, I had to sell the car due to physical impairments.
yes, we all know the STOCK motor is unlikely to have a valve drop. the problem is NONE of us leave the LS7 stock! we're all gonna do MINIMUM intake, headers, tune. Most of us do a cam as well. So we all replace the heads so that we don't grenade the motor
I used oil analysis to detect titanium in the oil, before damage. GM warranted the repair and I saved the LS7 in my Ron Fellows Z06. I used Blackstone Laboratories. Ask them about it. Dennis
Actual owner data point (one data point). I own a 2011 Z06/Z07. I ordered it and bought it new. It has 16,000 miles on it. This car is a toy, most of the 16,000 are track miles. The power train is stock right down to the air filter. I have always understood the torque curve of this engine and have made a habit of shifting around 6,000 rpm for the reasons given here. The car runs great and I have no plans for changing anything on the car or my driving style. Also, sodium filled valves are not new nor are they "trick". They've been around since WWII, a lot of radial engines used them. He is right about them being a good idea.
Wow, this information is so helpful. Its getting more and more difficult to find a Corvette that is bone stock . The head issues explained is very helpful as well. Thank you so much for sharing.
I disagree. Ive own 7 3-5th gens. 1st at 15 years old was a 85 z28 305 H.0 car. you wrong all Gm Ls dont ive been 5,8s on Gm somewhat factort vahle train. If you never own how can you call B.S.
All we have worked on for 48 years are Corvettes. We don't see a ton of C6 z06's down here, and have never seen this problem in our shop. That is why I went to GM to get answers. I knew going into this video that there would be disagreements, and I understand that there are two sides to every issue. Of the valve problems you have heard of / experienced, were they on stock (unmodified) cars? I appreciate any additional info that you can provide. Lyle
@@csvette I have a 2011 C6Z/Z07 and at 24k miles the GMPP warranty was running out. I took my car to an engine builder in Mooresville NC. He pulled the heads and found the intake valves way out of spec. Also a couple of lifers were galling the cam. The GMPP adjuster inspected the heads and approved the warranty work to replace the heads and cam. The new heads were taken apart and were machined correctly. Some of the valve seats were not concentric with the valve guide bores. He also sent the Del West valves back to DW to be recoated and polished. That is an issue most don’t know about . The valves were not polished correctly and acted like sand paper moving up and down in the valve guide. Del West cutting corners as the bid they won with was very cheap. The trunnions were replaced with CHE and Beehive springs added. I also had the cam upgraded with a custom ground cam. Not a crazy lift (.615) just to give me a little more torque between 2600 and 7000 RPM. I have put 8000 miles on the engine and is running great. My criteria for my engine builder was I want as bullet proof engine as possible. He build engines for a lot of dirt track cars that see 8000 to 9000 RPM for 20 to 30 minute heat races and he rebuilds them at the end of the season. I track my car on a regular basis. I have met many C6Z guys who have had at least one engine replaced under warranty. Met one guy who was on his 3rd engine under warranty. These were un modified cars as modding them would void the warranty. The LS7 is an awesome engine. I believe it was very poor machining on the head manufacturing company. I also believe the went too cheap on the valve guide material used. If GM had put an extra $500 to $1000 in quality parts and had tighter quality control process in place they would have had a bullet proof motor. The C6Z is a great bang for the buck. The head issue is real as GM probably ran the numbers and replacing engines was a cheaper route than a recall to fix the problem. If you budget for the head fix you can’t go wrong. With this platform.
So basically GM designed absolutely no headroom for modifying the LS7 (as in more airflow and fuel = more power)? Why would they build something so fragile or made of glass like that? You would think that the Corvette being a potential track car would be over engineered to be able to handle modification and abuse. Most German and Japanese cars in my experience are so over engineered you can mod them way over the factory spec and they hold together just fine as long as you run the proper oil and fuel. How disappointing as the Z06/C6 is the only newer Corvette that I like style wise and would buy.
My 2007 z06 with 25k miles, cream puff miles box stock. Had valves checked when I bought it and and over half the valves were out of spec. You have to rev engine to 7k or shifting from 4 to 5 or 5 th is a pig. I did valves lifters and spring with cam. Use moldstar90 valve guides
My stock 2008 Z06 dropped a valve on the highway @4000 rpm and cracked the block. Lost $30,000 when I sold the car. GM/Chev did nothing for my loss. Saved 10 years to buy that corvette. What a piece of junk!
I’ve had two LS7 engines (C6 Z06 and 5th Gen Camaro Z28) and without hesitation I will admit that the LS3 engine is better than the LS7 for tuning and longevity and reliability. LS3 is the best V8 GM has ever made in my personal opinion
A question was asked further down in the comments about the use of CIA and headers on the LS7 causing valve these items have nothing to do with valve drop. On stock LS7 engines the valve guides are not up to the task. The Ti intake valves are coated and polished at the factory. They are not polished enough and have burrs. ( Ask me how I know) they act like sandpaper on the guides and cause wear on them. The valve guide bores are not concentric with the valve seats which causes excessive wear on the valve stems. The exhaust valves are hollow sodium filled. The excessive movement can eventually cause the head of the valve to snap off and boom! When I had my heads checked at the end of my GMPP warranty at 24k miles the intakes were all out. ( burrs on the Ti valves) the exhaust were almost out. New heads approved and when they arrived at the engine builder they were out of spec. Ti valves were sent back to factory to be recoated and polished correctly. Heads were machined to fix the concentric issue. Add Ti exhaust valves and CHE trunnions. Also the cam was bad. Lifter was galling the cam. Had a custom cam with .615 lift. Not real big and new beehive springs. 10k miles on the engine and many track days as will with no issues. Another question asked was about theHi HP LS7 create motor with a bigger cam. My question on this would be what modification has GM made to the motor to accommodate the larger cam? Have they upgraded the valve guides? Have they made sure the machine work on the heads is correct? Have they put appropriate springs for the larger cam? If they have the motor should be great out of the create. The LS7 is an awesome engine. When on the track it’s a beast. It pulls to almost 7k. Flattens out around 6800 RPM but running it to 7k and grabbing the next gear keep the engine in the fat part of the torque curve when you let the clutch out. Nothing better than dropping the hammer and LETTING THE BIG DOG EAT!!!
I got a c6 z already canned and ported heads to avoid any issues not to mention it can beat or at least run next to a c7 z. 566 to the wheels which is what c7 put out And the answer is a c6 z is rolling the dice with out new heads.
Bronze guides, roller rockers, and methanol/water injection, you can run it leaner and meaner without the heat buildup in the cylinder head, upper block, deck mating surfaces, pulls the heat off of the exhaust valves chamber surfaces and piston crowns, and not only flushes large portion of the generated heat out of the exhaust, it consolidates the heat and exhaust gasses, puts less of a workload on the catalytic converters, letting the exhaust flow better because it has more mass per pulse, it improves the cylinder scavenging. It reduces the intake charge temperature, increases the density, and velocity, rapidly absorbs residual heat and vaporizes and enhances fuel atomization, more fuel is ignited and completely burned. Less concentrated heat in an isolated area (inner exhaust port) valve guides and stems don’t reach critically high temps, and the thermal cycling expansion and contraction are minimized, ceramic coatings on pistons cylinder head and valve faces (combustion chamber surfaces) for thermal barrier and lubrication augmentation. Roller rockers and improved valve train geometry can be achieved but that’s a lot to post.
One thing to consider is, with those tight tolerances, you should be very careful about high revs when the engine is cold. I always drove my 2008 Z06 very carefully so as to not rev above about 2500 until the oil was at temp. I owned that car from new until I got my 2019 Z06 and never had any issues.(48k miles) My 2019 changes the red line on the tachometer until it has reached a safe temp. Remember that all metals grow with heat and the engines are designed to be have correct clearances once at operating temp. They are out of tolerance when cold, so high revs will cause way more wear.
Even stock the LS7 needs vavletrain upgraded. Failure rates are way too common. As mentioned KSTech or RPM in Delaware (uses KS Tech parts) to have the valvetrain done. Throw a cam in it for more power while in there because the cam is cheap. It's the labor that's astronomical. Many with LS7s and knowledge of these motors knows the common failure component and it's well established as failing on stock motors with as low as 10k miles. Doesn't matter if stock or modded. It's a design flaw. You can't even buy the motor from GM Direct parts anymore.
I'm pretty sure that there was a valve issue that was traced to a problem with the rocker arm needle bearings that affected the VERY late build 2006's (June/06, July/06 builds) as well as 07's built between August and November of '06 (I once owned an '06). Edited to include this - and then there was the valve spring issue affecting '02 Z06's as well as a few of the early-build '03's (I once owned an '03 and had the springs replaced as a precaution measure). Seems it's always something.
I enjoyed my 2002 electron blue Z06 straight away 177 per hour tunnel vision for $55,000.00. Had 5 other vets various degrees lol. 3 C7s not impressed with Bowling Green. C6 felt kind of slippery. I probably will go back C5 when the dollar adjusts my way lol.
The needle bearing issue was not related to the valve drop issue with the LS7. It was a separate issue in 2006 and was corrected for the 2007 model year. The LS7 heads had machining issues and the valve guide bores were not concentric with the valve seat which caused wear on the valve guides. The exhaust valve was a hollow stem and was the weak point when the tolerance moved out side GM spec. Once out side the spec you we’re on borrowed time.
you must be working for gm. I bought 08 Z06 stock with 11k miles on it. Removed heads and first exhaust valve I checked had about 12 to 15 thousands play on it. My opinion is that valve guides were installed off center and that caused uneven wear.LuckilyI was able to fix heads before something bad happened.
I merely reported what Paul Koerning told me, and he is GM's lead Corvette Tech. I made a follow-up video after interviewing a former Corvette Engineer who wished to remain anonymous that details exactly what the weak points are and why the failures occur. Check out that video...I think it will make better sense than what GM told me. Lyle
I have a 09 C6Z and have tracked it since I got it. A track friend had one too and while running at Sebring with NCM he dropped a valve on the back straight. His was stock. Luckily, there were GM Engineers there and jumped on the car and had new heads delivered to the local Chevy dealer the next day and all was good. My engine, after my 2nd trip to Daytona, a distinct “ticking” was heard. It was under an extended warranty so my local dealer swapped heads for me.
Great content Lyle. I always appreciate you being straight forward, to the point, matter of fact. Cut through all the Bull and hype. Please keep up the great work!!!
Blown 2 engines. One at 34.000 km what was a warranty although the Importer did everything to blame me because i did trackday's with the car. The second blew ar 84.000 and was completely destroyed and was no warranty. Then i bought Katech "street attack" engine. That one is still running great.
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Owned a 2011 Z06, second owner, purchased at 14K miles, never modified from stock. Wiggle tested at 30K miles, exhaust guides out of spec, heads replaced under GM warranty with GM LS7 heads (due to factory warranty). Had those heads checked gain at 38.8K miles just prior to GM powertrain warranty expiring at 5 years, intake guides were out of spec. A second set of GM warranty GM heads were installed. However, both sets of replacement heads were of the same lot (2013), so expected intakes to prematurely wear. As predicted, had heads checked at 48XXX miles, intakes worn, replaced with aftermarket heads on GMPP warranty. Replaced that Z06 with 2011 Carbon Edition Z06 in Oct 2021, 6.6K miles, all original and stock. Had OEM heads replaced with aftermarket heads to be proactive. Checked guides on OEM heads and intakes were out of spec at only 6.6K miles.
My gosh. You just took me right out of that market.
Wow. That is really good info. Thank you for responding! Lyle
Well dang it that is very concerning all round! What the hell?? What are we to believe then?? I’m concerned my 2014 Z28 will spit valves any day. Constant concern.
@@540chevhell9 Buy aftermarket heads ! Additional power, eliminate worries 😁
Go buy a lingenfelter eliminator motor....amazing
This video was mostly BUNK! I've seen hundreds of out of spec LS7 valves/valve guides, they range from every model year GM made the LS7 (including in the Z/28)... ALL THE YEARS POTENTIALLY HAVE THIS ISSUE!!! It's more rare to not see a stock LS7 without at least one valve close to being, or being completely out of spec. Mileage isn't a huge flag either, I've seen them loose with under 10k miles. This doesn't mean they will grenade at any moment (it's a fairly low percentage that totally nuke), but the point is every LS7 is suspect and an eye needs to be kept on them to make sure they don't get to the point of excessive wear. Please do not listen to the BS GM is spewing that it was only a few cars and only 2006!
as a former ls7 owner I agree. They also love to have rod bearing failures.
What about LS3? I have one in my Holden Commodore SS paired to a T56... is there anything to worry about? (Mime still has the machined roller rockers not the cast ones btw)
@@GregoryShtevensh the ls3 is the most bulletproof out of the entire LS series. The only thing on them are the stock rocker arm needle bearings (all ls engines) if installing a high lift aftermarket cam.
@@KNS_Racing awesome haha
Very strong opinion. I have found that folks with a strong opinion are often not 100% accurate. Get the heads replaced by a reputable company, AHP comes to mind. Get a mild cam and you are set. I did that and dyno numbers were 550.18 HP and 503 lbft torque.
If you are going to modify your LS7, I highly recommend Katech Performance in Detroit. They've been working with these engines from the beginning. Worked with GM to develop it, and built all of them for Corvette Racing ( Pratt and Miller). They know and address all the pitfalls of this engine.
Very true
Good input and thank you.
I wonder who needs more than 500hp? 🤔
Lyle just said to find a bone stock LS7 and don’t screw with it. It’s the best it’s going to be.
@@toddhartmayer8327 which is pretty sad. And I don’t understand what this guy (original commenter) is saying either. Why would I go to a place that HELPED ruin the engine, to help fix it? 🤣
@@toddhartmayer8327 which is pretty sad. And I don’t understand what this guy (original commenter) is saying either. Why would I go to a place that HELPED ruin the engine, to help fix it? 🤣
Completely stock 06 Z06 with 30k miles dropped a valve without warning cruising on the freeway. Cost me the motor and oil system. 20k mistake thanks GM. This issue is very real. I high recommend anyone with an ls7 get there heads done.
Nice vid, however you forgot to mention!The LS7'S use relatively high lift camshafts.
Premature valve train failures can be caused by high lift cams that cause long rocker arm travel.
Long rocker travel causes lateral force on the valve stem when the valve is open.
This lateral force wears out valve guides.
Which causes valve and guide tolerance to go out of spec.
GM even had a service bulletin with a valve stem "wiggle test".
GM also acknowledged that several batches of valve stems were installed incorrectly at the wrong "angle".
Valve issues are widely documented.
Race Proven Motorsports to this day continues to find bad valve guides in LS7 Camaro's.
Excellent analysis 👍
Ya he missed a lot of stuff, like how high rpms are needed when holding a gear thru corners, going thru traps on a drag strip, etc... You know the kinda things you buy a Z06 for. My guess is he is either really stupid, or trying to cover GM's ass over a well known well documented problem GM doesn't want to admit to. I laughed when he said you don't need high rpm's and not to over rev your engine. You CAN'T over rev a engine with stock tuning, the ECU will not allow it....
@Milo Jones I'm a fan of roller rockers. Also, just wanted to ask, are those duration numbers @.050 or advertised duration? Cuz if that's .050, good God that's gotta be a rowdy camshaft, especially at 111 lsa 😂.
Unless the LS7 manages high duration well and those numbers are kind of normal for it. I know it is set up for high lift, so the 684/683 doesn't shock me.
@Milo Jones That's badass, man. And I agree on the rollers. I kinda think GM should have just used rollers to begin with. The thing has just about .6" of lift from the factory, and it's a nice, expensive engine. Just use rollers GM!
Of course, GM has been pretty famous about cheaping out on rocker arms. Needle bearings with open trunions that scatter the needles everywhere comes to mind.
But that is really, really good info about the swipe pattern with the rollers. I'm an Fbody guy, but of course one day would like to buy an ls7 car, probably a c6 Z06.
This video is another example of why I love this channel. Lyle lays it out with words everyone can understand and gives us the knowledge we need when making that huge decision to buy a Corvette. And this is coming from a former Corvette owner, five different ones over a 12 year history. Love the channel, Lyle.
This is BS. The issue was NOT fixed after 2006.The official GM bulletin specifically states the 08-11 cars which is also incorrect. Of course the GM engineer is going to say there was no issues but the truth is, its very much a real problem that still exists today. Please do your research before buying one of these cars even if its STOCK.
Totally agree, and can speak from experience...
Totally agree from experience too!! Dropped a valve on a 2007 1st gear pull w a customer while tuning him, (stock limiter). Needless to say, destroyed the engine. I typically love your content, but this was complete bs on the airflow and tuning aspect affecting guide wear. The whole stock engine lives is bs, related to the valve guide wear issue. I’m a GM tuner and Mechanical Engineer from the automotive industry, I can back up my info too.
I do generally agree w everything else that was said.
completely agree 💯. The only leg they have to stand on is that there are little to no issues with stock LS7 engines. Nobody leaves an LS7 completely stock! This is the most common form of manipulative statistics! Find a C6 Z06 without an intake or headers, and I'll show you a garage queen. Even when completely stock, and just well driven as designed, you'll have the same valve issues as they ALWAYS have eventually. Still a great platform if you're willing to spend the time and money necessary to make it perform and be reliable.
I owned my 2007 Z06 for 10 years and no engine problems (thankfully). However, I was well aware of the potential for a catastrophic engine failure. But I did have the clutch replaced under warranty due to something the dealer tech called an overcenter condition. In real world terms what this meant was the clutch pedal stuck to the floor and wouldn’t release until I backed off the accelerator. Even though a gm engineer told me the single disc clutch could handle the LS7 torque, I never believed it. It should have been built with the dual disc clutch like in the ZR1.
@@jamesw.6931why are you yelling?
Lyle, Sorry I missed you at Carlisle, love your videos and this one in particular. I have a 2013 427 convertible with a little over 30,000 miles. I have read all of the dread on the forums, so I have changed the oil and filter every 5,000 miles or year whichever comes first. I also send the oil off to be analyzed and the reports have come back clean each time. I plan on keeping this car and enjoying the drive. Keep up the good work. Wish your shop was close to me, need a good shop in Eastern Va.
Now here is a smart owner. Don't believe all the BS GM is spewing. You don't hear of ANY of these problems with the LS1, LS2, LS3, LS4, LS6, LSA, or LS9. There was, is, and are reasons for cause and effect.....
Is 5 000 miles not standard oil change interval? If, with Covid, one could put that many on in a year. I went to once a spring change the last couple of years. I would think spring is better than fall to get out any winter moisture in oil? Yes/No?
@@codyhatch4607 I change the oil and filter on all of my cars at 5,000 miles or once a year whichever comes first.
@@milojanis4901 , Katech HAS found the same problem with the LS9.
I'm currently planning on buying my first Corvette. Your videos have been so helpful with learning about these cars, especially the C5 z06 which I've got my eye on. Thanks for sharing the knowledge!
get a c6 from 2008 to 2013 with the Ls3 is just is powerful is the Z06 , or if u really want a Zo6 get a c7 Zo6 if u really want some power,,, I have my 2008 with Ls3 537HP and I don't have to worry about a dam head, or valve ,, I even install a Zr1 widebody fenders and bumper too, it looks a lot better than a Zo6 C6 ,,,
@@oscaresquivel8583specifically, a C6 GrandSport
I would get a set of new heads if I was buying Z06
Bunch of Wrong Information
Thanks for the video. But you were given wrong information. I own a C6 Z06 with an LS7, so I have researched it extensively. The titanium intake valves are chromium nitride coated from Del West (OEM valve) for guide compatibility. This is a good thing, but you got it wrong. The hollow stem sodium filled exhaust valves were supplied by the lowest bidder and the wall thickness is not consistent. Some will be as thin as .011". ALL the LS7 heads (not just 2006) had issues with the guides not being concentric with the seats. This was poor quality machine work done at a GM supplier facility in Canada. Combine these factors and the engine experiences excessive valve guide wear. When the wear gets to a point the thin wall exhaust valve stem breaks dropping the stainless-steel head into the chamber. The hypereutectic alum piston then hits the valve head and the result is catastrophic. Please add an addendum to this video to correct the information.
I have also seen cutaways of the GM exhaust valve. The stem material is NOT made with a consitent wall thickness, one side could be .030" then 180* its like .010" thick That valve is a POS!
After scrolling thru these comments, I STRONGLY URGE any of you who own an LS7 to join LS1 Tech, and/or the Corvette Forum. There are Engineers on BOTH forums who are just as smart, or smarter than Koerner, who do not have to answer to anyone higher up at GM, who will give you the flat out truth about what Koerner tried to bury. Coincidentally, the LS7 has been discontinued. Most people who have, or do own an LS7 (that hasn't blown!) absolutely love them. Now, if a product is extremely popular, and is profitable, why would a manufacturer discontinue it? GM still sells the original small block Chevy V8. They haven't ever stopped making it, since the Fall of 1954-68 consecutive years!!!
@@jamesw.6931 Exactly my point! They are popular, and they're profitable. The LS7 is also popular, so we're left with the "profitable" portion. There's only one reason they aren't profitable, and I think it's due to warranty claims.....
Great information, but..... I had a completely stock, 2008 Z06 that I purchased with 1,400 miles. At 19,xxx miles it dropped an intake valve and cratered the engine. It had not been tuned. It had not been to the track for a single mile. It was absolutely bone stock. So, while this is great information and likely applies to most people, just be aware that it does not apply to all. The likelihood that you will have a catastrophic engine failure may be small, but it is no small deal if you happen to be the one it happens to. Especially if you are out of warranty age-wise at the time the failure happens.
Asking a GM representative about failures is about like asking a kid if he stole a piece of candy. You might get the truth. How many times have I called the manufacture of a part and heard, "We've never seen that problem before". Sure..often I knew of others with the same problem that had called the same manufacturer. It's a CYA. While I don't know how legitimate the LS7 issue is, they don't seem to be as reliable as say a LS6.
@@jamesw.6931 Change the Ti rods, too.....
@@jamesw.6931 I believe that he meant the titanium rods in the LS7
@@BiscuitMcgriddleson yes bcuz they're meant to stay n/a, how much power can the ls7 block handle??
@@P71ScrewHead there are debates as to what the LS7 block can handle stock versus sleeved. Titanium rods have been used in forced induction applications before, notably the LS9 with their rods sourced from Austria.
@@jamesw.6931 Unfortunately, the LS7 rods do have issues even at stock power levels. They changed from Mahle to Pankl due to some of these issues.
Titanium is super cool, but the cost of a single titanium rod covers an entire set of powdered metal rods in the LT4
Great stuff, recently purchased a 07 . No more mid life crisis. Awesome beast, I am an ex state trooper, could never catch a Vette lol. Subbed and shared .Kudos..
ANDY, ON THE SERMON AMOUNT CHRIST SAID "DO UNTO OTHERS AS YOU YOU WANT DONE UNTO YOURSELF". OBVIOUSLY YOU'RE DOING THE SAME THING WITH YOUR CAR THAT ALL THE OTHER PEOPLE DID. THAT YOU GAVE TICKETS TO. AM I CORRECT ABOUT THIS?
@@Frank289100most definitely 😂
I've had three C6 Zo6s 07,08,09 about 50,000 mi driven combined and never dropped a valve, I was very aware of the valve drop issue, it never happened to me. I still have the 09 and am thinking about heads and cam. Best of luck to every other LS7 owner out there.
I just bought my first 06 z06, 75k miles. After buying it I read that they spontaneously combust every 5-10k miles so I’m debating on whether to check my guides or just just bury my head in the sand and have a backup plan if the ls7 does decide to shit the bed.
@@auditrevor Get the oil tested
Never had a problem with my ls_7 it was a 2008 zo6. Autocrosses it for 3 Years bought it 27k sold it with 56k. Between 2 drivers it won 14 of 16 races. I also personally ran about 100 to 125 quarter miles runs in the 4 years I owed it. I ran cold air intake and hypertech programer. At different times. I also very early on I reduced the rev limiter. 6500. Ran like a rolex watch. Never missed a beat. Miss everything but the arrest me red color. Just 2 cents.
When was your build date?
I also have a 2008 Z06. Ran the thing hard on the streets all the time. Bought it at 36K miles. Never had it tested for the heads. Just enjoyed it. Like you should. Tuned it and added aftermarket parts. At 52K miles finally upgraded the heads and cam and went right back to beating on it and enjoying it. Mines also red
@@joem1382 mine is a 07 but with a 09 service engine since I blew the original spraying a big shot lol. The 09 engine has now 70k miles and running strong.
You never daily drove it only quarter mile passes and autocross sounds like to me that's why you had no issues
How often have done your oil changes and what kind of oil did you use?
I just picked up a 15 z28 with 5k kms on it
Owned a 2009 ZO6. No mods. Ran flawless. Sold it with 73k miles. Bought a 2010 ZR1.
Wish I had, ha. I enjoyed my 2002 electron blue Z06 straight away 177 per hour tunnel vision for $55,000.00. Had 5 other vets various degrees lol. 3 C7s not impressed with Bowling Green. C6 felt kind of slippery. I probably will go back C5 when the dollar adjusts my way lol.
Great video, the Z06 platform is one of the best street and track corvettes that chevy has ever made.
For ultimate performance, saying "shift 1000 rpm below redline" really doesn't work. You ARE losing performance. OTOH, for a street car which is not in serious competition, it makes perfect sense most of the time. Few if any street drivers need ultimate performance. If you drive any hi-po engine right up to its limits, it will need more maintenance, repair and will probably succumb earlier. That's the nature of the beasts.
No point in reving to redline as power is dropping off a lot.
Wrong, my LS7 hits hp peak at 6800rpm. Get your heads worked and run the crap out of it.
I have a confirmed valve drop 26k miles and absolutely no aftermarket parts. Stock exhaust, air intake ect. I’d like to know why mine dropped then and if 7000 rpm is to much maybe redline should have been lower from factory
Yep, should have just said "ls7's have weak valve springs stock. Dont buy a car that isn't bone stock, unless it has aftermarket head work or heads in general."
instead we get this scotty kilmer spiel about how the engineers know better than you and it's just a bunch of mansplaining. Dislike from me. Gl with your vettes, wouldnt bring em here.
@@fry.master the issue with LS7 valve drops are not with the valve springs. It was related to the valve guides.
The broken valve spring issue dropping valves is with the LS6.
Am second owner of a stock 08 C6 50K miles with the original run flats. Once I learned about the "guide" issue I had Able Chevy put the caliper on to check tolerance. For piece of mind I allowed them to change heads for about 2500.00 ish. Driving the car home I could easily hear how much less rattley the new heads were. I know it's antedotal evidence but it was VERY obvious. I'm from a race car family been driving cars/karts for 50 years now. I fully restored my GT-1 car... I know sounds car motors make. I think what I did was the right thing for me
This is like asking the wolf if there are any problems with the Hen house.
I’ve had two ls7s both of them failed both of them completely 100% stock. Absolutely no modifications, not even a custom tune. First one failed due to exhaust valve failure, second one spun a crank bearing. I really think it is a problematic engine. I didn’t have any problems like this with my previous ls2 and ls3.
Hey Lyle! It was great meeting you at Carlisle before you left. Just got my C4 safely back to Arizona now. Thanks for your advice, and glad you enjoyed the show!
my 2007 c6 zo6 had catastrophic valve failure on three valves, at 42k. completely stock. Fortunately the extended warranty paid for two brand new sets of heads however at 84k, (42k on the new heads)...guess what the valve train is ready for replacement. So out with the factory heads in with a custom set... ls7 uses a 1.8 rocker arm ratio that puts a lot of side load on the guides themselves, if you get new guides, get bronze but also research longer guides to assist with the additional side load stress
The head problems persist in every year Z06. This is not even debatable at this point. I know 3 individuals personally that have had dropped values. Failure on stock engines due to the valves is well well documented. Sorry...
Yea... This guy post me when he said just don't hit redline. Like are you for real right now? If your engine can't handle 7k rpm maybe don't put the redone there... The truth is LS motors can rev higher then 7k just not with stock components.
Really?? I have had 4 Z06s and never had any head problems.
@@vincentbucci671 that is sweet. Yoy are one of the good ones!
@@vincentbucci671 how long did you have them...unfixed z06 are ticking time bombs. It's a matter of time before they let go.
@@defaultuser48 idk...I've seen a few for sale with over 200k on them.
love my 07 ZO6 boned stock103K miles
The head problem is so real I wouldn't take a chance on not addressing it, and GM didn't recall it.
Such bad information. It is a known fact that ALL YEARS OF LS7 have valve guide issues, even on bone stock, lower mileage cars. Too many forum members have dropped valves. There isn't an issue with '06 heads and that wasn't even the year GM claimed was bad.
And he didn't even mention things like:
- Rocker issues on the '07
- Rod bearing issues on the '12-13 when GM changed materials (though most of those have been corrected unless you found an ultra low mileage example)
- Coating on the connecting rods wearing away. Intake valves aren't the only source of titantium in your oil analysis
As a former LS7 owner, I left for a reason. I (fortunately) came out unscathed and profited a bit on the car, but many others aren't as lucky as I was.
Brass valve guides?! I think you meant to say bronze. I repair cylinder heads professionally. The guide problems affect all LS7 engines. There may have been some machining problems at one point, but the bigger issue is the nitride coating on the titanium intake valve eating up the powdered metal oem guide. There are various fixes, including a heat treated powdered metal guide, and manganese bronze guides. I have redone several sets of LS7 heads for local Chevrolet dealers that were trying to service customers, and didn't want to wait to get parts from GM. I used manganese guides in those, with very good results. No further problems, some in service 9 years now. It would have been better to use a valve seat compatible with a titanium valve, and forego the coated valves, but I guess GM found that cost prohibitive.
Well your’s is the most interesting reply here, thank you and yes he did say brass. I’m impressed you’ve had such success with your fix techniques. How do we got hold of you??
@@540chevhell9 To be clear, I am not here to solicit business. If anyone has questions you can message me, I am happy to try to help or point you in the right direction.
You are absolutely correct--I meant bronze. Lyle
hi, I thought the silicone bronze was prefered for ti valves- that is what the NASCAR guys use- pro stock too.
Hey Lyle welcome home .Glad to hear you had a great time when you were ..up the road . P.S. You make amazing great videos..Thanks 👍🚗
117,000 miles on mine so far. Bone stock engine. Even the air filter is the stock AC Delco Donaldson Power Core. Was very diligent during break in period, swapped the oil/filter at 1100 miles. LS7 continues to be a gem of an engine for me. A very interesting article in Corvette Action Center by Hib Hiberson "The Ruthless Pursuit of Power' states (if I'm remembering correctly) Feb 2011, GM asked or required Linimar Manufacturing (they machined the heads) to do a 100% inspection on them instead of spot inspections. And the valve guide issue was largely 2008-2010. My engine was built in 2012 for the 2013 model year.
One note: The C5-R and C6-R both used a 7.0L not a 5.5L. That was background on how the LS7 came to be. The 5.5L in the race car didn’t come along until 2010 when the team moved from GT1 to the GT2 class. The class restrictions limited displacement to 5.5L.
C5-R originally used a 6.0L LS1.R
Great video Lyle thanks I learned a lot I still have my C5 and love it but I always enjoy your videos thank you for posting great presentation of valuable information
Lyle, you've helped me tremendously concerning this issue. Now I can continue in my search for one of these with more confidence and knowledge. You're the man!!
Thanks for the LS7 information my question is l know the LS3 is a slightly different design than a LS7 the LS3 has a smaller bore 3.62 crankshaft and different heads and slightly less compression I've seen these engines run reliability and dependable for a fairly long time that rev to 7200rpm with a BTR EPS camshaft with 228 intake duration and 240 exhaust duration with good maintenance and surpass the LS7 505 horsepower rating by 55-65 horsepower with no ill effects while being streetable with a broad powerband from 2000-7200rpm just wondering why these engines modified seem to be perfectly fine while the LS7 is so much more finicky l could be wrong but l prefer the LS3 shorter stroke crankshaft of 3.62 over the 4.00 stroker crankshaft of the LS7 have a 2011 Camaro SS with a new GM performance LS3 495 horsepower that runs on E85 with many upgrades since December 2021 and so far I'm very happy with the performance and reliability of this engine
Gloria, I totally agree that the LS3 is an excellent platform for tuning and adding power. From what Paul told me, the LS7 isn't a good platform for those same things due to its design and the materials used. Lyle
What I've learned from getting involved with tuning the 96 C-4 with Jets DST is GM bogs these cars down with extreme knock tables and timing retard along with torque management in the ECM. Reducing some of these extreme measures they use for EPA, driveability and protection will greatly enhance performance as long as you know what you're doing. Tuning the stock 96 C-4 coupe with one of the tuner programs for the LT-1, I used JET, completely changed and enhanced performance. Slightly more horsepower but allot more torque over stock. I can only imagine what you can do to a C-5, C-6 and C-7 just by tuning them without bolt ons.
If you want to really have fun with a C4, replace the GM Injection with a Holley Sniper or anything else, even a Holley 750 double pumper carburetor. Put in a roller cam at 1970 LT1 specifications for street driveablilty. I also put in an MSD Distributor. My son has never lost street racing my old C-4 auto cross car when I put in my 1970 LT1 with the Doug Nash 4+3. scary fun
Head’s, Cam’s E85 an a tune is good for 640 reliable WHP. Mind you the transmission! If you behave and play like a nice boy all you theoretically need is a solid clutch combination and you should be good. Now! If you’re going to be banging that stick late at night with criminal intent! I would politely suggest you throw some axels in there for good measure. And again! We still playing nice here. Now if you really want to be naughty, and play with some oxygen supplementation… consider some good gears. A stock bottom end can live its entire existence @750hp, of course this is entirely dependent you your lvl of maturity.
@@carazo321 you must be talking about a C5 or newer, because that ain’t happening with an LT1 in a C4
You know it’s the weirdest thing, just as one of my pistons melted and the engine sucked two valves, my rear tires had gone completely bald down to the steel. I tell ya they were smoking somethin fierce.
My 08 Ls7 with 11k miles had valves out of spec with play. Dont believe the BS! Get your heads done!
Agreed! I learned a lot more about the LS7 issues from a GM insider who laid out far more facts about the weak points of an otherwise awesome engine. GM has it's story, as detailed in this video, but the truth is that doing the heads is necessary and encouraged. Lyle
I have a 2006 Z06 with 101,000 miles on it. I shift at 5800-6000. The engine has so much torque that there is no reason to rev past that. (only has had oil changes--still has the factor spark plugs-new clutch at 98,000)
I'm sorry,but if putting a cold air package,or a set of headers on an engine,can bring about an engine failure,I would have to say there is a problem with that engine,and your GM friend is just covering his ass!If it can't handle those minor additions,I wouldn't trust it to last very long even i stock condition.
Precisely
Lyle, I appreciate your U tube videos & respect your knowledge but the LS7 had (has) valve guide issues through the 2013 model year...even the Z28 LS7 Camaros had ( have) this issue. Corvette Forum has many posts about the later model year LS7 cars suffering catastrophic engine issues. I own an LS7 Corvette & love the power the car has but this issue is always in the back of my head. This issue is real & it follows all model years
99 percent of people in forums are modifying/modified the car. Lyle literally said you start having issues when you modify
It's a $2-$3k job. Peace of mind goes a long way. When I bought my '08 Z06, I had it in the budget right away. It is BS that this affects only modded cars.
@@jrobles1019 And you just chose to believe the propoganda Lyle chose to believe FROM Chevrolet ??
Also...the new painting process the used in the late 80's had zero issues, the owners neglected to properly maintain the finish !
People modify with heads and cam and have zero issues. Find a shop that has done hundreds and you'll never have a problem.
Not to sure if this is true , I’ve hade a few machinist tell me that gm had the LS7 heads machined by a second party and they made the valve guids to lose , witch made the valve go side to side when the valve closed eventually beating the valves to death and eventually braking the head off the valve.
As a long term c6 z06 owner this was valuable information, thankyou
I have a 2013 427 and no issues with 30k miles. Didn’t have any issues with my previous Z06 either with 44K miles. In 2011 GM improved the valves and created more allowable tolerances for improved reliability. They learned that from the C6R race-car in 2010. Good luck.
Just leave well enough alone ! it still kicks ass !
Very informative,Don't have a LS7,LM7 here,But knowledge is King,Thank You.
The valve guide bushing bores were mismachined off center. Enough for the engine to run and run powerfully, but it wore out the valve stems prematurely causing the valve head to snap off. Remove valve guides, press new unfinished guides in and machine shop final machines the valve stem bores in spec.
the story line here from GM just doesn't jive. Its the same one we've ALL heard before. Just look at all the comments here and around the Corvette forums of 100% bone STOCK cars dropping valves. These are limited production motors, not like there is 100K of them out there on the streets. Guys that have modded and upgraded their heads are probably at LESS risk, not MORE.
I have a bone stock 2007 Z06 corvette I purchased new and the engine dropped the valves in one cylinder at 44,000 miles. The failure caused the rod to punch a hole in the block which totally ruined the engine. I purchased a new complete engine from a local chevy dealer for $10,900. dollars and another $4,500.00 to install the new engine. The corvette presently sits in my heated garage with only 500 miles on the new LS-7 engine. I am now concerned about the quality of the engine which was purchased about 2021 and therefore do not drive it. It sits along side of my new 2023 corvette stingray collecting dust. It will serve as a collector vehicle. I got no help from chevy at all.
I trust his words. This is very useful info and normally I wouldn't care about info like this but since I own a 2007 c6 it was helpful watching. On a side note, this guy is legit, if anyone happens to read this comment or watch this video and has been thinking about buying stuff from their shop I would 100% recommend it. I've bought a harmonic balancer from them and it was shipped in less than three days, these guys work fast😂. Great video!
Thank you for for the information. This gives me some peace of mind with my bone stock 2011 Z06 with 6k miles on it. The chances of a valve drop appear to be very low due to the low mileage, being bone stock, and being a later year C6.
Please talk more about the C5. Thanks!
Good luck finding one that has not been messed with.
Thank You for this teachings
I own a 2007 ZO6 with corsa intake and corsa exhaust, from original owner Installed sometime before 37000 km when I bought it. It has 55000 km now and GM said my car was not effected by the valve guide issue. Pulled the heads off myself, and they are perfect, just like GM said they would be. It doesn't make sense that GM would say some are bad, and some aren't, if that wasn't the case. So, IMHO I think if GM says yours aren't effected then they aren't. If GM says they are bad then you better get that fixed. I have never tracked my car, but I do drive it hard. I mean red line all the time, almost every time I take it out, after the oil temp is up. I think giving it too much gas at low RPM is very hard on these engines. If I do ever track it I will definitely get the oil tank with the goiter attachment since mine came without. Super fun car!!! Highly recommend!
Very well explained!
We have a fairly large LS scene here, all the go to guys say the valves have issues no matter what. That's all I really need to know. Additionally, a lot of us want to mod the car. Especially an LS7 given the appeal of making over 600 wheel, NA. Shouldn't have to worry about mods wiping a motor, when done correctly and with a tune. Just my opinion.
Right? To me it almost sounds like this motor wants to be modified to rectify the issue with the heads. Like getting good heads and a good tune would actually be better for it than leaving it stock. Like those guys with the early 6th gen Camaros that got sick of the torque converter problems and just went and got a stall put in. No more torque converter issues lol
Thanks!
Hey, Lyle. Sorry I missed you at Carlisle. I looked all over the fairgrounds and went to your vendor spot, but I never saw you. Maybe next year.
Meh. I have an LS7 making 650hp. Heads/cam, FBO, SBE LS7. Been on the same motor. No issues. I learned the hard way, hot rodding ain’t cheap. I was once young and broke and couldn’t afford to do things right. Went through motors. Now, much older, different position in life I’ve learned. Quality parts, and it’s all in the TUNE. Car is on nitrous as well. I remember going to TX2K and running my car damn near all night, still was able to drive home after 8-10 spray passes. Hot rodding can be reliable, from my experience but there’s a triangle.
Cheap, reliable, fast.
You can only choose two. If you are not going to spend the money on the right, parts, tuning, safety measures, etc. Keep it stock.
Interesting to read all the negative comments. I bought a new ‘07 ZO6, and had all the forum negatives all around me. To save myself the possible $20K to $25K expense of a destroyed engine, I went to a local Chevrolet dealer and said I wanted the heads replaced. The work was done under warranty, new heads, but the old valves, springs, etc. The engine never gave me a bit of trouble, it was not modded, and maintenance was done by the book. Unfortunately, I had to sell the car due to physical impairments.
What about valve guide concentricity? Is the GM tech unbiased?
yes, we all know the STOCK motor is unlikely to have a valve drop. the problem is NONE of us leave the LS7 stock! we're all gonna do MINIMUM intake, headers, tune. Most of us do a cam as well. So we all replace the heads so that we don't grenade the motor
I used oil analysis to detect titanium in the oil, before damage. GM warranted the repair and I saved the LS7 in my Ron Fellows Z06. I used Blackstone Laboratories. Ask them about it. Dennis
Thank you for the heads-up on Blackstone Labs, Dennis! Lyle :)
The problem with titanium valves is that they can collapse and end up dropping a valve.
It can just happen.
Actual owner data point (one data point). I own a 2011 Z06/Z07. I ordered it and bought it new. It has 16,000 miles on it. This car is a toy, most of the 16,000 are track miles. The power train is stock right down to the air filter. I have always understood the torque curve of this engine and have made a habit of shifting around 6,000 rpm for the reasons given here. The car runs great and I have no plans for changing anything on the car or my driving style. Also, sodium filled valves are not new nor are they "trick". They've been around since WWII, a lot of radial engines used them. He is right about them being a good idea.
Wow, this information is so helpful. Its getting more and more difficult to find a Corvette that is bone stock . The head issues explained is very helpful as well. Thank you so much for sharing.
BS. This engine HAS VALVE ISSUES. If you’ve never had one in your shop you must not work on them very much.
I disagree. Ive own 7 3-5th gens. 1st at 15 years old was a 85 z28 305 H.0 car. you wrong all Gm Ls dont ive been 5,8s on Gm somewhat factort vahle train. If you never own how can you call B.S.
All we have worked on for 48 years are Corvettes. We don't see a ton of C6 z06's down here, and have never seen this problem in our shop. That is why I went to GM to get answers. I knew going into this video that there would be disagreements, and I understand that there are two sides to every issue. Of the valve problems you have heard of / experienced, were they on stock (unmodified) cars? I appreciate any additional info that you can provide. Lyle
@@csvette I have a 2011 C6Z/Z07 and at 24k miles the GMPP warranty was running out. I took my car to an engine builder in Mooresville NC. He pulled the heads and found the intake valves way out of spec. Also a couple of lifers were galling the cam. The GMPP adjuster inspected the heads and approved the warranty work to replace the heads and cam. The new heads were taken apart and were machined correctly. Some of the valve seats were not concentric with the valve guide bores. He also sent the Del West valves back to DW to be recoated and polished. That is an issue most don’t know about . The valves were not polished correctly and acted like sand paper moving up and down in the valve guide. Del West cutting corners as the bid they won with was very cheap.
The trunnions were replaced with CHE and Beehive springs added. I also had the cam upgraded with a custom ground cam. Not a crazy lift (.615) just to give me a little more torque between 2600 and 7000 RPM.
I have put 8000 miles on the engine and is running great. My criteria for my engine builder was I want as bullet proof engine as possible. He build engines for a lot of dirt track cars that see 8000 to 9000 RPM for 20 to 30 minute heat races and he rebuilds them at the end of the season.
I track my car on a regular basis. I have met many C6Z guys who have had at least one engine replaced under warranty. Met one guy who was on his 3rd engine under warranty. These were un modified cars as modding them would void the warranty.
The LS7 is an awesome engine. I believe it was very poor machining on the head manufacturing company. I also believe the went too cheap on the valve guide material used. If GM had put an extra $500 to $1000 in quality parts and had tighter quality control process in place they would have had a bullet proof motor.
The C6Z is a great bang for the buck. The head issue is real as GM probably ran the numbers and replacing engines was a cheaper route than a recall to fix the problem. If you budget for the head fix you can’t go wrong. With this platform.
Lyle, I've been binge watching your channel, great work! If you know of a C5 that needs re-homed, I'm adopting.
Hi if Gm states there were a handful in 2006 that had valve issues why did they not solve the problem ? Thks
The problem was present throughout LS7 production, with no discernible pattern. That is what makes it so frustrating!
Excellent video. Good information.
Thank you for the great advice, great seeing you Friday at Carlisle.
Excellent advice...for not only an LS7, but for all performance cars.
So what valves or internals should i go with if i want to keep high reliability with the power i want to gain?
Talk to Katech Engineering. They are the best at this fix. Lyle
Thank You for Covering the LS7. Going to the GM source ‼️😁👍
So basically GM designed absolutely no headroom for modifying the LS7 (as in more airflow and fuel = more power)? Why would they build something so fragile or made of glass like that? You would think that the Corvette being a potential track car would be over engineered to be able to handle modification and abuse. Most German and Japanese cars in my experience are so over engineered you can mod them way over the factory spec and they hold together just fine as long as you run the proper oil and fuel. How disappointing as the Z06/C6 is the only newer Corvette that I like style wise and would buy.
Great info as usual! Explained very well!
Lesson here is to leave them stock!
My 2007 z06 with 25k miles, cream puff miles box stock. Had valves checked when I bought it and and over half the valves were out of spec. You have to rev engine to 7k or shifting from 4 to 5 or 5 th is a pig. I did valves lifters and spring with cam. Use moldstar90 valve guides
My stock 2008 Z06 dropped a valve on the highway @4000 rpm and cracked the block. Lost $30,000 when I sold the car. GM/Chev did nothing for my loss.
Saved 10 years to buy that corvette. What a piece of junk!
I’ve had two LS7 engines (C6 Z06 and 5th Gen Camaro Z28) and without hesitation I will admit that the LS3 engine is better than the LS7 for tuning and longevity and reliability.
LS3 is the best V8 GM has ever made in my personal opinion
A question was asked further down in the comments about the use of CIA and headers on the LS7 causing valve these items have nothing to do with valve drop. On stock LS7 engines the valve guides are not up to the task. The Ti intake valves are coated and polished at the factory. They are not polished enough and have burrs. ( Ask me how I know) they act like sandpaper on the guides and cause wear on them. The valve guide bores are not concentric with the valve seats which causes excessive wear on the valve stems. The exhaust valves are hollow sodium filled. The excessive movement can eventually cause the head of the valve to snap off and boom! When I had my heads checked at the end of my GMPP warranty at 24k miles the intakes were all out. ( burrs on the Ti valves) the exhaust were almost out. New heads approved and when they arrived at the engine builder they were out of spec. Ti valves were sent back to factory to be recoated and polished correctly. Heads were machined to fix the concentric issue. Add Ti exhaust valves and CHE trunnions. Also the cam was bad. Lifter was galling the cam. Had a custom cam with .615 lift. Not real big and new beehive springs. 10k miles on the engine and many track days as will with no issues.
Another question asked was about theHi HP LS7 create motor with a bigger cam. My question on this would be what modification has GM made to the motor to accommodate the larger cam? Have they upgraded the valve guides? Have they made sure the machine work on the heads is correct? Have they put appropriate springs for the larger cam? If they have the motor should be great out of the create.
The LS7 is an awesome engine. When on the track it’s a beast. It pulls to almost 7k. Flattens out around 6800 RPM but running it to 7k and grabbing the next gear keep the engine in the fat part of the torque curve when you let the clutch out. Nothing better than dropping the hammer and LETTING THE BIG DOG EAT!!!
Great info, as always!!! Thanks Lyle!!!
This is awesome to here. Thanks for laying this evil tail to bed. Ive always wanted one.
Great information!
Thankyou for your hard work
I got a c6 z already canned and ported heads to avoid any issues not to mention it can beat or at least run next to a c7 z. 566 to the wheels which is what c7 put out
And the answer is a c6 z is rolling the dice with out new heads.
Best corvette information center 👍👍 respects
Bronze guides, roller rockers, and methanol/water injection, you can run it leaner and meaner without the heat buildup in the cylinder head, upper block, deck mating surfaces, pulls the heat off of the exhaust valves chamber surfaces and piston crowns, and not only flushes large portion of the generated heat out of the exhaust, it consolidates the heat and exhaust gasses, puts less of a workload on the catalytic converters, letting the exhaust flow better because it has more mass per pulse, it improves the cylinder scavenging. It reduces the intake charge temperature, increases the density, and velocity, rapidly absorbs residual heat and vaporizes and enhances fuel atomization, more fuel is ignited and completely burned. Less concentrated heat in an isolated area (inner exhaust port) valve guides and stems don’t reach critically high temps, and the thermal cycling expansion and contraction are minimized, ceramic coatings on pistons cylinder head and valve faces (combustion chamber surfaces) for thermal barrier and lubrication augmentation. Roller rockers and improved valve train geometry can be achieved but that’s a lot to post.
One thing to consider is, with those tight tolerances, you should be very careful about high revs when the engine is cold. I always drove my 2008 Z06 very carefully so as to not rev above about 2500 until the oil was at temp. I owned that car from new until I got my 2019 Z06 and never had any issues.(48k miles) My 2019 changes the red line on the tachometer until it has reached a safe temp. Remember that all metals grow with heat and the engines are designed to be have correct clearances once at operating temp. They are out of tolerance when cold, so high revs will cause way more wear.
Excellent point!!!
Even stock the LS7 needs vavletrain upgraded. Failure rates are way too common. As mentioned KSTech or RPM in Delaware (uses KS Tech parts) to have the valvetrain done. Throw a cam in it for more power while in there because the cam is cheap. It's the labor that's astronomical. Many with LS7s and knowledge of these motors knows the common failure component and it's well established as failing on stock motors with as low as 10k miles. Doesn't matter if stock or modded. It's a design flaw. You can't even buy the motor from GM Direct parts anymore.
A corvette guy tells us, “they’ve never seen that before”. Please. 😂😂
I'm pretty sure that there was a valve issue that was traced to a problem with the rocker arm needle bearings that affected the VERY late build 2006's (June/06, July/06 builds) as well as 07's built between August and November of '06 (I once owned an '06). Edited to include this - and then there was the valve spring issue affecting '02 Z06's as well as a few of the early-build '03's (I once owned an '03 and had the springs replaced as a precaution measure). Seems it's always something.
I enjoyed my 2002 electron blue Z06 straight away 177 per hour tunnel vision for $55,000.00. Had 5 other vets various degrees lol. 3 C7s not impressed with Bowling Green. C6 felt kind of slippery. I probably will go back C5 when the dollar adjusts my way lol.
The needle bearing issue was not related to the valve drop issue with the LS7. It was a separate issue in 2006 and was corrected for the 2007 model year. The LS7 heads had machining issues and the valve guide bores were not concentric with the valve seat which caused wear on the valve guides. The exhaust valve was a hollow stem and was the weak point when the tolerance moved out side GM spec. Once out side the spec you we’re on borrowed time.
you must be working for gm. I bought 08 Z06 stock with 11k miles on it. Removed heads and first exhaust valve I checked had about 12 to 15 thousands play on it. My opinion is that valve guides were installed off center and that caused uneven wear.LuckilyI was able to fix heads before something bad happened.
I merely reported what Paul Koerning told me, and he is GM's lead Corvette Tech. I made a follow-up video after interviewing a former Corvette Engineer who wished to remain anonymous that details exactly what the weak points are and why the failures occur. Check out that video...I think it will make better sense than what GM told me. Lyle
Thank you so much.
Good information. My 08’ Z06 is a blast.
I have a 09 C6Z and have tracked it since I got it. A track friend had one too and while running at Sebring with NCM he dropped a valve on the back straight. His was stock. Luckily, there were GM Engineers there and jumped on the car and had new heads delivered to the local Chevy dealer the next day and all was good. My engine, after my 2nd trip to Daytona, a distinct “ticking” was heard. It was under an extended warranty so my local dealer swapped heads for me.
Great content Lyle. I always appreciate you being straight forward, to the point, matter of fact. Cut through all the Bull and hype. Please keep up the great work!!!
Blown 2 engines. One at 34.000 km what was a warranty although the Importer did everything to blame me because i did trackday's with the car. The second blew ar 84.000 and was completely destroyed and was no warranty. Then i bought Katech "street attack" engine. That one is still running great.