Camshaft Lobe Separation Angle: The Untold Truth of LSA!! How to Pick LSA the right way
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- เผยแพร่เมื่อ 29 ก.ย. 2024
- Today on Unity Motorsports Garage, We (David Vizard and myself) talk about LSA and how the major Cam companies get it wrong! We discuss the how and why of picking the right Lobe Separation Angle that is right for your typical street engine.
Make sure you check out David's new Channel @DavidVizard and give him a sub as he is having to start over and has lost 27k subs!
#chevy #ford #mopar - ยานยนต์และพาหนะ
You gentlemen say it all to well I want to thank you and Mr Vizard for actually having a channel with real knowledge I am always looking forward to everyone video from Mr Vizard great job guys
I used to work for Summit Racing back in the day and I sold a lot of David's books. I have several of my own on the shelf and I find myself referencing these each time I build an engine. Great stuff!
I just went to the Summit in Georgia yesterday and was a bit disappointed to see that the only Vizard book on the shelf was the “high-perf. sbc on a budget.” That’s one of the best of his bibliography, but they could have filled another whole section with nothing but Mr. Vizard’s material.
Don't forget to hit the "Black" bell when subscribing to get a full notification every time.
I am not racing, just want torque in town with my LS engine in the 67 C10 that fell into my driveway with a "Panoramic" rear window. Or a large rear as they call it in 68. If I need to carry 30 sheets of plywood (If I could afford it) or drywall and shut the tailgate, I can. That is a truck. Put torque where you need it. Mine is that 2k-4,5k range. The next guy wants 5-6,5k range, well better subscribe to find out. Remember, Richard Holder gets his check from "Holley" now! Lots of talk, little explanation for cam's. Well, once maybe!
DK, ASE master retired.
Greg Anderson how we do it?
@@johnshackelford6965 I can't speak for Greg Anderson but the intended use, gear ratio in the type of trans (700R4) final drive (3.08:1) and tire size 245/65R16 year round tires, work great. My wife brags she beat several people on green light challenges way over a two block area. At "WOT" she says the tires squeal and thought it was the kid in the other car, until she realized it quit when she left off the gas. I did go crazy and wired the "Body Control Module" into the pickup, so I have light control, RKE, theft, power windows (OEM brackets welded onto Escalade regulators, moving pedals, door locks auto @ 7mph, warning sounds (Adaptor that plugs into factory harness), and more. DK, Omaha.
@@MCNicholasR 12:22 12:24
I've already subscribed to DV's new channel Andy.
And I was very glad to do it.
The information is great.
Thank you Andy.
Take care, Ed.
That men Is Like Joda From Star Wars
This is why dohc engines rock. You can change lsa all you want.
Alright Dave I subbed to your 'new' channel.
Thanks!
The only thing I learned from this video is how many times can I say the word, right?
Hey I guess that's better than nothing, Right? Lol
Thanks for watching seriously
Andy
Hi I been watching ur videos for a min now, all tho I have one question for a LS 6.0 on a truck SUV wat kinda cam is recommended for this motor wat duration and LSA does 6.0 like to be in?
You are a blessed man ! To be able to work with D.V. an his knowledge is priceless
Wide and lazy......tight and crazy😁
How about wide and legal, narrow and can't get plates
@@superkillr
Why would that be? Because of emissions tests required to register a vehicle?
@@dukecraig2402 Pretty much. Alot of people forget that many hot rodders still have to get their cars smog checked. And overlap is a bad thing for that.
@@superkillr
That's kind of what I figured when I read what you wrote, we don't have that issue here in Pennsylvania except for a few specific counties but I'm aware that states like Ohio require emissions tests every time that a vehicle changes hands and for other reasons.
@@superkillr luckily, in Ohio, most counties don't have that smog compliance stuff (is called E-Check here).
But, in the counties that do the eCheck, you just get a commercial plate or you provide a receipt showing you've spent $300+ to try and adjust your engine to be compliant and they give you an exemption.
Our eChecks only go back 20yrs though. So any vehicle 21yrs old or older aren't required to get checked.
Isn't crazy how all you have to do is spend a little money, and all of a sudden it seems like your pollution doesn't matter!? It makes me feel that it's all much more about money than it is actually protecting the environment.
Glad to see someone is pushing torque instead of just speaking max HP numbers. I developed a theory that since HP is torque x RPM / by 5252 then the entirety of HP depends on the measured values and a constant when it comes to a rotating shaft. There are 3 ways to increase HP and they all include torque. 1. Increase torque in a given RPM range. 2. Increase RPM while maintaining or not allowing the torque to fall off faster than the RPM increase or 3. Increase torque and rpm. Which method is used depends on a lot of different other parameters. A drag race is different than a road race that is different than stock car and offshore boat racing different from these other types of race. A 600 HP diesel or an 160 HP air plane engine at 2300 RPM are much different than a 600 HP small block running at 6500 RPM but they all depend on a measured torque number for the horse power number. Torque has no dependency on a HP number.
Engine masters and you busting out facts about cam shafts this week. This was a really good week.
Thanks for Watching! Im glad you enjoyed it
Andy
Was wondering why i hadn't seen new content on DV's channel in a couple weeks.... David's knowledge is a national treasure! Always puts out well rounded informational videos! Subbed his new one and looking forward to more content from both of you guys! (Andy - constantly referring to your tuning videos. GREAT stuff) LSA is something you need to tune so that your Dynamic Compression is correct for your build too. Learned about this many years ago when i set out to really learn cams and how they work. Nobody ever talks about Dynamic Compression and how important of a factor it is.
Dynamic compression is why I stopped using calculated CR years ago when it became 'meaningless'
On motorcycles, 102-103 LSA is quite common and stock motors run at about 175psi with redline anywhere from 9,500 to 13,500 rpm ( older bikes from 1970's to 1990's )
As long as I get around 210 to 220 psi I know things will be 'fine'.
The 'calculated CR' often works out between 14 or 17:1.
Suzuki actually stated CR on early RMZ250 was 17:1 but dynamic CR is much lower with under 200psi cranking.
Yes, your lobe separation angle determines your dynamic compression and the 'manners' of the engine.
Thank you sirs for a very informative video.
Sort of, indirectly …
Your intake valve closing point determines your DCR. LSA only effects this because a wider vs narrower LSA (given all specs being the same) can move the the Intake lobe centerline and therefore the closing point of the intake valve.
Vizard the wizard, the 'god' of engine development. Still got my 1981 Vizard spec Oselli built 1400cc classic Mini, recently rebuilt it, still goes like stink, too fast for me these days. Thank you David.🙏
Great discussion!
The LSA affects many aspects of performance. It can change the volumetric efficiency peak point/peak torque point. The optimal LSA is subject to the limitations/capabilities (RPM) of the engine components. I feel the bore to stroke ratio has an impact on optimal LSA/overlap.
Most of my race engines are in the 106° to 108° LSA range.
Street engines are completely different, LS engines have a wide LSA and reasons they have a broader power band. . Don't know why u would want a tight LSA. Id say 112/116 is better for street engines.
@@jessesyfie7244 Well, some people(like me) run a 5000 rpm converter on the street in a 2450 lb car with a 500+ hp small displacement(332) engine running 108 LSA. I shift it at 8500 when racing. So I don't care what the engine does under 3500, because at full throttle, it doesn't ever load that low. With a very lightweight car and a slippery converter, it works out nicely. My car is a handful when I put it to the floor, but at partial throttle, it's a very smooth, nice driving street cruiser. You can actually see it cruising along in one of my vids. Terrible fuel mileage is the only downside. lol
@@AmericanThunderwow 8500 is high. What is the engine and how can you go so high?
@@jamesmedina2062 It's a 332 cubic inch 302, bored to 4.030 and stroked to 3.25. A 4340 steel crankshaft, 5.5" H-beam rods,(giving a r/s ratio of 1.69) JE ultralight pistons and an induction system that can flow enough air to let it breathe up there.
Richard Holdener did an LSA video where only the LSA was change. 112 VS 120 LSA gave 34 ft-lb 108 vs 112 LSA gave 14 ft-lb. The peak power of the 112 was close to the 120LSA and the peak power of the 108LSA was almost 10 more rwhp than the 112LSA. LSA doesn't favor emissions, but a tighter LSA will makemore midrange torque but possibly less emissions than a wider LSA.@@jessesyfie7244
Opening and closing #'s are all that matter, lsa and Icl are just products of that , anecdotal results don't count, no real pro level builders are picking cams by lsa..
And they are wrong.. LSA dictates how much torque the engine will make and the overlap determines where it makes that peak torque.. while most "professional" built pump gas engine builds average 1.25 lbft per cube if they are really good they will get in the 1.30lbft per cube and we get in the 1.39-1.42 range
Thanks for watching
Andy
@@UnityMotorSportsGarage when you change the Lsa, what changes? ... opening and closing #s, , when you change lsa and it makes more power the events were the issue, If you understood cylinder filling, overlap, blow down ect, you would understand more easily, but many fall into the trap, and it's seem good when you don't really understand valve events. Keep studying,
@@UnityMotorSportsGarageLSA is not the determining factor on torque output. Kindve a circular comment imo.
Overlap controls where it makes peak torque? Big no-no there. I thought it had to do with the intake runner cross-section and it mah or may not, but I can bunk easily it isn't do to overlap or anything to do with a camshaft at all through an LS6 manifold, stock head LS1. You can run any off the shelf 0 degree to 25 degree overlap cam you want and you'll always end up with a 4800rpm torque peak through typical longtubes and exhaust. They'll cap at 6400rpm for horsepower too at a 46 degree ivc @.050" any larger and they just continue to hold power past peak in either case. But those peaks don't rise outside of a 1 in 100 deal that may read 100rpm higher on either one.
Wow, into this video a couple minutes and several points of misinformation.
Basically the opposite of what Billy Godbold says.
Before you go on about dyno testing, Comp cams has a better instrumented dyno than Crane ever dreamed of.
Two of the best experts I have ever seen in my 68 years of loving engines,!!!!!!
Thank you for the kind words. I'm no expert just an avid enthusiast! DV is truly the expert
Andy
There's no doubt that DV is a legend, but he also spends 80% of the time talking about his reputation (and I think I'm being generous with that percentage). I'm sold on his work, but it's downright painful to listen to him. He really needs someone to condense the information down into a listenable format.
I have a 1985 1 ton 4 speed dodge truck with a stock 360 engine. I want more power for moving heavy weight. How should I build it? Which camshaft, heads, intake, and carburetor should I use?
Good information, Andy and David! Sorry for your loss as well. Looking forward to more Unity and DV content!
Thanks Brother!
I had been wondering what was going on with DV and TH-cam. Subbed to your new channel David and looking forward to your new videos.
Many people, including engine builders, don't realise there is a science to engine design and that through R&D and many many many hours of testing engines can be built to be more efficient and create more usable power. One of the reasons I subscribed UMG and DVs channels because I know the testing and scientific process has been worked through. Keep up the good work.
The link did not appear on my screen. What's the new channel called?
@@jeffrykopis5468 th-cam.com/users/DavidVizard
Hey how much does a mixed up boss engine cost? it looks totally rad dude!
I have slightly over 14k involved in the build but I did some trading...
Thanks for watching
Andy
The fact that the following variables influence the ideal LSA, and that your 128 formula does not take them as input, is all one needs to know to understand that the 128 formula is not comprehensive.
Throttle size
Intake manifold
Port flow maps
Chamber flow trajectory
Intended RPM range
Valvetrain stiffness
Valvetrain mass
Valve acceleration
Header diameter, steps, collector dimensions
Exhaust system
Drivability requirements
Emissions requirements
Marty from Western Australia.
Was just about to do my 1st cam swap on my 6L Caprice when I come across this clip. Thought I knew what I wanted, and now to what you have educated me on I'm back to the drawing boards. Thankyou for being informative and in language most can understand.
Liking and subscribing to both of yous 👌💪
Thanks for the kind words and the sub as well!
Andy
Dont get lost in this too much I did 3 months research before I chose my LS1cam what cam are you looking at if you use a vcm or crow cam they will recommend the right one for your mods but i researched and chose my own. went with a Crow Cams 229/235 on a 112 lobe sep works awesome in my LS1. Mine makes 590NM torque my cam in a 6L makes 750NM according to a dyno video ive seen.
Variable valve timing changed the game completely you get the best of both ends tight on the top and wide at the bottom for smooth idle we could only dream of such a thing back in the day when the rev limiter was our foot and ears lol
You only get that with DOHC though. Something like a Hemi or LS or Viper with VVT is stuck with a fixed LSA. But being able to change the lobe centerline angle is still a big deal.
The ultimate is something like Honda DOHC i-VTEC, where you get to phase the intake and exhaust around independently AND have two different lobe profiles to play with. It's a big part of the reason why "lesser" 4-cylinders can't touch the might K-series. Even a stock K20 has a VTEC cam bigger than anything you can buy that's streetable on a Ford Duratec, even with VVT. They were running full pro-stock durations right off the dealership floor, still idling like a Mercedes and getting 35 mpg.
great video, awesome to see you both together. I took DVs comments on LSA to heart and applied it to my sbc and it is great, thanks for the knowledge. I still come across those who think that a tight LSA is for high rpm racing only, but I politely point out this knowledge to them and try to get them to see the light. if not they can look at my tail "lights"
Personally I blame squirrels
Give squirrels a chance.
@@hangonsnoop there actually tasty little critters!
They've F'd up a lot of shit.
@@hangonsnoop lol 😂
👀 🐿
Ha, and heres me thinking L S A stood for Lobe Separation Anxiety.
Great video as usual Andy! So sorry for your loss David. I've already subbed to the new channel. Thanks for everything you both do!
I'm glad you enjoyed it.. I will have a video coming up talking more in detail how to use the 128 formula to pick cams
Andy
Thank you very much for this video, and a companion to it by David Vizard: among other things it validated a cam selection I made for the street for a Buick small block I'm building. According to the formula you and D.V. put forth, my particular engine needed a 107.5 LSA. The cam I'd selected was a Howard's SBB grind with a 108 LSA and a half inch lift at the valve. I'd been catching some flack for my pick of cams by some Buick experts, but I now feel I made the correct choice. More interesting, I have a fairly sophisticated Comp Cams software program which predicts my build will top out at 408 HP @ 5000 rpm, and 400 lbs of torque or more from 2000 to 5000 rpms on 9.6 comp ratio / 87 octane gas. I've run the numbers on the TA Performance (the Buick Guru) high dollar software and it predicts the exact same thing, 408 hp @ 5000, and the same 400 lbs torque from 2000-5000 rpms. My build criteria was, street use only, "a million pounds of torque" from 2000-5000 rpms, 5000-5500 rpm rev limit, and 87 octane gas. With the cam I chose, as validated by your LSA calculations, I feel more and more confident that my build will work out per my plans, when completed. P.S, I snuck in a stroker crank, aftermarket forged pistons and ported aftermarket aluminum heads to help out the power output.
So glad I saw this, and found out where DV went. Subbing to his new channel now. And keep up the great work. I'm earnestly working on relating all this info into the LS platform.
You guys are the Best. Always very good information. I have Davids books and the videos really help clear up any of my questions. Hey Andy, when is Mixed Up Boss hitting the track in Casper?
Thanks for watching, as soon as I get it back from the header builder I hope to make it to the track soon!
Andy
Awesome video! I really enjoy this kind of tech content. Is there a way to calculate piston to valve clearance change with LSA change? I’m not a rocket surgeon so hopefully the math is easy.
That is a good question. But it really depends on the duration of the lobes.. a 220 deg on a 108 LSA will have more clearance than say a 230 deg lobe on a 108 LSA
I know that isn't a clear cut answer but with most aftermarket pistons you will have valve notches that will accept "most" cams
Andy
If I am building a roller motor, should the LSA be increased? Am I thinking in the right direction?
roller, doesnt effect the LSA requirement of the engine.
Andy
So..
If I buy horsepower, I'm _NOT_ buying farm animals?
DV needs to put out a "Big Whomp all at Once" package deal of all his videos and all his books, and all his software. This will free people up to dig, dig, dig for years to learn more!
So where do I get a cam recommendation from one of you?
so with BBC boat motors the conventional thinking is you need at least 114 LSA in order to avoid water reversion into the exhaust ports which otherwise would quench harden the exhaust valves and then snap - I have blown up two motors thinking it was valve guide clearance or some kind of after market head ( dart) manufacturing defect resulting in poor cooling on the exhaust guides - I am now a believer .. 114 is at least what is needed on BBC boat motors
Get to the point already
Usually when you look in cam listings . When the lift goes up so does the duration. I run a 108 lobe separation on my 540 engine and it works great. 262 272 at .050 299 310 advertised duration. What I've learned if you run nitrous or forced inducton you want to stay with a wide lobe separation. I switch to e 85 and my car is flying went from 6.00 to 5.90 in eight mile 2700 lbs car shift at 6200
Damn I love videos like this man you my type of man. I'm a Ford guy but love Mopar engines such as the Hemi and Magnum engines but I wanna 351w/408w stroker swap my 92 single cab short bed Dakota Sport V6 Magnum Ax15 and also wanna go with a Tremec 5 speed and a Hurst Pistol grip or short throw shifter
Okay, but now that we know the problem how do figure out the LSA we need for our particular engine. I’m in the middle of rebuilding my 351W for my wife’s street rod and I ordered a Howard’s cam, won’t ship til January, I still have time to cancel or change. I subbed the new channel DV.
thanks david ! a shop i know used your info to build a mini stock pinto engine ! they DOMINATED the local track for 4 years in a row ! ALL-PRO was the name of the shop ike moore owner the track even changed rules to try to stop the winning spree yet the WINS still came in every week thank you for the years of work david n
In pure stock circle track we had a lift rule. I had isky custom grind my cam and went several degrees tighter LSA only with 248 @ .050 with spec .424 lift besides lsa it was same cam everyone was running. All other specs the same. That woke up our lap times.
i dont know how long you have been building engines or if you are close to my age, but i have been building engines for 42 years ,im am a cam fanatic, i buy cams with spacific lobe patterns , im not you average 3/4 RACE CAM idiot , i under stand cam specs , i have a question for you you, probably havent heard on here ,back in the 80s most cams were 106 or 108 lobe separation as after market purchases, anything more 112 - 114 ,were considered blower or nitrous cams , what caused the change, now nothing comes 106 or 108. i remember you would open summit or jegs catalog and most aftermarket cams listed were 106 0r 108 lobe separation ,open the same catalogs today and all but 1 or 2 cams listed are 112 or 114 , something changed along the way, what did cam companys figure out they didnt know in the 80s, please tell me if you know.
One word Marketing.. back then people would always pick a cam too large for the application and the cam companies had tons of complaints because of this.. Cam companies knowing people would continue to pick larger cams they decided to widen the lobe separation to make the car more drivable they are in the business of selling cams.. not making sure what you buy is right for your combo...
@@UnityMotorSportsGarage
Having played with a lot of DOHC motors the LSA is more related to making it work with the exhaust system than anything else. It's a LOT easier to move the cams relative to one another than shorten or lengthen the header primary. Relative to compression it's where the intake closes that's most important...tighter LSA (assuming 'straight up' installation) closes the intake sooner and will trap more of the charge at low rpm and this tends to help power if you're not in an octane sensitive situation. If you leave the intake CL the same...then altering the LSA is just moving the overlap and how the engine likes it depends on the exhaust system which often is 'make it fit' rather than 'this is ideal' type of affair. Lots of variables to consider and just remember that the engine is a TEAM effort and everyone must play well with one another for best results.
Well said
There's much more to it on a single cam engine. LSA cannot be changed without affecting other lobe parameters. That's why VVT on newer engines, that no one seems to like, is so important. Wide LSA is also more important in forced induction applications as it is not prone to blow your boost out of the exhaust.
Hi guys thanks for your knowledge. Im currently running 230/236 112 on 355ci running 9psi with 2.4l whipple putting out 670hp /635ftlb @ 6200 but intake temps are up a bit would the cam specs affect this at all?
Definitely not. You either lower the pump via maybe different speed or try to cool the charge a bit. Retarded timing and high octane would be your friends if all stays the same.
Well I wouldn't say it's an untold truth, it was told by David in his books years ago, which I have benefitted from greatly over the years. Thank You David!
You are right! Just untold here on TH-cam... 😆
Andy
Cam companies can't spec a cam for everyone, there's too many variables. All considering, they do a pretty good job.
Yes, they're giving a generalization that will give the average guy a power increase. NO way to guess and give THE MOST power increase.... That requires dyno runs to time the cam.
Some time ago I built a spreadsheet to calc ideal cam events based on everything I could find that DV had written, included the 128 rule and LSA info. It spits out numbers just as Andy described and takes out most of the guesswork;)
Thanks DV, I have read most of your publications.
I'm working on a similar spreadsheet, but how do you tell the intake centerline angle (or how to install the camshaft relative to the crank?)
Also, I can't find much info on his rule of thumb for exhaust duration - what do you use?
Intake center line = small # subtracted from large # +90=In.CL. Same with the exhaust.
Andy you and DV make a great team!! Bless you both for sharing your knowledge and talents!! I have learned so much in such a short time regarding cams and heads I can’t thank you enough. I know you’re primarily a Ford guy and David is a Chevy guy but here is a Pontiac question. Using DV’s 128 rule the calculation comes out to 103. Working with what I have to build a basically stock 455 engine for the drag strip using race fuel. I have 2 sets stock heads, one with 72 cc chamber and 1.96” int valve and a 101 cc chamber and 2.11” intake. Oddly enough published flow numbers show the small chamber head has better flow numbers (unported). Porting the 2.11” valve head has more flow potential but I’m no expert and pocket porting without a flow bench is the best I can do and I can’t have the head cut enough to get above 10.5:1 CR without using a dome piston. The 72 cc head will be 11.7:1 CR with the flat top pistons I have. All that to ask this. Will it be better to use the small chamber head or buy domed pistons and use the large chamber head? The weak link is the connecting rod so RPM is the limiting factor until I can afford to build a stroker. Then the calculations will be different. All advice is welcome and Thanks again!!
I swear cam companies just want to sell "chop" now. That seems the only thing important to most buyers. haha...........
You're definitely right man it's because of people who don't know anything about engines and they just watch TH-cam videos with a choppy idle and all they want is that same sound, lmfao
I'm so glad to see mr. Vizard, I was Soo worried something may happened to him, or he gave up on you tube, I haven't been notified of any videos in a while!
Cam companies can't dyno test every combination for every manufacturer, that's ridicules.
Right now he's talking cam grinds.
There's more pieces to this pie. DV has emphasized that repeatedly.
I've always been David's biggest fan since around 1990. I've used his calculations on cam selection with fantastic results!
Along with your hat and decal, Andy, David needs a line of decals and hats also. Something like "Vizard the Wizard" (I've seen that one before) or "Torque Master", LOL. Anyways, keep the great movies going.
I feel the topic, as it’s discussed, is relegated to racing, 2WD, etc. I’ve got a 4300 lb 1980 manual bronco with a 10:1 aluminum headed 331 sbf, 35” tires, 3.73 LSD front/back, granny top loader dual plane w/ 1” open spacer roller cam 266/274 112 LSA, runs really good, 15mpg, 15” vacuum at idle, this was my first build and I feel it was mild and I aimed for mid range.
Great video.
PLEASE ask Billy Godbold from Comp Cams to explain why almost all the street-strip cams they spec for domestic V8s are 110 LSA. Billy is no dummie. So I expect a really good response, My guess is that they know people will go to the bottom of the catalog page and go for too much duration, and they are trying to keep them from complaining that they don't have enough idle vacuum or low end torque.
I can't put words in Billy's mouth, but I can say in our testing we have learned that LSA dictates the amount of Torque the engine will make and that the overlap determines where it will make that torque!
Thanks for watching
Andy
Thank you Andy and David. David, I did not know you had brain surgery but I am grateful you came out of it with your mind and knowledge intact. Back in the early eighties I purchased your "Performance With Economy" and I still find it useful when advising young builders in things like why their favourite drag racer has a cam that will be a mongrel on the street. I can't remember if you said it but I read somewhere that it will be hard to explain to your girlfriend's father why you need to rev your pride and joy to 3500 plus just to take off from their driveway late at night. I have subscribed to your new channel and look forward to listening to your vast wisdom. Am I a fanboy of your work, "bloody oath". I consider you a teacher that could stand together with such greats as Prof. Julius Sumner Miller, Carl Sagan, and Neil DeGrasse Tyson, just to name a few. Good luck with your new channel.
Terry from Australia.
I really needed to hear this information because I have been fed so much bullshit and spent so much unnecessary money building my small block Chev myself.
Thank you so much I have subscribed to both
Andy, Mr. Vizard, a few questions. Is it more important to have a specific LSA, or to have a specific lobe with a desired lift /duration. I ask because of this: if I choose a lobe with the lift/duration I feel will work best, then with a given LSA, the overlap will be let's say 40 degrees. If I desire 40 degrees overlap, but now specify a cam with a smaller LSA, the cam lobes will generate a larger overlap period. Do I then re-choose a lobe with a smaller lift/duration to match the recommended LSA to simultaneously achieve my desired overlap period? Is it correct to say the optimum overlap period is the central thing you are trying to achieve? If that is true, then I should first choose the lobe with the lift /duration that I desire first, then pick the LSA that will give the desired overlap period as a result, correct? They are inter-related from what I can see.
Or are you saying that most peoples cam selections have less overlap than they really need, so decreasing LSA is the best way to increase the overlap? The same thing can be accomplished with a larger duration lobe if the only change that is needed is an increase in overlap, correct? Otherwise, if the LSA is what dictates the best performance, then one may need to increase or decrease their lobe lift/duration to accommodate the LSA within the confines of the desired overlap period, true?
I look forward to subscribing to Mr. Vizard's new channel. Thank you once again for your shared knowledge, both of you. God Bless!
This is interesting. The first engine I built was a 289 for my 67 Mustang back in high school.
Given my minimum wage of $2.90 an hour, you could say it was a “budget build”.
Fortunately, we had a great auto shop at school and a good community of Ford guys.
So:
Started life as a 225 hp 4bbl 289.
Build:
10:1 flat tops
Stock heads with 3 angle valve job and heavy springs (don’t remember the specs).
Full length headers
Torker-II
780 Holley
Cam was a Sig Erson High Flow 2.
Everything on top of the short block and heads was scrounged, and bought used.
That engine ran like a graped ape!!! The car had a 4 spd and 3.91 gears. Won class at the local 8th mile most Saturday nights.
No one, including myself, understood why that miss-match of used parts ran so well.
It wasn’t till years later that I looked up the specs of that cam. Yup, 108deg LSA.
I just stumbled onto a good match if used parts, starting with that cam!
Obviously we should all be running 102 lsa
maybe even 99... we want all the sauce even if it's pouring gasoline out the exhaust.
This is one of the advantages of VVT DOHC engines. They can effectively vary the LSA with rpm just as they can vary the cam advance/retard.
🥝✔️alve Events. That's what y'all talking about. Drag Boss Garage did a live with Mark C, and he said the very same thing. Your name was mentioned, David. 😁👍
In my experience wider Lsa's make engines easier to tune by the average person. Also in my experience, a more efficient (ls/lt) engine is less sensitive to lsa. A little secret from pro stock back a few years: super wide Lsa's.
Bs !!! So you got the same dynamics going on as a 16 to 1 , 500 cu in engine needing to be fed to12,000 rpm huh ?? Youre Dreamin dude !!! Those Pro Stock cams measure their lift with a yard stick and duration with a sun dial compared to anything youve touched . They operate so far beyond peak torque that it dont matter either . Clown on a keyboard !!! Good luck with your theories LMAO !!!
As far as I'm concerned David Vizard has no need to defend the validity of his information. If you know engines then you know that DVs expertise stands on its own merit.
My brother recently had a 383 Chevy built with a mutha thumper cam cause it sounded cool. Doesn’t make enough vacuum to operate the brakes. Told him it was the wrong cam for his type of driving. Fell on deaf ears
He's talking maximum torque and HP.... Not vacuum.
@@hotrodray6802 understood
How's the off throttle response and general "nut" of the engine? Does it take a bit to wind up and "come on the cam"... that sounds dirty.
@@superkillr haven’t heard it run. They only drove a short distance because it had no brakes. It’s a 55 Chevy still under construction
@@superkillr also has a sniper on it
I subscribed to Sir, David Visards new channel. I really like your content and his. BTW, did DV ever get the Small block Ford book out for purchase ? Thanks Andy.
Are you in Charlotte NC? If you are I'm about 30 minutes from you.
Shane we are in Mt. Holly just west of Charlotte! Small world
Andy
Big into 4.6 mod motors ?? Ya shoulda known better !!!!!!!
It's a sickness... 😆
That's so True, when You do the math it shows. I really didn't understand too much about the Love Separation Angle. Now I do and just wanted to Thank Y'all for taking the time to make this video as it's going to help in the Very Near Future with an Engine Build.
good information, I waa thinking about changing my cam on my 318 bored 30 over headers,2-1/2 exhaust, crosswinds high rise rpm...9.3 compression...391 sure grip 2200-2600 stall....what do you think about changing from a 340 cam 429/444 114 lsa to a comp thumper cam 473/486...107 lsa.?..i have small chamber heads. 750 quick fuel..69 satty. .901-16 valve springs..looking for max torque...
Hi Andy! I really like the way you explain how things work. A big thank you for sharing David Vizards new channel. I was getting worried since he hadn’t any new videos on his old TH-cam channel in a long time. I am glad to see that DV made an appearance on your fine channel!
Thank you Frank! That means a lot to me.. I can say I've been trained by the best!
Andy
Every time I go down the camshaft science rabbit hole, it makes me want to sell every car and go back to 2-strokes. Think about what a reed-valve intake does. Timing? Duration? Automatically does whatever the engine wants at that RPM and throttle opening. You want overlap? How about 110 degrees of overlap, with the exhaust port pulling negative-8 PSI of suction all the way to the air filter, pulling a whole cylinder displacement of charge into the exhaust, and then the pipe reverbs to positive-8 PSI to supercharge that fuel back into the cylinder. Imagine being able to draw any combustion chamber shape you want, with no valves or reliefs or anything besides a spark plug. Imagine no valvetrain at all to worry about floating or sticking or timing. You can't make less than 2 hp per cubic inch unless you're trying to sabotage the motor. Yeah, I'm still salty that cars use these clattering things with these hokey valves and cams and chains and pushrods and stuff.
Great video Andy. Thanks for helping DV out with his channel. I subscribed to it several days ago, and have watched every video. For those of you reading the comments, David covers this subject in depth in his How to Build Horsepower book. I have no doubt that he also wrote about it in some of his other books. If you haven't read any of his books, I suggest that you do yourself a favour, and buy some of them. Regards Greg
Thanks for telling where this formula exists. The formula that's been stated before is by description of a cam optimised for a small block Chevy. I have something very different ... Datsun A Series 1400cc for road racing with some significant restrictions in the rules (valve size restrictions for example). Current cam does pretty well but I'm sure I'm leaving something on the table. I'm buying the book!
@@markmeller4996 yes. DV's 128 formula. The How to Build Horsepower book includes adjustments for compression ratio, canted valves, and other variables. It also talks about overlap, duration, and other cam features.
Thanks guys, good overview. As long as you are talking street cars, by all means Andy you are right. As soon as you go to the boat world, things get different. It's mostly about exhaust over there. If you are running dry headers your car recommendations work fine. But, if you are running wet exhaust, you start to get into reversion issues (where you can get water into the cylinder). And since most lakes are discouraging dry exhaust, if not banning it altogether, LSA becomes a tool to try to help with reversion.
So the logical extension of this video is not only LSA, but cam install and what intake center line to use with what LSA to get a desired result ...
Hi Broc Luno! I am glad to see that you have posted on YTUBE! I should have consulted with you about cams for marine engines. Hope to see you on BITOG sometime soon. All the best.
I had a temperature over 107, possibly over 108,, I can't remember things either after that, I can even forget words in the middle of saying it, and what I'm even talking about, I have gotten better over the years, I'm lucky to still be here,
David's 128 formula does not consider compression, so how is compression ratio (10.5:1, 400 sb) factored in using the 128 formula to get max torque at lowest rpm?
Are ypu suggesting a 106 lsa gives max/optimal torque??
I want torque as low as possible for a rock crawling 4x4.
I use EngMod4T to model engines and I move opening and closing events around in order to start to close in camshafts(16v inline fours) as I find this gives me much more appreciation for how different timings alter power and curves, which directly leads to "why?" Given simulated traces of an accurately modeled engine you learn more in a few months of simulations than you could in years of dyno testing. The engines I develop tend to be roughly 4 hp/ci, so lie outside of your intended audience, but I'll be following along 😃
Are you using a current engine as a base?
OMG. I've had my 2014 Chevy Camaro SS 6speed manual for over 3yrs and don't know what cam specs to use. Any help with the number spec would help great fully? Thanks
I contacted camotion about a turbo 414w sbf. They specs they sent me for the cam they wanted to make were bazar. First off the lsa was 115 degrees. No damn way. It's also lower on lift than I would like. Duration is reasonable but a little on the short side. I'll be calling them after Thanksgiving to ask where they got those numbers.
Since most do sbc will.this work for ford 300/6 daily driver not going to race it? Any help is greatly appreciated
Mr. V, you're my small block hero. So sorry to hear about Marvin, I know he meant a lot to you.
Very useful information and formulas! I used the two formulas to calculate the LSA for an AMC 401 and 304, assuming the same set of heads would be used (2.025 intake valves) If I used the formulas correctly, with all variables being the same except for CID, then LSA is inversely impacted by CID. For the 401 I came up with an LSA of 100.82, so 101 and for the 304 it was 107.235, so 107. Does that seem correct?
Half the intake duration plus half the exhaust duration divided by two equals LSA. So this also makes sense why the longer the duration added to push the powerband higher i to the RPM range, will usually have a wider LSA. but for an N/A engine, mechanically advance the camshaft so the intake center line is advanced by 2 degrees, and transversely the exhaust retards 2 degrees. * if that makes sense. Example
110* LsA camshaft with a 108 intake center line and 112 exhaust center line. Means having the preferred overlap but opening the intake sooner and holding the exhaust valve open to scavenge more gases. I hardly hear of this point in LSA camshaft talk
Won every race with a 4.6?? Were there only 4.6's in that class?
No, We we're competing against some of the best engine builders in the country.. it was a small block were limited to a 420" limit and BB limit was 470" combos under 331" we're allowed to run a .065 nitrous jet which is about 150hp
Andy
@@UnityMotorSportsGarage aaahhhh....makes more sense that you were allowed to run a power adder. But it's gonna take more than that or the competition was just terrible. A huge weight break or something. 4.6's are horrible.
So you say...th-cam.com/users/shortsItnea7kREpE?feature=share
@@UnityMotorSportsGarage you coulda built virtually any other v8/car with the same effort and only went faster
I'll try to be quick with my question: hypothetical motor, 1.94 intake valve, 350 Cid, 11 to 1 compression. I intend to use a 107 lsa, based on vizard formula, maybe 108. Question: should I try to keep the intake centerline around the 107-108 as well, or is it OK to advance the cam, based on overall duration, trying to keep dynamic compression around 8.3 to 1? Debating between running a smaller cam at 0 degrees, vs a larger cam at 4 degrees advance.
,,,.,Thanks Andy.....That diagram you put up at 5:04 vid-time shows it all.......As a kid when I first saw that diagram in my Isky cam handbook my mind said WTF,,,,,,,looked complicated .......For me , memorizing camshaft events and piston position started my camshaft education....e. g. , INT. opens BTDC on the exhaust stroke , the EXH. closes ATDC on the intake stroke , the INT. closes ABDC on the compression stroke , and the EXH. opens BBDC on the power stroke ..........Thanks again for your work....
Nicely done. I can't touch your experience, but I do note one thing that makes sense for a running engine: filling a cylinder begins with exhaust events, therfore LSA is a component of intake opening where good signal at the moment of opening intake is the focus. Managing pulse flow through an engine system functions like a tuning fork in a way: the center frequency shows up as peak torque rpm, and as you note the right [street] build increases power everywhere. As I see things, chamber volume and valve curtain area behave like an accumulator, except it dampens a negative signal instead of a positive one [as a hydraulic one would] - this does affect how cam timing is seen by the intake during the crossover event. As a simple comparison, would anyone pay attention to the volume inside a gas shock absorber relative to vehicle weight? You betcha.
Thanks for the channel update info.
Thanks to Reed Cams... I learned all of this many many years ago... Too bad the company went out of business years ago.. Valve springs are even more important, due to valve train harmonics..
It’s awesome to see you 2 guys enthusiastic about this! Marlins passing is a shock! He was just on DV’s video 2 months or so ago!!
It was a shock to both of us. Thanks for watching
Andy
@@UnityMotorSportsGarage your welcome Andy bud!! Looking forward to seeing the next video! As I’ve just bought a 72 Ford LTD. with the 400 motor! I’ve bought one of DV’s books on porting to help me!
Great video on that part of cam selection process! Running a 112 on my 427 Windsor 4.125 bore/4.00 stroke 10.3 comp. 2.08 valve and mostly street use. Close? Runs good ! How did the OEM's figure their cam specs for the various muscle car engines back in the 60's?
you make a good point, we never get to see how they decide their cam profiles, what we do know is the aftermarket has beat the factory cam specs pretty much all the time since high performance started being a thing.
Drivability. Power brakes. Decent idle. Gas mileage. Smog. Etc.
Building a daily driver sbc 400,.040over afr 195cc heads 2.08s 8.5 /1 comp w twin turboz... I hit the guys n Cali, that DV mentioned, on their site no word... I need a good cam number man.can go up to .060 w springs, rev limiter at 6500. Hogan's tpi. Stick shift.
Pleeeeeeeez ⁉️⁉️⁉️⁉️⁉️⁉️⁉️⁉️🔧🙏😁
Lots of years in the trade speaking in this vid.
But when the first thing that comes out of ones mouth is boasting about credibility, you know they are convincing you because of qualifications, not because they found thw actual truth.... Case in point, higher compression doesn't mean wider lsa for optimum results, and there's no single lsa that's best for an engine's intended use. If you go from 8:1 comp to 9.5:1 with a 200° cam, the same lsa has the same effect. But if you go to 13:1, then you need a wider lsa, and a later IO event. But a 270° cam will still respond to 13:1, and a tighter lsa.
There is no set figures in engine design. It's all about understanding the principles and what has what effect, with the materials supplied. Dyno time only gives 30% of the story, not all of it.
I have read that fuel injected engines like more LSA, is there any truth to this?
People tend to use wider LSA as a bandaid to cover up the fact they have too much duration. It's better to have less duration on the right LSA the engine will make more power through the entire curve.
Andy
@@UnityMotorSportsGarage why? Because it decreases overlap and idles smoother?
if your into ford engines why not run the twin cam 4 valve engine, put adjustable cam gears on it and play with the lsa on the dyno.
I was just watching this video again but I’m looking for information on the new hemi. With the cam to lifter angle being so flat who does this affect LSA? I’m seeing 116 LSA and 119 center line. Good or bad?
Very interesting ! I have been aware of David's work for over 20 years. I am now subscribed to his new channel. ( and yours) . Many thanks.
Thanks Bob! That means a lot to both of us... Hopefully you will like the next video its a part 2 to this one...
Andy
It looks like DV uses the 127, SBF formula and states lobe centerline and you state it’s for Lobe separation angle, what am I missing here?