PORT VOLUME-IS BIGGER BETTER OR IS LARGER LESS?
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- เผยแพร่เมื่อ 22 ก.ค. 2024
- DO BIG PORTS LOSE LOW-SPEED POWER? 3 MOTORS-FULL RESULTS. CHECK OUT THIS VIDEO WHERE WE COMPARED THE EFFECT OF PORT VOLUME ON POWER PRODUCTION? WE COMPARED THREE SETS OF CYLINDER HEADS WITH DIFFERENT PORT VOLUMES ON A 306 FORD AND A 363 FORD, THEN 2 PORT VOLUMES ON A 372 CHEVY. IS LARGER LESS OR IS BIGGER BETTER?
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Richard this channel is WAY better than reading threw magazine article ,then comparing notes .looking up others opinions.you do it spot on .all the "what ifs" and "idk s" are so we'll layed out it makes formula choosing for engines a breeze .thanx for this channel. us gearheads really appreciate you more than we take time to say .thanx again
thnx
Thank you for doing sbf pushrod stuff 👍
I love this channel, it's like enginemasters without all the fluff and filler
1 year later.... It's more of a lesson than a show
Richard is the most hard core dyno dudes I have come across on TH-cam.
Anybody that has ever listen to Steve Brule knows that compression and displacement have more effect on bottom end torque production than anything else.
Most of the people watching these videos don't know it, but the vast majority of the time is spent below 4000 RPMs. They just don't realize, or refuse to acknowledge it!!!
@@BuzzLOLOL towing? Come on!! Ok, the 460 is great for towing, it weighs 720 lbs, the crank weighs bout as much as a 5 liter block! If you're racing 4x4's in the mud bogs, go for it. I'm assuming he's racing a fox body, and mustangs aren't the only foxbody. Did 5 liter, 351,460- Start collecting 351windsor block's. Set of heads, cam and go for it, assuming you want to haul ass for cheap. Did this half as long as you've probably been alive. Heads, cam, Victor jr. Intake 780-850 double pumper. Speed pro premium cast pistons will do, big valve reliefs. Shoot 150 on them as long as timing is right. Raced a motor just like that for years. Spend the money on a set of victor jr heads or comparable..
Maybe ud marry your daughter to a plmp. Telling you we did it all. Had a 406 Chevy with iron eagle heads supposed to be making 550hp., buddy's ride. Bought a car complete with a 0.40" Windsor with roller cam and Victor jr. heads, we didn't build it. Out run the s$_t outta the 406!! Got all the respect in the world for ls chevy. Don't want one, but that's what I'd do if I'd switch. All of this is throwing money in a pit. Cost to get the ls into a fox. A Windsor with good heads and roller cam will drop right in, hell the headers fit. Stroke it and put canted valve heads, it'll run low, low 5 sec. 1/8 mile. Ur getting ready for motorsports or dart block, but it'll get u there. Seen them running 4:70s and 80s. It's your car, your choice, but it's throwing money down the toilet either way. Sell ur 302 and buy a set of cheap aluminum heads and a 351. Got a set still in the box for $400. Gonna put a set of rings in a .040 Windsor that wife ran hot and put it into my flare side f150. DGAS what you would do!!! It's your car, my truck. Do what you want.
There is no single variable that stands above the rest. You can easily screw up a large displacement engine with the wrong cam, compression, etc..., and lose all your low end torque. Classic example is Ford FE motors - they have terribly shaped ports, but they were efficient at low end. The 360 had terrible power, the 352 ran great, and the 390, 428 ran great, with efficiency/ good mpg's.
You can't single out a particular component and say do this and it works every time; there's no wisdom or truth in it. Building low end torque is harder than building top end horsepower; it requires understanding the variables of volumetric efficiency.
@@Faolan161 you do realize that a 360 is just a .050" over 352. Both have the same stroke. The 390 I'd a stroked .050" over 352. They were great truck and big car motors because the block was tall enough to get that long rod in it and keep rod/stroke ratio positive. Been a long,long time ago, but think the rods 6.4" center to center. Also had long piston skirts to stabilize it in the bore. Piston spends more time at top dead center. Rods are really beefy, unlike what we see today.
Richard you hit the nail on the head compression and to make it breath great job.love your work.
So glad you did this test, bought a set of big flow heads for small block Chevy so I could upgrade later, glad to see I won't be losing a bunch in the meantime.... You keep testing ..I'll keep watching
What are you running? I am looking at building a 600+ horse power SBC and looking at combos people actually get to work well on the street.
@@sebbonxxsebbon6824 a small block Chevy, w/220 intake runners, about a 600 lift cam with a sniper efi, planning to turbo later
Scott, did you get your combo together? How doers it run?
This is exactly the test I needed to see!!! Thanks Richard.
I run 210cc procomp heads on the 5.0 in my truck. Part throttle is fine, just put your foot into it a little more. It must still be fairly efficient as the truck gets the same mileage as it did with the 150hp 4.9 straight 6!
In a cyl head i always look for the low and midlift numbers and that gives me an indication on how efficient the port is by flow. It always seems that the better flowing head even if port volume is smaller in comparison to a bigger head w/ bigger port volume always seem to make more power up until the very top of the curve when some of the high flowing heads start to edge over.
Thanks for the testing. When i do my own porting I always try to minimize the port volume but make the transition smooth on the long radius and get rid of the "lip" to the valve seat along with minor work to smooth the valve shrouds. I have always gotten a good feel in the butt dyno but haven't done a before and after dyno.
Nice to see that going a bit larger won't destroy the low end power like a lot of people like to preach. Maybe next time I won't worry so much about trying to keep it so close to factory size, obviously would want to keep them constant across all cylinders.
*valve shroud comment applies to the non-ls engines I have messed with.
Ha! I was busy composing a comment on how the dyno only tests WOT and not street drivability when Richard starts talking about that. I should have known that Richard would be on top of things.
What would be cool is to do the same dyno tests at part throttle, say 30% or 50% and from low-middle rpm say 2000-5000. That would provide interesting data on driveability vs WOT
Hey Richard.. good morning! Sippin' on my coffee and was thinking.. can you do a header test? 302, 350.. "street" engines..
1 1/2 headers, 5/8 and 3/4 to actually see if people.are putting g to big of headers in their daily.. I read an article that says 1 1/2 primaries WILL support 400 hp. I think alot of people would agree on "street" engines and headers would be a good video... maybe heads and a cam. Nothing to crazy.
Awesome video Richard!!! Thanks for this info!
love all your test man , have watched them all
I think that the Cnc porting is significant. Port shape helps flow a low flow speeds at the lower rpm. It would also help at part throttle. Proper port shape right around the seat area and guide that is a result of the cnc porting is most likely more important at low rpm than port volume. I would have liked to see the dyno run start a 2000 rpm.
Smaller well spec’d camshaft with large heads on SBF always worked real well for me and made a lot of believers of others who swore my heads were too big after seeing my tail lights often
Was the car light?
Under 3,300lbs?
@@I_like_turtles_67 no car was heavier than 3,330lbs and why aren't you asking about gear ratios since you are concerned over vehicle weight?
@@msk3905 That would've been my next question. I personally have 3.89 gears and a 5spd in my 67 fastback.
@@I_like_turtles_67 306ci, 10:1cr, 3.73, 1 5/8 LT, 3,420lb cam 218/224 @.550lift, 112LSA on 108, 205 heads….absolutely screamed with exceptional throttle response even though everyone back in late 90s said head was too large because velocity would be low. 1st gear useless, 2nd gear had to be careful on full throttle rips cuz tires broke free in 5000rpm range, used the heads because knew stroker in future but pleasantly surprised how fast 306 setup was
I love how you give us the various in setups
Would like to see a 383 sbc test with an aggressive solid lifter flat tappet cam, 13.5-14:1 cr on E-85, single plane and a good carb, and a set of Vortec heads just to see how much power someone could make with them, and Richard is just the man to do it!
I have a .040” over 400 with 12:1 compression and ported Vortec heads. They make really good power with some porting!
What's it run at track ?
Great info here, we hear so many people suggest or insist small port heads for drivability and torque, this vid proves otherwise.
4👍's up guys thanks again for taking us all along with you for the great show
I was very surprised to see the results. Thank you for your input. An ET - MPH test would show what accelerates faster.
What I'd like to have seen was this. Pretend its a low RPM engine. lock the max throttle opening to 1/4 opening.. try and simulate the throttle opening you'd use for around town driving. pretend its a 3600 RPM max motor. start as slow a speed as possible. limit to 3000 R's . if the test is all about low speed performance of large port volume heads. wouldn't that be what you would do ?
I agree. If you're going to talk torque, you need to start at 1000 rpm and run to 4000 rpm on 1/4 throttle. That would be very valuable because that's where we all drive 99% of the time.
Is that not what these variable cam motors are about. Where you have one cam profile to max power and drivability down low and the darn things wake up above 4000 rpm
What I'd like to have seen would have been a smaller cam with the bigger heads. Look at the cam specs, and port volumes for an LS engine, big heads, and a small cam will make more average power, then big heads, and a big cam.
Yes I was thinking the same thing, the smaller heads would show the bigger heads up in this scenario for sure, in my opinion.
@@FXRSDriver current OEM engine design thought is big port/efficient combustion chamber with really mild cam timing. The pushrod engines ( LS/LT and Gen 3 Hemi ) are prime examples of this. The Coyote has the advantage of variable cam phasing along with the overhead cams so it can rev out past 8000 rpms and still act nice down low.
Those results were unexpected. Thanks for sharing! 👍
I simply love your channel!
Thank you , thiss helped me alot , with my porting plans .
and you comfirmed alot that i thought, and i have something to think about , thank you!!
Cool vid Richard.its all the variables that make our break our combo. Overlap very important helping with in coming charge before that exhaust pumping just get the show going.longer the stroke more tug effect piston has on intake pumping and ram effect. All that and more can effect cylinder ve.port size only matter when port mean velocity become redundant.flow brench holds a lot of secrets. Peace
Great test! Would have been more interesting to me to see it run on a more stock combination. Even so, more is better, but at some point you still have to ask yourself if those really large port $1500-2500.00 heads are worth the three hp at 6,000 rpm on the street for a nearly stock short block. My economics say no. A head with a smaller 170-180 cc intake runner volume would really wake up a stock or nearly stock 302 cu inch motor or even one with a 0.480-0.490 lift cam. Would a larger head help? Yes it would but, economics come into play. You can have a hp times hundreds of dollars stock motor or you can have a hp times thousands or even ten thousands of dollars stock motor.. How deep are your pockets and how much are you willing to pay for that last two or three hp is the real question. Economics. Really like your videos. They make us think and sometimes pontificate a little bit. Its a good thing to wake up them three brain cell of mine and watch them chase themselves around that big building we call a head. Lol. Thanks for sharing.
Great test, gotta admit I was surprised that there was no loss at ~2500 rpm and in fact small gains with the bigger head. That's why we test on the dyno!
I BEEN waiting on this!!
loved the 540, that is what I am doing now , great info!
Great video as always! Have you thought about testing turbo manifolds, fancy vs. stock? equal lenght tubular vs modified stock casting? Would be interesting to see what it does on different power levels.
I’d love to see the large head tests with anti reversion mufflers just after the header collectors and see if the torque dip gets filled in more…
Another great scientific video Richard. Reminds of huge cylinder head test you did for Super Ford back in 2003. Can't wait to see what all self anointed gurus have to say...😁
An old endurance race engine builder used to tell me, "I want the smallest port that flows the CFM I need to make the power needed"
As long as they are old, that means they are correct... right?
@@superkillr for sure, I know a guy that was building an engine and buying random parts some "big racer" he knows told him to get. Tried to tell him it wouldn't work. He would get my opinion on everything and buy exactly what the other guy told him to get. Ported factory heads with not enough spring (but but they're new!) for his solid lift roller cam and "HYDRAULIC" flat tappet lifters. You can guess what happened the first and last time it ran 😂
I'd rather have a smaller sized intake runner on a street based motor. As Richard stated. These numbers are based on full throttle pulls. Not part throttle driving.
Never forget the time motor trend put a set of 165cc heads on a sbf 410 and it made stupid torque through the entire rpm range.
The 195 head was the clear winner in that test. Because the cam was on the smaller side too. The 220 version would've done better in the test. IF the cam was bigger. But the longer duration will make the torque come in higher in the rpm band.
So part throttle and lower speed driving would be effected significantly.
* Unless you have a stick & a very light car.
Definitely saw this coming but thanks for testing! Before I went (Ewww) turbo LS power for all my Foxbody racing, my 8.2 deck with stock stroke/4.020” Keith Blacks/Edelbrock RPM/X303 made about the same low speed power with a 170 head as when I went to a bigger set of 200’s. Everyone told me I would kill the bottom end and I shouldn’t do it because it was a street car but I always figured I would just go to a 4:10 out back if necessary……..it never was. Bottom end power stayed just fine on the street with the 200s.
Peanut vs Oval vs Rectuangular - Test on the same Big Block Chevy engine! That would be interesting for half the world!
I run a 434 small block. 210 AFR heads which I think would be on the smaller size for this engine. 600 lift cam and a 950 Quick Fuel. It made 598 HP at 6300 and similar Tq at 4400. Yes it runs out of air but still pulls at 7000 through the lights in the 1/4 mile around 127 mph. A similar engine with more cam and 245 AFR heads make 700 at 6500 and same Tq as mine at 5400. A comp. check on mine was around 205 - 215 lbs so I think the small heads and less cam timing work well for me. In a 3300 lb street driven Nova I have run 10:43 at 127. 10.5 comp lets me run 94 octane.
Excellent work.
It is interesting to see the sine wave shape of the dips in mid range torque as port volume increases. My physics is too rusty to be certain, but looks like some flow dynamics resonance going on. Is there a known effect on air pressures at the valve related to runner length? I would guess longer runners produce higher pressures at the valve face to promote flow at lower rpms.
Another good comparison would be 2V vs. 4V Cleveland, or "Peanut Port" BBC heads vs. Rectangle Port (L-72/L-88) on otherwise identical engines (cam specs, compression, carb size, header size).
For years, there's been a lot of BS 'know it all' types that would swear that 4V Clevelands were too soft down low, and that they did'nt come on until 4000+ RPMs, and other crazy stories. I used to have a 72 "Q" Code (351C/4V) Ranchero that would spin the tires very easily from an 800 RPM idle, just stomping the pedal from a signal light. It had plenty of torque down low!
Gearing plays a big part.
@@sbfguy7793 True. My Ranchero was equipped with 3.25:1
@@biscuitboy3617 Odd, my 70 Mach 1 351C 4V with 2.35 and fmx was pretty soft in the lower ranges..exactly what I was expecting.
@@qball1of1 Did you have different rear end? I ask because I believe that 2.79:1 was the tallest gear ratio that Ford offered in the 9 inch axle. I imagine that most Mach 1 Mustangs came with 3.25, 3.50, or 3.91
@@biscuitboy3617 Oops 3.25..bad typo. Was a great car just thought a bit soggy on low end. Some others have have no complaints so I guess its all relative to what a persons expectations are. No denying the potential of the C though, doesn't take much to wake it up.
I'd like to see a LA vs Magnum vs W2 small block mopar other guys shootout
Was somewhat surprised by the low end gain good to know . The drop off in the mid range is mostly the transiting of the four barrel coming in to it's sweet spot.
BOSS 351 S WORKED GOOD BACK INTHE DAY FROM THE FACTORY
Re: your question about part throttle power-I never dynoed it, but I had a 2000 Silverado 2500 with LQ4. I added some mildly ported (basically a pocket port) 706 heads and a Vinci 210/218 .551/.551 cam. Overall power was up for sure, but the best part of it was the part throttle response. It was really snappy and fun to drive. Even with the lazy 4L80 first gear.
very good comparison i have also seen similar results comparing a victor jr to an rpm performer where the victor jr made more low speed power and top end but less midrange. Another
Yes, surprise... big ports are OK at low rpm...good research Richard!
Great video and explanation..
Set of vortec heads in this mix would of been nice.. I hardly ever see any mild cam vortec head dyno tests on You tube especially comparisons!
This would help a ton.
Yes!
Yes!
With 9.5-10:1 and a 205-215 cam vortec 350s make over 400ftlbs. I think they hit a flow limit around 500 HP. My neighbor has a vortec 383 mild, 900rpm idle and immediately lites up the street tires in an 80 Malibu. Great bang for the money.
👌 great test
Great video
My experience on the drivability with big heads and small heads on the same engine is 351C and Pontiac engines. Everyone has always said the Cleveland 4V heads kill bottom end and the 2v is better for street driving and will still make good power. That wasn't what I found. The 4V heads with a mild 224@.050 cam made enough torque to smoke 9" wide tires with a 3.00 gear in a 72 Mustang, stock converter, stock weight, stock intake and carb, with a set of headers.. If you whacked the throttle from idle, it boiled the tires. Not quite as much bottom end power as one of my 400s or 455s, but for a small Ford, the C rips and it drove around easily with HUGE ports. Its the only small block to impress me with only a cam and headers.
Port length matters more than the size, unless its a poor design. Increase the port volume on a Pontiac, you simply make more torque everywhere. Its damn difficult to kill bottom end on a 455 unless you put a huge cam (over 250@.050) in with low compression and stock ports and valves that come in a 190cfm 350 head. Its more the cam timing that does it than anything, the too small heads won't flow enough air to feed the 455 above 3500rpm and the cam wants to move the RPM range above 3500. Put a 330cfm head on it with that cam and its going to make 600ftlbs at 2500rpm... and 600ftlbs at 5000.
Maybe you could see it going with a 389 or 400 with the stock 3.75 stroke and some RA V or 400+cfm Tiger heads and a relatively mild cam, but usually its low compression(7.7:1), long duration cams(240 and up), single plane intake, and stock heads that make it so a 400 can't spin the tires or run quicker than 15s. Most guys seem to think that a flat top piston makes 10:1 on a Pontiac, they are thinking chevy. They almost all had flat top pistons and you can make 7:1 to 13:1 with a factory head on a 455. So they put a 76-79 vintage 6X on and think they need race gas, but its at best 8.8:1 on a 455, and 7.8:1 on a 400. Then they can't figure out why it doesn't run very well. If they have the 100+cc chamber heads from the 73-76 455s, its even worse. Its all in the heads on a Pontiac.
The cool thing about a Pontiac is you can bolt up any Pontiac head to any displacement block, though the small bores like the 326 might hit the 2.11" valves on the 67 and up heads, they will all physically bolt on. Unless you know what to look for the 455 or even a 540 on an IAII block is indistinguishable from a 326, 350 or even a 316. Most non Pontiac guys can't tell if its a 301 or a 400+ engine, they are a hell of a sleeper engine, especially since everything thinks they won't run. So far I haven't found a Pontiac head that is 'too big' and hurts bottom end, they are almost all on the small side or are too small for the 455. Go with bigger strokes like the 4.35" or the 4.5" and you make even more bottom end and need more airflow to rev over 5000. Cam timing and runner length are far more of an influence than port volume.
Thump Er : The joy of having a rope drive 1963 LeMans 326 is that it could be a Royal Pontiac 421 with just a little invisable work...The Ford side of things has been to play off various Windsor and Cleveland and even FE, FT and Lima families because, ultimately, they are from 4.38 and 4.625 and 4.90 engine transfer line plant stock.... that have not changed since the Y block, and the two sizes of MEL 1950s era engines. Don't be fooled by F and 221, 335, Boss, 385 engine family names wrapped in very Chevy-esque Canted or BOP215 style 221 heads or the reprofiled block "hair-cuts". We all know Pontiac used one bore spacing V8 and (occasionally) 4 cylinder from 55 to 81 and made 80-81 265 and 77-81 301 engines, lighter than 302s. Nothing new in Ford V8 engine architecture since the 1952 to 1958 OHV transfer lines. So Ford played off deck heights of the 352 FE/ 351W/351C/351M/400 and even the Lima 370 against everything else. Ford Cam masters there have only been 13 since the 252 duration 221/260 cam since 1962 to 1984. The next new V engines were the 1982 Essex 90 3.8 and the Vulcan 60 3.0 1986 engine. So Ford downgraded the 1981 351M to 136 hp and raised up the 351W HO to 163 hp. The Windsor HO had the Marine cam. So Ford was only interested in plant utilisation and emissons. The 4.2 V8 had a stump puller cam, useless for making power. Every time Richard Holdener dynos a Windsor 5.8 I think what one of Fords 12 deadly Letter Cams would wake this Baby Up Best....
intake pulse is maybe like the exhaust pulse. where if u make the port size the RPM and volume u want to make power...
Engineers spend countless hours working backwards from full-throttle dyno numbers to achieve those part throttle numbers they desire for a given combination of both emissions, fuel mileage, along with weight and gearing, and all to get those driveability issues worked out. Hopefully, Richard will get to visit with Gale Banks for a while and share the experiences. Mr Banks sounds a lot like Richard in that the most important place to start is with the power goals all through the RPM range.
As far as the heads. Flow, velocity, tumble, swirl, combustion chamber design plays the part in all the heads. I wish Roger Helegson was still alive.
How cool would it be to quickly and efficiently test these things on a chassis dyno where you could measure part throttle output reliably. Cool tests nonetheless! Hurry up with that Gen 2 LT1 SBC big bang test!!! 5.7 or that not very well known 4.3 V8 ;-)
I'm glad you ran this test, I am shopping for heads for my 400 (stroker Cleveland). I tried to build the open chamber heads and just wasted my time and money.
I just built a clevo recently, the head guy told me to use the heads I had and he worked them from there. I used 2v closed chambers with 1/16th oversized valves. He flowed the heads and is revving and making great power
Just over 500hp, still 351 CI. 12.5:1 comp.
@@amac5224 Is that on pump gas? I'm only at 9.5/1 and am fighting detonation by running rich and adjusting the rest out of the timing. I bet I've lost at least 100hp by detuning it because of these open chambers. I have a lot of time and money into these boat anchors.
Trigger Warning yeah it’s 98 octane
Trigger Warning also the ignition system you put on makes a huge difference
Hi Richard would love to see intake and exhaust extremes. Dyno runs of ridiculously small to ridiculously large pipe sizes. It would be fun to see the number. Maybe even something crazy like large intake pipe/small exhaust and vice versa I don't know if you've already made a similar video about this
@port nut Yes sir, I have seen it although 2.5" to 3" was properly sized to still keep that engine in it's efficiency range. That is why it was such a small difference on the dyno numbers. I mean going to the extreme side of things, not properly sized like that one
Would love to see the difference in results after adding boost!
Ive always compared NPI and PI heads in this regard. Pi is 159cc intake runner and NPI is 146cc. Pi flows about 160cfm at .550 and a NPI is 176 at .550. Despite peak flow being in the favor of the NPI, the PI head flows on average 9cfm more from .050-.550 lift. One could argue the NPI has better port velocity and peak flow, but they dont always necessarily make the same power.
Thank you for all the testing you do but in this case I would like to have seen the only thing you changed be the cylinder heads ! Again thanks 😊
The reason the low speed power is up is because the larger valve, see to have a port welding experiment with welded in material in the floors of exhaust and intake ports reducing their size to 185-190 cc after working is ideal for street. a larger valve always favors low speed torque. Just look at small cube (396 and destrokers) big blocks with large valves in peanut port heads can make exceptional torque. The keys to cylinder heads and power or in the case of speed and acceleration, are not simply the size difference, it is the efficiencies in the port energy and some swirl and keeping low speed velocity without losing whilst adding higher speed velocity this is key for a cylinder head to be able to use all of the lobe design on the camshaft and or valve movement throughout its range of movement.
I would love to see this test with a small bore ls1 and with a large ls3 head with 2.08 valve to fit. Most of these tests where with a 225 port head, when a better test would be with a 235 to 255 sized port.
Port volume is important if the engine setup can use the extra port volume. If the exhaust is restrictive or the intake manifold is restrictive or the valves themselves too small or the cam not extreme enough then extra port volume can sometimes hurt power production or not necessarily increase power production nearly as much as possible with a good combination.
How does forced induction change things up?
Test part throttle instead of asking what we think. :-) Also, to be fair most would match the cam to heads and motor as combination, but I guess the guy building up his daily would do it more this way.
I would love to see this as well
I would like to know your favorite engine set up for different things.
Or a shot out between ford, chevy, mopar but here is the kicker, $1500 limit for engine and upgrades.
Maybe a decent Dollar per HP shoot out between the big three.
I’ll save you the mystery, it’d be an LS based engine every time.
Have u done this same comparison cathedral to rec port? I know u have compared them in other ways but can’t remember u doing this test if not that would be a cool one keep up the good videos great content
i have
What’s the effect of bigger exhaust ports??
Is bigger better or does a smaller port port help exhaust flow velocity and improve cylinder scavenging?
Thinking back to some of your LY6 NA tests, the cathedral port heads always beat the rec port heads at lower engine speeds. Not to forget all this is at full throttle, too. But there may be another explanation-the cathedral port heads, especially 706s, had smaller chambers, so the increased compression may explain all. Compared to small blocks of yesteryear, LSs are all over-cylinder headed, thus the much smaller intake duration needed to make power. If a full point of compression is worth about 4%, that’s 16-20 ft-lbs or horsepower for most LS engines. That tells me I need to mill the heads on my LY6! Build in progress, probably for a lot of months...
I agree with previous comments.
Run the same comparison with the butterflies limited to 1/4 or 1/8 throttle. This should give a better representation of drivability and low RPM power output.
I built a 10.9/1 406 sbc based on your 406 build with but with 220 Flotek cnc heads that flow 315cfm at .600 lift with a .584 lift Schneider cam 240 @ .050 108lsa and 1.6 rockers and a proform hp950. (830cfm) and I can drive it all day and it has tremendous power 4 to 6800 and from 1k to 4k can smoke tires anywhere just with 3/4 throttle. Everyone said it would be a dog were wrong.
My research at UM showed that what the larger port volume does is that it dampens the effect of scavenging from the exhaust, which is why you see the effect most in the midrange. Any one of the many factors that improves your pumping efficiency in the midrange will also make your engine less sensitive to port volume. So an engine with a larger displacement, a tighter LSA, and properly spec'd long tube headers will not be as sensitive to port volume as one that does not have those advantages. One last note, where you have the volume is also important. I would say that the pocket volume is much less of a factor than the cross-sectional area. Keep up the great content!
Have you posted your studies anywhere on the internet. Something more long form and person can look at?
@@superkillr My comments are based on research conducted for GM and Ford on a variety of projects. Sadly none of it was posted in the public domain. That being said you can see the results in the cylinder heads that were developed from that effort. In this case that would be the L76/L92 head.
You have to do a part throttle Dyno session... maybe primaries only. Easy to do and would tell us a great deal on street drivability!!!
What about comparing flow velocity? Similar flow numbers but different size ports and valves. I would be interested in that comparison
Interesting test Richard. I wonder if the drop in mid rpm across the board had anything to do with runner length? It would be cool to see this test setup with an Edelbrock RPM Air-Gap intake and compare the charts to see if the mid rpms pick up at all.
I was surprised the low speed did not suffer as much if any, it's more than port volume.
I bet intake choice would have a more dramatic effect. Very interesting.
Or maybe I should say...better head till I"m dead.
I think ford found out long ago you can use bigger heads and mild cam with the boss 302.
Well, I'm going to be testing out my little combo towing around a trailer. I'll let you know how a small cam and big heads work out for me.
well?
Idle to 4k with 1/4 and part throttle would be the test.
Interesting comment below about tuning each combo and then comparing VEs . . . But I'm wondering if you could just look at part throttle fuel flow to calculate / compare horsepower.
Talk to Brian Tooley if you really want to answer that question, his heads do not have the greatest flow numbers at max cam lift but the greatest flow overall when measuring all points of cam lift.
I try to talk to BT daily
I think you are right about part throttle, due to velocity
I’m wondering about air velocity between cathedral and rec
Awesome feadback Richard. Is the EX274 your favourite cam you once mentioned or was that the ex276. Mike
I don't think there would be much of a difference, as the headflow wouldn't be the limiting factor. it would be the throttle blades. I'm thinking the variation you're seeing in the midrange is a function of port velocity and intake harmonics, and with the larger port volume the frequency at which the third harmonic occurs would be shifted slightly upward in the rpm band, and it would behave like it had a shorter (or larger diameter) runner. The same test on EFI (port) would yield similar, but slightly less dramatic results, due to the fact that the fuel distribution isn't affected as greatly by the velocity of the air in the port.
It’s more the factor that people run carburetor tune ups that are that terrible. 10-20cc difference the air speed will never know
Its called reversion, look at peek torque rpm, at half the rpm should have torque, and in between less. At rpm when reversion is happening, then its worse with the bigger port head. Effect is worse still with a carby, because some of the air coming in is carbureted three times, making it richer and less torque.
@@sheridenboord7853 not true or correct in any way
This was excellent. So it seems port lenght plays a much greater role than volume.
yes
This would apply pretty analogously to a chainsaw engine right? (non-reed, piston-ported single cylinder 2-stroke)
I've always flared-out my exhaust ports pretty dramatically, far more than my peers, because directly-after that exhaust flange is the big muffler-box that the exhaust pulse opens-into....seems smart IMO to flare-out that port to accommodate this since the muff's backpressure is a crucial part of the functioning of this type of engine.
Thanks for any insight you can offer on this!!
bee neat to see a small carb 400 cfm or part throttle ? tested on the head runner shoot out ,,as par normal A++ video
Can u do this same test on 4cyl and v6 combos, including the difference rather na or boosted as well
Very good. I was gonna run factory 624 heads on my low end torque 350 but they are so bad mouthed I just put them aside. I could not find a good enough deal on rebuilt factory heads and half the time they didn't put in the hardened exaust seats. The 186 and 041 are gold and I want accessory holes so. BRODIX 180 ik on a rv cam chevy 350 I think it will be alright. Thanks for the video
As for the part throttle... I think you could really see how it affects part throttle by looking at the VE table that would be generated when tuning if you were running fuel injection. You obviously couldn’t do the test on the dyno. It’s a little out of the norm for your videos, but I think it might be cool to see. When I tune a vehicle, I can get a pretty good idea of where the power is improved by the shape and numbers in the VE table.
Great video sir,, I'm personally not surprised at all.. However these test were done with small cams and wide lsa numbers in my opinion... I really loved my dart 230's running over 600 lift and a 106 lsa. 400 ish inch ish sbc.. need more low end? open the throttle... Just saying in my application it worked nice.
It would be interesting to compare BSFC between a big port and a small port induction at part throttle, same load. Logic tells it may make a difference with a carb, perhaps not with port injection.
Great video Richard. Am wondering is the power na a bit related to vacuum numbers?
power and vacuum are inversely related but we don't see vacuum in the manifold on the smaller heads like we do with a smaller carb or TB
351 Clevland 4bbl cars I road tested[in the 70s] after repairs as a Dlr Tech were huge performance disappointments. 2.19 intake valves and ports a pack of camel cigs could pass through unscathed were a waste given aprox5500 redline. Slo port velocity was the culprit. The 2bbl cars seemed better in redlight gran prix. 4bbl heads were great on blocks modded for hi RPM,but then exposed block defects. Prof. H has done us a service with emphasis on Combo, certainly as applies to street. Lo RPM, Slo port velocities make street/strip mtrs no fun. Thankfully modern combos r light yrs better than 5 decades ago. However, Prof H's test of big bore/short stroke here shows a sure recipe for modern superb HP/Torque curves from an old dog SBC.
take a look at the 351 C vids
dude i love all your vids. im in the middle of looking for parts for parts to make a chevy 302 out of oem chevy parts. i'm using a chevy 350 block and a 283 crank. im looking at LS pistons and rods, i just don't know what oem sizes to go with, if your able to help would be nice.
LS pistons and rods in a 350 Chevy?
@@richardholdener1727 yea I'm trying to use parts I have laying around my uncle's shop
Deck height won't line up. LS has taller deck than SBC by .215". Your 302 would require a piston compression height of 1.425 with LS rods. A 6.0 LS piston has a compression height of 1.33. The top of the piston would end up .095" down the hole at TDC.
It would have been nice to have the flow charts for each head. If the valve is the main throttle to the flow then the port would have little effect on the flow thru the engine.
Hi Richard!!!!I’ve thought of porting the 862’s but then what is the better way of going for flow. I think you covered it earlier in other videos for the ls 5.3. 224 head?? What was it?? Thanks Richard!!!
706 or 862 heads for the 5.3l-ported is even better
Duh! It depends on application. Drag or race requres port velocity @ high rpm with what for the application are acceptable compromises @ lower rpm.
Street requires velocity through a much broader rpm range. Usually from idle to about 5 000 rpm for larger displacement.
For nigh on 100 years the best road cars have featured one engine quality that endears them. Aside from reliability, the flattest, broadest torque response possible. This is actually more difficult to achieve. Because the diversity of driving conditions is so variable.
But careful matching of cam to port to induction & exhaust can give you awesome throttle response that is actually usable in traffic with surprising economy and WAY better drivability. BUT only if everything complements. IE the whole package. Gearing, road handling, brakes, driver position & ergonomics etc
Back in the day I built a 4.0 litre 4 speed in a TE Cortina. It weighed less than 1200 kg. Above 5600 rpm it lost any semblance of thermodynamic efficiency.
But....... below that it was and still is one of the best engines for power with economy you could get. The 250 crossflow iron head. Mine had 210 rwhp & with 2.92 axle gearing could get on a very cold day the economy of 10 litres per 100 km highway. That went out the window with 3.25 diff to 12 L per 100k That motor went in stock NA form from 100 kw to 190 Kw over a 50 year life span. In barra turbo form, aftermaket tuners have pulled up to 800kw from what evolved into an injected variable valve timing quad valve pr cylinder twin cam that served in everything from taxis to drag cars.
There was a contender that for a while eclipsed this gem. The hemi 265 in RT form & as the E49 it set records that were not beaten till the 250 had injecion, 4 valves per cylinder AND a turbo some 30 Years later.
All the E49 had was a lumpy cam, headers and triple webers. This was because it had a themodynamic efficiency that with that induction stretched to well over 7000 rpm. As was discovered by aftermaket tuners. But at the expense of any semblance to economy. Brakes were shit ,handling like a wet bar of soap in a bathtub. Economy? HaHa Ha 5 litre V8's bettered it. But 1/4 mile flew by in 14 seconds. Literally NOTHING could catch it that was built here. Not bad for a 50 year old but it didn't last. It like so many muscle cars was killed by the fuel crisis.
Lastly after this long winded tirade. To me its all a question of balance. Everybody loves acceleration that like the hand of God pushes you into the fabric of your seat. But if its a pig to drive & empties your wallet by guzzling fuel like pulling the plug in your bathtub it will loose its cheap appeal VERY quickly especially if the valvetrain needs rebuilding annually because the cam is so aggressive.
If I did a street engine today I would embrace roller cams (for ohv pushrod at least) & fuel injection.
The advantages for long term reliability tunability in real time to match climate altitude and driving conditions and style is unparalleled.
But we will all be driving electrics soon enough. Instant touque at any rpm & 90% efficiency vs 15% for I.C.E at best is a hell of a thing.
I have 2004 Chevy express van 2500 with a 6.0 lq4 I like that stage 2 truck cam. Can you tell me what to buy to make my van a rocket without going nuts? I like the idea of not having to change valve springs or the converter, but I would love to be able to get 500hp and ftlbs together or as close as possible. Excellent testing and mechanical engineering 💪💪
boost
I wonder what effects the different ports had on swirl. Would be interesting to see the tests done again with swirl figures included.
I wonder how torque production would be affected by intake runner length vs. port volume. i.e. would a TPI make more torque with a smaller port than larger.
it does improve low-speed with a change in port size on the intake