Cam Testing: Tighter LSA, Less Intake/Exhaust Split

[@teagreen2220]

Sweet, I’ve been sticking with 112 lsa for my LS builds for about 8 years now. No surprises. Keep racing! Great video.

[@edberry78]

Both Holdner (KZbin) & Brule (Engine Masters show) did a similar test, one on a LS, the other on a 440. The tests used same lobe profiles and duration, but different LSA. Interesting dyno results. Keep up the good work, Eric! This is fun stuff!

[@inscoredbz]

Richard Holdner also promotes procomp/speedmaster junk, so I lost all respect for him. His cam test went crazy as hell. He should have went with normal shit people actually use, 106, 108, 110 and 12 or 114. He went crazy wide with around 4° between each cam. I think he ended up with a 128 or 120 lsa as his wisest on a SBC. That's retarded

[@haroldjoyce7440]

man need to get out of the arm chair do something to get credit, when you have a dyno and 10002 of results let me know

[@slopoke22]

​@inscoredbz bet you can't take me out and I got some of those procomps on my Windsor. But those procomps can look and perform very well with someone who's knows heads

[@slopoke22]

I know that we built a 1030 hp 433, ls based, 9800 rpm and we used around a 118 lsa and some engines we used tight lsa. It's all dependent on everything else lol. We had a 400 sbf with 114 and 116 on the end lobes. But, I've personally had my hands on 6 engine masters engines that won and placed in top 5, all of them. Camshaft and people talkin about them is comical sometimes. Keep on building and racin!

[@abdullaalameri90]

​@@inscoredbz all the respect to richard holdener. He has done great for the youtube engine performance testing community.

[@kendyck7312]

I dabble in engines but one of my passions is reloading pistol ammunition for shooting Cowboy action. That statement about testing and knowing is important. But even testing and knowing will still make you wrong on the internet. I've almost stopped posting, far too many theoretical experts out there. And as you also indicated, the best LSA and split are tied with the compression ratio as well. Any racing organization that lowered CR to limit HP quickly found out that the good teams could tune around that limitation and gain most of the lost HP back in. Back in the day I was hired to help on a late model dirt racer, with a 030 over 400 SBC, to do the engine work. Yes, I was working way above my pay grade. Therefore I went back about 5 years and went with the combinations that were proven winners five years back. IOW, I selected a combo where I could go to just about anyone and get tuning tips. Winning was what happens, not dominating, but if the driver had a good day, he had enough car to get it done. Thanks for posting the video.

[@rickh8380]

Thank you for the information. Even this old guy learned something new today. I always thought the same way. Tighter lobe separation meant more horsepower.

[@ShovelMonkey]

Wow. I was not expecting that. I have a pair of Promaxx cnc shocker 185 heads for my 360LA. It's good to see their Chevy heads doing so well.

[@socleanmx6]

Cylinder head flow is so good it doesnt require nearlybas much cam to get huge gains !!!!

[@grrh77]

I ran a 236/248 111+3 in a 380” ls3 years ago. It had my ported 243 heads and 13.7:1 compression, worked victor jr. this was 2015 or so not as many options back then. 665hp on engine dyno and 540whp in my 2600# fb rx7. It was a great cam setup and street drove great on e85! I put thousands of miles on that setup and the t was incredibly fast. The ls3 heads are an odd duck when it comes to cams, you basically have a great BBC rec port on the intake side and a SBC exhaust port. On stock heads you will always see a large split due to the essentially having 2 different style of ports

[@hendo337]

665hp is pretty serious for ported 243s. Impressive.

[@edsmachine93]

Good test and evaluation Eric. This is certainly a very fair and honest comparison. Thanks for the great Tech. Have a great day.👍👍

[@timevans9710]

I am pretty sure you are onto the LSA and comp. ratio. problem. I have been specing cams for my own builds for years and use Vizard s formula for up to 11-1 for every point over increase LSA by 1 degree also for every step up in valve size increase your LSA 1 degree. Richard Holldiner did a test on a junkyard LS and for every cam with a tighter LSA it made more low down torque and more HP than the previous. Keep up the videos Eric they are all good.

[@Performance-101]

We did some testing in my lab to try to understand the best in/ex flow ratios and found the same thing. The main thing is to get the most you can out of the intake side, the exhaust is much less sensitive. In the end we ended up making a flow bench for testing the exhaust that combusted a given amount of fuel in a large cylinder and timed how long the pressure pulse would last in the combustion chamber at different lifts. This gave us a time profile that could be integrated against the cam lift, which gave us a number that represented the head's ability to dispose of high pressure and temperature gases. This matched most of our test data from multiple engines and dozens of cylinder heads better, but more testing needed to be done to understand how the header resonance was affecting the relationship. Sadly we ran out of funds for that test and had to move on. There's still all sorts of details we haven't figured out about IC Engines.

[@Stage2_392]

Too much intake Duration is why the 108 split loses power under the curve. Great test though. Would love to see a cam with similiar duration on the intake but the same 108 lsa.

[@pizzandoughnutspage7817]

Testing is the science behind it, I look forward to seeing the lower compression with the 108! I think speculation is based on people’s guess and lack of evidence. You go Eric always enjoy your work!

[@rickyfulks6656]

Thanks Eric,camshaft dynamics make my head hurt .Appreciate ur hard work n sharing

[@pedrocue576]

Great channel!!! Ok you HOOKED me!!! FINALLY, a No b/s channel, refreshing, with Intelligence, keep en’ coming!!

[@jeffwooton7138]

Thanks for putting out this info. I'm glad I waited till the end to comment. You cleared up questions that came to my head during the vid.

[@obbyjep7597]

It's not what I would have guess ed. Thanks for showing this

[@WildEngineering]

I love this. Thanks for the data eric. IDK what LS people were saying to get the intake and duration split to be minimized but theyre clearly wrong lmao. Ive always seen a lot more duration on the exhaust than intake for N/A stuff.

[@dennisrobinson8008]

Richard Holder did a LSA test on Chevy LS with 108/112/120 LSA. The 108 made more peak and average torque and even more peak HP. It's on youtube somewhere.

[@ezmny1387]

Yes on THAT PARTICULAR ENGINE

[@CK-mf6du]

@@dennisrobinson8008 another interesting point, they used the same intake and exhaust lobe, so it was a pretty apples to apples comparison. I'm just a keyboard warrior, but the comparison should be much closer the more I think about it.

[@dennisrobinson8008]

@CK-mf6du it surprised me because the assumption would be the tighter lsa would fall off earlier. In that test it did not.

[@CK-mf6du]

@@dennisrobinson8008 same here, I remember too when I first saw that. We have good information here, but it's honestly not discrediting vizards formula, not yet anyway. We would have to see a cam with same intake and exhaust lobe as Texas speed on a 108 lsa.

[@hendo337]

He did another test with AFR 245s on a 408 and it didnt make any more hp and less tq with a 246 vs a 240 deg int cam, so, I believe this cam is too big and is beyond the point of diminishing returns making 680hp on a 408 which is a lot for a 408 over 100hp/L, that article is called Stroker LS Cam Swaps: When is Bigger Not Better?

[@roym.9875]

I'm lov'n this testing work. Keep the good stuff coming !!

[@DavidB7474]

Lots of information here. But I’m still not switching from my gen 1 small block.

[@DavidB7474]

@@MasterWitchDoctor All the LS guys think burnouts and donuts mean fast. Most of the cars on KZbin don’t show time slips, and we don’t race dynos. And there is always someone faster. Still not sure why no one spins their LS engines past 7k when my flat tapped hydraulic cam sees 7400, And sustained 6500 rpm operation. Think if I ran some Erics promaxx or dragon slayer with shaft rockers. While you can have your opinion, I’m not basing my builds and wants off what others think. Plenty of really powerful high rpm gen 1 small blocks out there. The LS does not have the monopoly on horsepower. And these videos have proved you don’t get the magic big hp with just a cam change, cause the stock heads flow decent but not enough to make the amazing hp fiction even one believes, you have to have the aftermarket heads to make the big numbers. And this dyno engine has a 4.00 stroke. No stock production, LS other than the 7.0 427 LS has a 4.00 stroke.

[@DavidB7474]

@@MasterWitchDoctor I like 87 Irocs but the 305 was not really what I would call fast. Past few years circle track engines have gone this way with the 305. They said it was for cost and a saved many race series with these engines. Production wise, the 305 was a bandaid for emissions. When in reality they could have kept the 350 and done much better. Even the 302 ford engines of the day were making the same hp as the tpi corvette 350. That’s really embarrassing for gm. And why would gm even put the 305 or the 4.3 in obs trucks that weigh in at 4200 plus pounds. At least the aftermarket was there to save us. And once Dart and World came along in the late 80’s with better cast iron heads it got better. Be glad we have so many choices of good cylinder heads today. In the 80’s we had nothing. Good thing we figured how to port the factory heads of the day.

[@chatch2282]

13:1 Compression and heads and intake that flow very good numbers require less overlap (wider lobe sep) More overlap will help in a lower flowing intake port to scavenge more flow into the cylinder by the exhaust charge exiting. That gives you increased cylinder pressure.

[@StainlessTIG2]

Don’t mean to get off topic. But I was watching a video of David Wolf and he made 630hp and 625 ft lbs of torque with a 7.3 Godzilla for under $5,000. BTR camshaft, forged rods and pistons, aftermarket intake, and Ls7 lifters. He paid $1500.00 for the engine core. I know they’re hard to find because of being such a new engine. It would be awesome to see what you could do with one of these Ford engines.

[@GrandPitoVic]

Pretty much most of the Ls cams I've seen seem to be 112, 113,114 and 115 LSA. Great info brother.

[@golgothapro]

Funny, I say and always have said ft/lbs of torque same as you, same as it is in my old Chevy Power books; but I noticed a trend where younger cats are all saying lb/ft instead. I don't know where or when that S started but it was beginning to make me think I was suffering from the Mandella effect, stepped into a parallel universe, or some S like that. I'm glad to hear you speaking the same lingo man. LOL I run a Howards 110183-10 (237/243 @.050, 110 LSA and .592 w 1.6s) solid roller in my 1st gen. .060 over 350 for the street with Dart iron eagle 72cc and I like it the best of any cams I've ever run. I still get 10" of vacuum @ an 800 rpm idle with it and the response is better than any hydraulic I've run over the years. I did install a rev-spring kit though which made me have to upgrade my cooling system some; but it was worth it. Thing really rocks.

[@richardvanmarter8780]

There are a lot of factors that determine camshaft selection, the higher the compression the wider the LSA, more low lift flow and higher port energy the wider the LSA and there is much more!!!

[@scottsutherland7426]

This. There are many factors to take into account, most here are trying to oversimplify

[@DamienFrench-f3w]

That was great hope you do more of this stuff

[@rolandotillit2867]

Compression ratio has a big influence on LSA, I would imagine the higher the CR the wider you'd typically want to go with LSA, as a general rule of thumb. With a 10.5:1 the tighter angle may have been more appropriate. Still a great test that shows some interesting things.

[@johnmurray7682]

A closer result than I was expecting. The difference in duration may have been mitigated to some degree - from an IVC perspective - by the difference in LSA. In other words the IVC figures are closer than what you'd expect from a first-glance look at the duration figures. I love what you're doing here; one good test is worth a million internet opinions.

[@BEANS-O-MATICtransmissions]

I think alot of the tight LSA guys are coming from the DV camp. The duration and I to E ratio theories are what was pounded into us from the magazine days imo. From the testing you've done and what has been done on LSs, they seem to need less timing from an efficiency standpoint.

[@jamessincleair8164]

I'm glad to see that you're doing these kind of things. But I would like you to do some things on older engines from the 60's and 70's. Like the 350 , 400, and 455. By Pontiac. Along with the engines from Chevrolet, Ford, and Chrysler. Including the smaller engines like the 5.0 by Ford and the slant six completion cams

[@biastv1234]

Magnificent. I was here for the rant . Great factual analysis

[@ericwhitaker2011]

The Comp Cam had less cylinder pressure due to having over double the overlap. So the tighter LSA didn’t work as typically seen in testing. TS cam = IVC- 43.5, Overlap-12.5 Since we don’t know the intake centerline, I’m guessing the cam is advanced 2 degrees on the Comp Cam. Comp cam- IVC- 47, Overlap- 28 The LSA on the Comp (108) should be about right if the duration is matched to maintain the same cylinder pressure. 235/239 @ .050 on a 108 LSA, 106 ICL, 43.5 IVC, 21 degrees of overlap. This should lose nothing at the bottom and gain at the top.

[@chrisd078]

Exactly without calculating the dynamic compression ratio and valve overlap the test is not informative by just slapping parts in an engine and running it.

[@hendo337]

I think the tight LSA cam is beyond the point of diminishing returns for intake duration, Richard Holdner did a teat with a 240 and a 246 deg intake duration cam, the bigger cam lost tq and made no more Hp. It's called Stroker LS Cam Swaps: When is Bigger Not Better? The test engine was a 408 with AFR 245cc heads so it has just about the best as cast cathedral port heads available and it didnt benefit with more than 240° int duration.

[@jasonstormoen]

Eric, great test and info. It still comes down to combo, as you know, but I can't believe all of the people in the comments. I would not want one touching my sbc or bbc, and I'm old school SBC and BBC to the end.

[@OEMishGarage]

One thing I noticed is that the 112 camshaft has 12.5 degrees of overlap and the 108 camshaft has 28.5 degrees of overlap. I'd be curious to see how the engine would respond to a tighter 108 LSA with the same amount of overlap. So, the .050" duration numbers would be 221/236. This would at least keep the dynamic compression a constant in the test.

[@hendo337]

The dynamic compression could be increased by sciencing out the ICL and advancing it to the point where it adds as much cylinder pressure as possible while still being able to pull to the necessary rpms for the best peak HP.

[@grrh77]

IMO those heads are SO GOOD that on a 4" bore basically anything thats not 420+cuin that even an small cam is able to meet the airflow demands. So adding more cam is no different than adding more head, it simply doesnt need it! Sure it will make a few more hp but making BIG gains isnt going to happen

[@BEANS-O-MATICtransmissions]

I don't completely agree yet, because until a "big" high lift cam is tested, we won't know what it's truly capable of. I'd like to see something in the .670" - .690" lift 112-115 LSA .256/.272 @ .050 on the 13:1 setup to REALLY max em out. I feel like the slightly bigger dur cam would've done better on a wider LSA but it didn’t have enough lift if it did to go 715ish HP

[@hendo337]

this 408 with those ProMaxx heads is probably not benefitting because the intake duration is too big, here is a test Richard Holdner did with a 408 with 245cc AFRs that made no extra hp and less tq with a 246° int duration than it did with 240° int duration its called Stroker LS Cam Swaps: When is Bigger Not Better?

[@peskypeet]

Morning E. Love the camshaft stuff.

[@chrismichael5016]

In my opinion it seems like lower compression 9-11:1 like the tighter lsa and 11:1 and higher do better with a wider lsa... Can't wait to see what happens with the next set of heads

[@keysautorepair6038]

Love some tight LSA videos great info thanks.

[@itachiuchihathechosen1466]

The Master of all Masters is David Vizard

[@Drunken_Hamster]

I mean... He kinda got dragged in the shootout by a guy who individually chose valve events. However, I'll freely admit that's a more involved process than using an LSA formula and then deciding how much overlap and lift you want.

[@Melomanisch]

@@Drunken_Hamsterthere are a few guys that are sure that the cam DV ordered (I think produced by BT) did not meet the specs the cam really had in the end. Cattledog also calculated that and is also sure, that sth was wrong.

[@Drunken_Hamster]

@@Melomanisch Maybe BT sabotaged him. DV has previously called out BT for his poor cam designs and called the man foolish for his belief that LSA doesn't matter at all.

[@evilinside5984]

@EricWeingartner- ❤ your testing. We all have our best bench dyno thoughts, in our heads😉 I really enjoy actual data. Im really looking forward to seeing the test difference, with lower compression. I have always thought that 8 to 9 to 1 comp., regular/average type "street" engines, that use 87, or 89 octane, would benefit the most from tighter LSA's. I also think that "Any" engine, that responds well to a lot of timing= is not very eff., would benefit more from a tighter LSA. Since LS engines are typically very eff.= most run well with low timing, i feel they don't respond well to tighter LSA's. I also feel if a engine is limited in RPM capability, it may favor tighter LSA, especially if it responds well to high timing. Your thoughts would be very much appreciated. Im a former drag racer, that had a 9 to 1 comp., solid roller cammed 406 cu. In engine, cam was Comp 300 AR= street roller series ( 255° @ .050, .575 Lift 110° LSA +4°adv. ), in a "91" S-10(race wt. 3400Lbs. Im very Big, & it had a heavy ford 9" rear end w/3.50 gears), 28" drag D.O.Ts, it had average, unported, Iron Eagle 200cc cast iron heads, Edlebrock Rpm Air-Gap intake, 750 holley Dp, w/notched floats & jet extensions, blocked off power valve(buddy talked me into doing this= great throttle response, but sucked for cruising! Had 80 jets front & rear), 1" 5/8 shorty headman headers= way to small, w/manual exh. Blockoffs, w/3" dual exh., with 2 chamber flows( they dont flow but they sounded mean ), & about a 100 shot of Nitrous. 11.50s @ 115 Mph, on engine & 10s in the 120s w/the little Nitrous wiff! Im disabled now, & have not been outside in Almost 5 years now, so youtube videos help make my life much more enjoyable, so thank you sooo much, Eric. I Really Appreciate you. Thank you, for taking Your valuable time, to make these videos💖

[@JohnH.-qp6fb]

When I was in Cup engine cell, those dyno's hunted like yours. They ran a hundred percent second wherein it was really notable. They used two cells, the one used last was calibrated for 140 degree air temp designed into the software. Super Flow never worried about the surging as it always repeated. Just a tidbit today.

[@flicksifyr6793]

Still waiting for the someone on youtube to make a video comparing cams that all have the same over lap but different lsa/duration. (108lsa 224/228 and 112lsa 232/236) Both cams have 10° overlap at .050. I would love to see a test like this please

[@HeadFlowInc]

486 average HP will walk away from the 431 cam all day. Most manufacturers lean towards a wider LSA to avoid “Low manifold vacuum”. BTR has used the tighter LSA in the smaller cams with success. NA Race applications like the tighter LSA cams. Application specific LSA depending on where in the RPM range you want to optimize power.

[@brandonroseman1039]

I was wondering why this wasn't mentioned, 50+ more average?

[@WeingartnerRacing]

Because it wasn’t 50 average better. One pull started later so you are not comparing same range.

[@edpetrocelli2633]

Richard Holdener did a LSA vid with a LS. He ordered 4 cams from BT. Lift and duration exactley the same all run in the same motor. He only recieved 3 of them from BT and without exception the engine picked up HP & Torque through most of the whole sweep.The only variable was the LSA. There sees to be some variables at times you don`t concider or don`t recognize but for the most part most and I say most of my engines that I do dyno support the tighter LSA thinking. Good Video none the less. Any Info is good Info

[@ezmny1387]

This engine is 13:1 though

[@edpetrocelli2633]

@@ezmny1387 My dirt motors were 14.75 on a 106LSA with conciderable more duration and turn right at 8000rpm, as I said we engine builders may not recognize or concider all variables. In fact all my compression motors are at 106, ICL 102 or 3. None were LS motors that might be a varible I was talking about.

[@jarez3781]

Try both cams at 108 and 112 with the same specs and see what numbers it gives.

[@thomasmcgee3766]

frieburger did this on engine masters also

[@lukesimeon5756]

Holdener also did an LSA test 108,112 and 120 and the 108 made better TQ and hp with same duration and lift ... every combo is different

[@johnhein3915]

I can’t wait to see that solid roller in it

[@markcarter5491]

In my opinion the big cam has way too much overlap for a head that flows well. Great video keep it coming we love data like this

[@freelancerider100]

Less overlap?! Blasphemy!

[@jimlathrop8603]

Good testing, and i look forward to the lower compression test results.

[@genemanno1533]

Yes the LS don’t need as much cam as guys think cause they flow better. I would like to see the data down to 2500 RPM’s. Coming off a street light it would be interesting to see. SBC and LS are different animals as you show. Nice😊and better for power brakes vacuum.

[@natesaforverk166]

TSP S2 LS3: Intake open: 5.5 Intake close: 43.5 Exhaust open: 57 Exhaust close: 7 Overlap: 12.5 CC Mystery (advance not specified, assuming +4) Intake open: 17.5 Intake close 45.5 Exhaust open: 55 Exhaust close: 11 Overlap: 28.5 That's a lot of overlap on the mystery cam. No surprise that it killed the low end, but it is a surprise that it gained basically nothing up top. Too much of a good thing, I guess.

[@TimothyArnott-m7z]

Hey Eric, Tim here, yea, i tire of i-net warriors.....who REALLY dont know crap.......i think u said it best, when you said...."well did u watch him race??....oh, it was SO fast, u didnt even see him"......yep.....i was VERY surprised at the cam swap outcome......i wudda thunk the tighter LSA, and less spread wudda netted more.......each motor is its own dude......12° of seperation in common in an LS....i'm a Pontiac guy, i need a 6-8 spread, and like a 108-110 LSA for my shi% to perform, but each engine has its own thing.....i think ur MASSIVE testing proves certain i-net "GOTTA BE's" false/garbage, unless you've dyno'd it urself......i enjoyed my brother, and KEEP TESTING PLEASE!!!..i'm a gear head nerd.....i will trust ur testing, and #'s, b4 i wud blab, and say i-net garbage, as to what to do, again, EACH ENGINE is its own animal.......you are KICKIN BUTT!!!!...i am VERY proud i sub'd so long ago........PROVE IT THRU TESTING!!!....like Vizard preaches!!!...yep, enjoyed, TY sir, PEACE to you!!

[@bobgyetvai9444]

These LS engines sure do have some funny quirks . It seems each different style head brings its own set of rules too . Its hard to understand just why they hit a certain power level and Bam a brick wall is there ?? Especially NA ?? So much power comes so easy that this is truly baffleing !!! Ive run a big inch mouse for years and i just dont get it . I dont think the LS has truly been unlocked yet . This sure is a head scratcher !!

[@edwardwood3622]

LOL Eric, people are giving advice to the guy that competed in Engine Masters.😂

[@ezmny1387]

With good flowing heads and bigger compression, less duration and overlap is needed, pretty evident of that here

[@artlife6210]

I’ve always wondered why the LSA is so often the same for both on most cams, makes total sense to me.

[@crd-nz_001]

A wasted 2c, but I will pay. I will point to the intake closing being some +10° later for the 108lsa vrs the 112, thats assuming the 108 was not advanced? If the 108 was put at +4-6° (intake centerline of 102-104), then low rpm might come back. The reasoning is that this would put the intake valve closing event closer to the 112 helping restore torque in the lower rpm. However, I doubt that will fix the top end. To fix that, more head cfm is needed. 680 hp is around the "calculated" 340cfm requirements. Thank you for sharing your knowledge.

[@Tom-z1q]

I agree with everything Eric says here. Compression ratio definately can have a huge influence on LSA. Overlap flow and blowdown changes from engine to engine. Some may very well prefer 108 or even tighter. Back in the eighties. Tight lobe sep was more common. But also were less dyno cells less testing and a greater percentage of poor flowing heads. The head architecture, geometry, valve job profile, valve position, compression ratio, lobe profile, carb size on and on and on all afect lobe seperation. Every engine is different.

[@scottbennett3119]

Good test! How about getting Texas Speed to send you identical cams other than lobe separation angles? Is that doable?

[@joshuagarvey9362]

I had my cam reground and installed because I was curious about this from DV cam chart.I went from a 110 to a 107 in my 406 sbc.same lift and duration just changed the lobe.I did notice a little bit of a difference down low.Little more ufh.

[@magnusdanielsson2749]

I wonder how the different lobe shapes of the cam changes things. A test with two different duration/split but the same lobe shape would be interesting.

[@francfurian8215]

Good video Eric

[@brokejoebuilds5165]

I believe chamber and port position effect desired lobe seperation more. Low port sbc will need to be cammed differently then a high port LS at a 15 or less angle.

[@joshuashuck3994]

Real life testing hurting feelings, i love it!

[@Matthew-uj4zx]

So funny reading the comments and so many people believed they would have predicted the results. Next time Eric, do a summary video with the all the information before testing, and see most the predictions be wrong in the comments. I'll be honest, I would have predicted wrong. If it was an EFI with factory style intake manifold, I would have chosen the Texas speed camshaft, but being carburetor, I would have predicted the comp cam to be the winner. Goes to show, every combo is different.

[@chrislangdell117]

Cool video. The only problem I see is with a 13:1 compression ratio you need a bigger LSA. That's why the 112 LSA dis so much better. It made its power through the trapping efficiency. In a higher compression big block. Like this 114 or 115 LSA is where you would want to be. I know this is an LS motor but power is power. And torque is torque. The bigger LSA under high compression confirms my favorite camshaft Guru's statements and builds. Love it great video.

[@v8packard]

The design of the Gen III and IV heads can achieve very high volumetric efficiency, if the setup can support it. The 108 lobe separation angle sacrifices some VE in comparison to a wider lsa. That shows in the power curve. I tried looking at the dyno sheet, did you track VE?

[@realazliving]

His air hat has issues with accuracy, so probably not.

[@bdugle1]

Several observations, hopefully no parroting. That said it’s info from dyno results published by other folks. First, the BTR Truck Norris cam is tiny. The only way you’d want that in a 408 is for towing (obviously my opinion). The Texas Speed stage 2 is probably intended for a 6.2 (376 cu in), not so much a 408. It does very well, though. Holdener’s many tests show that LSes like big splits between intake and exhaust duration. The two “big” Comp cams Richard often uses, one cathedral and one rectangular port, have the same intake duration at 0.050, but the rec port one has more exhaust duration. Comparing the two cams on the same combo, usually a 6.2 but sometimes a 6.0, the rec port cam loses a bit at rpm below the torque peak and gains a bit above. As I recall all these variations are single digits. When Richard put the big Comp cam in a 5.3 with good heads and intake, he got a power peak at 7700. I would think the right cam would peak higher than 6600 or so in yours. Another “well understood rule” (parroting?) is that higher compression generally likes wider LSAs. My two cents would be none of the cams tested so far are really optimized for your 408. In spite of that, you’re doing the testing and that’s the only way to get real answers. Thanks, Eric.

[@senseimarvin454]

perhaps a better way to compare LSA effects is to have custom cams ground with the EXACT same lobe just at different angles. I know on all MY SBC and BBC engines I always get better results with tighter LSA's than similar cams with wider LSA's.

[@hendo337]

Yes, absolutely, I think that this cam had more duration than would be beneficial. Look at this test done by Richard Holdner with a 408 with AFR 245cc heads, 246 deg int made less tq and no more hp than a 240 deg cam, its called Stroker LS Cam Swaps: When is Bigger Not Better?

[@RichardSteelman-w4s]

Cam Doctor both cams for the truth.

[@richardvanmarter8780]

It would be fun to see what DV would come up with on his cam program, feed him some numbers

[@rolandotillit2867]

Overlap made the power band more linear and slightly better in the midrange, although that could just be run to run variation. Question is, which one has better throttle response/drivability.

[@yarrdayarrdayarrda]

I always thought a decent split on the exhaust duration helps the engine to carry out farther. (more gradual fall off past peak HP.) As an afterthought, when most of the big LS cam suppliers have wide separation angles and big exhaust splits, it's reasonable to assume they've done testing and their final grinds produce favorable results. I had a customer bring in a bone stock 2006 6.0 out of a truck, cam was something like 23x on the intake, and with the rocker fulcrum kit, a set of springs, and a carb/Victor Jr single plane the engine belted out 475 HP. I'm sure the engine had 100K original miles, and it belted out impressive numbers (to me) for minimal investment.

[@ChurchAutoTest]

Interesting stuff. Always love good data. Always wonder about the combo too. Changing more than one variable is always sketchy but...The TS cam looks to be peaking about where'd I'd expect based on past experience, but the Comp wasn't really any higher. Normally on LS stuff with a duration that big on the intake the power peak will move up the rev range, unless you're sticking with a stock/stock like intake mani, then the peak just hangs on forever, but doesn't really climb. Never did a Victor on the LS though so don't know where that thing does its best work. Keep posting!!

[@johnginnitti4598]

All the most powerful LS engines I see tested always have a 10-15 degree intake to exhaust split and the LSA is always around 112-114..........just seems to be what those engines want....they don't respond well to cams that would normally work well for gen 1 small blocks or even Ford Windsor engines.....

[@baby-sharkgto4902]

Exactly

[@hendo337]

Depends alot if the engine has Cathedral or Rec port heads. Cathedrial ports will perform well with tighter a duration split and LSA than rec ports that are bandaiding the huge difference in flow Int vs Ex.

[@lukeyb_07]

So the cam I specd for an LS 3 that made that made 550 tire through a dog box and quick change with only an 8* split must be fake news

[@slopoke22]

You makin me wanna start puttin up vids on my channel again! Im a cylinder head guy as well, also engine builder, but i love cylinder heads and cams. I could talk with anyone on these subjects. But you are correct everyone is a cam expert, lol

[@slopoke22]

Also, I'm gonna sub I've been seeing you a while. But what S&G machine do you have or use?

[@WeingartnerRacing]

I had a Rottler’s sg7 I now have a Robbins sg8. Both are good but the robins is better.

[@8wireracing694]

Would like to see your testing between a cathedral port smaller ls1 and your 408 ls.

[@WeingartnerRacing]

I already did a few videos back.

[@yadaelroiy]

i think the 13:1 compression made the 112 lsa cam the right choice. if it had 10:1 , i would go with 109 lsa.

[@confuse3671]

Talking with Herb Gebler many years ago (RIP), he would always talk about signal. A tight lobe separation angle would give better signal (better scavaging) assuming everything else was tuned. Gebler was a header guy (for the likes of Warren Johnson) and all about tuning headers.

[@cs2-llc]

Higher compression = wider LSA. Lower compression, restricted flow benefits more from the tighter LSA. Your real world testing proves this out. Looking forward to the next test.

[@drivinwithdrew7676]

If I was to guess, I would have thought the bigger cam would have traded more torque for a little more top end, makes me wonder if that intake is holding it back now, I haven’t seen many high rpm carbed ls setups, but with those heads, a cam that size would be in the 7500 rpm range with a holley high ram or low ram, with wayyyy less torque, wish I could afford to send you a holley setup with a carb adaptor

[@W.A.R.R.]

I’d say the low torque is from the duration, not the lsa. If you took that tsp cam with the same exact specs except made lsa 108, it would 100% outperform the 112. We know tight lsa increases low end torque. But more overlap decreases low end torque as well, which lsa plays a part in. If going for low speed torque, like the truck norris, the idea would be to have shorter duration and tighter lsa so your overlap is somewhere around 5° or less. Then you could do .600 lift or whatever and pick up a little on top if you feel like that’s going to make you slee better at night.

[@slicepizza3263]

Opinion: A couple flaws in the 108 cam. 1) the higher compression ratio needs a wider LSA. 2) The greater flow of the LS head needs a wider LSA. 3) The longer exhaust duration may help the the engine lengthen the over rev time which may improve the average power output.

[@hendo337]

I think you are wrong, I think the intake duration is beyond the point of diminishing returns. Look at this test Righard Holdner did with a 240 and a 246 cam in a 408 with AFR 245s, the smaller heads made more tq and the same hp. Its called Stroker LS Cam Swaps: When is Bigger Not Better?

[@dalewarriorofthesea3998]

The LS head design uses wider lsa then small block as the intake port doesn't need to be tugged on by the increased overlap timing event

[@hendo337]

Maybe that mystery cam needed to be more in the 238 intake and 246 exhaust neighborhood, .620/.620 lift 107 or 109 lsa maybe it got to the point where more intake duration wasnt helping and didnt have enough exhaust duration and lift and maybe it needed to go a degree up or down on LSA. Maybe the Summit Single Plane would be better 240/252 .569/.569 106 then maybe run it with 1.8 rockers to get .604/.604 lift or 1.85 to get .620/.620 lift. That is crazy impressive power from a 408 680hp is serious, that Super Victor is impressing me, those ProMaxx heads too. Here I was thinking that a basic bish 600hp if I was lucky 408 was stroker might not be worth my time, I was thinking about trying a 7.3 Godzilla or GenV L8T bored to 4.125" with a 4.125" stroke 441ci build to get 650-700hp. Super impressive test engine no doubt. You ever know what you are going to happen until you test the engine like you say. When it's a custom combination you never know exactly what can happen there can be idiosyncracies and something that people think will work might not.

[@MichaelOReilly-nf3bx]

Ls engines deffintly seem to love 1 7/8" headers as aposed to 1 3/4". Doesn't hurt them down low either from my experience. Would be interested to see a back to back in your setting compared to chassis dyno/hub dyno. I'd be inclined to say you will see a big gain from 1 7/8 and possibly a different result with 1 7/8. Just what I've found. Love your work and videos.

[@miniblackmog]

It would be interesting, to fill out a couple a spec sheets and order 2 or 3 cams from people who do spec (chris padget at bullet, mike jones at jones cam) cams and see which one works the best.

[@therealunknown123.]

It still boils down to the combination you have whether or not this or that cam will optimize more power! This is why you can customize your camshaft and Taylor it to your combination!! Trial and error my friend!!

[@cecilandrews7479]

Curious as to what the vacuum reading for between the two

[@stevenkirk2563]

Eric when are you meeting David Vizard? He mentioned you were visiting?

[@CLEEPER1]

That promaxx seems To be an excellent head

[@TK-eg7eg]

Great video as always!!!!! Have you ever flowed the GMPP LS3 cnc heads? I searched you're videos but didn't see them. Just wondering because I have a set on a 6.0 with a magnuson supercharger. Thanks!!

[@alonzahanks1182]

Id actually like to see both cams time 4 degrees earlier than top dead center and dyno again

[@michaelgiglio1571]

Been enjoying your shows Eric. Now. Can you try those type cam grinds in ford Windsor form, where the heads have strong response. Yes, to me I can hear something lazzy with the gm flow activity from start to finish. Those guys might have a point about ratios. Mike.

[@LynnTwinCustoms513]

Good information! Thanks for sharing.

[@thebradnoyes]

I like it. Anymore though, I think there is such a large aftermarket for LS motors, one cam/head combo is going to do something completely different than the other.

[@JOHNNY07-wu3cd]

Great experiment, keep them coming!

[@donbrutcher4501]

Guts are telling me, when you get near 700 HP, you are into 2" dia, or larger, header territory. Also, a lot bigger carb. Did you record manifold vacuum during the tests?

[@dannydurham5716]

I thought we learned in the early 90's that better flowing heads like a wider LSA. What about an LS motor would change that?

[@donaldgrove229]

I'm the best I've ever been. Lol Thank you for what you do! 😊

[@realazliving]

Thanks Eric, great video as always. Oh I heard if you put the cam in backwards and coat it with cheez whiz it makes crazy torque numbers. It’s on redit it must be true.

[@richardnelson2519]

I know that the racing side people dont care about the emissions part but it would be helpful for the street guys to know how lsa affects that part, thanks for any advice/knowledge you could bestow on the average person