LSA CAM TEST-108 vs 112 vs 120

FULL RESULTS-CHANGE ONLY LSA-LS CAM TEST. What happens when you change ONLY the LSA of the cam and keep the lift and duration the same? Does LSA change power? Do LS motors like narrow (108-degree) LSA or wide (120-degree) LSA?

[@Co-xm1nt]

My guy in 3 months has proved more combinations than ls1tech has for the past 12 years

[@n5yiz]

Agreed!

[@crw3673]

Sad but true!

[@RumblestripDotNet]

Three months of videos but if you pay attention when he's pulling up the graphs, some of these tests go back to 2007/8 if not further. They are an amalgamation of the tests he's done in print for 20+ years.

[@JunkGaragehome]

@@RumblestripDotNet yup amazing the information people have forgotten or ignored

[@jefflowry4112]

You have to watch generlizations. The reason this picked up so much is because the duration was so undersized to begin with. If you have much larger duration on this and do the same thing, the reverse will start to become true where a bunch more overlap kills low end

[@pauldulworth2768]

If I ever get a chance to either build or simply can swap an LS all I have to do is watch your video series, pick the combo I think will work best for my intended vehicle and just duplicate it. You’ve take all the guess work out of it for us all. What a service you’re providing. Thank you.

[@escuelaviejafarms]

Please, pass the knowledge along and share the crap out of his content!

[@kevinwest3689]

If I had Richard & Brian Tooley a large bank account a time machine a girl with a short skirt and a Long Jacket small hands...that would be all I need, ok the girl has a twin sister, That would be all I need, 😏

[@UnityMotorSportsGarage]

I did the same test on a 4.6 2v back in '09 for my buddy David Vizard... My results mirror what you came up with on the LS! David is a huge fan of tight LSA's and he even has come up with the controversial 128 rule.... Awesome job like always!

[@richardholdener1727]

David's has done a lot of crazy and cool stuff over the years

[@UnityMotorSportsGarage]

@@richardholdener1727 you sir are correct! I know that he is impressed with the work you have done as well... Keep up the great work!

[@Warloch1]

DV's 128 formula says an LSA 107 should be ideal for this combination. I'd like to see a cam test using an LSA of 107 with duration numbers starting at 225 and increasing by 15-25 degrees. I think this could show how David's thinking works across the range of street to race cams.

[@darrinstone49]

Exactly! LCA is a calculated using the ci & intake valve size. AKA allowing enough time for fill. We advance the cam to help lower the rpm when it will start making power. Every 2 degrees advanced lowers it 100rpm, aka 4 deg = 200 rpm sooner. This is a total shift, top rpm is also lowered the same amount.

[@darrinstone49]

Crazy part is BTR thinks LCA is a mear byproduct, I don't follow that line of thinking. I have never gone as tight as 104, 106 is my tightest & I usually shoot for a 108 by using better heads. Different rocker ratios (larger) can also allow a slightly wider LCA but is limited & small. All about choosing the correct combination of parts that will all work together.

[@chandannel]

What do I think? Hell, I don't know anymore...between you and Engine Masters everything I learned as a kid was false. Can't wait for the next installment.

[@chandannel]

I understand physics... and english. My point is, all the hearsay and conjecture are being disproved through a scientific method and theory to practice. Sorry, I didn't have all this information available so easily at a younger age. Thank you, Mr. Holdner for sharing.

[@shelbyavant5081]

@@bigboreracing356 All he said was that he was taught some things as a young person that wound up being inaccurate. No need to be a jerk, I'm sure you have fallen prey to misinformation at least a time or two. We all have. Some of us are man enough to admit it. They knew everything in the 1930s that we know now? You're out of your fucking mind.

[@shelbyavant5081]

@@bigboreracing356 The truth about what? That you're a keyboard warrior who thinks he's "the bad man"? How would I have your comment removed? It's not my video. I'm a commenter just like you, but with some substance. You talk about safe spaces, but probably drive a mustang. Kill any bystanders lately?

[@dburkh91]

STREET RACER what’s your point in trashing someone for something they learned or were told wrong when they were young? Don’t be a douche, we all have been told things that were wrong. Doesn’t give you the right to jump all over someone. 🤷🏽‍♂️

[@jaredfarney675]

@@bigboreracing356 I really enjoyed CT magazine growing up !

[@shotamakarashvili3714]

David Vizard published very good book with great explanation on LSA and how t choose best one for particular application.

[@jaredfarney675]

Great book!

[@adamsweet3587]

I have been reading and have David Vizards books from the early 80s and have built numerous engines on his specs, they have never failed to impress, starting on the Mini A series, Ford Pinto, Chev 350 and now finally the LS series.

[@jaredfarney675]

@@adamsweet3587 I really enjoyed his how to port and flow test. Also how to build horsepower. Really great stuff!

[@frankrizzo2724]

Shota Makarashvili whatever happened to him?

[@jaredfarney675]

@@frankrizzo2724 he has a KZbin channel to promote his lectures and books.

[@r.d.riddle2068]

Around 50 years ago I was taught to run narrow LSAs as much as conceivable to help capture cylinder pressure at higher elevations like in Denver. We were always happy when we got cams at 110, and really happy at 108.

[@GregHuston]

I think I need to dump the 112 in my Olds 350 for a 108!

[@MasterWitchDoctor]

My NHRA SS/J 66 Chevy II uses a custom ground solid roller with a 109 LSA I had ground using David Vizards 128 rule. My heads are NHRA Superstock legal Edelbrock highly modified by Edelbrock to coincide with NHRA rules. I shift @ 9000 so its wound up pretty tight and pulling off a consistent 8.60s with a .060 over 327 and M22 tranny is no easy feat. Listening to David Vizard and reading his books has made not only my Superstock fast but my Stock Eliminator K/SA Monte Carlo SS (with the factory L69 305). This test Richard just run backed up the 128 rule big time. For big blocks and Fords is 127 and he has videos on it if you are wanting to learn. Thanks for this video Richard you are very entertaining and easy to listen to unlike Freiburger and Dulcich.

[@iamblamb501]

Yes, it would be cool to see this test done on a 5.3L and 5.7L

[@msk3905]

Been watching david vizzard lately and he has a formula that puts this engine’s ideal lsa right around the 108 that made the most power, maybe he is on to something. Oh yeah and as always another great video by richard

[@davidreed6070]

Vizard is up to something He has been DYNO testing for 40 years

[@petercermak4095]

Me too. 128 sb chevy formula

[@edpetrocelli2633]

David Vizard been saying that for years and I believe it`s true. 106 seems to be the magic number for circle track and higher compression, 2bbl seems to like the wider LSA along with bigger CID like 454 and bigger.. There are so many contributing factors I don`t think a person could pick the perfect cam with out a dyno, back when I was a kid cams were listed by lift, duration (advertised) and overlap. I think Isky was one of the first guys to start tightening up the LSA and he made a high mark to reach for

[@AB-80X]

That really depends. If you have high compression, you need more LSA

[@MWR-lg9qp]

You run tests I've always wanted to see. Thank you again for the awesome data you create and provide. Great job!

[@BlueMountainRacingEngines]

Very interesting. I run in a tightly-regulated race club where LSA is basically all we have to play with (DOHC, adjusting stock cams) and we are typically living in the realm of 103-105 LSA. Our duration numbers are pretty high (streetbike engines) and we operate around 6000-12000 rpm. There is definitely a point of diminishing returns in wide LSA for top end! This is why we test!

[@dennisrobinson8008]

Excellent. Richard test gives the explanation point. I wonder about 104 or 106. I've even seen people run 102.

[@brianmeyer5535]

Richard giving the people what they wanted. Awesome. Patiently awaiting SBF combos.

[@aaronford7124]

Brian Meyer Cleveland’s forever!!! J/k. Me 2.

[@axlegrind4212]

my take away: don't rush out and buy a camshaft on a 108 degree lsa. the 112 degree lsa cam is so close to the same power numbers it makes more sense to use it in a speed density fuel injection system because it gives better vacuum at idle and allows the map sensor to work correctly.

[@dreece2000]

Good point, I hope most people can understand that.

[@Freebaggin]

GREAT test Richard! This test repeats ALL other dynos I've seen where only LSAs are changed. Yet you read all the tech info they say the reverse. Well done.

[@arthurrose6473]

Good video - people are realizing the tighter LSA means more acceleration torque AND NO LOSS upstairs- bigger displacement responds even better, of course vacuum drops due to more overlap and worse throttle response below 1500 to 1800, so an automatic and smaller engine should use a somewhat looser converter, BUT make sure converter stall speed is below top gear or overdrive RPM at highway cruising speeds.

[@rongravel4585]

I was always told this and all our drag cars had the super tight LSA. But it was nice to see it in a graph to prove the point. Richard. Your the man.

[@brianbrigg57]

Great test but with the 108 LSA looking better all the way it would have been nice to see another with even less LSA to see what would happen.

[@pandora1875]

I am learning so much from your videos! Thank you and keep them coming!

[@slow5oh89]

Was just trying to choose lsa for my new tsp cam last night! Thanks for the test Richard, you're the man!

[@ORego-em8yf]

Just subbed, you really get to the point without unneeded banter! Thank you for an informative video

[@richardholdener1727]

Welcome aboard and thnx for the support

[@jnieto490]

Gotta have that chop! Besides power down low with good torque is what I need!

[@bruceleroybell8139]

Thanks Richard, you have answered my next cam choice. This info is priceless and worth gold.

[@drakeolson2539]

Man, I have always wondered what the change in LSA would affect!!! Thank you for the information!!!!

[@velr50gt]

Exactly what I was saying on a different video about the intake tests. Just because you have a long runner intake you don’t need to run a wider lsa. The reality is that tighter lsa cams tend to make more power even more so when naturally aspirated. Thanks for the video!

[@RAZER1RR]

Back in the70's Isky and Clay Smith had a bunch of cams at 108, they were ahead of the curve compared to most cams. They also made very good power through out the rpm range. Nice test

[@darrellsomers5427]

Racer brown made good cams too back in the day

[@bobryan6474]

Another great informative video Richard. Thanks for showing what’s behind the curtain when it comes to making power.

[@timseely2422]

Great job explaining LSA. Tighter more chop & more bottom end, wider less chop more on the top ! Thanks Richard!

[@monsterzard1]

THIS IS WHAT IVE BEEN WAITING FOR!!!

[@bigal878]

Great test 👍🏻 Would be great to see these exact three combos now fitted with a blower. Richard keep up the great work

[@richardholdener1727]

same

[@mathewboyd3746]

Thank you! I only just discovered this vid of yours and I been looking for this test and demonstration for a long time. Now I'm really interested how this would apply to other smaller NA engines such as 6 & 4 cylinder engines which are not just V8's. Thanks again. Really like how you conducted this test in a real objective way.

[@V12LS]

Thanks for doing this test Richard, really interesting.

[@crash5811]

There is an exception to every rule, with a few exceptions.

[@notme8121]

Good one thanks. That's what I wanted to know and that was my hope that tighter lobe separation will give me better low-end power and a wild chop without increasing lift and duration.

[@johnhazel9986]

Thankyou! These dyno tests where you change one thing are the cool ones!

[@bowhite1293]

One of your best tests. Great job

[@Ginofia]

Nice this is a topic iv always thought about. Few things I knew for sure was the lower the LSA = more chop @ idle but also slightly more difficult too tune. Now we need the results on smaller cube, less radical builds like your budget 5.3 & 6.0.

[@TheTmshuman]

I feel like a certificate is in order after watching all of your videos.

[@marcstlaurent3719]

Great test , another always asked question answered

[@RunningJoe]

subbed! totally explained LSA's to what I was hoping to understand on paper! also totally explains my ls swapped cruisers cam behavior now too

[@TheSlim93gt]

I've had the opportunity to work with a few engines using a 108LSA over the normal off the shelf selection. Two 347 SBF's and a 388 LT1. All engines were amazing street strip combos. Still had manners down low, came on strong in the middle and ripped up top. For the 330 to 400ci range, I don't think it can be beat.

[@jerrymurphy247]

A lot of great info on this channel. Clearing up a lot of misconceptions. Keep doing what your doing brother!! We appreciate you!

[@frtaylor29]

Great video! Highly appreciate this one.

[@mannypantoja8252]

This channel rocks!! Very very informative!

[@jackpinnell3204]

Wow! Great video Richard! Had no idea that a tighter LSA (with choppy idle) would make more low end power!?!?! NOW.....I can have the best of both worlds!!! I can put a 108 LSA cam in my work truck, have a bada$$ idle and tow my trailers (enclosed tool trailer, 6T flatbed and my I/O boat trailer) all day! ALL your videos have awesome content and enjoy the heck out of them. I watched several of them more than once to make sure I'm absorbing the content for my LS/OBS swap coming up.

[@michaelangelo8001]

Don't get too excited... If that were the case, all cams would be ground on a 100 degree LSA. You get more low end to a point, and then, nothing... Makes your power-band more like a two-stroke.

[@EGGINFOOLS]

It has to be sized to the motor properly. In this case the 402 just happened to like the 108

[@n5yiz]

OVERLAP Ls9 = -24.50 Crane 210/218 122.5 = -18.00 Crane 232/242 (.624/.624) 120 = -3.00 112 = 13.00 108 = 21.00

[@indyrock8148]

Exhaust scavenging induction event. The fifth cycle.

[@autobodyspecialistsinc.4397]

all those number can change with different grind timing ...

[@n5yiz]

@@autobodyspecialistsinc.4397 If I hand you a cam with 10 degrees of overlap, you can change that?

[@autobodyspecialistsinc.4397]

Yes, I agree. for some reason i was thinking in terms of the timing events in relation to crank position...

[@glennmanchester1568]

The L.S motors are a whole different animal than the old small block when it comes to cams and l.s.a it seems to me they can do so much more with the l.s cams as far as all of the numbers more lift and longer duration and thus not needing to tighten the lsa as much and fight with the choppy idle and vacuum issues like in the past if I understand right it's due to the cam actually being moved up and ,made larger is this correct ? I'm interested in anything I can. Learn. Pls

[@mikie9077]

YOUR VIDEOS ARE GETTING BETTER AND BETTER. I LIKE THAT YOUR PUTTING MORE TECH DATA . I WOULD LIKE TO SEE A TEST ON HYDRAULIC LIFTERS VS LIFTERS LIKE RHOADS.

[@GreatLakesLogger]

Hey I stayed up late enough to catch the upload! BTW, awesome video Richard!

[@TheSteve1175]

Tell em what happens to the vacuum. The brakes 😁 Great video 108 centers rock ⚔

[@volvospede]

Do you think vacuum suffers much with smaller LSA? I need good vacuum for the brakes or need to go hydroboost.

[@ttank94]

@@RadRidesByCru I run a 228/234 .614 lift in/exh, 108 LSA in a 355 CI gen II SBC (LT1) and my vacuum at 825 RPM is 13.5 to 14 In/hg. So vacuum in that engine was likely similar given more duration and more CI @volvospede it really depends if you plan on running an auto or manual? As I just pointed out my engine doesn't produce a ton of vacuum at idle, but since I have a manual and a working checkvalve on my vacuum canister my brakes are no different than stock because on decel at cruising RPM my engine will easily produce 25 in/hg at about 2000 rpm with the throttle closed of course. This is plenty of vacuum to charge the canister, and have never noticed a change in my brakes. An auto would obviously be a whole different game though.

[@jgkk5862]

I have run as big as 266@50 on a 99LSA and still had enough vacuum for brakes...

[@Hitman-ds1ei]

Nice, separating fact from fiction as usual top stuff,

[@rifleman7313]

Great video, very informative as before watching your videos I did not know much about LS engines except for basic generalities.

[@tc6hp]

Thank you I been asking you to do this for 6 years!

[@richardholdener1727]

this was done long ago

[@Sir_Theodore_Wigglesworth]

The work never ends... Same test with turbo, supercharger and nitrous. Thanks for everything you do Richard!

[@richardholdener1727]

it's the same with boost

[@rayjon237]

Every cam is a turbo cam.. lol

[@danawilkes6174]

Now I know why I have always ran a 112 LSA advanced 4 degrees. Intake is always more critical than the exhaust. Also with a 10 - 12 degrees more on the exhaust duration. This is what I have found to work best in the vast majority of cases, over the last 45+ years. What we also found was that a 108 LSA, (MPG) suffered on the street. It was not worth the loss of gas mileage for the little HP that was gained. That was why we started advancing the camshaft, and it worked...

[@alphaghost1633]

Fool - that does not change the LSA - you need to go back and study

[@ezmny1387]

literally all wrong, you change the DURATION to bring the overlap down, you do not change the LSA to help with drivability, having too much duration and then widening the LSA to help drivability is all wrong, if you need to do that you have way too much duration for your application

[@danawilkes6174]

@@alphaghost1633 Really. If I advance a 112 LSA camshaft 4 degrees. Then the Intake would be 108 and the exhaust 116.

[@ELIRMN]

Very good experiment, thanks Richard

[@lacboiatl]

Truck norris cam makes sense now. I just revisited this video and glad I did. Truck norris is what I'm rolling with. Thanks

[@strong_voice_of_truth]

I would like to see this test run again, but this time with the icl set to 108 for every cam. 12 degrees advanced for the 120lsa, 4 degrees for the 112 lsa, and straight up for the 108 lsa.

[@86chrysler5thave]

this....if they were all installed straight up, then the 120LSA cam's intake valve is opening much later on the intake stroke.....would like to see them all installed on the same ICL, too. would be interesting to see idle vacuum and manners for each, as well as maybe some part throttle fuel consumption (say, 40HP load at 2000 RPM, about what running down the freeway at 75MPH in OD would be)....more than just power to consider with a street car

[@strong_voice_of_truth]

@@86chrysler5thave Also dynamic compression ratio should be the same if they're all installed on 108 icl. That would be a true comparison of lsa.

[@ezmny1387]

all that would change is make the wider LSA even worse as it would then open their exhausts even earlier, kill off all low speed torque and still make less HP up top, The low LSA would just make more power everywhere

[@carbf1942]

Nice I loved my Lunati Bootlegger in my sbc 406. 108LSA nice chop great power band. Running a Summit cam in my budget junkyard 307 build, 106lsa, gm 601 heads that I cleaned up a bit. Fun little mighty mouse motor. Going to build the 406 right and put a forged rotating assembly in.

[@BLUUCIFUR]

Awesome, awesome video Rich... Guess I now know what to expect when I install that Truck Norris cam into my Pontiac LS2... More chop, and more down low-mid range, and hell maybe even more up top as well

[@mikew6135]

Lobe profile helps with valve tran stability and longevity allowing the lifter to follow the lobe more accurately hopefully without bounce. Possibly allowing larger cams with less negatives towards the valve train.

[@ssoffshore5111]

More awesome work Richard, you're cranking out the best content on YT right now! Now can we see the 108 LSA vs the 120 LSA with turbos? Maybe even SC? I know you saw it's the same, but we'd love to see it proven!

[@tiitsaul9036]

I find it super interesting. Well done sourcing exact same spec cams other than LSA. If any cam had even a slight duration or lift difference, results would be controversial. Power increase up top with 108 lsa cam is confusing. Could it be due some kind of harmonics? Matching with Intake runner length or something like that? I’d love to see a test with same cams on different displacement Ls motors. Thanks for sharing. Love the content you putting out.

[@indyrock8148]

I'm thinking it's from extra exhaust scavenging during overlap. Starts air in runner moving more, sooner.

[@meetthecarolinas9638]

I am leaning towards exhaust scavenging as well. As for the increase in low end torque with tighter LSA’s, this occurs due to earlier IVC which increases the dynamic compression. That’s the whole premise behind variable valve timing. Advance the intake cam down low for higher dynamic compression (tighter LSA) then retard the intake cam up top to take advantage of port velocity cylinder filling (wider LSA).

[@zachganoe]

Love your videos Richard keep testing

[@thebedtimeranger3588]

Great Job Richard! I learned something!

[@ElPants21]

Would love to see this focusing on higher rpms on a 4 cam mod motor. Would be super easy to change only LSA without even pulling the cams

[@bartpang]

I think you needed to go below 108 to see the drop off on the top end because 108 is about the optimum lsa for that combo.

[@michaelangelo8001]

Good Point...

[@frankrenda2519]

great job richard. your engine tech vids are great and so are your books.

[@billythebake]

Hats off to ya for another interesting vid Got to be a bunch of work, setting up on the dyno, making pulls to get the time dialed in, then swap cams, then another pull or two (or more...) getting the timing and fuel optimized, then swap cams, then... yeah, a bit of a chore, even if you hold the front cover on with Velcro And when you're done - we want more! That being said, if you want a reason to swap more cams in the dyno cell... I'd be interested in seeing u yet *another* cam comparison: this time 3 cans with different LSA, but the duration adjusted so the intake valve closed point stays the same. So, a can with (for instance) a 112° lobe spread and 230° duration would be compared to one with 238° ground 108. To try to make things as even as possible, use lobes from the same family, with as similar lift and ramp characteristics. My theories: a) the length of the header tubes and exhaust runners on this engine was tuning in make peak torque from 4200-5400 RPM where the 2 bumps in the curve are) - regardless of where you set the IVC, and b) a tighter LSA combined with more duration might allow similar cylinder filling (or maybe even slightly better) up top, and allow the harmonic tuning of the intake & exhaust to make a bigger bump in the middle of the torque curve. Some of the tests you've run with larger duration cans, that didn't seem to pick up much top with long runner intakes made me kinda' think this may be the case Then again in theory, theory is as good as practice...

[@richardholdener1727]

Glad you like them!

[@creepycrawler43]

Thanks so much for answering my exact question is a very easy to understand format

[@haydensmith9064]

that was an awesome comparison in perfect time for me. could you do the same test on a gm lsa motor in relatively stock form? i would love to see how a cam that size goes with such a tight lsa on boost escaping

[@Lokomart]

How about some lsa +0 vs +2, +4, +6 intake lobe advance. That type of data would help understand ground in advance a bit more while helping with camshaft selection.

[@euba0149]

I would love some more information on this … currently trying to learn what I can and there isn’t a lot of resources I can find on ground in advance

[@hefftoneGA]

Valve event timing is what you need to be comparing.

[@bainracing]

This changes everything! this test is a bit missleading without optimal intake timing.

[@suarvemarv]

All you read/hear is tight LSA = peaky/narrow powerband that will fall off up top. Yet every dyno test ive seen they actually have more spread between between peak torque and power.

[@scrapmetal_sleepers]

Yessssss I've been waiting for this one!

[@l96sierra14]

The stroker needed the overlap. Stock 5.3 will limit how much overlap you can throw on it I think. We need to test that!!! Title “how much overlap a 5.3 can use? How does the graph looks!!

[@JACB006]

If you can only run a test over a limited RPM range .... Why don’t you run two tests? For a street car I would like to see what is lost low down.

[@johnagreen883]

Welp, I'm seeing this two years hence, but of course it's still very interesting. I've wondered the same thing about LSA for many years now. I'm positing the lower numbers at lower RPM for a wider LSA have to do with how the wider LSA bleeds off more cylinder pressure. Both valves are still open for several degrees of rotation, and you can't build cylinder pressure until they are both shut. My bit of homework on the newish cams sold for use on low compression engines run in line with this. Comp Cams' Thumper series, Hughes Engines' Whiplash cams, all have very tight LSA numbers. As you say, they give the hot rod guy the lope he likes, but the smooth out early. And they actually make more cylinder pressure than an OEM cam. The lope isn't desirable for an OEM for sale to the general public. All in all, very interesting and thanks for taking the time and effort to do it. One other factor I've wondered about for years, how about the installed angle of the cam? Would installing the 112 LSA piece, maybe even the longer one, make these valve events soon enough to compensate? Thanks!

[@jimmy_olds]

Hey Richard, camshaft theory is fascinating to me and watch this video often. In fact, I had a custom Bullet Cam for my 454 ground partially based on this video. Theorizing here, a tighter LSA generally increases cylinder psi, because it increases the dynamic compression, which may have contributed to not only the expected bump in low speed torque but also the power across the board.

[@andrewcammer2535]

Let's see the same test on a 4.8 (same cam). I think the smaller displacement will emphasize the torque differences much more than the stroker, and show the curves better.

[@ezmny1387]

you want tighter LSA with more cubes as it takes advantage of the larger displacement for filling sooner

[@obbyjep7597]

Very intersting, expected more low and mid but thought there would be loss on the top. Did they sound much differant at idle? I have offten used curci track cams in my projects with sbcs with narrow lsa they work well on the street but ruff idle

[@michaelangelo8001]

There would have been. He just didn't take it high enough. Those cams had a lot of duration.

[@dumbestoyster]

This test has always interested Me.

[@FrankKunkel]

David Vizard has a formula for 10.5 small blockks that agrees with the 108.

[@jonathanposs4448]

I don’t think the smaller engines will have such a dramatic change as the test engine you used. Prove me wrong😏

[@DavidViny]

Was the cam advance changed for each cam to keep intake valve closing the same? I have to wonder how much of the low end power was from the earlier IVC of the 108LSA cam then just LSA (or overlap) by itself. Obviously changing LSA moves all the valve events, but keeping the IVC the same might be more of an accurate test of LSA? Especially since IVC is considered the most important. Great vids btw.

[@hefftoneGA]

This is a really good point about the IVC. Changing.

[@crd-nz_001]

Intake Valve Closing is becoming earlier when LSA tightens. An interesting test would be to install the 112LSA cam 4 degrees advance. This would have the IVC point the same as the 108LSA. However, the difference would be that the exhaust would open and close 8 degreese advanced, as the intake would be 108 Lobe Center Angle and the exhaust would be 116.

[@baby-sharkgto4902]

I was wondering the same thing

[@FordMaverickFanatic]

Very good watch! Would be curious to see the same test on a few different engines!

[@CharlieBrown-pb9xn]

Great video!

[@jeffwooton7138]

From what I understand, which ain't much, it's all about the EVC point. Start there, and adjust the rest. This is per the great Harold Brookshire, and Mike Jones, and even David Vizard. It would be interesting to see that installed +4.

[@poncoolride]

IVC, is the most critical event.

[@codyrice5591]

Hey I recently bought the sum-8718 camshaft from the ls series line of cam shafts and I’m curious to see the torque gains out of a lq4 6.0 if you could maybe make a video.

[@johnhazel9986]

This is another great post by RH. That 210/218 duration cam might really wake things up with 102-106 LSA

[@Hipsters_N_Hippies]

another way of seeing this for someone with a DOHC engine. Is the stock camshaft timing, then advancing the exhaust camshaft 4 degrees. then another 2 more degrees. ( however because everything has an equal and opposite reaction this is Also decreasing the overlap period by closing the exhaust valves that many more degrees before. Thus decreasing the overall amount that both intake and exhaust are open together at the same time.)

[@timothybayliss6680]

The only thing I would like to see included in this test is Idle vacuum. Have a set rpm, 800rpm or something, and tune the idle for maximum vacuum to see how smooth they idle.

[@johncholmes643]

Who wants a smooth idle??

[@Ribbityibzki]

@@johncholmes643 certain race classes.

[@deantape2759]

@@johncholmes643 dailys, but its not just about the idle either. Theres a reason street driven ls cams mostly use a 112lsa. Otherwise everybody would use a 106lsa in their na builds.

[@timothybayliss6680]

@@deantape2759 the factory ls9 cam has something like a 122.5 lsa. Even the ls1 cam is 117 as far as I know. With short duration and 11:1 compression, they idle really smooth with so little overlap

[@deantape2759]

@@timothybayliss6680 im talking popular aftermarket cams sorry not stock ones, i agree they do always favour a really smooth idle on stock cams.

[@awebke]

Interesting to see that most basic "Turbo cams" have a wide LSA if tighter LSA produces more power down low. I would think that's what you'd want to spool the turbo up faster on most combos. It seems like you can't go wrong with tighter LSA for a street/strip motor where you aren't worried about driveability. I guess that's why the turbo cams have wide LSA, just to help driveability. Interesting to see for the build I'm trying to piece together, looks like I might try and spec out my own cam for the fun of it and see where it takes me :)

[@Tyler_Mattson]

awebke You’re exactly right. Back when they raced the grand nationals, Kenny duttweiler tightened the LSA on them for the very reason you stated.

[@TurboGreggZ]

Egt can sky rocket from tight lsa. Overlap causes issue due to the reversion.

[@ezmny1387]

​@@TurboGreggZhow are you getting reversion when most modern turbos have a pressure ratio close to 1:1 (pressure in the exhaust equal to what's coming in the intake)

[@sean5comet]

Thx for the upload...look forward to your content

[@SB-vb8ch]

Awesome as ever, thanks for the data!

[@dmc5681]

the other thing to consider beside a smaller engine and the relative difference, is with a smaller duration cam will the 108 still come out ontop? or is that the more duration you add the trend is towards tighter lobe centres performing better and vice versa? personally i belive with the same engine the trend will be there irrespetive of the duration.

[@michaelangelo8001]

The 108 will have a sharper cutoff at the bottom. You couldn't see that, because the sweep didn't go low enough.

[@lukemorgan3368]

I’d definitely like to see this on a smaller displacement engines possibly comparing the 4.8L/5.3L to the bigger 6.0L is also be interested as to how the LSA can affect specific boost pressure

[@baggedandlsswapped67suburban]

I was just thinking about making a very similar comment to this. Lol

[@toflaherty84]

it would be very interesting to see this on the 4.8L/5.3L, as well as comparing, for example, what BTR did with their truck cams between V1 and V2 where what used to be 113+3 LSA is now 110 LSA.

[@richardholdener1727]

same under boost

[@joew7897]

Have you not watched his videos? The difference it makes na will be the same under boost. Almost every time he tests a motor na vs boosted the curve is the same just higher up the graph obviously.

[@lukemorgan3368]

Joe momma I wasn’t really thinking when asking my question tbh initially I was thinking about degrees of overlap

[@richardsonracin-lw9zi]

Great test thanks again!

[@100amps]

At first I was wondering why you were on one knee in front of the truck. Then I noticed the nearly perfect Rembrandt lighting profile on your face. Well done. Oh yeah, the cam LSA info was great too. 👍

[@rideswift]

Great video, I would like to see this type of test ran on a stock 5.3 and 4.8.

[@chomin3025]

rideswift It will be pretty much the same, just shift the power curve towards the right, and it will be a more linear power band.

[@utahcountypicazospage5412]

I would like to see 108lsa waste gate spring pressure and the 120lsa waste gate spring pressure and see who makes the most power on five pounds and 20 pounds with egt gauge hooked up

[@Skoog.]

@@chomin3025 So with a smaller engine will it make hp and torque in a higher rpm than a bigger engine (lets say 305 vs 400 , or a 350 as they have the same stroke) with the same 108 lsa camshaft. Or??

[@chomin3025]

@@Skoog. smaller displacement = It makes the power and torque higher in the RPM (with the same camshaft as the bigger one)(Generally , bigger CI can take more advantage and make more power throughout the whole curve. and bigger CI always means more torque with the same mods as a smaller engine)

[@Skoog.]

@@chomin3025 Thankyou..!! I always thought it made power at the same rpm.

[@coolguy112286]

Richard, did you keep the intake lobe center the same? That will make a difference as well. Great video!

[@coolguy112286]

@ihategooglespooks right, which would have an effect on the test : ) but there are many many cams that have a different LSA and ICA

[@claytonnaber4143]

@coolguy112286 I agree - this is an important question. Richard didn’t state what the timing was set at for each cam, so we don’t know whether the LSA change change only affected exhaust lobe timing (constant intake center), or if both intake and exhaust were varying (any other situation, including making the “straight up” assumption). The torque curve difference in LSA can be partially compensated for by adjusting intake centerline. Richard, can you set the record straight about how you did the test? A timing sweep adds another dimension and more pulls to the test, but it completes the picture on how these variables interact. Great video as always!

[@woxie4990]

Thank you. Informative. Please continue!

[@rickyr7790]

Itd definitely be interesting to see header primary length, merge choke, and LSA comparisons. I hear the larger LSA the tighter collector choke can be, and shorter primaries can be too.