Would the 112 make more power at a higher rpm? Or should the 114 make similar power at lower rpms?

Like... 6500 rpms = 310rwhp
6000 rpms = 310rwhp

Just an example... or does a 112LSA just make more power up no matter what.

On stock manifolds... when would the torque corve and horsepower drop off? I was told that with a cam on stock manifolds, it should drop off at like 5900. Is that true?

BTW, i'm a 114LSA

 

The 112 LSA most commonly used in these motors is already a compromise for NA power, most carbed cams are more like 108. 114 is used by many to bandaid the fact that they fell into the old habits of overcamming the car. The only way I would recommend that wide a LSA in an LT1 would be with a power adder. If using it to make a cam livable or pass emmisions then pick a smaller cam. You want support of my opinion here do a search and see what LEs grinds are. That man has forgotten as much about making LT1 power as most of us could ever hope to know.

 

Get headers THEN a cam

 

well now that i see you have a cam GET headers lol

 

Not always true. Look at the stock LT1 cam, it's not big at all, but it's ground on a 117 LSA.

 

108LSA +4* if you want it to run hard.

 

Read what I said it DID NOT say big LSA means too big a cam I said if you have to use LSA to try to tame a cam it is too big. You know like all these guys with barly boltons done and they want the biggest cam on stock cubes but then don't wnt the nasty idle so they go 114. A detail lost in all this is overlap which is the primary thing LSA affects which affects low speed manners. One of the Impala guys was running an 845 with spray, then tried a custom Erson which was 221 intake on a 116 sounded stock and performed like the 845, LSA was too big for NA or even juice, turbo it might have been interesting but he went back to the 845 and kept the spray.
Sounds to me like you are dead set on making the oldest mistake in the book and overcamming so I will stop debating this with you. Hopefully though my comments make the next guy do some reading before he falls into the "HOT cam is too small" mindset.

 

Pro stock must be trying to TAME their cams,because theirs are a 120-125LSA with about 12-15* advance. They can't even pull up a driveway without reving to 8000RPM's

 

a+b+c+d+e = f

If that were a legitimate equation, f would be our LSA. Point being that LSA is always dependent on other variables.

Which is to say that different engines and setups have different cam needs. I can tell you from my own personal experience dealing with my comp eliminator car many years ago which paints an interesting picture on the subject. I made a change that just about everyone else at that time was making... from the GM 15º to the Brodix canted valve head and intake setup. The problem I ran into was with the camshaft and it took quite a bit of testing to figure it out. First things first, I changed over to a new billet cam with almost identical specs as the old, which was very successful using approx 294º @ .050 and a LSA of 108º. Even with the new higher flowing heads, same shortblock and same static comp (within .2 points) the car made less average torque and just a tad less peak hp from 6000 rpm and up.

This could be 3 pages long but to make it short, we played with lash and timing, we advanced/retarded the cam, then we went back to baseline and made another dyno pull, this time pulling it from 3000 rpm up. When we compared the new setup with identical cam to our old 15º setup dyno pulls we found something that confirmed what myself and one of the best engine guys I've even known, Herbie Mayes (may he RIP) were thinking.... Up to almost 7000 rpm the old setup was much stronger, having more average hp and torque than the new. Didn't mean much in getting down the track quicker cause this car would never see anything below 6k. We needed to close the intake valve later to take advantage of our new induction system, and we (the engine) also wanted an earlier exhaust valve opening. When we starting working in that direction we were amazed to find that this new induction setup worked extremely well with an LCA of 115º, 7º more than the old 108º LSA combination. With this cam, the engine made more avg torque and much more avg hp, peaking almost 400rpm later. The car was also much quicker at the track once everything was dialed in.

I've read on this forum and others where people have come up with this deduction after looking through a cam catalog that if wider LSA cams are the "sheet" for drag cars, then there's gotta be something to that and maybe they can adapt that approach over to their street car. There is danger in not really knowing why things are the way they are.

Larry's Pro Stock example with it's semi-hemi cylinder heads is not exactly going to have the same needs that your street engine does, nor is a 300 cid competition eliminator motor running a 114-118º LSA. Keep things in perspective.

If you want to talk generalities, the tighter LSA will make more avg tq and hp in the lower revs and may make for more fun on the street where as the wider lsa will pull harder from mid rpm to high and will hold on further past peak tq. This is all considering an identical engine... just the cam swapped. 2º one way or the other is not worth much IMO and there is some truth to what 96caprice is saying in terms of using lsa to run a larger camshaft. David Vizard has been saying the same thing for years and he's been around the block a few times. Pay attention to your dynamic compression and see how these changes effect it. Software can help.... trends are your friends.

Also worth noting.... most strokers, unless they have adequate cylinder heads, will probably respond better to a narrower lsa. Restricted will most likely want the wider.

-Mindgame

 

Well said.

It has been my experiance that a 108LSA is the best all around for a SBC.There are exceptions like sprint cars which I use a 106 sometimes.
I have also found that a 4* advance works best. Anything less and you don't see a differance,if you have to use more and you have the wrong grind for the engine.

 

Dwayne, were you talking to me?

I went with a 114LSA because I don't want to rev to 6500 on my stock old rotating assembly. Thats all. I didn't want to tame anything. A pro suggested this cam to me, I didn't pick it myself. I knew very little on cam manners and whatnot and reading wasn't really going to satisfy my questions because of all the different opinions. But Dave from Combination Motor Sports said that with the situation I am in and the direction I am looking to move in. This is the best cam for my needs. I want power and good 1/4 times but without spinning my car to high. He said that the XE227/233 cam was made specifially for LT1 stock heads so it makes great power out of them.

I am not really talking about a built engine, just a stock engine and manifolds.

Revving to 5900 on stock manifolds. Will my dyno chart curves see a tremendous drop off?

I was also curious that if a 112LSA or 114LSA would make more power around the 6200rpm area?

Or if PEAK power would be higher on the 112LSA?

Dave said that the cams should make very similar numbers, just the 112LSA would make a tad better 1/4 times because of higher revving.

 

Amen Mindgame.....

A dependant variable or it's the product of the rest of the cam specs is the best definition of LSA.

From what I have seen and I'm sure you have noticed the trend also any canted valve head motor will have problems with the exhaust poluting he intake charge easily so there is usually a need to cut down the overlap and in turn widen the LSA and shorten duration.

The other thing is a rule that Vizard uses.... every 25 cubes needs to lower the LSA by 1. His rule is a 300 cube motor likes a 110LSA, 350 108LSA, 383, 107LSA and 400 106LSA. A lot of things change that variable but for carbed small blocks it seems to work very well.

I really like how all of this applies to the Engine Masters contest. After seeing cam specs on some of those motors, I still wonder if they took some care fixing the hole in the TQ curves around 3500-4000 that they would not see better average numbers. Personally I think there is more to be had in fixing that part of the curve than there is anywhere else development wise. Emphisis on cutting down intake backflow so you cut down exhaust polution of the intake charge would be the first place I would start. This would also lead to higher LSA numbers too, but I that would need a really good exhaust port to pull that off.

Bret

 

Dwayne, LCA (or as some label LSA) means very little. I believe it to be in the better interest, of the group here, to shift their focus away from LCA, and toward the (all four) open/close points, and the subsequent resulting overlap. To attempt to characterize a cam by it's LCA, as many here do, is AFAIC, incorrect, or to think positively, very misleading. A good example would be to compare the LCAs of the oem B body cam, and the oem F body cam, with their differing LCAs. The LCA is little more than a convienent 'handle' with which to label or identify (in lieu of A,B,C, or D) a given cam. Such a comparo was made a few weeks ago, on the B body forum, attempting to show/prove this very point, although according to majority of the responses, unsuccessfully. I find it amusing btw, to note, the B body forum considers the B body cam superior, and of course, on this forum, just the opposite. And on a mopar fourm, oem STILL bolts on hemi heads, to new engines.

 

Arnie,

What are the specs of the F and B body stock cams?

Bret

 

I do realize there is a lot more to all this than just LCA/LSA, but I think you agree with my statment that too many try to bandaid too large a cam by spreading the lobes, and as far as I can see the end result is not worth it unless forced induction is involved. I have done some limited reading on how one well respected smallblock guru designs a cam optomizing intake and exhaust events against piston travel and speed and in the end just lets LSA land where it may. His results speak for them selves and honestly much of the tech on it is over my head at this point, but in the end most smallblock carbed NA cams are around 108, most injected are 112 with forced induction cams and bandaided larger ones being 114. Of course duration has to be considered when comparing LSA too because a tight LSA long duration cam could have more overlap than a smaller cam on a tighter LSA, lobe profile even plays in, but you know more than I(honestly no sarcasm) so I don't have to tell you. This is more for everyone elses benifit and to explain that my presvios post was maybe an oversimplification but in my opinion still valid.