blackz93

iTrader: (2)

what does lsa do to the horsepower. from what i understand a tighter lsa will produce more horsepower. but i have also heard people say that they are going with 112 vs. 114 to keep the rpm's down. is this true too? that the tighter the lsa the quicker it will peak.


thanks for the info

Cal

iTrader: (1)

What I have always heard from the cam companies is LSA has nothing to do with the peak horespower. It will just change the shape of the curve; a smaller LSA will make the powerband start later and end earlier, with the peak about 200 rpm lower for a 112 vs. a 114 LSA. In other words, the engine will be more "peaky," as well as hit it's peak sooner. IMO this makes the car more fun to drive, but it is also less predicable with a rougher idle, and harder to pass emissions. It's just all what you're looking for, but the same power either way.

nuzee

iTrader: (2)

Cal
Well said!

I noticed with wide LSA cams, the power doesn't drop off as quickly past the rev range as a tight LSA cam does. I do enjoy the BOOMing midrange pull of a tight LSA cam as it enters the power band.

blackz93

iTrader: (2)

so like if i was going to get a cam that was on a 112 that peaked at 6400, where would it peak at with a 110 lsa?

is there a rule of thumb for this or what? is it roughly 100 rpm for every one degrre of lsa?

Cal

iTrader: (1)

Yeah that's the rule of thumb, don't know how accurate it is. Other things like your exhaust system will have a bearing on this also; if you have headers you will peak higher for sure.

Cal

iTrader: (1)

Thanks man! This LSA thing is easy to understand but hard to explain to someone else. I'd run a 110 LSA myself, but didn't want the emissions head-ache. Now I'm going to be running at Bonneville on the Salt Flats, and I found out peaky motors are real bad out there because of the traction issue, so I'm glad I got the 114. Nothing like a spin-out at 160 mph!

Gary Z

My understanding has always been that with all else equal (lift, duration, intake centerline) a smaller LSA will increase peak horsepower and move the peak toward higher revs. A smaller LSA increases overlap which improves exhaust scavenging at higher revs thus increasing peak power. Cal says, “a smaller LSA will make the powerband start later and end earlier” without increasing peak power. It seems to me that if that were true, the area under the power curve would be reduced and there would be no benefit. Where am I wrong?

Inspector12

iTrader: (29)

Do not take my word for it but the guy at COMP CAMS ( I was on the phone with him for an hour) told me that the LSA would determine the power band like 1500-5500 rpms and the ICL would determine when it would come on. for every 2 degrees he said that you bring the power on around 200rpms sooner but he said that was just rule of thumb not exact. so now you are going from 1300-5300 rpm in your primary power range. That is what I got out of our conversation but just thought I'd throw that in there for thought I am not a cam guru though. I was in question my self so I called a cam co. thought it was the best source for information. Good luck with it!

Cal

iTrader: (1)

Yeah I know, it doesn't fully make sense, but that's what all the cam vendors say. I believe you are correct about the tighter LSAs having less area under the curve. The only "real" benifit of the smaller LSAs is bringing the peak power rpm down, which on some of the bigger cams is a valid concern. Note that on anything bigger than a 224, you never see a 114 LSA; it's always 112 or even less than that. I think that's because they would peak so high you couldn't use them.