Unaffliated Racing

iTrader: (15)

well..if you need more info..just give that guy at Comp a call. I know you have talked to him many times through e-mails and phone conversations...I hear he is pretty good with LS-1's

Naked AV

Well, I was trying to give that guy a break from my constant pestering, but now that you mention it, he does he seem to know a lot, and he always seems to be ready and willing to talk about cams and stuff...

Unaffliated Racing

iTrader: (15)

yeah..I hear he knows best about the LS-1 stuff..great guy to deal with.....lol

MyLS1Hauls

iTrader: (2)

From my experience, Comp techs aren't exactly cam pros. I've never talked to one over there that impressed me. If it were my truck, I'd get a split duration cam...probably a 212/218 114+2 high lift version (For FI use). You'll be able to get 36k on a set of 918s with that cam. I personally like a little tighter LSA for more midrange, but for FI use, I'd go 114. Its not going to be a very noticeable difference between 112 and 114 honestly. ICL plays a role too where a cam makes its power and is not related to valve overlap. I can promise you that you'll lose very very little if any low end with that cam. I've seen several cams personally in 5.3L trucks and they all had plenty of lowend. Lots of guys say "oh i lost low end"...its more of a perceived loss due to a large gain starting at 3k rpm.

Naked AV

Well, the guy I've been talking with at Comp knows his stuff, he builds motors, and actually recommended the 212/218 lo-lift 114 to me originally, then the 212/218 hi-lift once I said I might go with heads later. So he knows his stuff. But I did start talking with some techs who work for cam manufacturers, who said that the ideal cam for my supercharged application was 205/211 or 206/212. Their reasoning was, let the blower force in the air, no need to go big on the cam to achieve the same thing. Also, in their experience, blown applications actually showed a loss going from 205/211 to 212/218 - a minimal loss, to be sure, like 5 RWHP and 10 RWTQ - but a loss nonetheless. This affirmed that there was zero gain from going bigger in this particular instance, and even a minor loss. Keep in mind that we're talking a supercharged application, not a normally aspirated one. For an N/A application, hands down the 212/218 would be better.

Back on topic...let's say we get your 212/218 (just as a fer' instance), what would the power/behavioral difference be between these two cams:

212/218, .553/.559, 112+4
212/218, .553/.559, 117+4

?????

McRat

Here's why LSA isn't the absolute best # to use...

That 117 cam is quite a bit "hotter" than the 112. It's intake opens sooner, and it's exhaust closes later by a total of 5 deg. Or like the difference of a 212 grind vs a 217 grind.

8100hammer

Hey see if you get a back issue of "Best of Tech" mag. They had a whole half of the mag for cam science. they start at cranking compression and how lsa affects it, into the science behind overlap, lobe timing, duration, just about everything. I have read it close to 15 times since last year. too much info to take in one reading.

MyLS1Hauls

iTrader: (2)

The 117 LSA version will have a more broad power curve. You will sacrifice lots of midrange torque with a 117 LSA. The 112 version's power will come on faster, but not carry it out to as high of an rpm. The other thing that makes a big difference is that those two cams have different ICLs. The 112 version has an Intake CenterLine of 108* and the 117 has one of 113*, which make a fairly large difference. The ICL controls where the engines power curve is. Lower ICL shifts the power down and vice versa. The 117 will also idle noticeably better. Just because you have a supercharger, doesnt mean that a big cam will make less hp. Take a SC 3.8L GTP car...they love bigger cams. The key to making good power with a SC and a larger cam is to keep the overlap down, which traps more air in for higher cylinder pressures. With lots of overlap, the SC will blow the air in the intake valve and straight out the exhaust while both valves are open. Thats why I said to keep the LSA a little wider than an NA application.