modaddict

Okay boost lovers, I had a long conversation today with some guys over at comp cams. What really surprises me is that IMO (and they AGREE with me) these are the best cams for boosted cars...

Comp Cams
XE261H-115.5
#127300
.490" intake / .480" exhaust lift
222 intake @ .050"
235 exhaust @ .050"
115.5 lsa

I ordered these today for $742 and am surprised I didn't know about them or have ever heard about them. The have a slightly smaller duration and tighter lsa than the stage 4 cams which makes them much better IMO.

The BBR stage 2 are: 241/251 .050" duration, .492/.492 lift, 114 LSA.

The Comp Stage 4 are: 222/239 .050" duration, .490/.485 lift, 116.5 LSA.

The difference in the LSA (Lobe Seperation Angle) plays a big role in the cams. Having a lower lsa will narrow the "window" between the intake and exhaust centerlines. If the exhaust closes too early the scavenging will not be complete and the incoming charge will be contaminated.

Generally, tighter lobe separation angles cause an engine to produce more midrange torque and high rpm power, and be more responsive, while wider lobe separation angles result in broader torque, improved idle characteristics, and more peak horsepower. This is just a guideline of course.

Basically, the lsa is a main reason why I think there are so many 'their great - they suck' debates. it is CRUCIAL you get the right set up for you. IMO any N/A cars aren't going to get anywhere near the advantages running a wider lsa. The sucky part is that BBR has the lower LSA but has the higher duration.

What you N/A guys want is the Comp Cams with the BBR lsa of 114. Comp doesn't advertise it, but they can and will change any lsa up to one and a half degree with about a 1 week turnaround. So if you were N/A - the best possible scenario for you is the Comp stage 4 with a custom 114 lsa.

Okay, now the opposite for the boost guys and especially for those of us with strokers and extra cubes. We want the 115.5-116 lsa or we are actually hurting our blowers. All of the numbers I have seen (real world NOT advertised) were the BBR Stage 2 and the comp stage 4. Why I think I never saw anything impressive is the 114 lsa of the BBR's and the high duration of the comp stage 4's.

I think the BBR's will be decent on an N/A car but be counterproductive n a blown car. Geez, with extra cubes and big boost, your peak range with the BBR would be in the 5200 range which would suck. I think the comps will be counterproductive on an n/a car and also fall short and not be impressive on a blown car because of the duration. The Comp Cams I put in the beginning that I am buying are the best available for blown cars IMO. I'm expecting huge gains with these on my 331ci motor with decent boost.

I could be wrong in my thinking but this is where I'm at right now. Any other thoughts are appreciated...[sm=icon_cheers.gif]

MexGT

So, from your calculations and thoughts ... whats the HP increase you're expecting from using stock cams to this new cams ? in your future engine.

Menace

Question is... what would be a good cam upgrade for an N/A Stroker.

Hufenstang

thanks for all the advice on that CK, ive currently been looking for cams for my boost/stroker setup i just may do this.

Burnsy

good to have you back CK

hammeron

he was only gone for about 20 minutes
as i recall

+1 tho

TJ

Ok from my understanding I would have thought the BBR specs (251 dur, 492 exh vs235, 480 exhand thelsa of the comp)would have been better for FIVs than theCompcams and the Comp cams would be better for NA. The main reason being I would want more duration rather than less on FI, on NA its not as importantbut what do I know.

Burnsy

haha, yes, I was just expressing my gratitude for his knowledgable and tech-rooted posts, its refreshing around here, sometimes S197 gets like OT

modaddict

I honestly think on the new set-up, I may see as much as 50-80 hp/torque difference with these cams. (Hoping) I am gong to dyno before and after install so I'll have hard numbers.

I don't really care if I'm honest about the dyno numbers or hp increases. If I'm right, these thigs are going to give me the torque and midrange power gains I thinkn will make a considerable difference on my ET. I really beleive these things are going to be a BIG difference on my particular motor. We'll see soon enough anyway...lol

modaddict

I thought same as you but I've been talking to a lot of cam experts lately and was suprised to learn I was thinking wrong. I also talked to BBR and they admitted that their stage 2 were designed for FI cars but they noticed from their own tests that their cams really had the best benefits on n/a cars. (If you call them - they'll openly tell you) The opposite for COMP - they were aiming for n/a gains from start - That's what suprised me until the lsa and durations (exhaust is MOST IMPORTANT) were explained to me.

I really think this is because everybody came out with cams focusing on designs that were related around the stock grinds. Meaning specifically I think everyone was more concerend with a camshaft that would 'work'. Now I think people are finally looking at 'what works best' on this platform.

I am lost when it comes to valve train stuff so I am learning stuff everday and a lot of it has been opposite of what I have thought. I'm just sharing what I'm finding and hoping for some info from you guys too...