I just spent the day researching what cam I was going to go with after I pull the existing cam. What's in the car now is a 228/234 510/510 114 LSA ARE custom grind (courtesy of SSJet and Frank Racing <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> ). Well, now I'm not so sure I want to pull it.

I just got back from MTI. Had a long conversation with Chris about cams. I would've walked out of there with a T1 had they taken checks (they did on Dyno Days, but I guess that's the only exception). He said difference between T1 and C1 was negligible. But, on the drive back, I started to reconsider, which makes me glad they didn't take my check.

Chris dispelled my misconception regarding cam "size". I was under the impression that the lift is what really determined "big" vs. "small" cams. According to him, it's the duration that determines cam size, so I have a pretty "big" cam for a stock top end, which would explain the large amounts of misfire codes and the extreme choppiness. He called the lift "free horsepower" because it doesn't really effect emmissions like the duration does. He also talked about valve overlap. But, what really got me considering keeping the cam was this: we talked about peak HP with stock heads in combination with B1 through C2 cams. He was saying that the most I could expect rwhp-wise with a B1 and ALL the bolt ons (LS6 intake, ported TB, pulley, etc.), was about 360. Well, I was at 354 rwhp before adding the underdrive pulley, and everything on the top-end is still stock (intake, TB, MAF, etc.), so I'm already exceeding what I'd get with a B1, T1, C1, and quite possibly a C2. I'd have to go to the X1 to get close to where I am now. Based on his logic, my current cam is actually "bigger" than the X1! <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" /> I could allegedly add free HP to my setup by simply increasing the lift, and SLP makes 1.85:1 rockers for this very purpose, but my question is, would this be possible with such a large duration? If my calculations are correct, I'd effectively have a 228/234 555/555 114 LSA setup if I add the SLP rockers. Please correct me if I'm wrong.

I know I can get rid of all the codes with custom programming, but how feasible would it be to smooth out the idle and get rid of the surging with such a large split duration cam? My thought is, rather than spending the money to get a new cam, spend the money on custom programming and a LS6 intake. Thoughts?

 

The problem with all that "free" hp from extra lift is that it's very hard on the valve train. You will have a lot more valve train noise and much more chance of breaking springs with high lift. I'd just leave that cam the way it is and pass on the high-ratio rockers. It's true the duration tells you more about the cam than the lift does, though.

 

I have read numerous Horsepower books and here is what they said:

Duration: control RPM more duration higher rpm range less duration lower rpm band

Lift: Controls how much valve opens, really needs to be matched to the head lift can play a big role in horsepower if not properly matched to the heads.

Overlap/LSA: This will control ultimately top end power, more overlap the more top end power due to additional exhaust scavenging. More overlap makes for a rough idle and unburned gasses at idle.

I know I left out alot in how the cam changes horsepower just wanted to get the basics out.
Phillip

 

TTT. Anyone else have an opinion? Thanks.

 

running the 1.85 rockers will not only increase your lift, but it will also increase the duration at .050 lift. So rather than a 228/234 duration, it would be somewhere in the neighborhood of 231/237 (these are guestimates, since I'd need more info about actuall lobe profile). I'd say stay away from the rockers, in my opinion, that is just TOO much duration.

I've been thinking of a cam along similar lines as you have now. I was thinking something like a 224/224 .545/.545 112 LSA. I think this would give great power without valve spring issues, much like your .510 lift. Unfortunatly it would have to be a custom cam, since no one makes a cam like this right now. I believe that one doesn't gain much on stock heads with lifts over .550, but really increase valve train wear.

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Ackattack:
<strong> running the 1.85 rockers will not only increase your lift, but it will also increase the duration at .050 lift. So rather than a 228/234 duration, it would be somewhere in the neighborhood of 231/237 (these are guestimates, since I'd need more info about actuall lobe profile). I'd say stay away from the rockers, in my opinion, that is just TOO much duration.
</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">That's interesting. But one thing I was not provided was the cam card since I bought it used. Oh, well.

I think I'm just going to keep the cam installed, go with the remaining bolt-ons (intake, TB, MAF), have it tuned, and see where the HP/TQ is. I think it will be plenty with the stock 10-bolt and the LS6 clutch. Anything above 380 rwhp will either roast the clutch or destroy the rear end again or both, anyway. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Ackattack:
<strong>
I've been thinking of a cam along similar lines as you have now. I was thinking something like a 224/224 .545/.545 112 LSA. I think this would give great power without valve spring issues, much like your .510 lift. Unfortunatly it would have to be a custom cam, since no one makes a cam like this right now. I believe that one doesn't gain much on stock heads with lifts over .550, but really increase valve train wear. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Yeah that's what I think too. A little known cam is the Comp Cams 224/224 .533/.533 113 LSA. I'm thinking about trying this one; I saw a car that was getting over 400 rwhp on it.

<small>[ February 27, 2003, 05:57 PM: Message edited by: Cal ]</small>