split ratio rockers for turbo application

[thebeesgotboost]

2001 camaro 3.8 grand national turbo 8-13psi.

i'm looking into getting higher ratio rocker arms, and have the opportunity to get a set for fairly cheap that are 1.9(E) and either 1.7or 1.8(I). i was looking at turbo cams and it seems that they give the exhaust more duration but not as much to the intake. would it make sense for my application to get these and use the larger on the exhaust and smaller on the intake?

[TGP37]

The cam is ground for optimal performance, changing the lift is just gonna compramise the cams design.

Don't quote me but.....the lift isn't as high to maintain better VE in off-boost regions and let the turbo cram the air in. If greater lift was a desired route the cam grind would reflect that, IMHO.

However, if you got a cam not ground for turbo and want to alter the lift ratio between intake and exhaust to better reflect a turbo grind, I think that is possible considering the lifters don't interfere.

I deshrouded the exhaust valves to help the turbo I installed on an N/A engine. Plus it dropped the CR from 9.5:1 to roughly 9.2:1 by increasing chamber volume. There is merit to increasing exhaust flow versus intake flow when turbocharging.

[thebeesgotboost]

i'm using a stock cam, 182/192 .258/.258 115<-lsa
with 1.6 rockers thats .413/.413 lift

at 1.8 and 1.85 these are the lift numbers.
.464/.477
i've been lookin at turbo cams. and some have the same intake and exhaust lift some favor the intake and some favor the exhaust. kinda shocking to me that they favor the intake. i don't know if i need to find a cam with a simliar lsa or duration and mimmick it or what. i definitely have alot to learn when it comes to cams.

[TGP37]

i definitely have alot to learn when it comes to cams.

You and me both.

I do know the stock cam on these motors are surprisingly good for turbo.

From what I understand, turbo cams like more lift on the intake since they also like to be delayed slightly due to pressure differences from n/a. But since you have a stock cam, there is no added delay on the intake valve.

If you can get more lift over all, I do believe it will help gain more power but turbos tend to change the dynamics.



edit: Just realized you have a 3800v6, that is not the same as the 60v6 supported here.

[thebeesgotboost]

You and me both.

I do know the stock cam on these motors are surprisingly good for turbo.

From what I understand, turbo cams like more lift on the intake since they also like to be delayed slightly due to pressure differences from n/a. But since you have a stock cam, there is no added delay on the intake valve.

If you can get more lift over all, I do believe it will help gain more power but turbos tend to change the dynamics.



edit: Just realized you have a 3800v6, that is not the same as the 60v6 supported here.

what motor do you have specifically? and do you happen to know the stock cam specs. i was searching but couldn't find anything

[TGP37]

what motor do you have specifically? and do you happen to know the stock cam specs. i was searching but couldn't find anything

I have the 3100 v6 SFI, L82. I don't know my stock cam specs either, can't find any info on them.

Your engine being the 3800v6, you may have a supercharger camshaft or a N/A cam. Depends if your engine came with a supercharger from factory or not. A supercharge cam isn't too different from a turbo cam.

In that case, if you have a camshaft for a supercharger, using higher lifter ratios on the intake could help as the intake open time was probably delayed slightly in favor of reducing reversion.

If you have the N/A camshaft, raising exhaust lift will help reduce reversion from the added back pressure of the turbo.

[thebeesgotboost]

i appreciate your responses. my motor is actually the l36 n/a motor.
i've read soooooooo much. after reading this http://www.hotrod.com/pitstop/hrdp_1...s/viewall.html i've decided to just roll with my stock cam, and just do some porting work later on.