First here's the setup :


Stock sleeves b18A
Wiseco 8.5:1/eagle rod
SC61S
Tial Wg 15 psi spring
Tial bov with the small spring
JG intake
2.5 piping
3inch dp/exhaust no cat
750cc/uberdata 3bar
Ported LS head with Cranes cams/spring retainers9(reving to 8200)
Stock tb

With boost set at 15 psi I run 12.2 129mph/street tire and pump gas.
It's street tuned, 11.9 AFR and timming around 20deg.

Problem begin when I get the boost up to 20-25 psi (with C16), the car pulls not much more than at lower psi. Best run to date on slicks was 11.2 132mph.

The more I boost, the more my WB read richer mixture, I've try to lean it and it dosen't change anything. Play with timming...nothing...
Boost is not getting higher than 25psi too, the WG do not open at all and it's stable at 25.
The car feel fines no misfires, no nothings.(beside not doing the power it should be)

So what's holding me back?

I'm thinking toward my cams setup.

I'm running Cranes 20 cams:

Intake @Cam .260 @Valve .472
Exhaust @ Cam .260 @Valve .472

ADV Duration
Intake -- -- 262.0 °
Exhaust -- -- 262.0 °

Cam Timing: VALVE @.050
Lift: Opens Closes Max Lift Duration
Intake 14 BTDC 40 ABDC 103 234.0 °
Exhaust 50 BBDC 4 ATDC 113 234.0 °

That's make a lot of overlap for an LS but it seem to work so well for vtec head...

Maybe the exhaust pressure get higher than the boost pressure around 20 psi causing bad combustion efficency?
I will buy cams gears soon to try fixing this but it work so well at lower boost that I'm not sure if it will help.

It make sense or not?

 

those cams do have alot of overlap......if you have adjustible cam gears try dialing some of that overlap out......it will probably idle better and you should be able to cram more boost into those cylinders.

 

are you sure its not your turbo, or it may be your head setup, i would get it on the dyno, thats the best way to tell

brian

 

i ran Crower's 404 on my LS turbo and it screamed. you'll just have to tune the LSA and get it to idle correctly. that is if it's the cams that are causing the problem. remember to try to tune the exhaust cam first before messing with the intake cam.

 

Did you push over 15 psi with you 404? I will try tunning with cam gears for sure.

Others input/similar experience would be great too, thanks.