This post is pretty pointless because I know what has to be done to remedy this problem. I need to add another WG because I guess my manifold flows into the turbo too well
I guess first I can try upping the diameter of the dumptube, see if that helps.

Anyway, the car felt great the other night! So great, in fact, that I walked away from an 04 gsxr600! My car made 485whp on 16lbs on a hot 90 degreeday, and we set up the boost comp tables and boost cut to 20 psi. The other night I did some pulls against a gixxer and my car was hitting the boost cut, so I figure it was making around 540-550whp! He was really surprised that my car kept pulling on him!

I'm glaD I have my new 09 si coming on monday as my DD so I can pull the dumptube and re-do that first, then worst case re-do the WG setup.

 

the down-pipe and the exhaust size, if restricted, can cause some boost spikes. but yeaaa wastegate is a big deal too. i have that issue with the full-race manifold. but it only starts creeping towards redline (which i have no problem with

 

No, a less restrictive exhaust flows better and can yield boost spike problems with a turbo. The solution isn't to restrict the exhaust but, as the OP says, to add a bigger wastegate.

Smart move tuning for boost comp and cutoff. Saved your motor. All this happened in my FD RX-7 but my ECU didn't have cutoff as an option, so it felt like an absolute monster before I blew the motor. hehe Whoops!

 

dude i love you but the exhaust comment doesnt make any sense. Its pretty much all wastegate and wastegate position.

 

[QUOTE=m R g S r,Sep 20 2009, 06:37 AM] This post is pretty pointless because I know what has to be done to remedy this problem. I need to add another WG because I guess my manifold flows into the turbo too well
I guess first I can try upping the diameter of the dumptube, see if that helps.

 

i'm running 3" open downpipe with like one bend in it, so it's not because of exhaust restriction.

And i was watching the wideband (as much as i could with the car squirming all over the place when flooring it in 2nd lol) but it didn't spike over 12.5AFR. Which i know is a bit lean, but not in the dangerous range. either way, i will try not to beat on it when it gets cold because of the spike.

and yeah it was only spiking towards redline, so i guess it kinda felt like a supercharged car, it keeps getting faster and faster as it approaches redline

 

I'm pretty sure it's the opposite. Too restrictive of an exhaust will cause the turbo not to spool as fast, and possibly not hit full boost. It can also cause detonation.

 

haha nice, spoolup and power FTW with open DP.

My setup was hitting 12.2-12.5 AFR's on boost 11-12psi and when I went to the dyno and added +3% and brought it down to 11.8 AFR's it picked up 20whp and 11 ft/lb.

I know what you mean about 2nd gear. On 11psi 93 pumpgas 430whp I just get all over the road. And thats with falken 615's in 255/45/17 out back.

 

same dyno? Same timing? Sounds odd, because a leaner mixture should yield more power...

 

yea same dyno and everything. Thats what I thought too but maybe 12's is just a little lean on pumpgas and stock CR. It really picked up a lot across the whole powerband. It liked 11.8 the most and anything over or under that would lose a little power. Give it a shot.