Well today i got my car dynoed for the first time since i have been boosted.
the car made 266whp & 240wtq at the peak. at 18psi
seems very low for what it is, maybe you all can help me figure out the problem.
the tuner (JFK78) told me that it is more than likely my manifold and downpipe combination, in other words, my whole setup, lol
Dyno was a Dynapac

here is the setup:

Engine:
D16y8 block
d16z6 stock head
Vitara 75.5mm pistons
Eagle rods
stock d16y8 intake manifold
DSM 450cc injectors

Turbo components:
Precision SC50 turbo (50 trim)
.48/.60 A/R
2in piping from turbo to IC
2.25in piping from IC to TB
Stainless log manifold
2.5 inch a/c compatible dp
TiAL 38mm wg
TiAL 50mm bov

 

One reason could be b/c the compression is so low.

 

he showed me similar setups where people made over 30 whp more, its so weird. i wonder if the log mani really isn't that great

 

Post up your dyno sheet.

 

Yeah downpipe size, manifold design, intercooler piping size, small a/r on turbine all will help give you lower than expected power levels. I'd also look at the obvious things like boost leaks, timing set correctly, ect.

 

i don't think there were boost leaks, held 18psi fine. timing was done by him so im sure its good, plugs were burning fine too. i can get a basic pic of the sheet since i have to take a picture of it until i get a digital copy

 

Is it just me or does it seem like it levels off really early? Basically from 5200 RPM to 7200 RPM you're only increasing like 15 HP, which I would figure would be where you'd really start to see some more gains. I'm wondering if maybe once you hit full boost you're getting a restriction somewhere and that's why it's leveling off so fast?

 

some guys say i need a 57trim turbo with a .63 hotside

 

I would say its most definitly your manifold/downpipe/turbo combination. My vitara setup didn't make **** either with a stainless log manifold and I had a bigger turbo and downpipe than you. Now with just changing the turbo mani and intake mani its making quite a bit more power.

 

Nothing's wrong with your setup, it just is what it is.

Your log manifold is probably the biggest handicap, and the A/C compatible 2.5" dp which has an immediate ~85* angle cut/turn about 2" off the turbine housing are the largest restictions keeping it from carrying torque. The .48a/r exh. side isn't going to carry torque high either, and the air filter drawing hot air from directly behind the radiator also isn't helping.

Changing these things will be quite expensive (as in sell it all off and start over). You have a budget built, daily-driver, a/c compatible, mid-range oriented setup. Nothing wrong with that, it does it's intended job just fine.
If you want a more race-oriented setup, you will need to double your budget, lose the a/c, and lose ~1000rpm of spool time.

We have seen 90-100whp more at the same boost level by utilizing a .63a/r exh. side, 3" dp, tubular manifold with a merge collector, cam, and IM.