How large of a turbo would I need to run efficiently at 10 psi. I'd like to run the stock s5 turbo and manifolds for now with 550 primaries and 720 secondaries. Obviously I'll need to port the wastegate and I'm going to leave a cat on the exhaust. The exhaust is all 3" already. Will that be enough to keep boost creap to a minumum? I used the racing beat templates, street port on the intake ports and a race port on the exhaust. What kind of #'s do you think I'll put down at 10psi on the stock turbo? Almost forgot, I'll be running a standalone ecu and a fmic.



Thanks

i'm gonna say it puts down 238.72rwhp@6000rpms.



i dunno about a ported motor, but i had a similar setup with a stock port, and with no cat it would run .4bar from 2500-7500rpms, with the cat it would hit .9bar around 4500-5000 and then be back down to .3 by 6200ish rpms, cat totally ruined what was a fun responsive setup plus the .9 spike, kinda throws the safety factor out the window.....

Sounds shitty, did you get it all sorted out? I'm leaving the cat for now because the exhaust port is fairly large and I heard from someone that they had a similar set up and they were getting major boost spike so they put a cat on and the restriction in the exhaust flow was enough to eliminate the boost spike. What size of injectors were you running?

I realize it's an awfully vague question. Maybe it should say how large of a turbo can I run without sacrificing too much driveability. Looking for full boost by 4-5k at the latest.

I think T04E turbo with a T4 P trim divided exhaust housing would work great on your motor setup.

Then you'd probably want to upgrade the injectors....and of course you'd need an exhaust manifold, then a wastegate.

Depending on tuning you'd be just under 300 whp.

Thanks Joe, like I said when I was at your place, I don't know **** about turbo sizing. I guess I'll have to start reading up on them. Already have a delta gate waste gate sitting on the shelf along with a ton of other stuff that has yet to see the car.





Brent

i ran 550/680's. my take on my boost issue was that the turbo was spinning as fast as it could, and when i added the exhaust restriction, i got more boost. or less flow + same turbo rpms = more pressure. i should add that peak power felt almost the same, but the cat added a bunch of lag, and took away all of the throttle response.



i think what you're looking for is a 60-1 t04, with a .84-1.0 p trim exhaust

You'll definatly want larger secondary injectors, 720's would likely be good because with a standalone you can control how much fuel they spray out. Better to have large enough injectors than to run out of fuel.



A good exhaust A/R size for a streetport is .84-.96 a 1.0 might be a little laggy? I guess it all depends, so many variables

Already have 720's Joe. Need to take into account the race exhaust port, not that I know what size of turbo to run. Thanks for the input guy's. Just can't wait for the spring to come so I can find out for sure. I'm even considering running two black top sr20 turbo's. I've got one and I have a line on a second already. That probably wouldn't be til next fall though. Only have so much time.



Brent

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