A GT28...alright.
I think you´ll be just fine with that size exhaust AR.
The thing is...the streetrace crowd around here-the DIY boys that is-seems to find new ways to "el cheapo" turbocharging all the time,and they´re finds of lately has been that you can get away with a LOT of turbine AR if you build it right-the exhaust man that is.
Seing the NA power of the cossie..you´ll be just fine.
Mine btw..is a somewhat larger one-altho still on a T3 flange.
It´s a super T70,just cause i got it brand new for free
Compressor..is good for approx 600+
Yeah, the cossie engines really ARE full of good stuff right off the bat,and i for one settled for a little more static compression than you did.
In my case 9,2:1.
Reason..is that this is a street motor,and these days you can get away with that much comp under boost in a 16V head as they ain´t exaclty prone to detonation-as were the earlier 2 vlv designs.
Just take a look at the boosted M3 and M5 engines around and you´ll get an idea..
What one does is basically to emphasize a certain main area of use.
Ie;in my case..it´s NOT a race car,but a streeter-and i try n keep track of that.
To compensate..one simply backs off timing.
Take a look at the current crop Audis and you´ll get an idea.
Around here...they ain´t even opened up..retain the 9,2 comp IOW..and are boosted inxs of 2 bars on a 27 housing-rendering inxs of 400hp.
Exhaust.
Look.
With a turbo engine...its ALL in backpressure.
One simply measures the intake pressure vs the exhaust one to get a differential value.
The more thought out the primary piping..in lieu with the engines internals..the less exhaust backpressure there is,and the better the engine will run-EVEN ON VASTLY LARGER TURBINE ARs THAN COMMONLY BELIEVED.
Guess what....
Mercedes n cosworth..has already done the job for us
The 16V comes stock with one of the most beutiful headers i´ve ever seen-especially so in production.
What i´ve done..is simply to turn the MF upside down..
Had to reroute the No3 pipe a little,but that was about it.
This places the turbo far out in the pass side inner front fender.
Have...replaced the ASR to the intake side.
Swaped the radiator expansion box for one from a Volvo 740 series.
Exchanged the OEM windshield washer box for one of the Bosch "bag" series with built in pump and placed it right by the battery.
Works great.
Buuut....the thing is that mu turbo physicaly is about twice as big as yours.
Could say...that ample room is something i´m without broh
On the intake side..i decided to scrap the entire OEM setup.
Out the F-in door..
made up some new 50mm intake stacks and routed these to a 110mm dia plenum,which has an "entry" plenum welded atop of it to work as a diffusor-a´la the late design Audi sport intakes.
Throttle body..is at the intake end of the diffusor plenum,and is the modified stock unit.
Modified..in as much as that i elongated the throttle axle to be able to install a Ford/Haltech throttle position sensorn at the end(TPS)
IAT,CTS asf..are all Bosch/Volvo.
Same crap different day really.
The wiring n such..is all home brew.
Honestly..makes for a more "decent n clean" looking install than the average flying lead carpet most mans send with their ECUs.
IOW..it´s made to fit.
ECU is placed as pre the OEM one-Ie,behind the battery.
Btw.
As i run a somewhat larger turbo than you do,when the install is finalized it´ll sport a 3,5 inch downpipe into the full 3" sans catalyst asf already built exhaust.