I posted this in teh second gen forum, but I spend most of my time here and I figure maybe someone knows the info Im looking for:

I'm new to the FC turbos cause I'm a first gen guy, but I'm thinking about a S5 Turbo setup on my FB. I found a lot from searching, but still have a few questions. (My goal is 250-280RWHP). Are there any common mods that can be done do the S5 turbo or manifold without spending to much money? I know about wastegate porting to reduce boost creep, but are their any other things that alot of ppl do to their s5 turbos/manifolds? I read somewhere that the S5 has twin wastegates, is this correct? On FCs, the wastegate is mechanical, and controlled by the ECU using a vacuum line from the intake manifold to read boost pressure, correct? Since I am using a carb, and have no ECU, I need to buy an electronic boost controller? The engine is going to use S5 NA rotors. I'm unsure of what boost level would be safe and what would be required to achieve my HP goal. I've heard varying numbers anywhere from 6psi to 12. The motor is going to be streetported - approximately what boost level would be required to throw down 250-280 at the wheels and is this a safe boost level for NA rotors? TIA

 

I wouldn't boost NA rotors if you can get turbo rotors.

 

why not, I'm only going to be running low boost, and a higher comp motor would spool the turbo faster, from what ive read.

would an S5 turbo flow enough for a streetported 13B?

the turbo setup is not for sure, I might do it now, or I might build the car NA and go turbo down the line, i may not end up using an s5 turbo - but whatever i decide, its useful information.

 

Go for the S5 turbo,its far superior and with a direct connect from the turbo outlet to the wastegate,youll get about 5-6psi.It does have dual wastegate holes and it far better at controlling creep.No boost controller is needed if you want low boost.
The S4 turbo is set for a strictly mechanical 6-7psi, but has a small wastgate and inferior manifold.The S4 turbo uses no ECU intervention.The S5 turbo is controlled by the ECU and a factory boost controller to make about 8psi,but without the S5 ECU and solenoid,itll make about 5-6psi,strictly mechanically.
Itll feed a stockport 13B fine,a streeport 13B might drop the max psi a little due to extended port timing,but itll still be a fair amount of power.
250-280 WHEEL hp is pushing it for the stock turbo.Usually stock T18 guys stop at about 250-260 crank HP,which works out to about 225-230 wheel HP.The compressor is just too small and doesnt move enough CFM without excessive heating.A FMIC helps,but also just adds intake tract volume.The cure is a S5 with a TO4 compressor,also known as a hybrid turbo.Itll increase the CFM output of the turbo,but still bolt up like stock.I use one on my streetport S5 13B.It hits 14psi easily with a FMIC and makes about 300 crank HP without much intake temps or stress.

 

thanks Steve84GSTII -

that was very good information on the S5 turbo.