Hey guys, I have read up a bit in the turbo section and now I have a few questions of my own.

I will be getting my hands on a low miles S4 TII engine. I will be doing a Bridgeport on the motor with a Weber 48IDA. Max RPM will be 8200. I have a bridgeport template here and will be ordering the Pineapple Racing BP Exhaust template soon enough. I will be turboing the motor after I finish breaking it in with a GT4088, probably something like this: http://cgi.ebay.com/ebaymotors/Preci...QQcmdZViewItem

My question being, will this turbo work on the motor with the 1.19 turbine? Or would it be better with the .96? I would think the 1.19 would be better off since it will not restrict the flow up top, but I am worried about the lag it may have (even with the bridge). I am looking for full boost by 5k and 400whp on pump. Turbo will be ran with a W/A intercooler. If I am missing any information let me know...

EDIT: I hear that the rear S4 Iron is prone to cracking under high boost, so I would like to keep boost to around 15psi, or should I spring for an S5 rear iron?

 

I believe the rear iron on S4 only crack because of engine detonation. It can only take a small amount to crack it. Usually people running high boost with shitty tunes claim that the iron breaks just because of BOOST.

I could be wrong though and all in all it wouldn't hurt to have the extra strength of the S5 iron.

 

You will have 15psi by 5000rpms with the larger turbine housing. I wouldn't run the weber however, unless its an all out drag car.

 

Why would you not run the weber?

 

There is no way to transition into a richer mixture using a 2 barrel. With a 4 barrel you can stage the secondary jets to be much richer to compensate for positive pressure.

 

Not even when you go from idle to main circuit? That tends to happen around 3k depending on the E-tube used.

As far as everything besides the weber, would this set up be worth 400-425whp @ 15PSI?

 

If you do want to go with s5 irons, you might as well go with all three of them, not just the rear one. That's what I'm doing. The front one has thicker casting as well, and the secondary ports have a larger runner area (just compare the two stock LIM gaskets).