I'm planning a bit of a project for the summer. I have a new 94 Trans Am GT that has ever bolt-on as well as a sweet pair of GTP-ported AFR LT4 195cc heads and Comp valvetrain. What I want to do I put my fresh 355 shortblock under these heads and add boost with a new cam. Current cam is TONS of fun... 235/242 .568/.592 112... but I'll obviously be going smaller with boost.

My 355 is all-forged, balanced and running 9.2:1 compression ratio. I intend to add head studs, Spec Stage 3 clutch, Fidanza flywheel, Racetronix/Walbro 255lph pump, 36# injectors, and the LTCC coil-per-cylinder conversion.

What I need are experienced suggestions for the turbo build. I want to go with pre-fabbed manifolds to keep 'some' of the aggravation down, and then round out the setup with parts of my choosing. For the manifolds..... this will not be a daily driver, but it will see plenty of heat cycles and street driving, so I imagine I would want some thick walled pieces, right?

Now, for the rest of the kit... I have to re-educate myself a bit, but what are some suggestions? I'd like to have a setup where I can set it to a lower psi for regular driving and then turn it up for the track. The car currently makes about 500hp. My target would be in the 600-650hp at the flywheel for the track and 400-500 for street driving.

Can I reach the target track numbers on 93 octane? I.E., without adding race fuels or seriously retarding my timing, could I achieve those numbers on the street?

Other than that, I'd be interested in seeing what parts you guys would put together for such a combo if you had this situation. It ways helps to compare and contrast against my own ideas.

Thanks guys! With some luck and a lot of money, I hope to be turbo charged by the end of the summer.

 

You should look into a PTK kit and a 60 or 70 series turbo for your goals. And top it off with an electronic boost controller.

 

I think your questions were addressed in this post...

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The rear, suspension, chassis, clutch/flywheel, bottom end and top end are all ready to go on this car.

A question about fueling... I want to put the Racetronix kit in with the Walbro 255lph pump and swap my 36# injectors over from the RS. Will this be sufficient to power a 600hp engine?

Engine Management... how far can LT1 Edit take us when dealing with a turbo setup and an adjustable boost controller? I'm not the type who would need to adjust on the fly, so I'd be fine reflashing the PCM if need be on the weekends. Will stock management with tuning suffice?

Turbos themselves... where can I find a good DETAILED site for me to read up on the differences between brands, sizes, and components. I remember the hot thing last year was the T3/T4 hybrids for TT setups. I don't feel the need for a TT setup, but I want to educate myself better before making any decisions.

 

I'm about to go down that road myself. Agostino Racing Engines is doing a 2-stage build with my car.

Stage 1 is upgrading my fuel system (injectors and pump), installing a single turbo + intercooler and building custom exhaust manifolds. According to them, both left and right manifolds will be feeding the turbo. This will be bolted up to my stock LT1, that currently has the LT4 hot cam, 1.6 rockers, hardened pushrods and new lifters. They're going to push this motor to the breaking point to see what a high mileage (221,000km) LT1 can make before it breaks, to set a bench-mark as a resellable kit for stock-ish LT1s.

Stage 2 will be a 9:1 forged 355, ported heads, stainless stock size valves and up the boost. I'm looking for at least 500rwhp from this combo, maybe more.

I'll keep you updated as this project progresses.

 

IMO you are not going going big enough with the fuel system. we maxed out a set of 55lb injectors on a 600rwhp setup,and i have serious doubt's 36 will make it with a boosted 600-650 fwhp setup.

also the single 255lph might work with a boost-a-pump,but again,better to go big then to 2nd guess.

 

Ditto on the 36s being way too small for that setup. I'm using 50#ers on my single turbo 355, and they'll be close to maxed at 500 hp. I'd also look into a complete fuel system for what you're wanting to do with the car.

BTW- I think that 500 hp figure with the head/cam motor might be a little high.

-Chris