nfoster88

I am in the process of doing a frame off restoration on a 1975 Firebird Trans Am. I started this project back in March and have made some decent progress in the time I have spent on it. Not sure if this is the best place to post or not but since it is going to be turbocharged figured I would throw it up here.

I started by stripping the car completely and taking the sub frame off. I cleaned up the frame and coated in POR-15. Fixed the floor pan on passenger side and put back on with all new suspension parts, including a manual gear box. I added a set of QA-1 coil overs on the front with a set of Wilwood disc brakes. Out back I purchased a ford 9" with a 3.50 gear, 35 spline axles with a detroit locker. New rear leaf springs as well with new bushings. I plan on running a fuel cell in the back and running E-85.

For the motor I picked up a JY 4.8L, like many thought I was buying a 5.3, but was mistaken when I took it apart. I replaced the pistons and rods, all bearings, and put new rings in it that I gapped at 0.028. I bought a comp cam that Martin spec'd out for the build. I send the heads off and had them milled and a 3 angle valve job. While they were out I had the springs replaced with some Brian Tooley dual valve springs. I have yet to get an intake or throttle body for the car. I upgraded the timing chain while I had it apart.

The turbo is a Borg Warner S480 that I purchased from APEX online. Here are the specs on the turbo.

Starting from a base Borg Warner S400 we have fitted this with a 80mm extended tip billet high flow compressor wheel

Compressor cover fresh polish Compact S410 Compressor cover (small vband out)

Wheel assembly balanced. severe duty bearings + 360 thrust

Compressor wheel - 80mm inducer / 113mm exducer / 117.55 Exended tip
Turbine wheel - 77.5mm/87mm
Compressor inlet - 5" hose Ported Shroud
Compressor outlet - 2.5" v-band
Turbine Inlet - Divided T4 1.10 A/R
Turbne outlet for 4" v-band

capable of supporting 1175hp+

Plan on running a 2.25" hotside and a a2a FMIC. I have a set of 96cc/hr injectors to use.

I am shooting for 8-850 rwhp through a turbo 400. We shall see how it does.

Will most likely be running Microsquirt.

Car still needs painted and to install cage.

Open to any opinions about the build. Thanks.

nfoster88

Here is some more build pics

Sales@Tick

iTrader: (3)

Looks good!

nfoster88

Thanks Martin. I grew up around professional drag racing with racing a top alcohol funny car, but the LS world is something new to me. I am inspired by guys like you and denmah and hope my car turns out half as good as what you guys do.

SSZ

Nice car. Couple questions
The very first pic looks like the rad is leaned back, is that what you have done?
How do you plan on running your hotside and what size?

Im also doing a second gen but a Z28. Just installing the QA1 coilover on the front of mine. My turbo is higher up than yours i think.

nfoster88

I leaned the radiator back and made the brakets out of tubing to hold it in place. The reason I did this is because I am going to mount the ac condesor and intercooler in front of it, and still want everything to be on the back side of the core support. Also, I think it would breathe a little better angled back like this. The factory 5.3 manifolds would not fit without fabbing cross member so I purchased some ss headers that i am going to mount front wards. I will add pics and update this week. Headers should be here by wednesday.I am going to run a 2.25 hotside. What are your plans?

nfoster88

also look at the pic from inside the engine bay. It is a little easier to see the placement of everything.

SSZ

I ran truck manifolds flipped upside down and exiting toward the front of the car. I used 2 1/2 and wish that i had done 2.25 or smaller. Unfortunately the turbo isnt gonna clear the hood so i have to do something with the hood.
I may redo the whole hotside though. I was thinking of running the drivers side manifold to the rear and run a crossover around the back of the engine and into a modified truck manifold and into the turbo. It would clean up the engine bay a bit and i think i could configure the turbo in a location more to my liking.
May wanna think about that. I have seen picks of the modified manifold and it looks fairly easy. I modded the one manifold for a v-band and welding on the manifold is easy.

I dont have an intercooler and run a CHina GT45 but plan to upgrade after this has some miles on it. WHich, judging by weather wont be till next year.

nfoster88

The fab work doesnt scare me. The biggest thing that scares me about this whole project is the tuning.

I have thought about that but my motor sits real low in the car. With the truck pan I only had about 1.5" of clearance, so I am having to change pans. It would clean up some room under the hood, but I think I will have plenty. I have mounted the turbo to the subframe. I took a piece of 2" angle iron and drilled holes for turbo to mount to and welded to subframe. The way my motor sits in there and how far back it sits, I could not use the truck manifolds without fabbing it up, so purchased the ss v band ones off ebay. We shall see how they fit.

nfoster88

I looked for a pic of your set up but did not see one.

SSZ

Yep cause im a dummy and havent really tried to figure out how to post pics.
Im in the same boat for tuning but i have HP tuners and im sure some here will help when needed.
When i got the engine the harness was already modified. THe tune was wayyyyy off. After alot of reading it now drives in and out of the garage and starts right away whereas before it took forever to start, fouled plugs, couldnt get into throttle without it stalling even in park. But way better now. Baby steps.
I seriously think im gonna redo my hotside with smaller diameter pipe. Im just not happy with it. Gotta shorten my driveshaft and hopefully take it up the road for a drive.
Good luck with your build. Keep us posted. I'll be watching for updates.

nfoster88

So I picked up a set of SS headers from Speed Daddy on Ebay for 160 bucks. Seem pretty nice for what the are. I am going to have to trim about 3" off each one to give more room in the engine bay with the radiator and radius for the hot side. I also mounted my a/c condenser and am getting ready to make mounts for the intercooler. I also picked up some misc turbo parts like the oil lines and some flanges. I started on the tideous body work that I have been dredding so bad. So much fun. Getting closer every day. Cant wait to hear this thing start.