I have enjoyed this site for many years and I hope to be of benefit to others by sharing my build. I have owned my 1982 Trans Am since 1995. It has went through many changes and will continue to do so. It started out with a well worn 350 and T 10 transmission. My first pass was 17.77 at 77 mph. I built a hot little flat top 355 that went 12.19 with the T 10 and 12.14 with a TH350. I repainted the car black and upgraded to 1992 ground effect and nose cone. Next came a dyno confirmed 383 that made 552 hp and went 11.77 at 117 mph. I got married and had kids. Many years later I put in another 355 that went 13.60 and that's when I got the turbo bug. I bought what I thought was a s471 on ebay and put that on the car with a Demon blow through carb. That didn't last long with no knowledge of timing and hyperutetic pistons. After that came the current motor.

Dart Little M Billet caps 4.125 bore
AFR 195 heads reworked for 5/16 Titanium and Inconel valves
Callie crank
Manley rods
JE turbo pistons
Morel lifters
Howard 230/240 .555 .555 110 l/c roller cam
Comp cams stainless rockers/girdle
B and B pan
Team G intake that I converted to EFI myself
Holley HP EFI with crank trigger
ATI balancer, ARP everywhere
Edelbrock elbow with 90mm Fast T.B.
TH 400 with brake
ATI blown and fuel converter
10 point cage
Ford 9" with Strange center section, svo 3.50 gears, Detroit locker
3600 LBS
Homemade trailing arms, panhard bar, torque arm. Stock front struts, Strange Mustang rear shocks at full stiff


Best 60' 1.52
660 6.78 102 mph
1320 10.52 129.32

Now for the turbo. I was new and assumed the seller knew what he was selling. I bought what I though was a s471 T4 . ( This was bought for the 13.60 355 , n ot the current combo.) As it turns out it is a K31 that some has converted from a bolt on down pipe to a half marmon .91 T4. The turbo is front mounted, no intercooler, no boost control and no meth. I think the turbo is a real restriction. My i.a.t.'s are 245 ish which I believe is due to the small turbo and no controls on the discharge heat. Feel free to chime in. I really want a Borg Warner s480 with the 1.32 T6 housing. I just bought a PT 1000 cast end intercooler that I will add this winter.

 

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I'm no turbo expert, but a t4 is definitely way too small for a 400ci motor. Your exhaust is going to get really backed up flowing through that exhaust housing. In the Ford world (where I have spent most of my time) a t4 is acceptable for a 302, but anything 347+ is going to use a t6. Only reason you see a t4 is if they are running twins. But again, I don't know a whole ton about them and don't have any real world experience other than what I have seen at the tracks and on the forums. Maybe somebody else with more knowledge will be able to chime in

 

Agreed...a S471 is too small for a 400 with a decent cam and heads....especially since you have an automatic

I would be considering a standard T6 S480 as a minimum for that combo.........if it was a lower HP/RPM towing engine the S471 may be a decent option.

 

Yeah, it spools super fast but runs out on top. I shift at 6800 and am concerned about over spinning the shaft.

 

You're leaning on it too hard if you are seeing 245* temps...esp. on pump gas. You'll melt down a forged motor just as quick as a hyper motor, so be careful!

As mentioned your baby T4 turbo is bottling up the back pressure in the exhaust with that large of a motor. What is the LSA on that cam? Have yo figured out the overlap? Any real overlap will kill a setup with high back pressure like you are currently running.

Have you seen the VSracing billet S480s? and S488s? I'd go that route. Cheaper than the real deal Borgs and proven performers.

 

I'll have to check them out. I am really excited to try out the PT1000 intercooler that I just bought. I have searched on here a lot but can not find anyone that has a back to back comparison of running no intercooler at all to running a water to air. According to Borg Warners Matchbot software a 200 degree drop in air temp adds a huge amount of power, in theory. It will defiantly make it much safer and probably let me add some more timing.

 

Here is the newly relocated turbo. It fits great in this spot as long as the radiator is over ahead of the support. #ad

 

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Just as forcefed said check into the vs racing s480 clone w/ billet wheel they're less then $800. I just went 9.20 with mine on relatively low boost. 355ci.