Pennington55

iTrader: (3)

So im building a 370 for my 92 fox. This is my first turbo build so im looking for some help. Its an iron block being bored .030 over. Ill be using forged rods, forged pistons, and a stock crank. Ill probably get a custom cam and have around 10.5 compression. Im using a c6/truck manifolds to keep the air. Ill be running E85 the gas station right down the street has it. I havent decided on what tranny. Ive got a pretty strong T56 setup sitting around and really would like to row some gears but I also know with an auto it would be consistant and fast. Ive been reading alot of good things about the PT88. Whats nice is Precision is about an hour away from me. Ive got a set of 317s collecting dust and am thinking about using thoes.

My goals are 700-800 to the wheels. The car will see the track but will probably be driven on the street more than the track. If it ran 9s id be happy. My budget is to spend the least money as possible. I got a little over 8,000 out of my camaro so id like to build the car for around that. I know ill end up spending more than planned like any other build. Id like to have a setup I could upgrade down the road like throw a forged crank and a good set of heads on in the future and let her eat.

What do you guys think of my setup so far? The PT88 good for me, and should I get a T4 or T6? Do I use the 317s and save up for some thicker deck heads later on? Any tips or suggestions would me appriciated.

Thanks

skinnies

iTrader: (33)

I'd sure hope a forged 370 turbo fox would run 9's. Do some poking around on the FI area, lots of great info and should be able to easily get your goals, especially with e85. Might want to read the real price of FI thread also in the stickies.

Pennington55

iTrader: (3)

Ive been searching and reading. Lots of good info here. But its getting close to parts buying time for me so I figured id see what others thought of my setup.

pwrtrip75

iTrader: (8)

If it were me I would go w/ a smaller turbo, the 76mm on my 370 seems to work well and easily meet your goal. Especially if you go T56, spool way faster. An auto in a fox would easily run 8's. Im using stock valve 317's w/ just some bowl porting. Been using the same heads for 6-7 years never a prob. If it was a drag car only i might go w/ the PT88 of course an auto too.

Pennington55

iTrader: (3)

If I go with a 76mm turbo down the road if I put in a forged crank and some good heads will I be able to run more boost or will a 76mm be close to its maximum boost with my set up right now? Id like to be able to put the car together under some what of a budget right now then when I get the money for other parts throw them on and just throw a little more boost at it.

pwrtrip75

iTrader: (8)

You go by air flow, not boost. Like X amount of air flow will equal 700-800hp. The psi it takes the compressor to flow that amount of air will vary depending on turbo/compressor size. If a 76mm only flows enough air to make 1000hp, then if your goals are higher than that....you need a bigger turbo I only recomended a 76mm because your goal was 700-800 at the wheels and you mentioned a manual trans....it would spool up fast and be great for driving around. Versus a bigger turbo w/ a manual trans would spool up slower, if you had a auto/stall to compensate, its daily driving characteristics would be way better. Depends on what you want to do w/ it really... you need the entire picture laid out in front of you to design a perfect system.....perfect being for YOUR needs.

miatainthe10s

Well said pwertrip!

I'm doing a similar 370 build with m6. I'm going bw s475 110 ar 83 exhaust wheel. Easy upgrade to 480 later. Didn't want to limit myself with a t4.

9sectruck

iTrader: (9)

Im building damn near the same engine combo and I went with the pt88 t4 (auto)
that fox will go easy 9s on a 76 and like stated above will spool alot better with the 76 on a manual.
we have a car here local that had a 76 on is car (manual) granit the guy could no drive
made 830ish to the tire and traped 140 and had a slip of 11.3et... I hate to even think how slow the car would have been with a 88,
go with the 76 and work up to the 88 or go auto from the get go

Pennington55

iTrader: (3)

Ok so after seeing your guys responses, reading, and searching for hours today I think ive decided the PT7675 CEA will be my best bet. Sounds like its worth the extra money for a billet wheel. That way I can keep the 6 speed. And in the future I could always just sell this and upgrade. For my first turbo build I shouldnt be trying to go all out anyways. Almost everyone that has this turbo loves it. I even read a thread on a guy switching from a PT88 to a PT76 because he wasnt reaching boost till around 4500. That was on a 347 but I still got the idea of the lag I dont want. What A/R do you guys suggest? They offer .81 or .96.
Thanks for the suggestions.

9sectruck

iTrader: (9)

370 go .96 or you will have a ton of back pressure

boss79z

iTrader: (1)

.96 .....has more potential

Pennington55

iTrader: (3)

Sweet! .96 it is. Thanks guys.

5w20

iTrader: (21)

Bring the compression upto around 11.0, E85 loves it. It also helps with spool.

Pennington55

iTrader: (3)

Ok, I really wasnt set on compression. I havent ordered pistons yet. How would I go about picking pistons? The way Ive seen the compression ratio measured is see how far the piston comes out of the block, cc the heads, add in the head gasket thickness ect. But If i have no piston in the block to see how much it comes out how would I pick a piston according to the compression ratio I want? I wouldnt want to mill the heads because I want to keep the stockers as thick as possible.

skinnies

iTrader: (33)

Yep go 11.0 compression and .96 housing, no reason on the 6 speed it won't make 900rwhp.

9sectruck

iTrader: (9)

its going to be hard to get 11.0 using 317 heads
best case I can only come up with 10.0 with the 317 thats using a .036 gasket and the deck perfect to the top of the piston.
I would look into 243 to get the compressin up to the 11.0 with a .051 gasket it will be right at 11.0 if the deack is perfect with the top of the piston.
thats using flat tops on both with only -3cc valve relifes

Pennington55

iTrader: (3)

I do have a set of 799s laying around. Wonder what the deck thickness is compared to the 317s.

9sectruck

iTrader: (9)

same (thin)

Pennington55

iTrader: (3)

So im going to bump this up instead of starting a new thread. Im trying to do the math and come up with 11.1 compression. Anyone run or know someone that runs domed pistons with forced induction? I cant find much while searching. I found alot of guys going from nitrous to turbo and switching out the domed pistons for some flat tops or dished. I did the math and if I have 4.03 bore, stock 3.622 stroke, .040 head gasket, 64cc 799/243 heads, piston deck at .07 and a 12cc domed piston puts me right at 11.1. Its going to be a street car so im not looking for a huge cam. Would piston to valve be an issue any other issues with boost and domed pistons? Or should I just not even try to use a domed piston?

5w20

iTrader: (21)

Get some good valve springs. What would some flat top pistons do for your compression?

You necessarily don't need 11.0 compression, I just suggested it because you are going to run e85. If can get it up there it will only help you. The smart thing to do with the shorter stroke engines with bigger turbos, is to rev them higher to broaden your power band. They might spool later than bigger cube stroker engines, but you can have the about the same rpm power band range just at a higher point.