dasorcha21

iTrader: (6)

So im confused with turbo sizing let me explain my setup and goals and limitations...
the car is a 98 corvette a4
the motor will be a 366ci
heads that flow over 370cfm
built a4
2.73 gears
3500-4000 multi disk stall

the hot side is from hinson motorsport's single turbo kit.
which limits me to t4 flange turbo and 3inch downpipe.
and also limits the size of the turbo to the physical dimensions of a T76 or T78

my goal is for the car to have 800hp daily driven and 1000hp on race gas.

now the issue is what turbo would get me there with the above description and limitations?

thanx for the help in advance

67Firebird455

iTrader: (27)

You're almost going to need a T6 flange turbo to get those numbers with 336 cubic inches of fury. Generally, running a T4 and trying to get those numbers will place you way off the compressor map. I had heard about some sort of "compact" setup, but I'm not sure if it will get you 1000rwhp, even on race gas.

dasorcha21

iTrader: (6)

im sorry just edited it
i meant 366ci

67Firebird455

iTrader: (27)

That's better... explain a little more on that turbo you've got there...

dasorcha21

iTrader: (6)

i dont have one i need help picking one out that will meet my hp goal and 3inch downpipe and t4 flange limitation

67Firebird455

iTrader: (27)

Forcedinduction's FI66 with an 88mm wheel MIGHT get you close. A precision PT88 also flows something like 125lb/min, which is good for around 1000rwhp.

67Firebird455

iTrader: (27)

Borg warner (Airwerks) also makes a good unit for that kind of power...
The ST80, but I think with a T4, you're going to still have some issues with back pressure vs a T6 flange.

dasorcha21

iTrader: (6)

anybody else?

dasorcha21

iTrader: (6)

nobody has input?????

GT67METHV

67firebird455 won't stear you wrong...
other folks may confuse you.

dasorcha21

iTrader: (6)

i checked with half of those turbos. some are to big dimensional wise? and others cant use a 3inch DP

GT67METHV

let the fabricating begin. lol
you had to have 1000 hp didnt you?!

67Firebird455

iTrader: (27)

Appreciate that man...
A lot of the bigger turbos will use a larger DP than 3", it HAS to be 3"?

dasorcha21

iTrader: (6)

i do appreciate your help and knowledge. from my understanding the kit comes with a 3in. dp. here are some pics

67Firebird455

iTrader: (27)

Eeesh, that's rough. That is one tight squeeze in there. I personally wouldn't do it, but you could always reduce from a 4" DP to 3" since you're not going to be running it at max all the time, but I honestly believe you'll lose some efficiency with it being choked.

dasorcha21

iTrader: (6)

hence the question of with what limitations i have to work with (t4 flange, 3inch downpipe, hood clearance) would i even be close to touching 800hp?
im not to good at looking at compressor maps and figuring out if a turbo is gonna choke etc... thats why i would like people who have experience or are experts at this to give me a little bit of help.

dasorcha21

iTrader: (6)

would a T78 or even a 78GTS work?

67Firebird455

iTrader: (27)

A 78GTS is gonna get you very close. It'll be blowing its lungs out, but you may be able to get there with that turbo.

dasorcha21

iTrader: (6)

what are your thoughts on the overall hot side plumbing?

67Firebird455

iTrader: (27)

I think what you have now will take you a ways. Looks good, no pinches, mandrel bent, and 3". I'd try and find a 76GTS and see how it works out, what kind of boost do you WANT to run, and what kind of rpm does the motor see?