resizing turbo
 

so i was looking at some new options for a turbo, right now i have a stock port 13b-re motor with a microtech, hks log manifold and enough fuel to set florida on fire. the turbo i have been using for the past year and a half is a precision 6776e with a .60 a/r comp housing 66.7 inducer 84 exducer and a p trim turbine with a 84 inducer and a 76 exducer in a ..68 turbine housing. now ive gone threw 2 motors on this setup with a mazsport tune(also bought the turbo from scott at mazsport). now i dont like to get into turbo sizing stuff because it makes my head hurt but, everyone else i see has a huge turbine housing compared to mine and still has full boost at around 4 grand. so my question is would a .81 housing better suit my motor and have less back pressure but still spool fast?

the last dyno numbers i had were 330 at 14psi, and the car is primarily used for autocross and spirited driving. so a big laggy turbo is not an option. and help is greatly appreciated. zack

You've got actually a pretty large turbo. It's T66 sized, which is no auto-x sized turbo. It looks like the turbo builder over shot with the size and tried to compromise with a tiny turbine housing to make up for lag. Well, it doesn't quite work that way, espcialy on a rotary. Keep the turbo, up-grade to either a .81 or .96 A/R turbine, tangical and you should see same spool up, but massive gain in mid to high end torque and horse power (you should see 400 at the wheels at 1 bar of boost). You could downgrade on the turbo compressor size and make roughly the same HP and torque but gain 1000 RPM spool up times (like a T04E 57 or 60 trim, or 60-1 compressor with a .7 A/R compressor housings {AKA: T04S} or even a more modern GT35R compressor). A more street and auto-X oriantated turbo set up. You wont loose a thing by going with what I recommended on 1 bar of boost and pump gas (power wise, and gain in low to mid torque). But if you keep what you got, and raise the boost to 18+ PSI you've got a 500+ RWHP monster (the smaller turbo comprssors I recommended will fall flat on their faces after 1 bar {14 PSI or so}, but you'll need race gas or aux injection to be safe and reliable (more then 1 bar), unless you've got or are one great tuner.

~Mike.........

BTW, 330 RWHP @ 14 psi (1 BAR) is LOW in power, (you should see that at 10 psi) all contributed to that extremely teeny tiny turbine A/R.

awesome thank you. i have been looking for a .81 exh housing for a little bit, you dont by chance know anyone that may have one. so what your syaing though is keep the compressor housing the same and just exchange the turbine housing? and also dont forget this is on the stock re oval port exhaust housings. thanks very much

and also this turbo was bought from scott at mazsport and then tuned by him. he said this turbo was a good all around turbo and i should have had no probs with it. but this was also bought a few years ago when i didn't know very much about turbos