Help! Need Turbo sizing assistance!

Hello Guys,

I am building a single turbo setup LT1, the engine is a forged 355 with 8.7:1 compression, ported heads intake 58mm TB, msd etc etc.. all the good stuff needed.. question is on size and model turbo most are running to see in the vicinity of 600 RWHP. this is a goal on race gas for me to start with.. a more conservative goal on pump gas would be around 525-550 RWHP. I have been considering a T66 or possibly a T70. but would like some input from those of you who have done it.

I would rather have a turbo as close to what i will need for these power levels so i don't have to wastegate the hell out of it, and so there will be a minimal lag time before boost. any of you running a single setup who have been determined enough to do the work and R&D I am asking for your input to avoid spending money unwisely and get through this with as few headaches as i can.

Also injector sizes for this would help tremendously.. a double intank racetronix pump will be used and i would like to know if the stock ECM on an OBD-II computer could support the tuning this package will need.

Any help and input on this will be greatly appreciated!

Thanks everyone!

Chris

I would go PTE67. Should make 650 on race, 500-525 pump, and spool very well.

Mikael,
thanks for the advise... do you know where i could take a look at the compressor map of this turbo? any help would be great!

Chris

do you have any flow numbers, VE, bore/stroke data for this? how many psi can your internals handle reliably? you really need it all to 'size' the right turbo. <BR>
i've done some preliminary work for stock ls1 numbers, and it looks like you'd want at least a T72 or GT40 or GT42. don't listen to the people that tell you you can't go beyond .60 exhAR or you're gonna have lag. the good part about 355cubes is that even at 2000-2500rpm you're flowing so much air, that you can see positive boost, even with a .96 housing. Also, the newer turbos have much improved wheels, which means you can hold in trubo's high efficiency range for much longer/broader rpms.

so basically give me the data and i'll maul over the numbers and tell you what you need.

I have almost the same setup and I was going to use a q-trimmed 67 until I got a smokin' deal on a Greddy 71mm. The 67 should make good power and spool quick.

-Chris

MM&FF made 750hp on their 408ci ford with a 66mm turbo and 6.5lbs of boost. Why does he need a bigger turbo for a smaller motor to make less HP?

Originally posted by 96TurboTA
MM&FF made 750hp on their 408ci ford with a 66mm turbo and 6.5lbs of boost. Why does he need a bigger turbo for a smaller motor to make less HP?

Because engine size and max horsepower are not the only factors to consider when sizing a turbo.

FWIW, I called my tech at Turbonetics and told him the application, specs, and goals, and he confirmed my belief that the Q-trimmed 67 was a good choice for my application. NC-LT1's motor is essentially the same as mine, but he's running a point less compression.

-Chris

Chris,

I would be very interested in talking with you on your setup, seems like we are both on the same page here.. my install is on a vette however but all things else being equal, I htink both of us are building similar setups engine wise. my email is lcvette1@aol.com, if ya have a second or two shoot me an email, would be interested in your setup and some of your fuel system setup and your engine management arrangement. hope to hear from ya!

Chris