301 turbo

I am wondering what would be a good turbo to replace a old to4b air research on a 301 engine it has had the pump turned up some and shows 150 horse on the dyno the motor is in a 180 allis thanks

Not sure what you are trying to do, but if all you want is 150 or so horsepower, stay with what you have or upgrade to a 7020 turbo. It would be a direct fit to what you now have.

Edited by O.P.S. Heads - 02 Oct 2014 at 8:20pm

Any current models from Holset, Garret, or Borg Warner will be more efficient than the old Air Research. Measure the wheels on what you currently have particularly the inlet of the compressor. Find something of the same size in a current production unit (HX35 - GT30 - S200). You are correct. Anything newer will be more efficient.

Some of the HE and HY models and possibly some HX series Holsets have variable geometry turbines which in my mind would not be ideal for pulling. Would work great on a farm tractor.

Good question. I'm not sure I can answer it intelligently. My first and probably best answer would be that anyone serious about pulling does not use them nor do any of the pump / turbo shops that build high performance parts recommend them or use them in a pulling application.

From what I understand the VGT turbo's are similar to a waste gate as they are a controlled leak within the exhaust housing. The more exhaust gasses released from the engine, the bigger the "leak" gets in a effort to keep the turbo shaft at a reasonable RPM and the boost pressure at a reasonable level. The leak is wasted energy which is affordable in a stock application - not so much in a pulling application. They were designed to have faster spooling time than a typical fixed exhaust housing so when you leave a stop light with your Dodge Cummins pickup it has good power at low engine speed. Typically the turbine wheels on VGT type turbo are smaller in diameter which isn't great either for pulling. With that said, I have wondered how the correct waste gated turbo (with mods done to the gate) might work in a 3,000 RPM limit class. Never tried it.

Google VGT turbo's and you will see the variable vanes built into the exhaust side surrounding the turbine wheel.

With a pulling turbo on a diesel, you want to drive it as hard as possible without blowing it up and yet have enough exhaust flow so the engine isn't constipated. The properly sized turbine wheel and standard exhaust housing is best for the job with no energy being wasted.   

Edited by O.P.S. Heads - 03 Oct 2014 at 1:07pm

If a waste gated turbo was used, and the gate was set to open starting at 40 lbs. of boost vs. 12 lbs. It might work better than a standard housing for a paced class or limited RPM class. The gated housings would be easier to do this with I would think. I'm not sure how a VGT is actuated or if it can be bypassed / monkeyed with easily.

also with a good scan tool on a pick up you can build about 8-10 psi of boost just settin there in park at a 1200 rpm. by moveing the vain% threw the scan tool. most places it in the rules "no VGT turbos" thats more truck guys tho i think