Turbo selection


Dec 31, 2004
Hey all... Been reading a bunch of threads about turbo selection but it really seems vehicle specific so I will throw out my question here... Looking for a turbo to run approximately 9.50 or so in a 3200# car (w/driver). Stock block with Champions, etc... Car currently runs 133+ with a TE45 and I think it is maxed out. Advice so far is leading me towards a 72-76 mm dual ball bearing but I am still looking for more specifics on A/R ratio, trim, etc... Thanks in advance for the advice - all is welcome. It needs to be a 4-bolt to match a new set of TA headers.

If this is going on a Buick V6, then I personally would recommend a PT74 GT-Q dual ball bearing with either a .68 A/R T4 tangential or a .81 A/R T4 tangential v-band style PTE turbine housing. (A/R would be determined by CI of the motor) If the CI is 248 or smaller, then the .68 would work just fine as it will definitely out flow the 3-bolt .85 PTE housing. If the motor is larger than 248CI, I'd say go with the .81 A/R. But in order to maintain decent spool up manners, you will need the dual ball bearing cartridge no matter what. The 74mm compressor wheel has a much more usable power curve than the 76mm compressor wheel does, and you have an advantage with having a 3200# car with driver. This turbo will easily support 850 flywheel hp when maxed out, and if you car weighs 3200#s with driver, you only need to make in the neighborhood of 760-780 flywheel hp to go 145mph in the 1/4, which should be enough for easy mid 9s. The 76mm compressor wheel will make slightly more hp at higher rpms than the 74 will, (about 15 more) but the 74 will make more power in the low to mid range of your power curve. Either one will get the job done, but if you intend to play with the car some on the street, the 74 will feel more peppy. You do not need the GT-S turbine wheel on such a small V6. (231-248 CI) The GT-Q will get the job done just fine.
Hope some of this helps a little.


Patrick -

Thanks... This is for a '87 T-Type. The motor is a 109 bored .030 - so about 235 CI or so. It is a race only car - I do not care at all about any street manners. I just want it to be able to spool up faster than what I currently have and provide more HP since I seem to be out of turbo at this point. I will definitely go with a 4-bolt dual ball bearing turbo, if for no other reason than to buy it once and not need to swap again if I go to a larger (stage) motor.

Does this info help refine your selection at all? Inlet size would be 4", outlet 3" I assume? Would still like to understand more about the A/R ratios of particular housings and how they all work.

Thanks again for your help.