CGeek2k

I have been reseaching turbos for my car and thus far I have found several compressors that have a high efficiency in the flow range that I plan to be running:



BorgWarner K27

GT2860R

T04B 60-1

T04B 62-1

T04E 54 trim

Mitsubishi TD06 20G



The T04B seems to be pretty popular from what I have read however the T04E and the K27 have the best compressor characteristics. I am sure there is a lot more to choosing a compressor than just the efficiency map but at the moment I'm not really sure what to be looking for. Are there any geometry or size issues with these compressors?



Next I am trying to find good information on the hot-sides of these turbos. I have heard a lot about the turbines choking at the high flows of a rotary. My first intuition is that as long as the turbine is the right size to give you boost when you want it, any extra flow can be offset by a large wastegate. The big thing there from a fluids perspective would be the geometry of the manifold. My goal is for full boost between 3000 and 3500 RPM. I also think I heard something about different turbines being attached to the same compressor?



Thanks for reading through all of this. Any extra knowledge you can throw my way would be greatly appreciated.

j9fd3s

except for the 2860, all of those are popular choices and would work just fine.



60-1 vs the 62-1, both are good, the 62 is gonna spool a tad slower, but have more top end



TO4E is a little newer design, but i think a 54 is a little smaller, prolly great for a lower lag broader power band, but peak power might be down a bit



turbine sizing is a little trickier. you need enough flow to support the engine, but most of us want full boost around 3500ish too. revvins had good luck with a smaller compressor and a larger hotside than most people run.



so its useful to look at the sizes of the turbo wheels, the stock turbo (i think) is a 63mm compressor and a 62mm turbine. the key here is that they are almost the same size. keeping a similar sizing ratio is a good idea, just make the wheels larger.

CGeek2k

Any guidelines as to good turbine A/R's? From what I understand, smaller A/R means earlier boost, but more restriction. Couldn't this extra restriction be overcome simply by using a bigger wastegate?



For the turbine trim, a P trim is pretty much standard for street cars, correct?



A divided housing is best?



Other options I am seeing are dry vs. wet bearing housings and dynamic vs. carbon seals. Any enlightenment here?



Finally, are ceramic ball bearings really worth all the extra cost for a moderate HP street car?



Thanks

Andy

1Revvin7

Difference in " lag " between smaller and larger turbine a/rs is minimal in my experience.

Wastegates were never designed to compensate for too small of a turbine a/r, if that were the case lets run .3 turbine a/rs and 4 90mm wastegates.



P trim is standard for street cars, running street boost/power levels..



Yes always run divided on a street car



Wet/dyn

CGeek2k

Is an A/R around .8-.9 good for a moderate streetport running about 8PSI? I'd like to hit boost early, and I don't mind loosing some top end. This will be an around town car, not a drag racer.



Sorry about all the questions. The Corky Bell book is in the mail.

j9fd3s

.8 should be fine, should be at full boost around 3200ish, it may fall off over 6500, but thats prolly ok in a street car

1Revvin7

Smaller compressor = lower boost threshold



Of your choices I'd get the 54 trim E...