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Couple simple questions

Old 06-21-2007, 12:28 PM
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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.
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Old 06-22-2007, 01:01 PM
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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.
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Old 07-02-2007, 05:19 PM
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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
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Old 07-03-2007, 12:25 AM
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Originally Posted by CGeek2k' post='876824' date='Jul 2 2007, 05:19 PM
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


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
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Old 07-04-2007, 06:09 PM
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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.
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Old 07-05-2007, 04:51 PM
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.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
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Old 07-06-2007, 12:24 AM
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Originally Posted by CGeek2k' post='877030' date='Jul 4 2007, 06:09 PM
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.


Smaller compressor = lower boost threshold



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