Think of the counterbore as a pocket in which the comp wheel sits. For each comp wheel diameter (exducer), there exists a unique center housing with a matching pocket.

You could conceivably machine a center housing to accept a larger comp wheel, but not the other way around.

Best thing to do with that 2876 chra is to put a 30r turbine wheel in it and go for 400 whp.

http://www.boostedmiata.com/t3_turbo...rebuild001.jpg

the wheel your curious about is only 60mm, yours is 71mm so there would be a 5.5mm gap around it if you stuck in on your CHRA.

I can simply swap out my backing plate or machine it out if need be.

Yeah, it's only the small-frame bb stuff (35r and smaller) that has the counterbore integral in the center housing. Everything else has a separate backplate.

JB weld the counter bore down to 61mm :)

Ummm, I think that conversion chart was completely wrong; at least the version I saw sure looked that way.

Oooooooohhhh; that's why it looked fucked up to me....

Note to self; keep up and read all the way through the thread BEFORE posting.

I think I'd rather find a dirt cheap turbo with the NS111 .64 hotside and compressor I want. so much easier. and lazier.