Turbo Guys, again . . .

I've been researching all the different compressor maps out there to size one up, and here's what I've found:

6 psi doesn't fit any one that well. I can't find a map for the Garrett T25 or T28, but I've read complaints that the T25 is great for quick boost, but leaves you lacking at about 5k rpms. The turbo sizing calculator on http://www.turbofast.com.au/javacalc.html
says that I should look at a T25 with a 60 wheel for the low boost (6 psi, my starting point), but then go up to a T3 with a 40 wheel for 8 to 10 psi. For the T3 option, I'm only looking at 72% as my best efficiency at 6 psi. It gets better at 8 and 10 but not much. I have no idea how to tell spool up speed from that.

My goal is three stage: Stage 1: simple, 6 psi, easy engine management. Stage 2: 8 to 9 psi, more advanced engine management. Stage 3, up to 15 psi, new ECU, the works

I'd like the same turbo for all three phases, but I also don't want a laggy beast for the next year or so. So, I was wondering, is 70% to 72% enough? Red, what efficiency are you sized for?

As usual, all help is appreciated.

Thanks,
ac

 

Okay, after some reading, I found that anything in the 70's is pretty good. So it looks like I'm going with a Garrett (Turbonetics??? -- see other post) T3 turbo with the 60 compressor wheel.

So now, Red, Random, Cheuk: how should I size up the turbine. I have found it's easy to get A/R ratios, but performance maps are nowhere to be found. Any advice?

ac