I've got a brand-new T25 .48/.49 sitting here that'll be on the car in a month or so. I'm getting ready to pull the trigger on the manifold and DP, so this is sort of my last chance to change my mind as far as turbo choice goes. My goal was 200-220rwhp at 12psi with as much low-end as possible, so I think the T25 would be perfect for me.

I'm interested now in finding out how hard I can twist the little turbo, though. If I wanted to tune for 100 octane (available 20 minutes up the road for around $5.40/gal at the pump) and/or water injection, how much boost can I realistically run with this small a turbo? 15psi? More? If I were shooting for 250rwhp+ on 100 octane and WI would a T25 take me there? Should I dump the turbo and find a T28 or a T3? I don't want 300hp, since the drivetrain won't hold up and I don't have the money to be building motors/trannies/diffs, but will a T25 support 250, even 260rwhp with 100octane and water injection?

 

Well, if it means anything to you, i just got megasquirt up and running on my t2554 1.6 setup at 8psi and would not want a bigger turbo at all. Im bet this turbo could push 260 at 15psi and a good tune on 100 octane alone. The secret to that extra power is the extra spark timing you will be able to run. However I dont know how much smaller the .48/.49 compressor is.

 

I'm hoping that the extra heat from running huge boost on the tiny turbo will be offset by the water injection, which means very little lag, a HUGE midrange, and pretty good top end.

 

i dont think 250 should be to hard with WI and premium fuel no race gass requiered since you have MS. i cant seem to find any specs on the turbo in question though if it flows 400 cfm atleast you should be able to push the HP no problem.

 

what kinda power are you making, and what kinda cars do you "run with" at the track?

 

Agreed. I have a dyno graph of that turbo pushing up to 18psi... but then dropping off to about 13psi. You'll need to figure out how to control the boost. It's a standard complaint in the DSM turbo about boost creep. I had a rather severe overshoot problem. The usual fix is to port the wastegate flapper hole. Do some research on the DSM forums.
I would say though, that 250rwhp is probably the upper limit of that turbo, even with MS and WI.

 

FWIW that is the exact turbo I am using for my DIY. I have a part number on it that tracked it down to an Eclipse originally.