look at the compressor maps for it, i bet at 5.5 psi+6200rpm that turbo is inefficent as ---- (ie heating the air more than it is compressing it)

 

I really doubt the size of his turbo has anything to do with the problem he's having. That turbo should not drop from 7psi to 1 psi ever! I had a T3 with a .38 housing on my B18A1 and was running 9 psi and it would never fall off. Try bypassing your boost controller, retard your timing, drop your plug gap down to .025, and run the wastegate line back to your turbo. Try that and see how it runs. Then hook your boost controller back up and start to increase boost slowly. Do things one at a time so you can possibly pin-point the problem. What kind of boost gauge do you have? If it's an Autometer, maybe buy a new one. They are so ------- inaccurate. By the way, what size is your downpipe and charge pipes? And are you running an air filter on this turbo?

 

autometer is inaccurate? i have a $15 carbonfiber (+20hp!!) autogauge one from ebay. it reads vac fine, dont know about boost yet.

what are some better brands i though autometer was the pimp ---- in gauges.

 

I've had 0 problems with my autometer, and it's as accurate as my $200 Snap On Boost/Vac gauge.

 

sounds like a faulty wastegate to me...?

 

Is a 42/48 smaller or bigger than a t25? physically speaking.(like if you looked at em side by side)