hey there,

Well, we just installed a t28 IhI ballbearing turbo on my b18a1 motor and at higher rpm's it lags.. from like 2k to 4k the pull is unbelievable, the tires start spinning outa control at like 40mph in 2nd gear and stuff, but right when it hits rpms around 5k and up, the pull decreases dramatically...

I was told that this is happening because of the lack of exhaust flow... Since we had insufficient supplies the day we installed my turbo, and it was a weekend, granted, the shops were closed and i also ran outa money, I had to "improvise" and used pieces of pipe from my stock b18 downpipe to make the down pipe for the turbo...

I believe the pipe from the turbo exhaust flange is 2 inches, then we welded on the 1 3/4 inch pipe which came from the stock downpipe and then to a 1990 1.5L DX catalytic converter.. THEN to 2.5 inch mandrel bent piping to a turbo N1, which was professionally done by an exhaust shop when I first had gotten my motor swap... by the way, this whole thing is on a 1990 civic hatchback, OBD-1, b18a1 motor, w/ t28 turbo, boostin 8.5psi.. got greddy type s bov, mandrel bent charge piping, spearco intercooler and high heat expensive a$$ silicone hose for connecting the charge piping together...

so, will it do my engine damage if I don't change this a.s.a.p.?? will the excessive back pressure give me higher EGT's and possibly jack my motor up. and turbo for that matter?? oh ya, im only running 14.4@100mph i've been told that I should be running quicker times than that boosting 8psi LS turbo in a light 90 civic hatchback..

 

Could be backpressure, but it could also be the charge being too hot. I don't see an IC on your list. There is a good chance your charge temps spike at high RPMs.

I have seen t25's do this alot.

Try running it open pipe (remove the cat) and see what happens. She'll be loud and whiny, but you will see if it makes a difference.

Also, what is your tuning method? You could be too retarded or too rich.

Randy

 

small turbo + poor flowing LS head + small LS cams = drop off on torque and power in the high RPM's.