Suggestions on Turbo resizing invited...
 

My 1600 motor is running a T28 from a Nissan GTiR, this turbo appears to have a .86 hot side (i know nothing about all this coding etc except that .86 is probably too large for my motor).

At the dyno it couldn't achieve more than 14psi... in the interest of full disclosure we did have a "slight" hot side leak at amx boost but neither the dyno guy or I feel that was the issue....but we think it was probably more that the motor didn't have enough puff to push the turbo rather than a leak etc...

In addition my new long runner manifold seems to have exagerated the exisitng late boost issues (max around 4k) to the point where it is hard to drive and (I think) would be considerably quicker if it didn't hit full boost at 5k!!! :giggle:

Having just spent considerable money on new manifold, inlet piping, IC etc I am reluctant to change the turbo out completely (if necessary I will next season when I have replenished funds) so am looking to the MT mafia for suggestions as to what I should be doing to get through this season....

Are there bolt on hot sides that are more effective for this motor? Should we be looking at cold side impellors...etc...(remember, cheapest solution possible to improve drivability till the end of the season...)

Yes there are plenty of other turbos that would drop right in.

But before you go throwing money away why not diagnose and fix the issue? Your car should absolutely be able to hit more than 14psi on this turbo, and it should be able to spool it quicker than 5k. You obviously have a leak and/or other problems.

This, find the boost leak.

Probably a stupid question, but have you played with the adjustment on the wastegate actuator? I remember having issues with my gt2560 building boost slowly until I tightened it up a turn or 2 and it was like a completely different car.

Thansk for the replies.

No questions are stupid to me, I came from bike racing so have ZERO knowledge or history of turbo setup....

What should we be looking for to adjust the wastegate actuator? Can you tell if it is mis adjusted....before playign with it, it would be nice to know if it was the cause of the high revs before boost...(this would really please my manifold guy!)

You said you swapped the exhaust housing on the turbo... is there any chance you used a housing for a turbo with a much larger turbine wheel? </pulledfromass>

Edit: That may have been someone in another thread? Not sure where I got that...

Pull the E-clip and separate the actuator rod from the wastegate lever. Then make sure the rod causes the lever to fully close the wastegate. You may spin the end of the wastegate rod fitting a few turns if necessary to preload the wastegate arm to hold the wastegate closed a bit more tightly.

Exhaust leaks between the head and the turbo work just like an open wastegate and will kill boost and spool.

Boost leaks on the fresh air side will kill boost.

Sounds like a hotside leak or mis adjusted iwga. Or completely garbage tune thats way to rich and with no spark advance.

Just to come back to this thread we have gone to a .42 (?) hot side and made massive amounts more torque at 3k (went from 80 to 175) and gained about 15 HP on top. Car was fast before (with no torque) should be amazing now.....

265HP at the wheels with 14/15 PSI boost...all at much lower revs than before...motor should appreciate that... :)