Power Issues

[cactus]

Hey guys,

Have an RB30/25 (series 2 R33 head) which I have just strapped a GT35R on. Now before this turbo, it had a GT3082R and made 382rwhp @ 18psi (built auto and big stall) and was mental. Upgraded turbo because the old one shat itself, and was thinking this time round I would crack 400rwhp easily and rev just as hard (prebiously made peak power at 7100rpm).

Now, had the car tuned yesterday, made 347rwhp @ 11psi @ 6900rpm which was promising, then went up to 18psi and wouldnt go past 355rwhp...@ 6000rpm! As soon as it hit 6000, the power dropped off as if it was hitting limiter, but limiter was still set at 7000rpm. Very much confused. Makes bullshit torque and still goes hard, but cant understand why it wont rev past 6000rpm and why it made little power with such a massive increase in boost. Unfortunately I dont have a dyno graph. Any words would be greatly appreciated!

Matt.

Edited December 19, 2009 by cactus

[GTScotT]

thats a big volume of air your pushing there.... definitely sounds ignition related.... checked spark plugs? may need to gap down OR run a colder plug rating.. like an 8 or 9, unless youve already done so.

try gap to 0.6 and see how you go, GL

[StealthX]

maxing out injectors or fuel pump?

[STATUS]

valve springs... worth a check.

[R31Nismoid]

^ yep. Valve springs maybe. Could also be a blocked cat or something in the mean time.

Did you change ANYTHING else? Or just the turbo, bolt off/on.

[cactus]

It was a direct swap. Last time with the 3082r it reved fine to 7000rpm and made 380rwhp... So yeah. How could I best check to see if it is valve float or something similar? Shouldnt the series 2 head be OK under that power? It was refreshed about 5000kms ago so eally not that old at all.

[STATUS]

It was a direct swap. Last time with the 3082r it reved fine to 7000rpm and made 380rwhp... So yeah. How could I best check to see if it is valve float or something similar? Shouldnt the series 2 head be OK under that power? It was refreshed about 5000kms ago so eally not that old at all.

ask the shop what the seat and nose pressures were.