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Anyone on here who has constructive thoughts on this power curve, im interested to hear how you solved/diagnosed the problem. As you can see it drives as it should up to 5500rpm, then makes 120rwkw by 7000rpm. Dyno run goes to 7600rpm.

cam timing correct
3" straight exhaust
3" metal intake
ignition timing correct, and checked maintaining its set 20degrees at 6500rpm
splitfire coilpacks, no misfire
e85 sucrogen
AFRs been tested between 10:1 and 12:1, using two widebands, no change
Boost tested between 16 psi and 22psi, no change
No boost leaks
No blow by
Compression is even
two dynos, 3 tuners, remapped from scratch 3 times using power fc and nistune
water temp and oil temp are normal

post-79203-0-41489200-1375020724_thumb.jpg

Edited by Dave.TAS
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There is a restriction somewhere, and a bad one by the looks of it, but with such little information to go by it makes it very hard to help find the cause. Didn't the tuners offer a reason?

Can you post pics of your setup perhaps?

yeah my vote is for a boost leak or weak valve springs....

it looks to me like the whizzer can supply the pressure but not the volume up top. if there is a smallish boost leak, the wastegate wont open untill the correct pressure still- but the poor ittle whizzer is working overtime to supply the engine and the leak. same thing can happen with blowing open valves, eg weak valve springs.

the last boost leak I found on the gtr wasn't to be found on the dyno... but as soon as I hit the track I found it.

Cheers

Justin

Mine was more related to movement... the sudden application of torque moved the engine more than when on the dyno.

It was very supprising to me. I had all really good quality clamps, trust pipe work, trust silicone, all rolled edges at each connection.

... this is a tough one

Cheers

J.

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