120Rwkw @ 7000Rpm Rb20

[Dave.TAS]

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

Edited July 28, 2013 by Dave.TAS

[XRATED]

Wow thats crazy...

Valve springs?

What turbo is it?

[Kane_R32]

got a dyno printout with boost aswell?

[scotty nm35]

Looks like the wastegate is leaking, is it internal gate? As above, what turbo?

[Simon-S14]

Torque graph suggests that is bleeding off boost once it's peaked

[Dave.TAS]

Forgot to mention it holds 18psi in the manifold in that run flat with a spike to 22 at peak power

[Dave.TAS]

Genuine trust td05 18g internal gate

[Dave.TAS]

From other dyno

230ish at 5500, 110 at 7000rpm. Boost solid, afr solid, timing solid.

[Simon-S14]

How does it drive?

[scotty nm35]

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?

[wasnt me]

have you tried dropping the exhaust while its on the Dyno?

[Dave.TAS]

Drives/accelerates poorly as it has about 1000rpm of useful power.

Exhaust is 3" straight pipe, not a restriction.

I will be pulling it apart on Saturday to find the problem, but that leaves 5 days of constructive thoughts here first.

[XRATED]

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

[XRATED]

didn't leave a rag in the cooler pipe work? been there before

[Dave.TAS]

Have smoke tested the entire system from pod filter to head, also pressurised to 30psi, no leaks.

[XRATED]

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.

[Yeedogga]

Where is the boost signal being taken from for the dyno runs?

[Dave.TAS]

Inlet manifold as above. Irrelevant, but Air flow meter is next to the throttle, not affected by any potential leaks in cooler pipe.

[XRATED]

... how close if the afm to the tb?

got any pic's handy of the engine bay?

\cheers

Justin

[Dave.TAS]

It's above the turbo, normal spot. Normal shape intercooler pipes for rb20