Flat Spot In Power Curve

[JAP033]

He said that it knocked slightly but nothing near serious. He said that its like something is holding it back and thats when he said the manifold

[Rolls]

I would try a different tuner perhaps, nothing like a second opinion...

Do this, looks like a timing hole because he went really safe or something was making it ping at peak torque. If it is a timing due to detonation then try dropping the exhaust and see if it still pings if you add the timing back in.

Basically I would just find another tuner, not saying he is bad, but a second opinion is important, I've gotten one lots of times after seeing good tuners.

Edited November 17, 2013 by Rolls

[Dose Pipe Sutututu]

there's a massive timing hole and the timing does look quite relaxed, could be some form of exhaust restriction at peak torque.. he's got enough fuel there too at 0.8 lambda.

usually RB motors prefer a flat timing, opposed to SRs 4Gs which love a timing hole.

[Lithium]

That is a very average looking timing map, very soft up high and not really (well from memory) that soft down in the low rpm. Put up the fuel map too - that should give a reasonable sign of if there is a restriction.

Only time I've ever had to do anything like that was with a car which had really erratic trigging, and I just put numbers in there to keep the car runnable and as far as possible away from knock while the cause for the triggering issue.

[JAP033]

Thanks everyone for the help. Dump pipe is one of those bellmouth that are sort of flat and then goes to 3inch, if that makes sense. Could that be a restriction? Here is the fuel map

[Lithium]

Cheers. Wow, that's not a very nice fuel map - I'm not sure who your tuner is but my confidence is not high that they are on top of everything. The "not nice" about it isn't due to them working around an issue, it looks more like they've just been plugging numbers to try and get the right AFR and power curve on the dyno... whenever you can see what cells the engine runs through on the dyno (look at the yellowish cells amongst the sea of green - full boost in the area of 4000rpm) and then have leaner cells at higher loads, as well as richer cells in the same area. Run that car at any different boost level, or just drive it different to what happened on the dyno and the AFRs would be interesting.

The fuel map looking like that makes it a bit hard to be sure of what to read into it, it'd be easier to tell what was happening if you could trust the numbers are representative of what the engine is doing, but at a glance it doesn't necessarily look like the engine is choking on some restriction - could be an issue with the actual tuning, whether it be the tuner or if there is some issue with the ECU determining crank angle.

[Dose Pipe Sutututu]

looks like on certain columns your tuner has highlighted those cells and press the 'I' key to linearise the map...

Go back into that map and press 'T' for trace, then do a run in 3rd or 2nd (whatever is safe and you're comfortable with) then do a print screen, repeat for the ignition map. This will trace the cells it goes into so we all can have a better understanding of what's going on

[JAP033]

Also here is a boost plot. Boost is middle column

[r31 25t]

I'm allmost certain it's tuning now looking at fuel and timing maps. That boost plot backs it up too. I find when tuning if I run too little timing in power i'll get boost creep. What you've posted shows boost starting to rise as the timing drops off, that means most of the energy is being released in the exhaust.

New tuner time.

[Karadeniz]

Just wondering what the problem ended up being in this case??

[32rrr]

Would be shithouse tuner karadeniz, you can tell by the timing map!!

[JAP033]

Wasnt tuner, ended up being restriction causing car to not take timing in that part of the map and if it had timing it would knock. dropped exhaust and everything with nothing changing. Ended up changing turbo to an Op6 r34 highflowed by gcg with 3076 core and made same power and torque on way less boost. And can now take Alot more timing and has smoother curve. So in my personal case it was the turbo that wasn't performing as meant to.

[hypergear]

From a couple of GCG's high flows I have seen, They are a trimmed down GT35 turbine with a 76mm comp. That is closer to a 3576.

Replacing the turbocharger made no differences in out come. Means it is still pining if more boost is added.

While the G3 has fixed set of boost level. So it just ended up with less boost and more timing compare to more boost with less timing. With no overall gain.

Regardless, both turbochargers has under performed. The turbocharger is not your problem.

[JAP033]

Replacing turbo eliminated the flat spot in the curv and is more efficient on less boost. And makes more power on 20psi than what the g3 made. G3 made 255 on 20 and highflow made 274 on 20. Everything on car is the same the only thing that has changed is the turbo itself. doesn't overboost like the g3 used to either, holds 14 psi flat to redline where the g3 spiked to 22psi then held 20psi and creeps to 24/25psi in higher revvs. Im not dissing your turbo by any means Stao, im just stating that in my personal case it was the turbo that was the problem.

[hypergear]

That's ok, I need to know if there is a issues on the actual turbo and sus out any issues on that model.

After the stud fouling against the gate removed was the turbocharger back on dyno again for check ups?

[JAP033]

Yeah was on dyno just before changing turbo. Still overboosted with 14psi actuator and still choked up and wouldnt take timing.