A friend of mine is having some dyno problems and I figured since turbo enthusiasts on here are very experienced maybe someone might be able to give us some suggestions. Here are the mods, all bolt ons, dual intake, inconel manifolds, forged motor, stage 1 heads, 530 ball bearing turbos, I am guessing its the valvetrain he is running stock cams and springs, but the shop who did his build cant give him a straight answer. In order from lowest to highest power, 1st dyno 19psi on 100 octane, 2nd 19psi 105 octane and 3rd dyno 20.5 psi 105 octane, Could this be pinging? thanks for any help-sorry its not in color, this is how he sent me the dyno

 

I say it's the cam, but I'll let people with more experience pitch in.

 

maybe he's floating the valves?

it looks like its just dropping off towards the higher end of the graph.

Maybe he doesnt have enough fuel either?

 

Is the boost climbing more and more to Redline.. If your seeing 19psi of boost early on and stay at that psi till redline, a dyno graph like this could result...

Also Timing? Are you lowering timing in the upper rpms VS the mid range?

Fuel looks good..

Clint

 

I doubt stock springs are up to the task.

 

thanks for the responses guys, the timing on all the runs was 23* and he has NISMO 555 injectors, could the timing be to high? I just talked to him and he was saying there are many other 300zx's with bigger turbos on stock cams/springs with no power dips. He is running an identical setup as most 300zx's making over 500-600rwhp. His max boost for his turbo is 25psi, he is doing another dyno friday morning.

 

No expert here. Just a few observations.

The dip gets worse w/ higher boost. The A/R shows fuel stays somewhat consistent, except for one which dips slightly richer (I'm guessing it's the highest boost run that yielded this).

The thing that makes the most sense to me (with the information given) is that the wastegates are opening around that rpm and possibly open too suddenly causing a small drop in manifold pressure (which is exaggerated as boost pressure increases). What's controlling his wastegates? If springs then u can ignore my stupidity. If electronic (which is my guess), I'd look into it.

Ask your friend if he can get a map plot and a egt plot on those charts (unlikely or he'd prolly have sent it) for a more educated guess...