Well got it to the dyno today and the dyno showed a lose of 15hp and 40tq, It just dynoed at 327/343,Power falls off at 5800rpm bad(we have a problem) when I first put the cam in it dynoed at 342/389. Im alittle pissed off cause the car runs smooth and doesnt miss a beat, the the dyno just shows a drop off. Now the hard part where to start my search for the power loss, anyhelp guys would be greatly appreciated. Thanks

 

What cam and springs? Could be valve float.

What MAF etc?
Need more details.

 

216/220 525/532 New 2002 z06 springs. Stock MAF, And it is running 12.8 airfuel,29 degress timing,No knock,nothing has been changed from my previous dyno everything remains the same ,just have the loss of power now. The cam and first dyno was done 2 months ago.

 

could be weather or gas, did you use the same fuel, maybe the oil needs changed, ect..

 

Weather was 20 degress colder this dyno,same fuel, oil was just changed, the car still has the same LS1 edit program when the car was first dynoed, nothing was changed just a power drop off

 

A 15 RWHP drop...hmmm...lemme throw a few things out there.

I understand you said there was NO KR on the low HP run. There was 29 degrees of timing advance. The fuel/air was 12.8:1 as tested on a wideband. Again, we're saying that ALL of these factors were actually observed on the low HP dyno run. Correct?

And, the converter was either locked or unlocked on both the high HP run and the low HP run? Not locked on the high HP run and unlocked on the low HP run...Correct?

If there was no detonation then fuel has nothing to do with this problem.

If the fuel/air ratio was spot on then the MAF has nothing to do with it.

The oil, so long as it's there, has nothing to do with this. I don't care what brand or viscosity it is, it's not going to cause a 15 RWHP drop.

So long as the numbers were corrected on both runs, the weather should have only a little to do with it. This point is debatable.

Different tires could matter.
Different tire pressures could matter.
Drivetrain changes could matter.
Drivetrain and engine temperatures could matter.
Ignition problem at high RPM?
Valve float?
Compression loss?

 

Everything was observered,I was standing right there. converter was unlocked on all runs,they are corrected #s, How would tires affect it, dont get that, as I stated earlier power would curve over at 5800rpm , as for 2 months ago it wouldnt fold over till 6400 rpm.

 

"power would curve over at 5800rpm , as for 2 months ago it wouldnt fold over till 6400 rpm."

Well, tires wouldn't have anything to do with that. That sounds more like a weak ignition or valve float problem to me since you already know the mixture is fine up there.

Tires can change the numbers though. The harder it is to accelerate the tire, the lower the numbers (from being heavier, for example.) Lower air pressure will also lower the numbers a bit.

 

Thanks again everyone, time to get my search going on my car again. Has anyone heard of 2002 ZO6 springs failing or gettin weak after 500 miles.How would I check for weak ignition. Thanks

 

"How would I check for weak ignition. Thanks"

Pull the plug wire off the plug but leave the other end attached to the coil. Start the engine. Now...(this is the important part) insert your tongue into the open end of the wire. Did your head hit the hood of the car as you violently cursed my name for suggesting this method of ignition diagnostics? Good. That one works fine. Repeat for the other seven.

...Or, you could use a diagnostic scanner to check for misfires at the troubled RPMs.

 

he he he good on colonel! I have actually been hit by an oler style HIE ignition on my othe ca... it WASN'T anything I care to do again!

Josh S.