I went and dyno'd the car yesterday, and it put out decent numbers...nothing exciting wanted a little more, but they were ok. 298.6hp and 314.9 tq.

But the problem is that over 5600+ I have some valve float...what can be done for this...besides new heads...

 

You don't have to get new heads, just new springs. The stockers are notoriously weak, but still they shouldn't be floating at 5600rpm. Could be a warranty issue, worth a try <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> .

 

sure its valve float and not detonation? If it is vavle float, you need some springs....if you are trying to fix this cheaply...try a hotcam kit or a pick up some z06 springs

 

Sorry if this may be a dumb question for most of you, but how are you able to determine a valve float problem just from a dyno graph?

<small>[ September 15, 2002, 10:25 AM: Message edited by: snake_charmer ]</small>

 

You can see the pattern flutter pretty heavily, almost like heavy knock, but it didn't seem that drastic.

 

Something like this?

http://ts.cranesystems.com/2002Corvette/dyno.htm

 

even worse...if i can i will try and scan it

 

how would one go about bringing up this as a warrenty issue?

 

I would bring it in to them and have the service manager explain to you why you are getting th eratic readings rather than a smooth power curve and leave uit up to them to pinpoint the exact cause. They have their own diagnostic equipment (I hope) so it should not be a problem, though I would probably recommend a few pointers of what you think is the problem as a starting point, just so they have an idea that you do know something about the engine's inner workings and they don't try to BS you with some unrelated explanation such as adding an after market exhaust or changing the air filter, etc.

 

you don't think a dyno pull would void a warrenty <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

 

Maybe someone can answer this better than me, but my persoanl opinion would be why would it? The local dealer I use actually prefers to see this and will be even happier once the Autotap logs are set up, so that they have a reference point from which to start and something hard to look at rather than just guessing based upon a description from a customer based on their persoanl feelings or sounds they think they hear.

That is unless you ran the car up to 7000rpms and the dynograph shows this, or something like this. Otherwise you are doing nothing different with the car than you would be on the street by getting on it hard and taking it up to the redline.. something the engine itself and engine management software was designed to do. From the looks of your numbers, I would think your car is pretty much stock anyway, so therefore even less of a case for the dealer to try and void anything.

Anyone else have any ideas on this or experience with other dealerships?

 

I was loosing 50 RWHP at 5600 RPM's. I took it to the dealership where a friend works. Anyways to make a long story short, they started out with every intension of fixing the problem. It started out as "it's the plugs" didn't work took it back. Then "#5 coil" didn't work took it back. Then it was the "PCM calibration" didn't work took it back. Over and over for a total of 6 trips and seven weeks. They never fixed it. I even tried to get them to think about the valve springs. "not possible with only 9000 miles" they said. I called GM from the dealership and started voiceing my concerns. When it was all said and done with out me loosing my cool and no foul language (remained cordial and mature <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> ). The service manager said that 5600 RPM's was operating the engine beyond it engineered parameters and that if I continue to do so that my motor would "destroy itself" and that he has notated in my warranty history that the motor has been subject to abuse and it would not be covered under warranty if it suffered a serious problem (blow up). Let me tell you I argued asking him OK geneius whats the rev limiter set at? And the rev limiter is there to prohibit operating the engine beyond it's limits etc...etc.. Meanwhile my wife is dragging me out of the place saying, "lets get go". I do not look at a warranty as a sponsorship to beat the crap out of my car and let them pick up the bill, but that was rediculous. Anyways, this whole senario gave me the chance to repair the problem and make it better, and that I did. $100 for the 2001 LS6 valve springs, $300 labor and problem solved <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> . Sorry I was so long. Good luck.

<small>[ September 18, 2002, 03:02 AM: Message edited by: cool Z ]</small>

 

So for Cool Z, in the end it WAS the valve springs causing your HP loss?

 

Yes sir. Dyno'd it before the spring swap, then 500 miles after to allow the springs to go through a few heat cycles. The horsepower dip is gone <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> !!!!

 

Most of the employees in dealerships should be shot. Takes a lot of shopping around to find a good one.