What would a slipping clutch look like on a dyno sheet? I only dynoed 300rwhp @ 5300 & 316tq @ 4600rpm.
Car in signature did not start registering power until 2400 rpm and started losing power quickly after 5400rpm. By the time I was at 6100, power was only at 220rwhp. Opti is new. Coil, ICM are new. Plugs & wires are decent. Rockers have been readjusted. Still same results. AFR was 12-12.5 throughout run. I would think the clutch would catch, slip, catch, slip, causing the power to go up and down, however, my power is just in steady decline after 5400rpm. MPH goes from 82 to 95mph during the 5400rpm-6100rpm drop in power if that helps. If anyone can provide a pic of a dyno with a bad clutch for comparison or give any insight that would be great. The dyno operator/tuner said it was my clutch as well, so he would not tune it until i get a new clutch to hold the power. I just wanted a 2nd opinion before hand.

 

here's the sheet

 

The dyno I used didn't start until about 2000 rpm and cut off at 5500, so this doesn't look all that odd to me. What kind of numbers were you expecting?

 

i was expecting at least 320rwhp. my dyno is not shutting off at 5500, the rpms still increase but the power is dropping.

 

probably valve float. If it was the clutch it would have started slipping earlier in the run. Give it some gas in 5th and 6th gear on the street and see if it holds.

 

valve float? I would tend to think not. I have crane's double valve springs 10308s installed brand new.

 

Does not look like valve float considiering the RPM. VF usually occurs much higher than 4900 RPM and you seem to have plenty of spring. Speed and I both had it right around 6K RPM with older cams. CC503 has no history of VF as far as I know.

If the clutch were slipping, you would definitely smell it. It does seem to happen at peak torque so I can see why you might consider it.

BTW, 12.0-12.5 A/F is a little fat IMHO.

For a LT1 with a CC503, it should be hitting a peak HP much higher than 5400 as shown in you graph. Something is bad wrong here either with your car or the dyno.

I would start looking into fuel starvation. Put a guage on the rail.

 

thanks for the responses. fuel is @ 40psi full throttle. I know it's a little low, but i do not believe it would cause the huge drop off. I took it to a Chevy dealer and asked them to do a diagnostics test. I was expecting to get scanned readings of all sensors & knock counts. I did not get that. Codes were read, no DTC's stored. Injectors tested for leaks & firing...checked out fine. Which scanner from autozone/kragen would be useful in providing info on more than just trouble codes? real time counts while i'm driving around would be useful. i want to check for knock, 02 sensor readings, etc.

 

You've misunder stood! What I was saying is that MY dyno cut off at 5500rpm so I don't know what the graph would look like after that.
Based on what you have listed (CAI, shorty heades, and a big Cam.) I think, it is what it is! Looks to me like your just running out of AIR. I think the 320rwhp is reasonable.

 

320 is doable if dialed in.

 

IMO if you are going to have a car this modified you NEED a laptop and TTS Datamaster. You can get a cable and the software for about $150. It will let you see all you wanted the dealer to look at and more.

 

As Dwayne said, the only thing that will do what you want (and need) is Datamaster. The dealer can only do what he did for you, nothing more. A performance car needs a real-time data log that you can examine and take apart.
I would be most concerned about the way it starts to fall off at 5k. There is a reason (or reasons) and you need that datalog to find out what it is. If you can borrow a wideband, such as an LM-1 that would also be extremely helpful.