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Discussion Starter #1
Hi all,
During a recent clutch job, I recently replaced my OEM flywheel (among other things) with a lightweight fly-wheel and upgraded to a stage 3 clutch (both Exedy). I love parts, and the clutch is incredibly responsive and the car is very peppy. However, I have been noticing during some on-ramp pulls, the car seems to lose a bit of power between 5000 and 6000 RPMs. It isn’t a full power loss, it feels like I am at 70% and it feels almost a bit jerky like it is going 100%-70%-100%-70%. Before my flywheel/clutch job I didn’t notice any such thing, and my car used to pull hard and consistent through redline. So I am wondering if anyone has any ideas/suggestions. I thought of possible causes:

1. Tires slipping - experience tells me this is not the case, and if it was traction control it would be much more of an on/off.
2. Clutch slipping – No RPM spikes so this seems unlikely
3. Tune/engine issues – This is my gut, but I am open to suggestions
4. Other?

Also, in case it is relevant the car is heavily modified with a Vortec supercharger and accompanying Vortec tune. I also have had random misfires on startup in the past on hot days, but oddly enough ever since I stopped using the AC the problem went away. If I start the car with the AC on…I still get the MIL. But I digress…
 

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Cover all your bases. Do as bullitt suggests and check your gap, check the belt for slippage, datalog, check for pending codes and verify the clutch isnt slipping. Another possibility is the traction control or abs cutting power due to a bad wheel sensor.
 

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Discussion Starter #4
You could be getting "spark blowout" at higher rpm due to an excessively wide spark plug gap.
Now that you mention it....I just swapped out my small gap plugs back to OEM plugs as part of my "fix the random misfires at startup" troubleshooting endeavor late last year. Maybe I am just noticing this effect now.
 

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That's probably what it is. I have a Saleen supercharger putting out 8 psi and it needed gapped plugs.
 
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