Engine Stumble at 4,000 rpms

[Tomcat]

Took my 2001 with tubes/filter, high flows, and 3" Corsa to the dyno Friday. With 5,200 miles on the clock the car produced 418.5 rwhp and 458 rwtq.

The question I have is this - There was a stumble at 4,000 rpms on each run. I reset the PCM after the first run and still a stumble. Does anyone have any ideas what might be causing the engine to momentarily cut out at 4,000?

Thanks, Tom

 

[KenH]

I don't really know what might cause it, but your peak HP and TQ seem reasonable.

Did the dyno also do an air/fuel measure and if so, does it show anything around the 4000 RPM mark? Might give you a clue.

Also, I have almost the exact same setup on my '01 (Corsa 3" and tubes & filters, but without the HF cats). I posted a dyno chart from my last dyno in the 'dyno smoothing' thread below. Might give you something to compare your curve to around the 4000 mark.

--- Ken

 

[jgfurr]

Not sure how big your "stumble" was, but I think that's normal. Sean Roe posted lots of dyno graphs over the course of his supercharger development and I remember something like this coming up. Try searching and see what you dig up.

 

[Tomcat]

Thanks. I will do a search and take a look at some dyno graphs. I thought the stumble was odd since my gen1 did not have a stumble and put out 390 and 468.

Tom