Ok, before yall laugh, I'm still in that capitial deficient stage of my life and, ie without a vehicle of my own (another year of college and then its time for something my own ). Anyways...I was watching the NHRA race from Atlanta over the weekend, and I noticed that they set the fuel cars to run an idle speed right around 2000 rpm. Question that stems from this is, how do you determine what idle speed to run, and what goes in to making that determination? If this isn't the right forum for this, thanks to the mods for moving it.

 

To me, idle RPM has mostly to do with the powerband, and requirement for bumping it up so that off idle you are able to release the clutch without killing the engine OR having to give it a ton of gas to avoid bogging.

The stock PCM in the LT1s I believe is limited to a peak of 1300 RPM for idle(?), and smog tests here in CA wont allow anything I think over 1200, and with a cam idle RPM bounces around a bit so 1150 or so would be "safe" but not needed on anything that had to pass smog anyway.

 

I like mine set at 800prms, nice lobe there. It really just depends on where you want it. On a late model car, 800 to 1k should be fine.

 

Gotcha, thanks for those responses. I know where most cars idle (at least street cars) from 800 up to about 1200, but I just didn't understand why the fuel cars set their idles all they way up around 2000. I also didn't know if that is because they run such huge cams in them or because it get's the blowers in to a point of where they are starting to boost. I'm assuming from the sound of the 500 cube PS motors that they let them idle right around 1000 to 1200. No better sound in drag racing as far as I'm concerened then a PS car staging, lobing at idle, cleaning the motor out, then sitting on the launch rev limiter waiting for the ambers to come on. Again, thanks for the info, that kinda clears up some of the cloudiness I had.