Gnarly,
Do any of your computer dyno runs show the 'dip' I usually see in the dyno run I usually see around 3k +- rpm for various vehicles?
This is for my Sportster (883): first is dyno at dealer, second is something called a 'road dyno' (search images 'road dyno software')
![](http://i957.photobucket.com/albums/ae59/emsvitil/M06%20Sportster%20Dyno%20Runs/Bartels-20011128.jpg)
![](http://i957.photobucket.com/albums/ae59/emsvitil/M06%20Sportster%20Dyno%20Runs/HD-calibration-1bmp.jpg)
I've used the 'road dyno' on my 86 22RE truck and 64 Plymouth Valiant slant 6 225, and they both showed the 'dip' (don't know where I put the .jpg of those) that DON'T show up on a computer simulation (Desktop Dyno 2000 & 2003)
That is a good question. Let me do some checking and see. I've seen "dips" in dyno curves. I believe it is not unusual and is almost always a question (What's the dip and why is it there?) when tuning on a dyno. My software simulates an engine dyno (still possible to show a dip), so a chassis dyno may read several factors that can cause peaks and dips in a curve.
I'll get back to you on that and I can post some curves from my software.
Gnarls.