Dyno Results!

as written by Bryan Cope...

How 'bout that?! Those are the best before and after curves as measured on the same Dynojet chassis dyno here in Austin. The stock torque plot was pretty amazing how flat it was until it began to roll off. But the after plot is great! It you look very carefully, the car hasn't even quite hit it's power peak at 6100 rpms where they let off! To be honest, I wish the peak wasn't QUITE so high, but the car just doesn't stop pulling all the way 'til redline (currently 6400 rpm)!

Notice that spike around 5200 rpm? If anyone has any idea what that could be, I'd love to hear it! I think it must be ignition related, but I haven't figured it out yet. I plan to install an aftermarket coil soon, and have already tried everything else (plugs, plug wires, installed MSD, checked PCM, fuel delivery, etc...). It's bad enough that you can actually feel it when it happens! Ouch!

Given the standard correction factor of about 15-17% driveline loss for the car, the 373 rear wheel horsepower comes out to about 440 - 450 engine HP. Not too shabby! :) I still need to add a custom PCM program, and a new clutch also. Otherwise, I'm quite happy with the new combination!

October 26, 1997 - More details on the 5200rpm spike. It's worse... At the moment, I have a broken catalytic converter, so I'm sure I'm getting some vibration through the exhaust which is causing up to 12 degrees on knock retard!!! Yikes! I'll be getting a replacement cat soon, and then will start to debug further. I can't do anything until then...

I have recently replaced the coil, but unfortunately that didn't help at all... As a matter of fact,the overall problem is worse. Not due to the coil I don't think. It happens almost anywhere above 5K rpms now... Sigh...

March 5, 1998 - I have been lack about updating this information, but I have solved the spike problem... Turns out my optispark was going bad. I removed the MSD-6AL and coil to replace them with an Accel 300+ (stock coil), and the car had all sorts of problems. When I removed the optispark, I spun the input shaft and there was a grinding noise... Not good!

So, I replaced the unit and the car ran great. However, I am now getting some knock on WOT runs. I think it's due to noise in the exhaust. So, I installed a switch to disable the knock sensor when I'm at the track. It works fine, but I don't run it that way on the street. Just in case I get a bad tank of gas...