From what I'm seeing, the pulley is the ONLY change there. IMO, I'd leave the extra power on the table if its going to make my Tq curve jagged like that. I want to see more pulley dynos, but at this point, it isn't a consideration for me!

 

Sorry for being stupid, but what is a crank pulley?

 

a crank pulley is the main pulley attached to the end of your crankshaft that drives all your accesories; a/c, PS, alt.
the underdrive pulley does exactly what it's name says. underdrives... it's a smaller pulley so less revolutions are achieved and it's lighter reducing rotational mass and parasitic drag.

 

Ok, I will post some more dyno runs hope this helps in seeing what the Crank pulley did.

 

 

Thanx for posting the graphs. (I hope I'm not reading things backwards)

Why did your A/F change (Red line) when you put the pulley on? It shows being very rich...the torque and horsepower drop off, except for the spike in richness at 6100 RPM, it's like it burps then drops off. Are you going to change your A/F back to what it was and hopefully gain a smoother power curve? At 5500 is when stock, but leaner makes more power.

Are the graphs saying that you can approach the power of a leaner tune with just a pulley and stock (I assume) A/F?

 

Sorry for all of the confusion, I was helping TXEVO with his testing/modification, we did both of our cars on the same day. I have access to the Dyno Jet software and created these jpegs for him. My car has very similiar mods only with the stock ECU and no fuel/ignition adjustments yet. In some of these (especially with the A/F ratios) what you are looking at is the difference between his car and mine.
If you look at this thread https://www.evolutionm.net/forums/sh...threadid=39869
You will get a much better explination of these graphs.

The first graph posted by TXEVO was actually a 2nd gear and 3rd gear pull. I like to do a couple of 2nd gear pulls before doing the third gear comparison runs to get the car properly up to temperature. They were there pretty late and Brice obviously pulled up the wrong runs for his comparison print out. The system they print from always defaults to STD correction factor and they often forget to switch to SAE (the preferred standard IMO). That is why the before pulley 2nd gear run looks so much smoother, it accelerates so much faster that small variations in the engine output are not as pronounced. Here is the actual before and after pulley 3rd gear runs for his car.

 

Hell, if anything the pulley helped to smooth out the graph.

 

Yes, I had mentioned that in my pulley thread. The car does feel like it idles and accelerates smoother with the under drive pulley and the dyno runs seem to agree.

https://www.evolutionm.net/forums/sh...665#post452665

 

I've always made my dyno pulls in 4th in my cars. Its the closest to a 1:1 gear, and you get longer physical time to build a nice fluid log on A:F. Doing it is second is ridiculous, IMO. Its a little harder on the car AND the dyno than it needs to be. Third is okay, but I still like 4th best.