Went back to the dyno today with the new tranny and driveshaft installed. The first dyno in third gear 1:1, before the driveshaft blew up I had pulled a pretty steady 250 ft-lbs and a mad 207HP. That was about 2 weeks ago. Today did it in 2nd gear, 1:1.75, to keep the speed down and TQ was down to ~228 and HP up to 215. Is there some inherent difference in the output in those gears, maybe timing related. I just wouldn't expect a 20+ ft-lb difference as the conditions today were nearly identical to last time, if not better (first time it was cold and raining - today just cold). This is with the new trans. It's just weird that the power went up and TQ went down. Any ideas?

Andrew

Red is the 3rd gear pull, blue is the 2nd gear pull

 

Did he have the converter locked on your orginal run in thrid?Also it should show a differance usally around 10-15 hp and torque is differant as well when comparing 2nd gear pulls to 3rd gear pulls.Normally speaking the thrid gear pull should show better numbers.Even if the verer is not locked.
Your thread had me worried on Monday lol...I went to get my truck retuned and standing there having him run it up to 147mph made me nervous lol.But all is well and she's retuned.

 

O yeah when you got the new tranny did you change your verter?Or is it still a stock unit?That can affect your numbers as well.

 

Same converter and I'm pretty suire he locked it in 3rd. Once I get the headers and exhaust on I'm going to do back and re-dyno. For that I'll do a pull in 2nd through the RPM's and then a 3rd gear run up to 95MPH or so just to see how the numbers compare. I'm just not sure why 2nd would have higher losses, turning faster in the transmission? It's opposite of that though, it's geared down. I'm so confused.

 

When you dyno you want the gear that will give you the best 1.1 to show the most power.In second i think its a 1.7.1 so it shows less power.