View Full Version : Any way to convert 2nd gear hp to 3rd gear hp?


tdrumm
05-02-2005, 07:32 AM
I dynoed my truck this weekend, the first pull was done in 3rd gear, but we hit the factory speed limit at 4000 rpm. The rest of the pulls were done in 2nd gear up to 5900 rpm, and the curves are noticeably lower than the 3rd gear curve. Is there a way to convert the 2nd gear numbers to what they would have been in 3rd gear?

Thanks

foff667
05-02-2005, 01:18 PM
generally 5-15hp/tq less when done in 2nd gear...no set way that i know of to convert it though :(

lsx24
05-02-2005, 02:49 PM
Check the stockdyno thread, there are some graphs that will help estimate.

tdrumm
05-02-2005, 03:07 PM
On my dyno print out, it looks like all the 2nd gear pulls are about 15-20 hp and tq less than the portion of the 3rd gear pull that was done. Is it safe to assume that would continue to hold true above 4000 rpm? I was hoping there would be a mathematical way to convert it so that when I dyno after my cam swap with the speed limiter removed, I'd have a true before and after comparison.

foff667
05-02-2005, 03:09 PM
On my dyno print out, it looks like all the 2nd gear pulls are about 15-20 hp and tq less than the portion of the 3rd gear pull that was done. Is it safe to assume that would continue to hold true above 4000 rpm? I was hoping there would be a mathematical way to convert it so that when I dyno after my cam swap with the speed limiter removed, I'd have a true before and after comparison.

just have them dyno it once in 2nd gear after your cam swap if you really need a before/after #

lsx24
05-02-2005, 03:14 PM
On my dyno print out, it looks like all the 2nd gear pulls are about 15-20 hp and tq less than the portion of the 3rd gear pull that was done. Is it safe to assume that would continue to hold true above 4000 rpm? I was hoping there would be a mathematical way to convert it so that when I dyno after my cam swap with the speed limiter removed, I'd have a true before and after comparison. Did you check out my stock graph? There were two lines one for 2nd another for 3rd. Peak hp started to approach the value in 3rd.

tdrumm
05-02-2005, 03:36 PM
Did you check out my stock graph? There were two lines one for 2nd another for 3rd. Peak hp started to approach the value in 3rd.

Yep, I am guessing that the green run was the second gear pull. I see that 2nd did start to approach 3rd, but I can't read the number. It looks like 3rd you hit 298 and 2nd was around 285???