what is the difference if you dyno in 2nd instead of 3rd

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Oct 5, 2003 | 10:18 AM

Nick's WS6

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From: Madison Heights, MI

what is the difference if you dyno in 2nd instead of 3rd

I dynoed my trailblazer and we hit the speed limiter do we had to use 2nd. how will that affect the dyno numbers.

Oct 5, 2003 | 11:53 AM

unit213

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Re: what is the difference if you dyno in 2nd instead of 3rd

The numbers will be skewed because 2nd gear is not a 1:1 ratio. They won't be "true" numbers.

Oct 5, 2003 | 12:00 PM

Nick's WS6

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Re: what is the difference if you dyno in 2nd instead of 3rd

but would they be skewed high or low. It dynoed 200 horse and torque btw.

Oct 6, 2003 | 01:36 AM

soundengineer

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Re: what is the difference if you dyno in 2nd instead of 3rd

you will have to re-calibrate for the other gears using simple math....
If at 2:1 you did 200 then at 1:1 you would do 100... at 0.5:1 you would do 50...get it...simplew math...find out your gearing....do the math...

at lower gears it would read high...

Oct 6, 2003 | 06:57 AM

trackbird

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Re: what is the difference if you dyno in 2nd instead of 3rd

Quote:

you will have to re-calibrate for the other gears using simple math....
If at 2:1 you did 200 then at 1:1 you would do 100... at 0.5:1 you would do 50...get it...simple math...find out your gearing....do the math...

at lower gears it would read high...

Good logic....I thought that too, so I tested it. The following dyno charts are in 3rd and 4th gear in my 2002 z-28 (stock with a lid). The 4th gear pull is 15 hp stronger then the 3rd gear pull (due to friction losses in the transmission and the same acceleration factor that makes you loose HP with steeper gears (3.23 to 4.10, etc). The other pull is 3rd, 4th and 5th up to the speed limiter.

http://home.columbus.rr.com/trackbir...01%20small.jpg

http://home.columbus.rr.com/trackbir...no%20small.jpg

I expected more power in 3rd than 4th and didn't get it, but I tried.....

Run 'em in 4th (3rd for automatics) !

Oct 6, 2003 | 07:45 AM

Nick's WS6

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Re: what is the difference if you dyno in 2nd instead of 3rd

Gear ratios (:1)
1st 3.059
2nd 1.625
3rd 1.000
4th 0.696
Reverse 2.294

I don't know math so someone figure out what the Horsepower would be in 3rd gear when I have 200 horse in 2nd gear.