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Effect of having a dyno in fifth vs. 6th combined with a higher gear ratio

AlleyCat

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#1
On a dynojet, dynoing in a transmission gear of 1.29 vs.1.00 I have been told I will have less horsepower at the rear wheels. The reasons being multiple. More frictional/parasitic loss through the transmission. Also there is a better chance of tire spin in fifth gear vs. 6th which is at 1 to 1. This is further enhanced, the loss of horsepower, with a higher gear ratio in the rear. 3.09 vs. 2.62. The parasitic loss with the fifth gear ratio of 1.29 to 1. I dynoed over a year ago with those variables. It only made around 878 to the rear with about 895 in torque. Mr. Barth my tuner stated if dynoed in 6th it would of made over 900.

I am going to the same dyno this wed. with 2.62s and the dyno will be done in 6th. If nothing else was changed i am wondering what percentage the horsepower would go up. 2 percent, 5 percent.
Then i have some improvements. 29 pound wheels instead of 41 pound wheels. a carbon fiber driveshaft, a 2.5 upper instead of a 2.65,

i am thinking i will dyno at about 925. Any scientific estimates based on what I just stated. I tried reading all this stuff with mathematics and my head is just spinning. And to think I was pretty good at math in a former life.
 


Last edited:

WNELLES

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#2
Did you end up running the car in 6th gear on the dyno?
 


OP
AlleyCat

AlleyCat

500 Posts Club
9 Second Best E/T
Member ID
#1332
Messages
801
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724
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82
City
Oro Valley
State
AZ
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United States
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16 HC Challenger
Thread Starter #3
Yes. 955 hp
1010 torque. See other post.
 




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