it did change my dyno numbers.. went 3.36 to 4.08 big change size
no matter what gear we dyno'd in the numbers were different..
both Dyno's between the 2 gears were exact same setup for my car..
i have done lots of research to find the answer and almost every forum i went to everyone had a change in dyno number with a gear change .
why your did not change is weird..
https://www.corvetteforum.com/forums...post1590896300
Quote:
Originally Posted by SS_Firehawk
I'm still waiting on the diff work to be complete, but I was doing some more research and this is what I came upon.
If you change your final drive, it should not reflect on a dyno when using a 1:1 gear. If you're running a lower final drive any dyno in 4th; your numbers will be lower because the rpm delta is greater when you calculate 4th gear with the lower final drive gear.
formula: rpm = (mph x final gear ratio x 336*) / tire diameter
(you get the gear calculation by multiplying the transmission gear ratio with the final drive gear ratio)
Using 4.08 as my final drive
with a 1:1 gear; 75 x 4.08 x 336 / 26.9 = 3822rpm
with a 1.27:1 gear; 75 x 5.1816 x 336 / 26.9 = 4854rpm
delta = 1032rpm
Using 3.69 as my final drive
with a 1:1 gear; 75 x 3.69 x 336 / 26.9 = 3456rpm
with a 1.27:1 gear; 75 x 4.6863 x 336 / 26.9 = 4390rpm
delta = 934rpm
Hopefully this helps make a bit more sense. There was a post on a forum talking about how the dyno calculates power, but I can't find it in my search history. It was a lot of math. But the calculations above at least make sense to my why anything but 1:1 reads lower.
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