engine speed / gears / road speed
 

i am trying to calculate my engine speed based on my gps datalogs. when i put in all the data like wheel size, road speed, gear ratio and diff ratio, the rpm is always off by 500 rpm. anyone know what it could be? is our gauge that far off in terms of revs or is the gear ratios incorrect or is it my gps

here is what i used

2nd gear limiter is 69.4mph
final drive is 3.446
2nd gear ratio is 2.324
tire size is 26.8 as i have 285 35 19

what do u guys think

Final drive on 6MT is 3.692 according to the spec sheet. Or do you have some other gearset in yours?

Also tirerack is telling me 26.9" for that size tire, but that's just a tiny difference, and if your tires are worn at all your value is probably closer.
http://i.imgur.com/xGrET.png

This. 3.692 for the 6MT and 3.357 for the 7AT.

Edit* just saw you added the table. :tup:

It is spot on when I calculate it - using the 3.692 ratio.

great catch guys, thats my 500 rpm. thank you

BTW 3.446 is reverse, which means you can do 47 mph going backwards!

:driving: