ktoonsez

Like the title says, which gear is closest to 1:1 ratio? My guess is 4th, original ratio with the stock Z51 2.73 gears was 1.15, with the 3.42's in there I am guessing it is now 0.92:1?

Thanks
Ken

glennhl

4th is closest to 1.00 at 1.15. By the way, the rearend gears do not affect your transmission ratios, you didn't change any gears in the tranny. It does affect the overall ratios, but you were correct in asking which TRANNY gear was closest to 1.00. Are you doing your dyno pull at AZ Dyno Chip?

HOXXOH

5th is .85 to 1, which gives you an overall of 2.90
4th is 1.15 to 1 for an overall of 3.93
your old 2.73 rear in 4th was 3.14

As a rule, the higher numerically the overall, the lower the HP shown. Unless you're wanting the results for bragging rights, consider the dyno just a tool to help tune and don't be concerned with the numbers.

ktoonsez

Thanks Glen, no doing dyno over at SRD.

ktoonsez

Using the dyno as a before and after for a few mods. Just out of curiousity, is there a correction formula that gives the actual HP then. I.E. if my car dyno's at 450 with these gears, it would dyno at XXX with the old 2.73 gears? Just want to know for people that don't have the same gears so I could give accurate guess of HP on a car that has different gears.

Thanks
Ken

HOXXOH

I'm not aware of a correction factor. I'd make one pull in 5th, just because the overall ratio is much closer to the previous one than the current one. The downside to a 5th gear pull is the wheel speed required would be slightly higher and the dyno guy may not approve. It never hurts to ask.