FormulaZR

iTrader: (7)

Oh joy, another one of these threads...sorry, but I searched and couldn't find anything that fit my application.

So here's the deal, I have a full weight 99 Formula with a 383. 500 rwhp n/a, 238/244 cam, 4L60E w/ 3600 converter, 9" rear end, 28" rear tires, and a 150-250 shot of N2O. The car is not a DD, but I would like it to be somewhat street friendly for a weekend cruise every now and then. Would I be better off with 3.89 or 4.11 gears?

My main hesitation with the 4.11's is that I'm more concerned with 1st being too low and about running out of gear in the 1/4 (in 3rd while spraying), not as much with the cruise in OD (although that is a factor also)...what do you guys think?

AGRV8TD

iTrader: (1)

4.11's with a 28 drag radial will be plenty for your car

EPP

iTrader: (22)

You could run out of gear with 4.11's with the horsepower you have, it is going to depend on how high you're willing to have it rev through the traps. Bob

FormulaZR

iTrader: (7)

I'm thinking I'd like to stay between 6500-6800, I'm sure the engine could handle a little more...but I just don't want to push it. I'm kind of leaning to the 3.89 also, because IF I pick wrong, I can always drop to a 26" tire and make up for it...but I can't fit much bigger, if that makes sense.

SlideRight

so how do you get the ideal tire to gear ratio? do you want bigger tires with the higher gears or the opposite?

fleetmgr

Depends on what you're trying to accomplish.

A shorter tire = a net increase in gear ratio (numerically larger). Taller = net decrease (numerically smaller).

FormulaZR

iTrader: (7)

You use a smaller tire to lower the overall effective ratio of the car. For example a car with 4.11 gears and 28" tires will drive similar to a car with 3.89 gears and a 26" tire. Putting 28" tires on a 3.89 geared car would be similar to a car with 3.55's and 26" tires.

SlideRight

Lol, you just totally lost me.......Im still trying to wrap my mind around some of this stuff

FormulaZR

iTrader: (7)

Ok, let's just say that you have 4.11 gears in your car, 26" tires, and you're hitting the rev limiter before you cross the stripe of the quarter. If you switch to 28" tires you will have decreased the effective ratio and will maybe be able to make it through the quarter without hitting the limiter.

Putting larger tires on a car has the same effect as putting high gears (numerically lower) into it...

Jawsgear

iTrader: (2)

Try our calculators out on our website. It will help you make a decesion on tire and ratio you wnat to run. Here is the link.......

http://www.jawsgear.com/calc_rpm.html

Jeff