what is a 393 gear ratio good for in a 68' firebird with a 12 bolt differential, with a chevy...

[Killa Drew]

what is a 393 gear ratio good for in a 68' firebird with a 12 bolt differential, with a chevy...

...350 enging? does this help for top end speed or drag like conditions. What are some good gear ratio for these conditions?What will putting in new rear axels do for proformance??? any help will be great=)thanks

 

[paul h]

3.55 is a good compromise for street /strip use....as you go higher you gain off-line performance but sacrifice general cruising economy for street use If you don't mind gassing up more often, go with a 3.73, 3.90 or 4.10 ratio for more punch off the line but be prepared. Higher gear ratio's also limit your top-end speed.

 

[Goatman]

...350 engine? does this help for top end speed or drag like conditions. What are some good gear ratio for these conditions?What will putting in new rear axels do for proformance??? any help will be great=)thanks

Depending on what your engine has done to it you would be much happier with something a bit higher gear wise (lower numaricly) like a 3.08-3.73 max
the car will be much more driveable with the lower ratio and you can enjoy driving the car .. having a low ratio gear like a 3.91 will get the car off the line quicker but the engine will be screaming at highway speed and severely limit your top speed , especially with a stock or close to stock engine ..
even a modified engine will strain if used for a daily driver with low gears .
you need to think about the intended use of the car and gear it so you can use it or it will get old fast trying to drive with too steep of gears..
the aftermarket axles should only be used if you plan on putting the car into a racing situation
the stock axles are plenty strong for everyday use and won't justify the expence of the aftermarket axles for street use..