rear gear ratios

[hunt2elk]

Hey guys, I'm looking for some advice from people who have experimented with different ratios in their cars. I'm wanting a little more pep from my 383, 4-speed, 28" tall tire, 3.23 Road Runner. It runs 2400 rpm @ 60 mph now and gets 12 mpg if I don't open the 4 barrels. What can I expect from a 3.73 setup?

 

[Cranky]

You're doing about a 15% change. Your in town driving may get better. It really depends on how you drive for the most part but your highway mileage will almost always be worse whenever you go with lower (higher numerically) gears. What carb are you running? A double pumper or any carb that's set up with healthy squirters will most likely get worse in town....

 

[SUPERSTOCKRACER]

I went to a 3.91 with great results, my mpg however did suffer but it has more pep off the line and more midrange. It feels like a different car.

 

[hunt2elk]

I went to a 3.91 with great results, my mpg however did suffer but it has more pep off the line and more midrange. It feels like a different car.

What did you 60 mph rpm go up to?

 

[hunt2elk]

You're doing about a 15% chance. Your in town driving may get better. It really depends on how you drive for the most part but your highway mileage will almost always be worse whenever you go with lower (higher numerically) gears. What carb are you running? A double pumper or any carb that's set up with healthy squirters will most likely get worse in town....

I am using an Edel. Thunder 650 with larger metering rods and secondary jets.

 

[Redpolara]

I went to a 3.91 with great results, my mpg however did suffer but it has more pep off the line and more midrange. It feels like a different car.

I agree, I went from 3.23 and a 28in tire to 3.91 and a 30in tire.....As Chris said.....it feels like a different car.
No tac in the car at the moment, but from memory the gear/tire calculator said 2600 or 2700 @ 60mph.

 

[Cranky]

A 15% gear change will change your rpm about 15%. With a stick, it's pretty set in stone....your rpm should go to around 2750 with a 3.73.....