Gear / Tire Diameter Question

[JFontaine]

3200 lbs
740 hp
TH400

I want max rpm of around 6100 due to hyd & pumpgas.

All things being equal whats the preferred way to go?

30.9 diameter tire with 4.11 gear (6185 rpm)
or
29.5 tire diameter with 3.88 gear (6120 rpm)

Car will be street driven locally.

Thanks!

[Scott @ DLS]

I would go with a 3.73 since you will have to factor in some torque converter slippage. What rear are you running?

[JFontaine]

I would go with a 3.73 since you will have to factor in some torque converter slippage. What rear are you running?

None. :)
It came with a 4.56. The guy was a 1/8 mile bracket racer.

[Scott @ DLS]

None. :)
It came with a 4.56. The guy was a 1/8 mile bracket racer.


What ttype of axle is it? 9 inch, GM 12 bolt?

[JFontaine]

dana 60

[JMatt]

The motor only cares how many inches forward the car has to move each revolution. So your two choices are pretty similar.

Assuming you're not traction limited, the smaller tire will have less rotational inertia, and will accelerate slightly quicker. I'd also think the smaller tire will drive and turn a little easier.

But those are just opinions. No science quoted.

[Scott @ DLS]

You will have to change the spool since the Dana 60 has a carrier break, 4.56 and numerically higher and 4.10 and numerically lower.