Well I switching the rear around in my car. Im debating over a couple different gear ratios to run. Its a boosted car with a 4L60e. Im debating between 2.94s or some 3.45s. Help me choose.

 

How much HP you running?

Ken R.

 

Right now pry 450 with a 25.7 in tire(275/45/17) but would like the gear to grow with the car.

 

What kind of rear are you running now? Those aren't your everyday ratios. I would say a 3.45 would be a good ratio. 2.94's may be a little steep just yet, but if you throw more power at it, they might work out good. Is there anything in the 3.23 range for your rear (assuming your not running the stock 10 bolt anymore)? Run some online calculators for RPM based on different gear ratios and tire sizes along with your trap speeds from the track if you know them and try and get an idea on where each ratio will put you rpm wise through the traps. If you can keep it in a range where your making most power without shifting into OD, then thats the ratio i'd shoot for.

Ken R.

 

Pry just gonna go with the 345 then. Its a 9"

 

Assuming that you are into drag racing and planning on throwing big power at that 9 inch 3.45s are probably a good choice. They allow for about a 120mph trap speed at ~6000rpm in 3rd which is ideal for most.

I thought a 3.31 gear was also available??? That might be more appropriate if you plan for slightly higher trap speeds or you want more mpg and a quiter cruise.

 

Big power and 120mph trap speeds dont belong in the same sentence

It really depends on the tire. a 29" tall tire with 3.55's will allow me to trap over 140mph @ 6k rpm.

I think 3.45's are fine.