rocky46

I cant decide over the 3:73's, and the 4:10's. I have looked for a RPM calculator but i havent been able to find one. My first thought was to go with the the 373's because i have to drive at a minimum 120 miles a day. Could you guys tell me what rpm's you are running at 70 and 80 mph please. After reading some of the threads i am more tempted to get the 410's, but how bad is the gas mileage on both?

Any advice would be appreciated.

I just bought the car a week ago (2001 GT Automatic)and put a o/r x pipe, flows, k&n filter with the inlet tube. I am wanting to buy something else with the gears before i buy the diablo programmer. Been thinking 75mm tb and plenum and some ud pulleys. I ran it saturday and on my only pass i ran a 13.9. I am wanting to get in the 12.7 range and be a vette killer. Would love to do more, just have to drive the car so much.

Thanks again for ANY tips or advice.

Rocky

Aereon

What is your overall goals for the car? Most will tell you to get 4.10's for an auto but if your gonna go f/i down the line, you may decide then that you need to downgrade... I have an 03 auto gt, and I'm deciding to go with 3.55's because I will be going with a positive displacement sc.

BleedinBlue

My car is an 02 auto. Off the top of my head I am at 70 mph and I am at ~2600 rpms, at 80 I am at 3000 or so.

I've only put 2 tanks of gas in my car since I got the gears installed, but I haven't seen a change in mileage. <<<I haven't checked...and don't check very often, but do reset my trip every time I fill up. It seems to be about the same...it is probably a few miles less, just not enough for me to notice.

Regardless of the gears you get, get a tuner also. Firm up and adjust those shift points, and adjust your speedo for the gears.

13.9 is a good time for your mods. I'd guess that with 4.10's you would probably be in the 13.5 range. It'll be hard to break that 13 second barrier though...

Aereon...dude, at least go with 3.73's...3.55's isn't much of a change at all from stock.

Aereon

I've heard people are having a hard time hooking with 3.73's/kb. I'm planning on running 500/500 whp/wtq on an autocross/open track car.. so traction would be a major issue.

BleedinBlue

With a KB and 500/500 you'll have a hard time hooking up with the 3.27's

Its up to you though...but I think when you get used to the power, do suspension and tires to match the power, you'll want more gear.

Either way you go I'm jealous

Aereon

I'm almost finished with the suspension, (till i get more track runs and test out what needs improvements) I already have mm c/o and lca's installed just need to find time to get the TA and phb on... the kb will come after I beef up the rear and stick a tr2 lsd in there.. so I hafta decide right now that I wanna go a bit lower with a 3.55 setup

superman71

I have a 03 GT 5 speed, should I look to replace the gears too? What kind of boost in hp does that give me? Thanks.

Aereon

Gears do not give you any boost or hp. They effect your car's overall feel in acceleration, most owners of standard's end up upgrading their rear gear ratio's to 3.73's to help acceleration

BleedinBlue

It doesn't boost the hp at all. But it makes the car feel like it does You definitely SHOULD get gears. It is the best mod for the dollar on our cars and is the first mod that should be done.

I'm not tech savvy enough to explain it well, but bigger gears keeps the rpms in the power band. Change stock 3.27 gears to 4.10 gears and it feels like a 50 shot of nitrous and will probably knock 3-4 tenths off the quarter mile time.

My auto went from chirping 2nd to chirping 3rd gear

OzzDOA

Gears act as a torque multiplier, which means your engine has to work less to get you moving. Say with the stock 3.27's you are putting down 280 ft/lbs at the wheels, with a higher ratio gear you will put down more "effective torque". So with say 3.90's you would be putting down the equivalent of 456 ft/lbs from a 3.27 geared car. Effectively you end up getting more "work"from the same amount of force. You won't see this on a dyno since when they put your car's info into the computer it compensates for the different gearing.