HRE

I've got a stock 93 camaro and i'm starting to do the bolt on's. One of them will be to change the gear. This is stock auto and converter with 27 tall sticky radials. I would like to know what your trap rpm is so i can better decide on what ratio to use. I'm thinking either a 3.90 or 4.10. I've calculated a theoretcle RPM but i would like to hear what you guy's actually have thanks. Any other tips would be appreciated.

HRE

Nobody !?

sc68z28

4.11 gear, with a 28" tire, I trap 6850 rpm at 143 mph.

HTH ---Bill.

Z-RATED94

Not to change the subject but, you will have a far greater et reduction if you go with a converter swap first. A quality converter in the 3600 range will easily knock off a half second. A tranny cooler and a shift kit would be a good idea too, if you do go that route.

JakeRobb

I go through the traps at about 4800rpm in 4th gear in my stock-ish LS1 M6. I don't think that helps you much, though.

Ideally, you want to go through the quarter mile traps just below your preferred shift point RPM in whatever your 1:1 gear is (3rd, in your case).

slomarao

109 in mid 4th gear. 3.73 gears, boltons, 255/50/16 dr's

M6 car

Stephen 87 IROC

Gear ratio needs to compliment tire size and rpm range of the engine. For best performance, you should be crossing the finish line at or just before your peak shift point and in whatever your 1:1 gear in the tranny (no OD).

With a 4L60E, third gear is 1:1. If your peak power has your shift point at 5800, you want it geared to cross the finish line at 5800 or slightly higher rpms. The higher the rpm range of the engine, the deeper the gear needs to be while using the same tire size to achieve the same results.

I have 32" tall tires, 4.57 gears and cross the finish around 7200 rpm. The engine still has more power above 7200 so I need to put in some 4.86 gears to get the rpms higher or drop the tire height down which isn't an option.

Without knowing what your current performance results are, it's hard to give a proper suggestion.

Bob Cosby

Disagree with the rpm. If you're serious about ET, you should go through the traps ABOVE your shift point. Serious racers will gear the car so that it is hitting the limiter just as it is going through the traps. Why? Because the last 100 ft of the 1/4 mile means virtually NOTHING in terms of ET. Ever see a car let off or even hit the brakes before the finish? MPH dives....ET barely changes.

To be more specific...as a general rule, shift points are typically 600-ish rpm above peak (though that number can vary significantly up or down depending upon the tranny gears). Finish line rpm is 800+ above peak.

Again - if serious, gear it so its on the limiter in the traps.

Z-RATED94

I'd have to agree with Mr. Cosby as I've heard that before from an old Super Stock racer.

HRE

Thanks for the replies but i need to hear from the guys running an automatic with stock type engines with bolt on's. I want to gear it so it'll hit around 6000 rpm thru the traps. I'd like to hear from someone that has done the same as i want to do. Thanks.

JakeRobb

I think LS1Tech's ET Database might be helpful for you.

mdacton

7000@ 128mph

HRE

What gear and what tire size.

mdacton

28 4.56

Z-RATED94

The way your going about this, you might as well throw some 4.10s in it and call it good.