Chevrolet Camaro 1967-2002 - how much time would i gain in my 1981 camaro with different rear end gears?

I have an 1981 camaro berlinetta and it weighs 3363 pounds and it has a 350 vortec in it and its pushing 390 hp and 415 foot pounds so thats about 312 hp and rear wheels and 332 foot pounds at the rear wheel and I should be getting in the high 12's on street tires , being faster than the old 69 yenko and that had a 4.10 rear end in it , but my problem is i dont know what rear end gears i have and i dont feel like pulling them out right now but i was wandering and suposedly it has 2.73 rear end , but i dont know it feel faster then 2.73 because when i bought the car the guy did a whole bunch of stuff so i dont really know what i have for gearing but can someone tell me how much time will i gain for each of the follwing rear end gears = 2.73 , 3.08 , 3.42, 3.73, 4.10 , i just want to know how much time about on average do you gain by going higher (numerically higher in gearing ) I mean im not a drag racer , its a street car i just want to get it to run in the high 12's and i know it can with the set up i have i just need to know how much of a difference is their between of the follwing gears i wrote up above THanks a bunch everybody ! Dennis

It all depends on the transmission, your powerband, wheel/tire size, etc.
And there's a huge difference between 2.73's and 4.11's.
olly

I'd rec'd the 3.42 or 3.73 gears for a street car, and it depends on what the car gets used for. My Nova has a 3-speed auto trans with a 3400 stall convertor and 275/60/15 tires, and with 3.73 gears turns 3500 rpm at 70 mph. 3.42 gears would probably drop that to 3200-3300 rpms. You have to look at what you use the car for the most, trans choice, tire size and go from there.

Derek

I'd rec'd the 3.42 or 3.73 gears for a street car, and it depends on what the car gets used for. My Nova has a 3-speed auto trans with a 3400 stall convertor and 275/60/15 tires, and with 3.73 gears turns 3500 rpm at 70 mph. 3.42 gears would probably drop that to 3200-3300 rpms. You have to look at what you use the car for the most, trans choice, tire size and go from there.

Derek
You have to look at what you use the car for the most, trans choice, tire size and go from there.

Well its a street car not a race car , its a th-350 tranny , so like for your nova i know its fast the way you set it up but what if you drop it to 2.73 gearing which i know is stupid but im just wandering about what would your 1/4 time would be then on a guess Thanks Dennis

Did you put a 96+ Chevy truck engine in that?

I'm sure the 1/4 time would suffer a bunch because of the elapsed time wasted trying to get it into the powerband that would be made more difficult by the lower gearing. If I had to guess it could be half-a-second or more.

Derek