I read a few posts that say changing gears i.e 2.73 too 3.73 will not lower times in the 1/4 mile? With an A4.

What would be the right gears for a bolt on LT1
and for a HOT cammed LT1

Will it raise MPH
Is there any reason to do it?

BTW i have A4 2:73 and thinking of getting 3:73


Also have LT headers
and HotCam kit in the mail

 

Gears will definately help your et but you will probably need some tires to go along with those like Nittos or BFG drag radials. I went with 3.42's b/c I bought them used off the board for $50 but I think 3.73's are a better choice for dragracing.

 

You usually gain anywhere from 2 to 3 tenths when going from a 2.73 to a 3.73. I also recommend getting your speedo recalibrated for the proper gear.

 

Are 3:73's good for daily driving....i only race about once a month and have a 30min trip to and from work. and i wont be running DR's because i have to drive in the rain and my wife also uses the car sometimes and i cant have my rear going out.

So would u still say go with the 3:73 or lower?

 

deffinitly not lower then 3.73s higher would be moderate.. i went from 3.23s to 3.73s in a 6 speed. Affected daily driving a little cuz i shift more (and speedo isnt recalled) but as far as that no. if you get on it you get alot more tire spin. but if she drives your car NICE and easy she will notice no difference except for it will shift a little sooner, and cruise at a higher RPM or a higher gear

 

Lower gas milage......Less top speed For When you want to do 165.......on the test track.......lol.

 

will i still be able to hit 140 MPH with 3:73....
i had the speedo limit moved up from 120 because mustangs where killing me

 

yes, it wont drop your top speed by 15mph

 

ET change from a gear change really depends on the car and whats done to it. Give you an example with my 97 Formula I had. It was a 350 block w/ LT4 AFR 190s on top and a 150 shot of spray. << M6 Car >>

w/ 3.42's it ran 11.19@127 1.8 60's

w/ 3.73's it ran 11.19@125 1.7 60's

w/ 4.10's it ran 11.19@123 1.6 60's

My old car could just be a rare example, but the damn thing ran 11.19's everytime I went to the track no mater what the gears were. The only difference was my 60' times and my mph.

Now I will say that on motor there was a very large difference between the gears. The main reason was the cam needed high RPMs and it needed 4.10 gears. When I broke my rear end and put a stock one in it w/ the 3.42's. The car went from running 12.4's to 13.3's. Then with the 3.73's it would only run like 12.7's. I was getting a lot of bogging problems off the line. The nitrous was enough power where bogging was not a problem, hence why my times didn't change.

Also I had a 97 Z28 (A4) I did some minor stuff to including 3.42's over the 2.73s. I'd say it probably picked up .2 tenths if that. The main thing I would say is a torque convertor on the A4's. If you went with 3.73's and say a 3200 Stall convertor, I bet you'd gain .6-.8 tenths... Traction depending of course. Also the more power you are making the more you'll notice the above.

Just my .02 cents.
Jason

 

I doubt the 3.73s are going to hurt your topend. It's not like you can pull overdrive to redline now anyway. Right?