sketchy00

Just thought I'd post a few MPG numbers demonstrating the difference in changing my '11 MT6 from a 2.73 to a 3.55. All samplings are with a Bama 91S, and an Airaid CAI. Typical driving for me is 70/30 Hwy/City. Same station, no top offs. All figures were manually calculated.

Last 4 tanks while on a 2.73:
390 Miles. 14.051 Gallons = 27.76 MPG
375 Miles. 13.359 Gallons = 28.07 MPG
406 Miles. 14.368 Gallons = 28.26 MPG
407 Miles. 14.523 Gallons = 28.03 MPG

Avg: 28.03 MPG

First 3 tanks while on a 3.55:
353 Miles. 13.338 Gallons = 26.46 MPG
393 Miles. 14.802 Gallons = 26.51 MPG
361 Miles. 13.726 Gallons = 26.30 MPG

Avg: 26.42 MPG

Average decrease in MPG: 1.61 MPG.
Improved fun of gear change: Priceless

Bokeo

Nice #'s, I couldnt agree more... love my gears.

livinloud98

i guess i have a heavy foot lol.. i went from 23mpg with the 2.73s to 19mpg with the 3.55's but i just cant keep my foot out of it, its to much fun..

However, if I reset my mpg calculator and do a trip from home to work all highway i can get 28 mpg out of the car.

USallBlacks

Hey not trying to thread jack, but my question is on gears. I am really wanting to get away from the 2.73s since my driving is mostly city and this limits my ability to 'enjoy' the power band as much as I would like. I know i need the gears and since I have a 12' v6 then I also need the 8.8 rear gear pinion. Is this all that I need to bring to a shop if my car only has 4k miles and nothing is worn out? Thanks, and sorry again for the thread jack. Those 3.55s sound like fun!

hogasswild

I just got an estimate for 3.73 Gears and the installer said to order a gear pinion bearing too and bring it with the gears. He told me just order off AM because if I didn't bring them in, that's where he would get them from.

livinloud98

my car had 1500 miles at the install and the stock crush sleeves were worn unevenly from the stock gears and the pinion bearing didnt look to great. Do your self a favor and buy a bearing / install kit. Yukon makes a great one.

snaf2u

I put 3.55`s on mine last fall. ran them in the spring and gained about .3 in the 1/4. Still easy to launch and shifts out of 3rd just after the trap, as I thought it would. I am very happy with them. Combined with the magnaflow streets it makes enough rpm at moderate speeds to make the exhaust sound good.

Milage down about 2 at 75, about the same in town.

3.73`s are close enough they would probably would work well too for a car that is more a cruiser rather than a racer.

I`m happy.

oldncrusty

Did the tune recalibrate the speedo/odometer for the new rear end?

sketchy00

Yes. I requested the tune change a few days in advance so that I'd have it loaded up on the tuner to be applied right after it came off the lift.

z28th1s

Good info, looking at doing a gear swap in my wife's '11 V6 M6 2.73 geared car soon.