I have the 3.31s and I get 31-32 running 70 MPH. The slowest I can go in 6th is about 62 mph. I need to shift to 5th at the slightest hill if I am going under 65mph. Does yours lug down at 65? I've been curious if the 2.73 gets better mileage in real world driving.

 

Do you have a tune or intake, or use premium? I wasn't impressed with the 2.73-geared cars and my current Mazdaspeed3 guzzles 91/93 octane to the tune of 25mpg, so getting 30mpg on 87 pisswater in my new Mustang would be a big improvement...

Another question about gearing: Does anyone here have experience autocrossing the V-6 with 3.31 gearing? I've read the F Stock section and the V-8 guys says it's ideal for their cars since they run out of 2nd gear quickly with the 3.73s. Since the V-6 is kind of peaky, I was hoping the 3.31 gears would keep it in the powerband while in 2nd gear. Need to keep dat Ti-VCT kicked in, y0.

 

According to the owner manual, 59mph is the slowest you should go in 6th gear with the 3.31 gears. So yes you will have difficulty with hills near that speed. A tune does help. 3.73s also help because I am now able to go into 6th gear at 53mph which helps alot in 55mph speed zones and when the speed limit is 65 I have plenty of torque to accelerate.

 

3.31's in 6th gear at 62 MPH is 1820 RPM's ... or 75 MPH with the 2.73's which is where I do 80% of my driving with the cruise set. It may bog down / loose a little speed going up hills but nothing major.

I'll dog my 2.73 geared manual down to 1000~1100 RPM while running in traffic on flat ground.

I'm typically ...
in 5th at 35 MPH
in 6th at 45 MPH
Doing this does not harm the engine and if I need any torque / power due to a hill or change in traffic speed, I'll obviously downshift.

I ran the SCT/Bama 91 Octane Street tune for 5 weeks and noticed an improvement in the 1000-2000 RPM Torque ... however since this is where I do most of my driving I lost a 1/2 MPG running it.

Switching to the 91P tune, low end torque is similar to stock but I'm now getting 1-2 MPG's better.

With the 2.73's, the only time I wish I had shorter gears is coming out of a slow right turn when in 2nd gear ... there is plenty of torque available off the line in 1st gear.

My average economy over 40k+ miles since new is just over 30 MPG's ... running only no-ethanol 91 Octane. Best on one tank of gas so far has been 32.81 MPG's with a mix of 80/20 Hwy/City running the SCT/Bama 91P tune.

Doug

 

Can I change it only with pinion and ring without programming the ecu or something else;

 

If you change the ring and pinion but don't adjust the tune your speedometer and odometer will be off. The only way to change the input is with a tune after putting new ring and pinion in the rear end.

 

Thanks you for the answer. I can tune my speedometer with Forscan program or only in a ford workshop. I have already change my speedometer with 2012 premium model my Color with 4 gauges inter middle and when I’m looking with forscan in IPC information comes 3,31.