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3.73 gears - don't feel much of a difference

6K views 23 replies 16 participants last post by  Strange Mud 
#1 ·
So I recently went from 2.73 to 3.73 gears on my 2014 v6. I also got a custom 93 dyno tune afterwards. Based on what I've been hearing, I was expecting to feel something very different. However, it actually feels like the car pulls less hard now than it did before, with less of that feeling of getting thrown back in your seat. Even my wife agrees.

The only thing that seems to have changed is the gas mileage. I was already getting horrible mileage due to my primarily city driving with a not so heavy foot (14mpg). I was told that the gear change might actually improve my city mileage in stop and go traffic, but now I'm getting 11 mpg. One of the reasons I went with a v6 over a gt was for the mpg. On the highway on level ground in cruise control at 65 I can get 23mpg. I guess I just feel like I wasted a bunch of money on nothing ... Is this normal or am I crazy?


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#2 ·
11mpg with a 14 v6?

There is something wrong with your car.

With shorter gears like that and the same type of driving you should pick up some mpg in the city. Even my 2001 4.6 with 4.10s gets better mpg than that. And i get some of the worst mpg out of all the other 99-04 4.6 guys i know.

There is something wrong with your car. Or you are crazy.
 
#4 ·
3.73 gears and a tune are the best upgrades for our mustangs and its a night and day difference over stock. I got my tune before anything else and it was a big difference then i got 373 gears as one of my last mods and that was another big difference. i can peel out good off the line with an automatic and heavy ass 29 inch tires in the rear. And city driving i get about 1-2 more MPG over my old 273 gears. your gears where either not installed right or they never installed them to begin with. I let my gears break in for around 200-250 miles before i went all out testing them out.
 
#5 ·
As far as MPG, is that NYC mileage? How much time are you sitting still in traffic without moving? Maybe you're getting siphoned?


2012 Grabber Blue Mustang Convertible V6 Premium
1979 Solar Gold Trans Am
1995 Bright Red Trans Am Convertible
 
#6 · (Edited)
Out of everyone that has done a gear change from 2.73s to anything, this is the first time I've ever heard anyone say their car pulls less, and your MPGs are terribly bad. For me 2.73s to 3.73s were night and day! There is something wrong with your car or your butt lol, and yes your crazy!

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#7 ·
Assuming this is not a troll post. You have something wrong with your pony and good luck getting it fixed now under warranty. No way in the world one could not feel a huge difference with a tune and 3:73 gears. The only explanation assuming this is legit post, your car is jacked up.

Who installed the gears? You, stealerahip, etc? Where you get the dyno tune at?
 
#11 ·
:facepalm: Just because a tuner can dyno tune doesn't mean they know how to dyno tune a Ford 3.7 cyclone engine. You should be feeling a night and day difference between those gears.

The gears not really being swapped could be another cause, but you wouldn't be at 14 mpg. I'll lean towards your dyno tune.
 
#12 · (Edited)
You said you have a dyno tune. Umm do you have a full bolt on car? What are your cruising rpms at 60mph? If theyre under 2000, you're definitely not running 3.73s

Other thing: it is your tune if your car isn't pulling hard as it used to. I'd also double check condition of your spark plugs, intake couplers, throttle body etc to ensure everything is tight.
 
#13 · (Edited)
I wish this WAS a troll post ... I will investigate the cruising RPMs and get back to you here to see if the gears really were swapped.

If people are saying maybe it's the tune, I could call up the tune people. It was Realspeed automotive in New York, one of the more expensive and one of the more reputable (I think) mustang shops. The tuner was a former engineer at Steeda, who said people usually don't dyno tune 3.7s so he didn't have too much experience with it, so he spent a DAY and a HALF tuning it. He sure seemed like he wanted to put the time in to do it right. But I will call give them a call.

I am primarily driving in super stop and go New York City traffic, so would the 14mpg before the gear swap be considered normal? It's still strange to lose mpg all the way down to 11mog in the city after the swap.

Is 23 mpg on the highway with cruise control on level ground normal with 3.73's?


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#24 ·
i THINK the 23 mpg hwy would be right for 3.73 and did you check readings B4 the swap. The surprise is it feels like it's pulling less? WTF I did a test drive with MT and 2.73's and am way happier with the 3.31's I bought. Good luck keep us posted. I wonder if your butt dyno is out of calibration.
 
G
#14 ·
You could use the info reset button to try and recalculate your average MPGs. However, if someone told me they didn't have much experience tuning my car, I would have taken it somewhere else. Something like a tune is not to be taken lightly with any car. As it can mess up your engine if not done right.
 
#16 ·
Agreed. Beforehand they claimed to have a lot of experience with mustangs (it's a mustang specialty shop that had good reviews on other forums). Only when I picked it up did he mention that 3.7's weren't too common in terms of dyno tuning.


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#15 ·
Jack the rear end up, rotate the tire one complete rotation and count how many times the driveshaft turns. 2 3/4 turns is 2.73, 3 3/4 turns is 3.73.


2012 Grabber Blue Mustang Convertible V6 Premium
1979 Solar Gold Trans Am
1995 Bright Red Trans Am Convertible
 
#17 ·
I would say there is a good possibility that it's the stop and go New York City driving. When ford says 19 city it means normal city driving and not being stopped a lot. Put a full tank of gas and start the car and let it sit long enough you'll get 0 mpg. Do you be take road trips? I would recommend driving it a normal 150-200 miles and manually calculating the MPG and see what it is.


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#20 ·
Must be the tune. I went from the factory 3.31 gears to 3.73's, night and day difference. Just saying....:)
 
#21 ·
Wild post, the pony should be movin out fast enough for the op to feel the gear change.
 
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