3.73 vs. 3.55 vs. 3.31

[Soulowd]

Hey guys I am trying to decide between 3.55 vs. 3.73 to add to my 2011. I searched a ton of forums and found some really good info that I just wanted to share. I am going to upgrade because I want better times at the track dont really care about MPG's cause its not a daily for me. Anyways chime in if you like but im leaning toward 3.55's at this point...This is the info I found interesting:


Technically the redline of the new 5.0 is 6850 rpms.
Fuel cutoff is 7000 rpms.

So I'll give you the top speed in each gear at the 6850 rpm redline for 3.55's and 3.73's
If you take it the extra 150 rpms you'll get another 1-4 mph out of each gear (about 1 mph in 1st and around 4 in 5th).

3.55

1st - 42.4 mph
2nd - 63.8
3rd - 91.8
4th - 117.5
5th - 155.1
6th - 155 limiter


3.73's

1st - 40.0
2nd - 60.3
3rd - 86.7
4th - 111.1
5th - 146.6
6th - 155 limiter

I'd have to run them but off the top of my head 3.31 is about

1st - 44
2nd - 65
3rd - 95
4th - 123
5th - limiter
6th - limiter


Now do you guys see why I've said I think the 3.55's are the best gear for 1/4 mile racing, especially if you add 30-40 hp to the car?
With the 3.73's you finish the 1/4 mile right at the top of 4th as you bang into the fuel cutoff around 113 mph (which would give you a trap speed in the 111.5-112 mph range). If you have an especially strong running car and you'll need to shift to 5th to finish, and that will end up costing you time and trap speed.
Add 10-40 hp and the same story applies.

With the 3.55's you get 117 mph at 6850 and close to 119 at fuel cutoff.
That allows you stock to run the 1/4 in 4th with no problems and you should cross the line somewhere in the 6600 rpm range...right in the peak of the power range.

Further, add up to 30-40 hp and you could still get to the stripe at the top of 4th with a traps in the 116-118 mph range.

Also notice with the 3.55's you get to the 155 mph in 5th gear.
In the 3.73's you need the shift to 6th.

The reasons above are why I will most likely order my 11 GT with the 3.55's
I think they'll produce slightly better 1/4 mile times stock over the 3.73's and probably up to .2 and 1-2 mph faster than the 3.73's on a car with up to 40 hp in mods. (and could possibly still be faster with more power in mods, as 3.73 gears will offer less traction at launch and between shifts as power rises, costing time and speed).

For auto-x and track junkies, the 3.73's will probably be the best choice.

You can also see why Ford has the 3.55 gears as standard everywhere else in the world but the U.S.
As they measure 0-100 kph (62.1 mph). With the 3.55's this is achieved right at the top of 2nd gear.
The 3.31 gears offered as standard here was simply to improve the ever stricter EPA fuel economy regulations.