3.55 gears make much difference over 3.31?

[Marvinmadman]

I won't be swapping my 3.15s. 0-60 is good enough for me. 5.3 with stock skinnies. I need to get a run in with my new wheels and 285s

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[xmadror]

Sorry to hijack the thread,

But is the 3.31 faster 0-60 than a 3.55, or a 3.73?

What benefit do you get by going to 3.73 then? Are you just in the torque curve more often, rather than waiting?

For the same speed you'll be revving ~11% higher (3.31 to 3.73).
That means you'll stay in each gear a shorter amount of time since the car will rev faster. This is a trade between top speed and fuel economy vs acceleration (although since 6th gear is usable sooner with 3.73 it might negate the fuel economy of the 3.31, I didn't had much time with my 3.31 gear so I can't verify this)

For 0-60 its most likely slower (with a 6 speed manual at least) since you won't be able to reach 60 in 2nd gear and you'll have to shift to 3rd with a 3.73 rear end (I think the same can be said for the 3.55).

 

[TorqueMan]

I don't get the comments that 6th gear is "unusable" with 3.31 or higher gears. It's perfectly usable for what it was designed for: it gets the RPM down at highway speeds to improve mileage. If you want to accelerate hard simply downshift to 5th. If you don't like having to downshift to accelerate then why did you buy a manual? ;)

 

[Marvinmadman]

Same with my 6R80. 6th is for MPG. When I'm in traffic I just put the shifter in S and it'll shift perfectly fine and stay out of 6th.

 

[Juben]

I don't get the comments that 6th gear is "unusable" with 3.31 or higher gears. It's perfectly usable for what it was designed for: it gets the RPM down at highway speeds to improve mileage. If you want to accelerate hard simply downshift to 5th. If you don't like having to downshift to accelerate then why did you buy a manual? ;)

I'd be inclined to agree. I've never reached a point, while racing, where I needed to use 6th gear. 5th gear, yes. 6th, no.

The factory tire height is a 27". Going to a 26" tire, via aspect ratio, would net similar gains as going from the 3.31s to the 3.55s, however, if you didn't like it and/or mileage dropped below an exceptable point, then it would be easily reverseable with a tire swap. If you had a buddy with a set of 26" radials, you could try those for a few weeks to see if the improvement would be worthwhile for you.

That said though, I'd probably stay with the 3.31s (if it was me). I've got 3.55s in mine and thought about going to the 3.31s just because turbo cars generally seem to like a taller gear to stretch their legs a little bit. I've always had good success with doing so as well (in my street cars).

 

[Blue Moon]

I use 6th gear with my 3.31 and MT all the time. Just get it up to at least 55 mph, put it in 6th, set the cruise control, and unless I come to a very steep hill, she'll run all day.

 

[Blue Moon]

Sorry to hijack the thread,

But is the 3.31 faster 0-60 than a 3.55, or a 3.73?

What benefit do you get by going to 3.73 then? Are you just in the torque curve more often, rather than waiting?

For a GT, I loved driving the 3.73, but honestly in my Ecoboost (PP with 3.55, I for some reason wish I had a 3.31 or maybe lower due to the bounciness of the turbo).

With my MT my 0-60 improved by about .2 seconds when I swapped from 3.55 to 3.31. Mainly because it will now reach 60 comfortably in second gear. I probably lost a little acceleration off the line, but more than made it back at top end.

 

[justme97]

I keep going from wanting 3.55 to 3.73 to 3.31.
Wouldn’t it be cool if it was made with adjustable gears??
For me I mainly want performance for every day driving not the track. But it does seem logical that taller gears would help the turbo stay in the zone...
Maybe once the updated fp tune arrives I’ll decide..

 

[Ebm]

.

I use 6th gear with my 3.31 and MT all the time. Just get it up to at least 55 mph, put it in 6th, set the cruise control, and unless I come to a very steep hill, she'll run all day.

Wow. And what rpm does your car spin at going 55mph in 6th gear with the 3.31? About 1k?

 

[TorqueMan]

Wow. And what rpm does your car spin at going 55mph in 6th gear with the 3.31? About 1k?

Mine's turning around 1600 or so; just loafing along. At that speed I routinely see 35+ mpg. My wife's Escape has the 2.0L EcoBoost with 6-speed auto. It's similarly geared, turning around 1600 rpm at 55 (2000 rpm at 70). I pay close attention to the way Ford tuned the shifts on her auto. The car remains in 6th for all but the steepest hills, only downshifting when the speed drops 2 mph.

The horsepower required to maintain speed on the highway is but a tiny, tiny fraction of that required for acceleration, even for a car that doesn't have the best aerodynamics (Ford doesn't publish aerodynamics data on the Mustang, but I don't think it's particulary slippery).

 

[Ebm]

.

Mine's turning around 1600 or so; just loafing along. At that speed I routinely see 35+ mpg. My wife's Escape has the 2.0L EcoBoost with 6-speed auto. It's similarly geared, turning around 1600 rpm at 55 (2000 rpm at 70). I pay close attention to the way Ford tuned the shifts on her auto. The car remains in 6th for all but the steepest hills, only downshifting when the speed drops 2 mph.

The horsepower required to maintain speed on the highway is but a tiny, tiny fraction of that required for acceleration, even for a car that doesn't have the best aerodynamics (Ford doesn't publish aerodynamics data on the Mustang, but I don't think it's particulary slippery).

Spinning that low, there's no way to keep up with the flow of traffic. One hill and you're done. This isn't a knock against the 2.3, but more the overly long gearing. For me, that's too close to the danger zone(lugging, lspi).

 

[TorqueMan]

Spinning that low, there's no way to keep up with the flow of traffic.

Hmmm. Never been an issue for me. The engine is in no way straining to maintain 55 in 6th. Then again, I don't do the speed-up-slam-on-the-brakes thing when I'm in traffic. If I get slowed below 55 then I just downshift and accelerate normally.

One hill and you're done. This isn't a knock against the 2.3, but more the overly long gearing.

Or you can simply downshift to 5th, no problem.

For me, that's too close to the danger zone(lugging, lspi).

This was a concern for me as well, which is why I paid such close attention to the auto trans tuning in my wife's car. Ford has been at the forefront of LSPI mitigation technologies, so I assume its engineers took that into account when setting up gearing and shift algorithms for the EcoBoost in the wife's Escape.

I don't have all the details of the LSPI testing programs used by different manufacturers, but I believe the conditions conducive to LSPI require high torque demand, such as hard acceleration under high boost. My assumption is that Ford's engineers determined that maintaining speed uphill doesn't generate the kind of torque demand required to induce LSPI.

Then again, if you're worried about it, just downshift. I don't mind rowing the shifter; for me, it keeps the drive engaging.

The next time I go up a hill at 55 mph in 6th I'll watch the boost guage and carefully check throttle position. I'll let you know what I find.

 

[justme97]

If you had taller gearing you could always just use 5th gear on the highway? My 2.5 L six-cylinder z4 had five speeds and on the highway 5th gear was very perky, never had to downshift when going over 75 but it stayed at around 4K RPM when cruising. The 3.0 that year had 6 speeds but equal fuel efficiency because of that extra gear.

 

[Blue Moon]

Wow. And what rpm does your car spin at going 55mph in 6th gear with the 3.31? About 1k?

Just like TorqueMan said, about 1600 rpm, and if I need to accelerate or climb a steep hill, drop it into 5th for a few moments. That helps me stay awake and alert on long drives. If a driver isn't willing to do that, he might as well buy an automatic to do it for him.

 

[Marvinmadman]

Instead of just mashing the throttle and hoping the car decides to downshift for me, I downshift with my left paddle to accelerate from a low speed cruise. Helps keep it from lugging/LSPI and saves fuel.

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