2015 Mustang EPA DATA!!!! for most models.... UPDATE 2 ALL MODELS

[JonnyMustang]

So, I'm totally a new guy when it comes to gear ratios....

Can someone fill me in on why some like smaller ratio and some like bigger?
I got the GT premium without upgrading to any gear ratios, so I guess I got 3.15?

I mean anything is going to be a boost in power considering I am coming from my 13 v6.

Some people like bigger (3.73/4.10) because they want to accelerate quicker while others may want to keep the power band higher in the rev range and choose a lower gear (2.8x-3.55). Also some prefer different gearing based on transmission choice.

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[phil1336]

Now You know just as well as I Do Phil, that just because the Speed Limit in Florida is 70 mph that doesn't mean that People are going to Obey the Speed Limit. If You're doing 70 you're going to get passed by 75% of the People, Like You're Standing Still. It's not uncommon to be going with the flow in a pack of Traffic and look down at Your Speedometer and Realize You're doing 80-90 mph.

Take the Florida Turnpike South from Palm Beach County through Broward into Miami-Dade or for that matter do the same heading North and drive a steady 85-90 MPH, guarantee FHP will be waiting for you! Not much better luck on I 95 either. Been here for 17 years and counting.

 

[scottpe]

So, I'm totally a new guy when it comes to gear ratios....

Can someone fill me in on why some like smaller ratio and some like bigger?
I got the GT premium without upgrading to any gear ratios, so I guess I got 3.15?

Here's a fairly good education on the topic: http://www.carcraft.com/techarticles/ccrp_9812_all_about_axle_gears/

There's a ton of factors that go into the decision on gearing, but in general, taller gears (lower numerically) will yield better economy at the expense of acceleration, and higher numerical gearing will yield more torque multiplication/better potential acceleration, at the expense of some economy.

Part of the decision on which you should choose comes down to your driving habits. Do you drive a lot of miles? If so, MPG may be a factor, and you may want to stick with numerically lower gears, as you will generally get better mileage with them.

Bottom line, it's really all about your priorities and how you intend to use the car, e.g. if performance is more important to you than efficiency or vice versa.

 

[JimmyTwoTimes]

Take the Florida Turnpike South from Palm Beach County through Broward into Miami-Dade or for that matter do the same heading North and drive a steady 85-90 MPH, guarantee FHP will be waiting for you! Not much better luck on I 95 either. Been here for 17 years and counting.

Lol speed traps.

http://jalopnik.com/meet-the-guy-who-drove-across-the-u-s-in-a-record-28-h-1454092837

 

[Spartan]

So, I'm totally a new guy when it comes to gear ratios....

Can someone fill me in on why some like smaller ratio and some like bigger?
I got the GT premium without upgrading to any gear ratios, so I guess I got 3.15?

I mean anything is going to be a boost in power considering I am coming from my 13 v6.

Unless you plan on consistently flooring it to show people up at the lights, I think you'll be fine with 3.15. It will still give you good acceleration while giving you better MPG at higher speeds. That's what I'm going with in my GT I'm ordering.

Now if you drive in the city non-stop and not much highway driving, then a 3.55 might just be more fun and your MPG wont suffer much since you'll be in the city anyway. MPG suffers with the 3.55/3.73 on the highway vs the 3.15

Still not sure why the 3.33 aren't available in auto...any idea?

 

[DivineStrike]

Really has nothing to do with your car/motor specifically. Pretty much ALL combustion engine cars experience a substantial reduction in MPG for each 5 MPH increase above 55-60 MPH. The average MPG hit going from 70 to 75 is about 7-8%. Going from 70 to 80 is about a 13-15% reduction.

Higher Speed = Lower Mileage = Higher Cost. It's that simple.

Of course this is true but with turbo vehicles this is usually exacerbated because above certain speeds your car will be using boost without being able to stay out of it if you want to maintain that speed, which significantly decreases mileage vs an N/A engine going the same speed. In my Focus the reduction was much less dramatic than that. averaging 70 I was able to eek out 32 mpg's and averaging 80 or so it only dropped to 30. At higher highway speeds my Focus was more efficient but at lower speeds my GTI was way more efficient.

 

[Herr_Poopschitz]

Of course this is true but with turbo vehicles this is usually exacerbated because above certain speeds your car will be using boost without being able to stay out of it if you want to maintain that speed, which significantly decreases mileage vs an N/A engine going the same speed.

I have NEVER EVER seen a petrol car cruise at interstate speeds w/ positive manifold pressure, much less 71 mph as you stated.

Can you provide specifics on the vehicle? Heck, I'd like to see a video of it too, if you could...

 

[Trackaholic]

Gearing is mostly pointless for the street, IMO.

It really only matters for the 1/4 mile, where you want a balance that will give you a good launch yet still allow you to finish at the top of whatever gear you would be in (probably 4th).

For example, for the GT PP with 3.73 gears, you'd get a very good launch, and 4th tops out at 116 MPH @ 6900 RPM. That might be just about perfect for the car in its stock condition. Guessing from the power/weight, 116 in the 1/4 seems reasonable.

With the non-PP and 3.55 gears, 4th tops out at 120. If you start modding your car, this might be a better choice, because it gives you a few more MPH at the end of the 1/4 before running out of RPM.

On the street though, a 1st gear launch is less critical, and you don't need to worry too much about the top end because if you want to accelerate hard you can just downshift. Yes, a shorter gear will give you more time in the power band, but if you aren't really racing it's not going to make that much of a difference, especially on a car like the EB which likely has some pretty good low end torque anyway.

IMO a taller gear is probably fine unless you plan on racing or really, really, want that tiny bit of extra acceleration.

Look at the results from that linked article. They went through a wide range of gears and it didn't even make a 1 MPH difference in the trap speed and a only a 0.5 second difference in the ET (and with the high stall converter the difference was only 0.25 seconds).

I don't think going to a taller gear would make much of a difference on the street, except for a few specific cases.

-T

 

[DivineStrike]

I have NEVER EVER seen a petrol car cruise at interstate speeds w/ positive manifold pressure, much less 71 mph as you stated.

Can you provide specifics on the vehicle? Heck, I'd like to see a video of it too, if you could...

I'm just telling you what i've observed. You can choose to believe me or not, I could really care less. You can use 71 mph all you want but when i use a generalization such as 70 or below and I mainly reference 75 or 80. Then I'm pretty sure I have never stated 71 mph. Just saying.

 

[scottpe]

Look at the results from that linked article. They went through a wide range of gears and it didn't even make a 1 MPH difference in the trap speed and a only a 0.5 second difference in the ET (and with the high stall converter the difference was only 0.25 seconds).

In drag racing, .5 seconds is a pretty good whipping.

I don't think going to a taller gear would make much of a difference on the street, except for a few specific cases.

In my experience, steeper gearing makes the throttle more responsive in all gears, and actually make 5th/6th gears more usable in the city (at least where I live).

But again, steeper gears do usually cost some fuel efficiency, especially on the highway. For someone that races very little and drives a lot, taller gears would probably be a better choice for the fuel cost savings alone.

 

[Trackaholic]

In drag racing, .5 seconds is a pretty good whipping.

Yeah, I wasn't very clear. I was trying to emphasize that the rear end ratio may be important for drag racing, but isn't as important for the street because you have several ratios to choose from.

-T

 

[Grimace427]

Gearing is mostly pointless for the street, IMO.

It really only matters for the 1/4 mile, where you want a balance that will give you a good launch yet still allow you to finish at the top of whatever gear you would be in (probably 4th).

For example, for the GT PP with 3.73 gears, you'd get a very good launch, and 4th tops out at 116 MPH @ 6900 RPM. That might be just about perfect for the car in its stock condition. Guessing from the power/weight, 116 in the 1/4 seems reasonable.

With the non-PP and 3.55 gears, 4th tops out at 120. If you start modding your car, this might be a better choice, because it gives you a few more MPH at the end of the 1/4 before running out of RPM.

On the street though, a 1st gear launch is less critical, and you don't need to worry too much about the top end because if you want to accelerate hard you can just downshift. Yes, a shorter gear will give you more time in the power band, but if you aren't really racing it's not going to make that much of a difference, especially on a car like the EB which likely has some pretty good low end torque anyway.

IMO a taller gear is probably fine unless you plan on racing or really, really, want that tiny bit of extra acceleration.

Look at the results from that linked article. They went through a wide range of gears and it didn't even make a 1 MPH difference in the trap speed and a only a 0.5 second difference in the ET (and with the high stall converter the difference was only 0.25 seconds).

I don't think going to a taller gear would make much of a difference on the street, except for a few specific cases.

-T

For the most part I agree with your post here. For the highlighted part this was something I experienced first hand but want to clarify something. You mention the 3.73 gears topping out at 116mph and that if you plan on modding you might be better off with 3.55 gears that top out at 120mph. One issue here is that once you start modding you can both raise the redline RPM and/or mount taller drag tires both of which will up your trap speeds and have your car cross the finish at peak horsepower. Adding taller rear gears will lower your trap rpm's possibly costing you some ET and MPH.

 

[Old 5 Oh]

One issue here is that once you start modding you can both raise the redline RPM and/or mount taller drag tires both of which will up your trap speeds and have your car cross the finish at peak horsepower. Adding taller rear gears will lower your trap rpm's possibly costing you some ET and MPH.

Logic error here. The effects of taller rear tires on overall gearing are the same as the effect of taller rear gears. While you might not want to do both at once, both will indeed have the effect of lowering your RPM at the end of the 1/4 mile. As you increase power, that's important because additional power will accelerate the car faster, to a higher trap speed.

Usually, what you will want is to have that combination of tire height and rear gears that gets to the traps right at the top of 4th gear. If you have to shift to 5th, that costs E.T. So counter-intuitively, the higher gear can improve the E.T. if it saves a shift. I believe that's what was being said above in suggesting that a modded car with a 120 mph trap speed would benefit from 3.55s versus 3.73s.

On the street, no one cares about times. The low gears will add responsiveness and will make 5th and 6th more usable around town. That is often a good thing. But for some of us, the fuel economy difference is a big deal. I estimate that the 3.15s I ordered will save me about $750 a year in fuel versus 3.73s, which is enough for me to care about.

 

[DivineStrike]

I would prefer 3.55's but I wanted the PP more w/ the Torsen. If I want to later I can just swap in a 3.55

 

[Grimace427]

Logic error here. The effects of taller rear tires on overall gearing are the same as the effect of taller rear gears. While you might not want to do both at once, both will indeed have the effect of lowering your RPM at the end of the 1/4 mile. As you increase power, that's important because additional power will accelerate the car faster, to a higher trap speed.

Usually, what you will want is to have that combination of tire height and rear gears that gets to the traps right at the top of 4th gear. If you have to shift to 5th, that costs E.T. So counter-intuitively, the higher gear can improve the E.T. if it saves a shift. I believe that's what was being said above in suggesting that a modded car with a 120 mph trap speed would benefit from 3.55s versus 3.73s.

There is no logic error there. I am quite aware of the effects of taller tires being similar to taller gears. What is easier to change, tires or rear gear ratios? If 3.73 gears are just borderline for stock then modding the car then installing slightly taller drag tires is far easier than changing gear ratios especially if raising redline RPM's.

People don't buy cars with specific trap speeds in mind for the 1/4 mile, they mod then adjust accordingly. With the high-RPM capabilities of the Coyote it is better to take advantage of that with aggressive gear ratios combined with engine breathing than keeping RPM's low with tall gear ratios.

Let me be more specific:

1. Trap speed with 3.73 gears, 27.7" tires(stock PP), 7,000rpm redline: 117mph.
2. Trap speed with 3.55 gears, 27.7" tires(stock PP), 7,000rpm redline: 123mph
3. Trap speed with 3.73 gears, 28"(275/60/15 MT drag radials)tires, 7,500rpm redline: 127mph

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