I get 24-26 on the highway and about 16 in town now, what is my approximate MPG with 4.10's? someone said i could gain MPG in the city from 4.10's? please explain that!


* didnt buy a mustang for MPG, just wondering

 

20-23 hwy

and depending on what gear you normally drive in vs with 4.10's makes a difference. if you usually use 4th you will now use 5th and your you could be making the same or better MPG, usually about the same.

But thats just my guess.

 

I havent tested mines yet but that sounds nice

 

I drive mostly city (80-90%) and I've had 4.10 gears in for about 800 miles. My city mpg dropped about 2 mpg. I don't really see how 4.10 gears would help mpg at all. I drive the same as I did before.

Stock gears = 21 mpg (mostly city), 4.10 gears = 18-19 mpg

 

4.10's help city driving because gears are a torque multiplier.

The formula to tell you how much torque your gear is putting to the ground is the following: 1st gear X flywheel tq X Final drive gear

Example: 2003 GT puts out (rounding down a tad) 300Lbs of torque and weights around 3300lbs. 1st gear is 3.3:1 and final drive gear is 3.27:1....So..... 3.3 X 300 X 3.27= 3237LBS OF TORQUE... which is alot, but still just a tad under what the weight of the car. So the engine has to push harder to get out of the hole.

Here's what happens with 4.10 gears....

3.3 X 300 X 4.10 = 4059LBS OF TORQUE!! That's much more torque than the weight of the car, hence the reason why it takes much less engine strain to get out of the hole. This also translates into better mpg.

If you're getting worse city mpg, either you have your foot into it more than you realize, there's other underlying issues somewhere else, or your math is off. There's no logical reason why steeper gears would give you worse city mpg.....worse highway, yes......but city no.

Hope this helps.

 

Good thinking but sadly a bit off, that would be more for an electric motor remember a set amount of gas goes into the engine per rpm.The way to save mileage with gears is based on the same idea but you have to skip gears or just be in a different gear.I can still pull off 20 mpg no problem when im cruising on the highway even when going quite a bit over the speed limit.In town before gears I got 16 mpg now I get 14-15 but ive always liked the loud pedal.

 

^^^ripped camel is not off. He is right. Torque multiplication is a function of gears. Torque just straight from the flywheel would not be enough to get the car moving fast enough. His theory is on the right track...the one thing that people don't realize is just because the car weighs an X amount of pounds doesn't mean it takes the same X amount of pounds to get it moving. The car rolls on wheels, or at least I want to think it does...lol...and that is going to reduce the friction that it would normally take than if you were just going to push the car or drag the car with no wheels. Another way to look at it is no human is going to be able to exert that kind of thrust(in his example 3237 lbs of torque) but if you were to put the car in neurtal on a fairly level ground you can push the car within reason...why is this...because the actual torque that would be required to get the car moving has been helped(reduced) by the rolling resistance of the wheels? What we are looking at is a complex calculation to figure the exact torque to get the car moving? There are many factors that go into that equation...tire resistance, whether or not the car is going up hill or down hill, weight of car, wind speed, and the list goes on and on.

I know I am a tad off topic here but I just wanted to say ripped camel is not throwing chit up your ***...he has the right idea and his figures are not out of this world either.

 

what Ehmark was was saying is that your engine does not always make peak torque, which is what ripped camel calculated for.

thats why He mentioned the Electric motor.

But Ripped Camel's math is still correct.

 

Rippedcamel is correct. You will gain MPG with gears especially if you got a good tune at the time. My car is heavily modded with 4.10 gears and my wife's car is lightly modded with stock 3.27 gears. When we drive to Nashville togather she uses more fuel them me.

Ehmark is wrong because while at cruise fuel is delivered according to the maf, tps and ect not the rpms. Rpm only matters in that equation at wot. So the less you need to push the pedal to get moving because of gears the less gas that is used.

 

The mileage difference is almost impossible to figure out since the driving style changes with a different gear. But, if you were to fill up now and set the cruise at 70 and drive it until it runs out and do the same after, you will be within 10 miles of where you ran out the first time. Just get the gears, you can even go much higher and still not see a significant mileage change, 4.56's are fun or better yet 4.88.