Squeezing a few more mpg out of a mustang gt

[UltArc]

Originally Posted by gk_ghig14

Picked up some new wheels and tires yesterday which dropped a few more pounds of rotational mass, and the new tires are larger in diameter and stated to have lrr technology by Yokohama. And due to the offset of the wheels, I'd say 98% of the wheel/tire combo is tucked in behind the body work

Also should be getting my vehicle specific tunes within the next 5 days, so I'll be installing the fuel economy tune in hopes of squeezing out 1-2 more mpg in combo with the new wheels and tires

Will also be doing a grille block. Zip ties are cheap enough that I can do it on the outside for Monday-Thursday then take it off for Friday night car meets

I spend some time over at Mustang Evolution and Insight Central, and the opinion I have formed is that ECO modes aren't always the best for economy, and PERFORMANCE tunes often help fuel economy.

In Mustangs, people on the forum often just drive the same. They put the tune on, and nothing else changes- maybe they have more fun. Of course there is ZERO testing done whatsoever, but many people note it. True, this is not a fact or established empirically, but often the only difference people notice is more miles per gallon/tank, and improved performance.

People who actively and carefully drive Insights (gen 2s), often mention they get better mileage when driving in Sport mode rather than eco. I think about how the majority of people drive an eco minded car- Prii, Insights, so on. They drive it like an ON/OFF switch, and just think it will get great mileage because they bought that car. So smashing down the pedal in Performance mode vs Eco mode will most likely show better mileage in Eco, but I imagine whatever is done to the computer will help the overall performance (read: more efficient) in Sport mode if driven appropriately.

I am not saying that the fuel economy tune is bad, or to get the most aggressive racing tune, but just offering my experience on why it may be a good idea to try different tunes, and maybe do some testing for the rest of us

[American Viking]

Originally Posted by gk_ghig14

I apologize if this is in the wrong section

I'm attempting to squeeze out a few more mpg from my 2014 mustang gt. I know it sounds weird but coming from 2 trucks, my mind can't comprehend getting less than 320ish miles a tank. Currently I'm getting between 17 and 19 mpg but would like 21 mpg minimum(16 gallon tank)

What I have done so far:
1. Lighter wheels. Dropped about 12-20 pounds rotational mass however the back wheels and tires are now wider(planning on ordering smaller back wheels)
2. Limited my top speed to 80 with the ford my key(speed limits are 75 so no going 55-60 here)
3. Tried 93 octane instead of 87(noticed no difference)

What I am considering doing:
Front splitter
Partial underbelly tray
Grill overlays(cover up the fog lights slightly)
Lowering springs

Any tips or other suggestions as far as my plans go?

Hey I had a GT (a 96) as recently as 2012 and will again, so I get you.
There are plenty of things you can do to help with your mileage.
1. Change the rear end gears. I don't know what ratio you have in the rear end because they differ between the Automatic and the manual - And there are optional rear ratios for both. If you have a manual trans get the 3.15 gears from an automatic, if you have an automatic get a set of 2.73's from either ford parts or a junk yard. You will need an ecm reflash to correct the speedometer for the gear changes, but that will bring down the cruising rpm.
2. Get the lightweight aluminum driveshaft, it can handle pretty much anything your throwing at the car right now and the reduced mass will help with coasting.
3. The lowering springs WILL help with mpg, because there will be less turbulent air under the car and less turbulent air coming from the wheel-well openings.
4. If you have a tire pressure monitoring system, ditch the spare, carry plugs, a small compressor (the slime one is great) and a can of slime foam instead.
5. If you got a gt with a manual, when the clutch needs attention, swap it out and install a lightweight flywheel, the factory flywheel on my GT weighed 27 lbs. The aluminum one with Steel friction facings was only 17lbs. Less wasted energy overcoming inertia.
6. lightweight pulleys on the front engine accessory drive. Standard but lighter weight (or no more than 5% underdrive pulleys) or you will have charging issues.
7. Replace that mechanical pump with an electric pump (meziere used to make them with a idler pulley on the outside of the pump case so you did not have to change the belt arrangement).
8. This will sound odd, but get a good set of High power heavy duty coils. Ford COP coils have a terrible reputation. Replacing them a top aftermarket brand will help make sure that combustion starts when it supposed to and that it then is as complete as you could hope for when the exhaust valve opens.
9. Get a good ECU reflash, Ford left plenty of efficiency on the table when they authored the programming in your car in exchange for 100K mile emissions certification.

That should let you get back more than just a couple of MPG.

[gk_ghig14]

Originally Posted by American Viking

Hey I had a GT (a 96) as recently as 2012 and will again, so I get you.
There are plenty of things you can do to help with your mileage.
1. Change the rear end gears. I don't know what ratio you have in the rear end because they differ between the Automatic and the manual - And there are optional rear ratios for both. If you have a manual trans get the 3.15 gears from an automatic, if you have an automatic get a set of 2.73's from either ford parts or a junk yard. You will need an ecm reflash to correct the speedometer for the gear changes, but that will bring down the cruising rpm.
2. Get the lightweight aluminum driveshaft, it can handle pretty much anything your throwing at the car right now and the reduced mass will help with coasting.
3. The lowering springs WILL help with mpg, because there will be less turbulent air under the car and less turbulent air coming from the wheel-well openings.
4. If you have a tire pressure monitoring system, ditch the spare, carry plugs, a small compressor (the slime one is great) and a can of slime foam instead.
5. If you got a gt with a manual, when the clutch needs attention, swap it out and install a lightweight flywheel, the factory flywheel on my GT weighed 27 lbs. The aluminum one with Steel friction facings was only 17lbs. Less wasted energy overcoming inertia.
6. lightweight pulleys on the front engine accessory drive. Standard but lighter weight (or no more than 5% underdrive pulleys) or you will have charging issues.
7. Replace that mechanical pump with an electric pump (meziere used to make them with a idler pulley on the outside of the pump case so you did not have to change the belt arrangement).
8. This will sound odd, but get a good set of High power heavy duty coils. Ford COP coils have a terrible reputation. Replacing them a top aftermarket brand will help make sure that combustion starts when it supposed to and that it then is as complete as you could hope for when the exhaust valve opens.
9. Get a good ECU reflash, Ford left plenty of efficiency on the table when they authored the programming in your car in exchange for 100K mile emissions certification.

That should let you get back more than just a couple of MPG.

1. Next highest gear is 2.73 out of the v6 but would easily cost $800 after parts and labor. Not really worth it

2. Another high dollar option, not really worth it at this moment

3. I'll probably get some eventually since it'll also help with my appearance

4. Spare is already out

5. Mine is automatic

6. Nobody makes UD pullies for the new 5.0

7. E water pump is over $1,000. Not worth it

8. I've actually heard the exact opposite on that. People always say coils are waste of money

9. Already have some on the way

[gk_ghig14]

Originally Posted by UltArc

I spend some time over at Mustang Evolution and Insight Central, and the opinion I have formed is that ECO modes aren't always the best for economy, and PERFORMANCE tunes often help fuel economy.

In Mustangs, people on the forum often just drive the same. They put the tune on, and nothing else changes- maybe they have more fun. Of course there is ZERO testing done whatsoever, but many people note it. True, this is not a fact or established empirically, but often the only difference people notice is more miles per gallon/tank, and improved performance.

People who actively and carefully drive Insights (gen 2s), often mention they get better mileage when driving in Sport mode rather than eco. I think about how the majority of people drive an eco minded car- Prii, Insights, so on. They drive it like an ON/OFF switch, and just think it will get great mileage because they bought that car. So smashing down the pedal in Performance mode vs Eco mode will most likely show better mileage in Eco, but I imagine whatever is done to the computer will help the overall performance (read: more efficient) in Sport mode if driven appropriately.

I am not saying that the fuel economy tune is bad, or to get the most aggressive racing tune, but just offering my experience on why it may be a good idea to try different tunes, and maybe do some testing for the rest of us

Yeah I've read the same thing too. I have 3 tunes coming; the fuel economy 87 octane, a performance 87 octane, then a performance 93 octane with harsh shift that will be strictly racing usage. I figured I'd start with the fuel economy since it may have earlier converter lockup, then test out the performance 87 and see if anything changes. After that I'll stick with whichever works best

I wish I knew how to tune that way I could set a super lean AFR for fuel economy while sacrificing some power. I mean I already run 12.8@110 so a 13.0 wouldn't hurt much

[UltArc]

Originally Posted by gk_ghig14

Yeah I've read the same thing too. I have 3 tunes coming; the fuel economy 87 octane, a performance 87 octane, then a performance 93 octane with harsh shift that will be strictly racing usage. I figured I'd start with the fuel economy since it may have earlier converter lockup, then test out the performance 87 and see if anything changes. After that I'll stick with whichever works best

I wish I knew how to tune that way I could set a super lean AFR for fuel economy while sacrificing some power. I mean I already run 12.8@110 so a 13.0 wouldn't hurt much

That would be nice, I would like to have that talent, too. I look forward to seeing your results.

[gk_ghig14]

This tuner is supposedly really good about working with clients so I'm gonna have him formulate the economy tune to be as lean as safely possible, while also adding tons of torque converter lock up

But I'll be data logging the original tunes to see what the difference is between his fuel economy and performance tunes(timing, afr, converter lockup,etc)

[ECONORAM]

Originally Posted by jeff88

I can see why you got no improvement in MPG for the higher octane fuel. Unless your engine requires it, nothing changes to the FE. Higher octane doesn't mean higher energy content.

Good luck and have fun!

Do you have a tuner? I am not surprised you saw no change, as the engine tune was the same. I run a Superchips 91octane tune in my truck. It was worth 1-1.5mpg, and 20hp.
[edit] just saw the last post. I don't think you'll see any mpg with the 87 performance tune, but it should have better drivability than stock. If you have a plastic intake manifold like I do, and an electronic throttle, I suggest you install a ground wire from the throttle body to the car body. It helped the wife's car, which has both (my truck has an "older style" cable throttle)--reduced offline hesitation. HEMI guys report good results (they are electronic throttle).
[edit2] I like my ATI under drive; it's 25% so that might be a bit much for you.

[gk_ghig14]

This mpg saving is gonna be hard with this new tune. The throttle is super touchy now, almost like an on/off switch. Hopefully the economy tune is less sensitive than the current performance

[gk_ghig14]

Well I was gonna make grille blocks with acrylic sheet but it's taking forever to cut, so I'm just gonna use black foam board

Also I loaded my economy tune and the throttle seems to be back to stock level. However it's a rich tune(14.7 afr) so I'm gonna see if he can lean it out more

[Arragonis]

Correx (aka Corroplast) is better. Sign places usually have offcuts you can pick up for pennies, or recycle signs from houses for sale or local elections - sprayed to your taste. Can be cut with scissors and secured with tape or plastic ties.

EDIT - It is cheap new too, I got 5 sheets of 1mx1m (3ftx3ft) for under £20 from Amazon.