holy hell, 25MPG!!

[accidentprone86]

I just switched to 3:73s and put some underdrives on.
OK so the low gas light was on, i put 20 dollers in at 2.37 dollars a gallon
I drove 212 miles before the low gas light came on again.
DO the math!! thats 25 miles per gallon!!And 100 of those miles were cruzing at 70 on the highway.

Maybe i am going crazy. I was expecting a slight increase in milage in the city and a slight decrase on the highway but Damn i wasnt expecting this. Befor the gears I averaged 18 miles per gallon. Thats a 7 mpg Increase!!!

 

[larrendeuce]

I noticed my mileage go up as well with 3.73's from 2.73's. I used to go about 220 per tank before it was in the red on Empty. Now I can go almost 300. I got 19 miles to the gallon with 2 runs at the strip. I fill it up and drive, then when I fill up again I use the gallons added as measure for gallons used, then I calculate the mileage.

 

[HISSIN50]

Report back after some more driving. The fuel light is about as accurate as the fuel gauge IMHO.

 

[carbed87]

yeah, that AND it pulls like a mofo, i rode in it. good job jeremy

 

[giddyup306]

Report back after some more driving. The fuel light is about as accurate as the fuel gauge IMHO.

Ditto. The only accurate way to calculate fuel economy is to record the mileage and gallons between fill ups. I always run my tank till near empty and then fill up and reset my trip meter.....

 

[KB5.0GT]

god I would kill for 25 mpg, i just got gears and I seem to think my gas milage will go up a little due to staying in 5th pretty much everywhere.

 

[Daniel50]

damn i get about 15mpg but i drive it hard as hell

 

[stang0f87]

accidentprone86 that is impressive mileage your gettin. Like how many RPMs are u pullin at 70 mph?

 

[mustangGT85]

the way i manage my fuel consumtion is to top it off, and reset the trip odometer. drive it for how ever long, then go top it off again. write down the amount of gallons put into the car(until it topped off) then divide the gallons per miles driven or somethinglike that. if i drove 35 miles and put in 1.25 gallons of fuel, thats roughly 28mpg. right?


~Steve

 

[Michael Yount]

You didn't calculate your fuel mileage, the way you're trying to figure it has the potential to be very inaccurate because the light and gauge aren't always accurate.

Top it off, zero the tripmeter, drive it til it's time to re-fill, keep track of the number of gallons to fill it and divide that number of gallons into the mileage you covered with it (trip meter reading). Then report back to us. And if you drive it the same way, I'd EXPECT a slight mileage improvement around town with a change from 2.73 to 3.73 gears.

 

[85mcLaren]

You have to learn how to control the gas pedal with 2.73s. I got 27 mpg with my stock 86 capri the other day driving at 70 mph. The rpms were now in the cam range and power range. I have gotten near 30 with my 85. When in the city. It is better to drive in fourth than fifth since the further your gas pedal goes down by using 5th, the more gas you are going to 'suck.' Just takes some use to knowing when to downshift and not put the pedal to the floor in the upper gears.

 

[ninety15.0]

I have a quick question...did u change out the speedo gear...because that could be the difference right there. I noticed a decent change in MPG when i went to 3.73's too but it went from about 14 to 16-17....and on the highway i went down from about 24-26 to 20-22. the gears help out a lot in town to get the car up to traffic speed with minimal gas pedal movement...but the rpm on the highway is just too high to be efficient.

 

[vristang]

You have to learn how to control the gas pedal with 2.73s. I got 27 mpg with my stock 86 capri the other day driving at 70 mph. The rpms were now in the cam range and power range. I have gotten near 30 with my 85. When in the city. It is better to drive in fourth than fifth since the further your gas pedal goes down by using 5th, the more gas you are going to 'suck.' Just takes some use to knowing when to downshift and not put the pedal to the floor in the upper gears.

There will be a huge difference here when comparing carb to EFI

The computer will not enrichen the mixture until about 85% of WOT usually (don't remember what it was for the stangs). Sometimes you can actually feel the WOT triggering.

Most carbs will continuosly enrichen as the throttle travels down.

So at 75% of WOT an efi car should be running leaner than a carb. This would mean that there may be less efficiency benefits to running taller gears with efi. I am ssuming similar tunes on similar motors.

Does anyones experience contradict this?

 

[accidentprone86]

I have a quick question...did u change out the speedo gear...because that could be the difference right there. I noticed a decent change in MPG when i went to 3.73's too but it went from about 14 to 16-17....and on the highway i went down from about 24-26 to 20-22. the gears help out a lot in town to get the car up to traffic speed with minimal gas pedal movement...but the rpm on the highway is just too high to be efficient.

OOOOPPSS
Yeah no i didnt, that is the reason right their isnt it. it is still stock i havnt got around to changing it.
It was kinda weird seeing the speedo at like 90-100mph driving on the highway, i know i was never going faster then 85.
DAmn how could i over look that with such little regard.

 

[sodaking663rd]

you also have to remember that just changing the plastic tooth gear is not very accurate...your speeds are actually showing higher than they really are meaning that it is also showing that you've gone farther than you really have.

 

[TheUser]

I have a quick question...did u change out the speedo gear...because that could be the difference right there. I noticed a decent change in MPG when i went to 3.73's too but it went from about 14 to 16-17....and on the highway i went down from about 24-26 to 20-22. the gears help out a lot in town to get the car up to traffic speed with minimal gas pedal movement...but the rpm on the highway is just too high to be efficient.

I was reading down through this thread wondering when someone would think of that! That was my first instinct. Good catch ninety

Yeah, I think my GT reads about 10-15mph over what I'm actually doing, more than that once you get over 100, I'm sure. I replaced the speedo gear w/ a 3.73 unit from Jeep (supposed to be stronger), and mine is still off - but that could be installation error or something....I really need to look at it sometime, but since I've driven the car maybe 2 or 3 times this year, not too worried about it

 

[90mustangGT]

I would have to second your OOPS there accidentprone86, that would make a difference.

These cars do get damn good gas milege. A foxbody 5.0 EFI 5-speed and you have a gas sipping machine. My Thumper headed B cammed combo got about 240-250miles per tank. Not bad for a V8 performance car. Now my old Ford Escort GT 1.8DOHC with a 5 speed got me from North Atlanta to Clearwater FL on one tank, about 13 gallons cruising at 80-900mph the whole way. Which that was "back in the day" when premium gas was only $1.30 a gallon.

 

[aaros]

im geting 26-27 mpg on road trips where i can keep it at around 70.

 

[Michael Yount]

Simple ratios - so if you didn't fix the speedo with the gear change your 212 miles would be 212/(3.73/2.73) = 155 miles.

Assuming you used 8.4 gallons (which you didn't -- we don't know how much you actually used to cover the 212 miles 'cause you have to fill up AFTER you read the mileage) your 25 mpg just became 18.5 mpg.

 

[ninety15.0]

Simple mistake....i had forgotten a few times before i changed the speedo gear and thought for a few seconds that i was getting like 30 mpg...haha