Gears and mileage
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From: South Kitsap County, WA
Gears and mileage
In many of of our threads including a current one, here in the '97-'03 forum, the question has been posed about gear swaps - going with a lower gear for better towing performance.
I don't discount the increase in capability when a lower gear is swapped in, but we have issues concerning how fuel mileage is affected. I want to see real world numbers before and after a swap. Ideally all other things stay the same...
So post your truck (year, engine, drive, tranny type, daily driver or tow specific, mileage, and mpg) all before the gear swap, then give the mpg after the swap and which gear set you went with... also comment if your truck is still seeing the same duty type as before. If you added other things at the swap - like a tuner, exhaust, brushguard, etc... that information would be helpful as well.
Thanks for your posts and information.
-Kerry
I don't discount the increase in capability when a lower gear is swapped in, but we have issues concerning how fuel mileage is affected. I want to see real world numbers before and after a swap. Ideally all other things stay the same...
So post your truck (year, engine, drive, tranny type, daily driver or tow specific, mileage, and mpg) all before the gear swap, then give the mpg after the swap and which gear set you went with... also comment if your truck is still seeing the same duty type as before. If you added other things at the swap - like a tuner, exhaust, brushguard, etc... that information would be helpful as well.
Thanks for your posts and information.
-Kerry
Last edited by kspilkinton; Nov 5, 2006 at 02:31 PM.
Post Fiend
Joined: Aug 2006
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From: Yorkton Sask
not a swap but a comparison, i had a 96 f150 with the l6, 3.08 gears, e40d, 2wd, got consistantly 16-18mpg city, 20-22 highway. an aquaintance had basically the same truck with less miles, 4.10 gears, 5 speed trans, and he's lucky to get 16 on the highway. before anyone jumps on me, the numbers are in canadian mpg...usually a little higher than american...
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From: South Kitsap County, WA
Glad to here from ya, Sherm.
It would be nice if we had a direct swap, though, as it would be the same vehicle with the driver... and hopefully the same habits. More of an apples to apples comparo.
I was beginning to wonder if anyone had any insight... making Jimmy and I look rather foolish here - as we were trying to get interaction so we can give those wanting to do the swap (Jimmy - LxMan1 - is one of the peeps wanting to do a swap, BTW) a better feel on what to expect.
-Kerry
It would be nice if we had a direct swap, though, as it would be the same vehicle with the driver... and hopefully the same habits. More of an apples to apples comparo.
I was beginning to wonder if anyone had any insight... making Jimmy and I look rather foolish here - as we were trying to get interaction so we can give those wanting to do the swap (Jimmy - LxMan1 - is one of the peeps wanting to do a swap, BTW) a better feel on what to expect.
-Kerry
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Joined: Apr 2006
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From: city of angels
'86 FSB 5.0 xlt that had 200+k on the O.G. motor...turning 33's on 15's with 4.10s...she got 9-10mpg highway...and actually - shes never gotten better than 10mpg - even with smaller 31's when she only had 110k on the motor (when i first bought her)
now - shes got 4.56s and over 230+k on the same motor (turning the same 33/15 setup) - and on the last trip out she got 15mpg highway...NO S*##!! i swear - i couldnt believe it myself - but its true.
drj
now - shes got 4.56s and over 230+k on the same motor (turning the same 33/15 setup) - and on the last trip out she got 15mpg highway...NO S*##!! i swear - i couldnt believe it myself - but its true.
drj
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Joined: Mar 2005
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From: Wichita
It wasn't a dramatic swap, but I changed for 3.55 to 3.73 and didn't notice any drop in mileage. Driving habits stayed the same and nothing was added during the swap. I have an SCT chip that Ken programmed, an intake and catback exhaust on the truck, and get about 17 mpg with a mix of city and highway driving each day.
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From: city of angels
lets try to include year - model - motor size - odo.mileage - wheel & tire setups...and any mods if relevant (if you havent already)...
drj
drj
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Mods in signature...
Before (stock, 3.31 gears): 14mpg
Add supercharger.
3.31 gears: 10 - 12mpg
4.10 gears: 10 - 12 mpg
Mostly in-town driving in all instances.
I have gotten 14mpg on in mostly highway driving with the 4.10s and supercharger (really babying it, driving very slowly). What a waste of a tank of gas!
At fast highway speeds (80+), I think I'd suffer a bit more with the 4.10s.
But like I said, I'm mostly in-town.
Before (stock, 3.31 gears): 14mpg
Add supercharger.
3.31 gears: 10 - 12mpg
4.10 gears: 10 - 12 mpg
Mostly in-town driving in all instances.
I have gotten 14mpg on in mostly highway driving with the 4.10s and supercharger (really babying it, driving very slowly). What a waste of a tank of gas!
At fast highway speeds (80+), I think I'd suffer a bit more with the 4.10s.
But like I said, I'm mostly in-town.
Last edited by pronstar; Nov 9, 2006 at 09:21 PM.
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No gear swap here, but a big tire size change which effectively lowered my gear ratio to about 3.05. I have a 2001 Ford F-150 SuperCab 4x4 with 5.4. Stock I got 13mpg mostly city. I added a 6inch Fabtech Suspension lift and add-a-leaf in rear with 35 inch Mickey Thompson Baja Claw tires on 16X10 M/T Classic II rims. After those mods I went upto 14mpg, thats an increase of 1 mpg (yes, I corrected mathematically for the increased tire size). Then I purchased a SuperChips Programmer and I run the 87 octane setting and Superchips shift points with my tire size properly programmed for my 35 inch tires. I now average 15mpg. Highway I average 19-20mpg if I keep it between 65 and 70mph. If I go 75mph it drops to 16.5-17mpg. If I do 80 I get closer to 18mpg. If I do 80-85mph I get 16mpg. I usually don't take it faster than that, but one time I did 90mph (emergency) for 25 miles and averaged 15.6mpg. All of these numbers are legitimate, believe it or not.
And for those of you who are curious, it turns 1650RPMs at 70mph.
And for those of you who are curious, it turns 1650RPMs at 70mph.
Last edited by STLBluesRams34; Nov 22, 2006 at 01:13 PM. Reason: Additional Information
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From: South Kitsap County, WA
That makes sense for highway driving... the effective ratio being smaller with the larger tires and also driving for long distances. Now if you said all of it was city driving, that would be suspect.
When I drive at 50-55 for long distances by myself, or draft at 70 behind trailers or large motorhomes, I get the better mileage - around 17mpg. When I do 70 alone, then I get 15. That's with the stock 3.73s and stock height tires (29.6").
They have VVT in the 3V motors, why couldn't they have variable gearing in the rears for long distance driving? Larger trucks use different speed diffs. Just a thought.
-Kerry
When I drive at 50-55 for long distances by myself, or draft at 70 behind trailers or large motorhomes, I get the better mileage - around 17mpg. When I do 70 alone, then I get 15. That's with the stock 3.73s and stock height tires (29.6").
They have VVT in the 3V motors, why couldn't they have variable gearing in the rears for long distance driving? Larger trucks use different speed diffs. Just a thought.-Kerry
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From: San Diego, CA
San Diego CA, 97 F150 5.4L 4x4 E4OD 265/75/R16 Michelins 4.56's/55mph/OD/2300rpm 102,000mi
3.55 gears, towing heavy horse trailer 8-9mpg, empty city driving 11-12mpg
4.56 gears, towing heavy horse trailer 9-10mpg, empty city driving 12-13mpg
Terrific improvement in towing power. Never took a road trip with 3.55 gears but recently drove a 200mi and 300mi round trip (no trailer) with 4.56's, all freeway with cruise on 65, avg 15mpg both trips. The cam and headers were done 2 years after the gears and improved the power 40-50hp on the dyno but the mpg has stayed the same??? Go figure.
3.55 gears, towing heavy horse trailer 8-9mpg, empty city driving 11-12mpg
4.56 gears, towing heavy horse trailer 9-10mpg, empty city driving 12-13mpg
Terrific improvement in towing power. Never took a road trip with 3.55 gears but recently drove a 200mi and 300mi round trip (no trailer) with 4.56's, all freeway with cruise on 65, avg 15mpg both trips. The cam and headers were done 2 years after the gears and improved the power 40-50hp on the dyno but the mpg has stayed the same??? Go figure.
Last edited by Fasterhorses; Nov 23, 2006 at 02:26 PM.
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Getting ready to install 4.56s on my 02 FX4...5.4L, stock 3.55s with 35" tires and a lift! Question...Ive heard this mentioned once on here about a year ago...is there a "limited slip additive" that you are suppost add after the gear change is done and youve added all your fluids back in??? Thanks...
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From: San Diego, CA
Originally Posted by stang3O2
Getting ready to install 4.56s on my 02 FX4...5.4L, stock 3.55s with 35" tires and a lift! Question...Ive heard this mentioned once on here about a year ago...is there a "limited slip additive" that you are suppost add after the gear change is done and youve added all your fluids back in??? Thanks...