MPG and gear change question
#1
MPG and gear change question
Question, whats gonna happen to my mileage when I change my gears to 4.10 from 3.73. Right now, I am only getting like 20 mpg on the highway and the truck really feels like it is boggin. I think I am having to use more gas to keep it going lets say at 70 than I did. So, will my mpg go up when I change to 4.10 or go even more down?
#2
#4
Swap in a rear end that already has it. I'm talking to a guy about it.
If I am in a good head wind, it is 4th gear most of the way.
Over winter break, I tuned the truck up. All new plugs, timing belt, timing belt tensioner, water pump, air filter, changed oil, new radiator fluid, cant think of what else.
I was just wondering in general if the mileage should go up or down more.
If I am in a good head wind, it is 4th gear most of the way.
Over winter break, I tuned the truck up. All new plugs, timing belt, timing belt tensioner, water pump, air filter, changed oil, new radiator fluid, cant think of what else.
I was just wondering in general if the mileage should go up or down more.
#7
#11
Are you sure you're calculating it correctly? With 31" tires (stock is about 27.5") your speedometer,
odometer are going to read about 13% slow. That is when the odometer says you have traveled 100 miles.
You have actually traveled 113. Using that as a basis, if your odometer says you have traveled 100 miles
and you use 5 gals, that would indicate your getting 20 MPG.
However if you have actually traveled 113 and use 5 gals, your mileage would be about 23. Pretty close.
Easiest way to find out, is to check your odometer against the mile markers on the hwys. Pref an interstate.
odometer are going to read about 13% slow. That is when the odometer says you have traveled 100 miles.
You have actually traveled 113. Using that as a basis, if your odometer says you have traveled 100 miles
and you use 5 gals, that would indicate your getting 20 MPG.
However if you have actually traveled 113 and use 5 gals, your mileage would be about 23. Pretty close.
Easiest way to find out, is to check your odometer against the mile markers on the hwys. Pref an interstate.
Last edited by MemphisSenior; 03-01-2009 at 11:42 PM.
#12
Top speed would be about the same. Lower gearing would be offset by the
larger diameter of the tires. If the tire size remained stock, then you would lose
top speed because you would reach max RPM at a slower speed.
#13
#14
I've spent a lot of time in the last 6 months studying MPG at 70mph. (I have a FX4 w/4.10s)
What you need to look at more than anything is "load". Reducing load will gain you the most mpg.
Things like headwind, height off the ground, dragging brakes, being behind another car/truck, ambient temps, rpms, & timing (vs the octane used) all play a part in "load".
As load goes up.. timing goes down & fuel gets added.
Just going from 3.73s to 4.10s alone will do two things at 70mph. Load will go down.. and rpms will go up. So your gaining in one area and loosing in another.
IMO.. adjusting the timing VIA a tune would give you more feeling of power than the gear swap would.
What you need to look at more than anything is "load". Reducing load will gain you the most mpg.
Things like headwind, height off the ground, dragging brakes, being behind another car/truck, ambient temps, rpms, & timing (vs the octane used) all play a part in "load".
As load goes up.. timing goes down & fuel gets added.
Just going from 3.73s to 4.10s alone will do two things at 70mph. Load will go down.. and rpms will go up. So your gaining in one area and loosing in another.
IMO.. adjusting the timing VIA a tune would give you more feeling of power than the gear swap would.
#16
I think you'll pick up some mileage swapping to 4.10 gears. It won't be as good as stock, but it will help.
Hell a lot of the 4 cyl rangers come with 4.10's from the factory with 225's or whatever, you could probably afford to swap to 4.30's with 31's.
My Jetta (6 speed vr6) runs high rpm's on the highway (around 3000rpm at 70mph), but gets 28-30mpg at that speed. Sure, the rpm's are high, but it requires little throttle (little load).
Hell a lot of the 4 cyl rangers come with 4.10's from the factory with 225's or whatever, you could probably afford to swap to 4.30's with 31's.
My Jetta (6 speed vr6) runs high rpm's on the highway (around 3000rpm at 70mph), but gets 28-30mpg at that speed. Sure, the rpm's are high, but it requires little throttle (little load).
#18
I have a 05 ranger with the 4:10 gears. They came with the truck from day one. I get terrible mileage usually... sometime if I drive really really nice I get 17 combined. The truck does feel like it has more power with them. But if I was not going to get teh truck brand new for 16k (whicha t the time it was a really good deal).... I would have ordered the truck with teh 3.73, I believe the fuel economy would have been better.
Also I noticed with the 4:10 my truck wants to roast the tires if its any bit wet out... but im not gear head... just seems like it to me compared to the old f150 1992 I had with the 373 and a standard... I have an auto now.
Also I noticed with the 4:10 my truck wants to roast the tires if its any bit wet out... but im not gear head... just seems like it to me compared to the old f150 1992 I had with the 373 and a standard... I have an auto now.
#19
I have a 05 ranger with the 4:10 gears. They came with the truck from day one. I get terrible mileage usually... sometime if I drive really really nice I get 17 combined. The truck does feel like it has more power with them. But if I was not going to get teh truck brand new for 16k (whicha t the time it was a really good deal).... I would have ordered the truck with teh 3.73, I believe the fuel economy would have been better.
Also I noticed with the 4:10 my truck wants to roast the tires if its any bit wet out... but im not gear head... just seems like it to me compared to the old f150 1992 I had with the 373 and a standard... I have an auto now.
Also I noticed with the 4:10 my truck wants to roast the tires if its any bit wet out... but im not gear head... just seems like it to me compared to the old f150 1992 I had with the 373 and a standard... I have an auto now.
#20
I have a 05 ranger with the 4:10 gears. They came with the truck from day one. I get terrible mileage usually... sometime if I drive really really nice I get 17 combined. The truck does feel like it has more power with them. But if I was not going to get teh truck brand new for 16k (whicha t the time it was a really good deal).... I would have ordered the truck with teh 3.73, I believe the fuel economy would have been better.
Also I noticed with the 4:10 my truck wants to roast the tires if its any bit wet out... but im not gear head... just seems like it to me compared to the old f150 1992 I had with the 373 and a standard... I have an auto now.
Also I noticed with the 4:10 my truck wants to roast the tires if its any bit wet out... but im not gear head... just seems like it to me compared to the old f150 1992 I had with the 373 and a standard... I have an auto now.
Even the new 4.0L engines can be slugs with 4x4 and 3.73 gears, especially if you're towing or hauling (it is a truck after all).
The SOHC 4.0L doesn't have as much low end as the older OHV 4.0L, but it revs much higher and smoother, and makes more top end power, which is why the 4.10's work well with it.
I got 18 mpg on the highway a few times with the sport trac in stock condition with 4.10's and 255/70/16's.
#22
I just need to find what I am looking for in the junkyard still. I go every chance I get.
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