Gear ratio to lower engine rpm

[19Walt93]

I currently average 18mpg. Drive very gentle and use torque rather than hp to accelerate. Driving is a balance of 4 lane roads and 2 lane with 10 % on logging roads

If 10% of your driving is on logging roads, you're doing something right. Nothing gets good mileage crawling through ruts in lower gears.

 

[Ranger Dolly]

I recently removed the cap on the box to replace a rusted front crossmember and noticed it does not downshift on hills as much rolling along at 55mph. That indicates to me possibly lower rpm average, so maybe better mpg.

 

[Shran]

Highway gears do not necessarily mean better mileage. My wife's Ranger had 3.27's in it and it topped out at a solid 15mpg. It felt like it had absolutely no power. I swapped some used axles with 3.73's into it and the drivability is significantly improved, not sure on mileage yet but my educated guess so far is that we will average at least 15 if not better.

18mpg is really good - FYI I have a 2018 Ram 1500 at work that has a 5.7 in it. Best I have ever got out of it is about 16.5mpg. My old boss drove it and was doing a little better but his driving style is not like mine.

 

[19Walt93]

Higher gears(lower numberically) will obviously reduce RPMs but at a cost. As mentiooned, power will suffer but a bigger concern is that more downshifts means more wear. We sold a pile of Super Duty trucks to contractors, loggers, and commercial plowers, most bought 4.10 gears. The ones who opted for 3.73's 'to save gas" experienced way more transmission failures. Compared to a transmission overhaul, gas is cheap.

 

[rusty ol ranger]

I currently average 18mpg. Drive very gentle and use torque rather than hp to accelerate. Driving is a balance of 4 lane roads and 2 lane with 10 % on logging roads

Ive found with these smaller V6's they do better if you accelerate normally, rather then trying to hypermile them and constantly be accelerating under its powerband.

Dont stand on it, but dont feather it either.

 

[RonD]

4.10 ratio at 2,500rpm with 30" tires in OD(.75) should be 72.5MPH

If you changed BOTH axles to 3.73 then RPMs would be at 2,300 at 73MPH

If you changed tire diameter to 32" then RPMs would be 2,350 at 73MPH

If you did both then 2,150rpms at 73MPH

Calculator here: https://spicerparts.com/calculators/transmission-ratio-rpm-calculator


A better investment, in my opinion, would be a vacuum gauge on the dash
Yes, old school but still the best way to see engine efficiency in real time

Outside of idling, 0MPG, having the highest vacuum when cruising will show you when your engine is at it's most efficient, getting the best MPG under load

Just as a tip, never shift to Neutral when coasting, that applied to carb engines
One of Fuel injection's best MPG advantages is being able to shut off the injectors while coasting, when you take your foot off the gas pedal(TPS under 1volt) and RPMs are above 1,500 computer will shut off injectors, once below 1,500 it will restart them at idle level

 

[Shran]

Higher gears(lower numberically) will obviously reduce RPMs but at a cost. As mentiooned, power will suffer but a bigger concern is that more downshifts means more wear. We sold a pile of Super Duty trucks to contractors, loggers, and commercial plowers, most bought 4.10 gears. The ones who opted for 3.73's 'to save gas" experienced way more transmission failures. Compared to a transmission overhaule, gas is cheap.

I can totally concur with this, I think 4.30 gears were an option for my '07 Super Duty and I wish it had them! It has 4.10s which are fine but even with stock size tires I wouldn't mind having a little more gear reduction.

Highway gears were fine in old 2 and 3 speed automatics where you settled into your high gear pretty quick and stayed there.

 

[sgtsandman]

I’m averaging about 18.5 with 3.73s and 31” tires. It wasn’t getting much more with the factory 29” tires on average. Maybe about 1mpg.

The higher RPM isn’t necessarily hurting your fuel mileage and can actually help it some to a point.

You also don’t want to get too low in the RPM range since it will tend to lug the engine and hurt fuel mileage in a different way.

At the speed you are talking about, 2,500 RPM isn’t unreasonable and puts you in a better place in the power band for driving up hills.

This is just my opinion but I think all the Rangers should have come with 4.10 gears due to the engines Ford put in them. 3.73 is a little tall and 3.45 or 3.55 is way too tall.

Ford was chasing those EPA numbers and on paper, those higher gears helped them get there. In reality, they didn’t help much after you got above 3.73 and there wasn’t much of an improvement going from 4.10 to 3.73 to justify the cost.