Fueleconomy estimates on a 1995 F150 300 Stright Six 5 SPD with 2.73 gears?

-Welder

 

2.73 sure is pretty tall gearing for a truck that came with a factory overdrive gearbox. The biggest effect on mileage is of course engine tune, but mileage on 300's in a good state of tune can be anywhere from about 12 to up into the low 20's from what I've heard. The personalities of these engines seems to be pretty varied, and some 300's just happen, for whatever reason, to be 'thirstier' than other 300's. I'd say with a good state of tune and an easy driving style, stock tires and those gears. You would probably see 15MPG

 

I get around 14 with a carb, 3.70's and no overdrive. My guess would be a smidge higher than 15MPG.

 

https://www.ford-trucks.com/forums/8...ur-milage.html

https://www.ford-trucks.com/forums/3...nline-6-a.html

Try the "Search" function and you will find the subject has been covered ad infinitum.

 

I'm estimating 22 highway....my math says it should cruise at 60 mph just over 1400 rpm.

 

Definitely been covered many times.
One thing you didn't mention was the size of your tires, which is a big factor.

Personally, I have an '81 carb'd 300 with a 3.00 rear end and 30" tires and I get 20 - 22mpg on the interstate at 60 - 65mph. At 75, I get around 16 - 17.

 

I have the factory 235/75/15's

-Welder

 

That should put you at around 1800 RPMs at 75mph. Two ways to look at that, one is that the low RPMs are going to keep wear and tear down on your engine, but the other is your engine is going to be struggling to keep you at that speed because it's below it's effective horsepower range. Depending on how you drive, that can increase and decrease your mileage.

Either way, if you drive it gently at those RPMs, you'll get good mileage.

 

On this subject you could even say: "Subject covered ad nausem"

 

And ad absurdum

 

i get 17.8 ,with 3.08s and 4x4 both city an hw mixed

 

The 300 doesn't struggle...it's peak torque is like around 1600 or something...nothing like a V8

 

Yeah, but from what I hear, horsepower is what you need to keep you going at higher speeds. If you're pulling a load up a hill at 20mph at 1600 RPMs, you'll have the torque to pull it all day. But if you're going 65 - 75 at 1600RPMs and start to go up a hill, you'll quickly lose speed until you downshift into a more useable RPM. If you floor it at 1600 (assuming you have a manual), you'll pretty much just dump gas and not really go anywhere.

That's where the debate comes in, when you're at "too" low of an RPM, where's the fine line between sipping gas, and dumping gas without knowing that your engine is actually trying to accelerate but can't.

 

You are right, especially with 2.73 gears and OD. In fact it could downright be very annoying. The truck mentioned is a good example of a specific type, and nothing more. That being excellent fuel mileage on freeways and fairly level rural roads with no huge load either pulling or payload. For any other needs you get a different setup, but with less fuel mileage. Mine is a 4OD with 3.08s. I've had it since new in 83...it fits my utility uses and sips gas.

 

I pretty much have the same truck that Welder79 is asking about. I have a 96 F150 300 six 5 speed 2wd with 2.73s out back. The mileage isn't that great, actually I am a bit disappointed with it (around 13-15). Powerwise it's okay, it was terrible when it had the M5OD... I couldn't tow much of anything. Last summer I swapped in a ZF 5 speed from an F250 and it's much better from a usable power standpoint. I can actually tow a car on my trailer with it now, the ZF has a much deeper first gear than the junk Mazda tranny had. In the up coming weeks I am going to be pulling this truck into the garage to complete a 4x4 conversion that was started as a result of the tranny swap. The F250 that my ZF came out of was a 4x4, rather than trying to hunt down a 2wd tailshaft I decided to convert this truck to 4wd. As many of you may already know converting a 2wd 1980-96 F150 to 4wd is a bolt on swap. I picked up a set of axles (front and rear with 3.55s) for free from a buddy of mine.
I really believe that it's possible to be geared too high, and it can effect the mileage in a bad way. If the motor is lugging all the time at WOT just trying to get up to speed, it's going to drink more fuel. I hardly ever use overdrive, even on the highway... there's no power!
I did a gear swap on my 84 F150 4x4 300 six granny 4 speed several years ago. I went from stock tires with 3.08s to 33s with 4.10s and mileage did not get worse if anything it got better (last I checked around 16-17). To add to that it had noticably more power.