Better MPG in an old pickup truck?

[sgtlethargic]

I frequent a hot rod forum. Somebody's asking about Ford engines that get good gas mileage. He's gotta '56 Ford F100 and it sounds like even if he goes with a more modern engine (4.6 L) he's going to use a carburetor. Most of the discussion is about engines and tall gearing, and somebody mentioned BSFC but it was a mystery to him, and frankly I'm not up to speed on it either. Another thing mentioned is a vacuum gauge. I vaguely remember reading articles about "RV cams" and such. What (gasoline) Ford engine would you recommend? What gearing would you recommend? Can you provide links to some good BSFC threads? BSFC charts? What else? Keep in mind that the audiences differ.

Thanks,
Kurt

[Big Dave]

If you're gonna stay with a gas engine, get the smallest engine that you think will give you adequate acceleration.

If he insists on using a carb, I'd recommend a 300 Six.

[BackroadBomber]

I had a 68 ford f100 with a 240 inline 6 ( under bored 300) single barrel carb, three on the tree (no overdrive), and 3.50 rear end gears. I got 17 mpg driving the hell out of it so I would think a 240 with a 4sp with overdrive could possibly get 20. Not to mention my 240 felt like it could push over a house and also had enough power to spin the tires.

[graydonengineering]

I have found (with the help of my ultragauge) is that I must keep my RPM super low. I go ahead and rev it up to get up to speed like the average driver but once I am up to speed, i pick the highers gear that doesn't lug the engine. Before i figured that out, i would go 40 in 3rd gear and my instant mpg in that case is only about 25 mpg. In 5th, I can hit about 35 mpg. If I am going up hill, i have to go with 4th gear.

The 5 speed on my truck is too low to pull good mpg at over 65 mph and most older trucks rev high at even lower speed. I am planning on buying taller tires next time around to up my gearing.

[Big Dave]

Bigger diameter tires are counterproductive.

Rotational moment of inertia goes up with the square of the radius. Bigger tires mean four bigger "flywheels" that you have to pour energy into to accelerate everytime you pull away from a stop.

Gearing works and bigger tires don't.

[Frank Lee]

Someone on here a long time ago put a turbo 2.3 in an Edsel. They reported good results then... heard no more. This truck is a play toy and it's at least 1000 lbs lighter than today's trucks... could be comparable in weight to today's small cars. A 4 would move it right along.

[darcane]

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I know you said gasoline... but it needed to be said.

Aiming for fuel economy and ditching the EFI is like trying to run a marathon in Army boots. You might be able to make it, but you're adding a huge challenge for no good reason. I rarely see carbs on modern engines at the classic car shows I go to, but it does happen every now and then.

If you gotta stick to Ford and gasoline... maybe the new V6 Ecoboost from the F150?

[graydonengineering]

Originally Posted by Big Dave

Bigger diameter tires are counterproductive.

Rotational moment of inertia goes up with the square of the radius. Bigger tires mean four bigger "flywheels" that you have to pour energy into to accelerate everytime you pull away from a stop.

Gearing works and bigger tires don't.

I agree, bigger tires are not a subsitute for inproper gearing. Significantly larger tires will bog down the engine. Depends on the type of drving you do also. If your do a lot of highway driving, they could give decent returns.

Re-gearing is so expensive unless you can find the parts in a yard. I wonder if the v6 frontier has taller gears..

[redneck]

Put a GM 3.8 V6, a five speed manual transmission and new gears in the rear.



>

[sgtlethargic]

Originally Posted by Frank Lee

Someone on here a long time ago put a turbo 2.3 in an Edsel. They reported good results then... heard no more. This truck is a play toy and it's at least 1000 lbs lighter than today's trucks... could be comparable in weight to today's small cars. A 4 would move it right along.

Cool. I found the thread and an article:

http://ecomodder.com/forum/showthrea...n-14594-9.html

Curbside Classic Special: 1959 Edsel

I find it very interesting because I have a '61 Comet (which has Edsel relations) with a propane-carbed turbo 2.3. I wonder what kind of mileage I could get if I redid it with EFI.

I half considered mentioning the turbo 2.3 to the person with the pickup, but since he doesn't want EFI I don't think that's a good choice.