Better MPG in an old pickup truck?
 

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

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.

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.

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.

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.

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.

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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?

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..

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

;)

>

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.

Non turbo carb would be perfectly acceptable.

Google tells me a '59 100 should be 3000-3300 lbs. so yes this old full-sized truck weighs less than most cars on the road today.

'59 is a third gen.

http://www.fordforums.com/f645/1953-...weight-138183/

Honestly, a Focus engine would do fine if you could find a transmission to fit it. For carbs, possibly an early Fox body? Edit: Yep, that's the 2.3L you guys were talking about. Hook that up to a 5 speed with a tall rear end and you're golden.

A bed cover and belly pan wouldn't hurt either.

A carb can be very efficient, but, it takes work to stay on top of it and requires a very light foot. If he wants max FE while putting down the road at consistent speeds, a carb is fine. FI kicks it's butt because it can maintain perfect stoichiometry during WOT, whereas a carb goes too rich when you put your foot in it. Pretty much rules out P&Ging.

Wonder if it's possible to have a carb with an O2 sensor and variable jetting? I'm sure it's possible, actually. Just don't know if anyone has bothered doing it. I suppose a TBI setup makes way more sense.

Honda was doing that back in the 1980's, but they also had 56 vacuum lines running around that carb to help control all the parts of it.
Fuel injection would be the best route, either that or a turbo diesel, a 1959 F100 weighs about the same as a VW jetta TDI so that might even be an option, a bit more frontal area in the truck but people also toss all kinds of stuff on the roof of some of those cars too.

The key to getting good fuel economy in an old car is a manual transmission with an OD. A smaller sized engine goes a long way too. The 4.6 being contemplated is actually a decent choice.

I had one of those damn things. '84 Accord. A beautiful running car till one one those 56 vac lines started acting up. After battling it on and off for a year or so, I got rid of it.

What's your take on this recent comment on same thread on another forum?

Easiest 'secret' to fuel mileage is long stroke. Make the fuel WORK!! Chevy 305 always did better than Ford 302. Why?? 3.48" stroke vs. 3" stroke. Less fuel (smaller chamber) did more work. Look at today's mileage champs - longer strokes, some engines are going back to undersquare (longer stroke than bore).

Next up is breathing. If you're gong to make the fuel work more, make it easier to get to work.

Odds and sods will take up most of the evening, but a good start is to look at what the OEMs are doing for better mileage. Whatever you can adapt, do so. Probably the cheapest for most hotrodders is to actually be HOT!! Run a 195º thermostat for better thermal efficiency. Thinner tires. Underchin spoiler to keep air from under the car.

I have my doubts about whether the stroke thing is all that critical. Seems to me if it's geared for 1000-1200 f/mn piston speed (gasoline 4 stroke) that's what counts.

I would hate to taint that truck with the great but imported vw diesel, it would work well perhaps to well but it would kill the trucks personality. I 2nd the ford 300 straight six, that motor is a champ.