hello everyone, newby to this forum.
I own a towing company in memphis and have a 1992 f-superduty with the all wonderful 7.5 liter v8 gasser in it and im getting 120 miles at best loaded or unloaded on it with the 16 gallon tank, the truck weighs 7300lbs and im lookinng into possibly swapping out the motor trying to get 13-18mpg unloaded.
currently im putting 40-60 per day in gas in my truck, so my question is what engines can i put in my truck to achieve best mpg and still stay reliable.... any help would be greatly appreciated.
thanks to all who read all my post

 

you'll find that most of the engines available in that year range will give you about the same mileage with the weight of your vehicle - 8-13 mpg, give or take, depending mostly on driving habits.

When banging through the gears because I'm late, in a rush, or whatever I've gotten as low as 8mpg and if I'm gentle and shift "early" I can typically get above 13 mpg - this is in a very high mileage F350 SRW crewcab. Mine weighs a hair under 7K with all the junk in the bedbox, bedfull of ladders and tools, and my 300lb homemade bumper ;-)

A diesel however typically gets far better mileage overall, however diesel engines cost more than gasoline engines and of course you'll have to change your transmission as well to be able to mate to the diesel bell housing.

Ford had two IHI diesels of the same vintage as your truck, though the displacement figures escape me. I'm sure with the vast knowledge here someone can toss those out faster than you can blink. Some of them were also available in turbo form and you can add an aftermarket turbo kit as well.

A lot of guys swap in a cummins 6 cylinder, 2v or 3v with great results, some turbocharged some not.

Basically, depending on your mechanical and electric skills, you could in theory swap anything that fits in the engine compartment.

Before doing a swap, you might want to check your rear end axle ratio, because if you're not towing 24/7, you probably don't need 4.11 gears. But of course if you are or towing towards the limit of the truck in weight, then obviously you would.

Gear Vendors also has an aftermarket overdrive unit - I used to have one on my 81 F350 crewcab and that made a huge difference in mileage because if not towing (or in 4wd) I'd kick in the overdrive and that would essentially lower my rear axle ratio to "reasonable".

All depends on how you want to do it.

However, you do need to be realistic because of the vehicle size, weight, and what you do with it.

 

Anyway you do it you you will have to change the tranny. The 460 has a different bell housing than the small blocks. I believe the diesel is differnt too. Anything smaller than the 351w probably wouldn't have enough power for you. The gas mileage it will give you isn't going to be much better than the 460. The diesel would be the best but its going to be the hardest swap.

 

i tow constantly, my truck sees more towing time than you would believe, also forgot to mention ive got a repostyle lift and aftermarket bed on the back. i was looking at a cummins swap, but dont know all what would need to be done to do the swap.. ill keep it dually and rwd, but as far as staying auto. i havent decided, just need to know what im looking at buying..

 

im deffinately going diesel, no question about that, just dont know where to start with this, i can get a complete dodge ram 1500 cummins with no problem as a donor

 

i have 3 thoughts, 1 what transmission do you have? is it overdrive? 2nd what gear ratio do you have in your diff? 3 have you considered turbo charging or supercharging it?

 

i believe its an allison 4 speed with overdrive and no clue on the gear ratio, but the truck will do 85 on the interstate, and would rather do a motor swap than turbo or sc the gasser 7.5

 

Scott, you don't say where you hail from so I can't make a solid suggestion. Kalifornistan has so many rules regarding engine swaps, it's not funny. That's why my truck is still a gasser. Your mileage, though seems on par with my '97 F250HD with a 7.5/E4OD/4.10 gears combo.

If you don't have to smog it, a rotary pump 12V Cummins 6BT would probably fill the bill. Those things last forever, as long as you keep them serviced. It might out-last the truck, too. It's possible to tweak them up to a 250 hp tune and still be rock-reliable. Another (somewhat oddball) choice would be a 6V-53 Detroit. coupled to a small Clark direct-5th transmission/3 spd brownie setup.

If you do have to (heaven forbid) smog it, find another '92 F-SD parts truck with 7.3 diesel and swap the entire drive-train into your truck.

That's all I've got at the moment.

 

luckily im in memphis tn, no smog for diesels under 2001, sooooo just visual vin, signals, lights ect

 

Id say swap to either a powerstroke, IDI diesel and turbo it or cummins. Ford diesels will be much easier to swap since alot of it can be put together with OEM stuff cause its ford. Cummins takes a bit of work but your rewarded with the power, tunability and reliability of the cummins.

First off whatever you choose try and see if you can source at least a 5 speed trans like a ZF. They can be built to tow very easy or in stock form it should be ok.

the truck if its a hidden repo type will handle the setup fine with any of those engines. Shop I used to work for had an early 90's non turbo IDI super duty (f450) flatbed and although it had no turbo it moved good enough for local use.

He cant really swap the gears to much, he needs to low gears to be able to tow properly so thats outta the question unless he finds he needs even lower gears when he swaps engines. The truck should at least have 4.10s in it.

 

scott, its an e4od transmission .

 

im leaning towards a cummins.. now its down to a parts list, i know i need a ford cumins engine mount kit,
but need to know what other parts im going to need, can i use a 6speed 3500 trans and call it a day with the trans, im towing all kinda cars, ive ven had to tow 08 kingranchers with extended cabs, 13000 lb trucks, i need something i can rely on, i can do the maintenance, i just need some direction on what i need to get

 

Check out DeStroked.com. They sell cummins adapter kits so that you can hook up a cummins to just about any transmission. IMO, your best set up would be a 12V Cummins 6BT and a Ford diesel ZF 5sp. The ZF has a granny low which is great for towing and an overdrive 5th for fuel economy.

 

My diesel tech teacher told me that the frame of a diesel engine truck and a gasser truck are different. Is this true in Fords case? b/c i was going to put a diesel engine in my 90 f150 extended cab but my tech teacher discouraged me from it with that statement he made :-( he said that the frame of a gasser wouldnt hold up to the tense vibrations of a diesel

 

Any F250 HD and F350 etc are all the same frame no matter what engine they have!

The F150 and LIGHT duty F250 are the 2 with smaller frames.

An F150 frame will still hold up a Ford Diesel, but you'll have to upgrade the front end.