EcoMod This!

[Gasoline Fumes]

I picked up this beast of a pickup over the winter.


1980 Chevy K20, aka The Mule. 3/4 ton 4WD with a gas 5.7L V8 and 4-speed manual. It's really a 3-speed with a "crawler" gear. Originally from Arizona, but starting to rust after a few years in NY.

Not driving it saves the most fuel. It gets single digit MPG towing at 45-50 MPH! The first planned mod is more displacement. A 6.2L diesel V8. That alone should get me an additional 5+ MPG.

Axle ratios are 3.73. And there's no overdrive. I wanted taller gears until I towed 4000 lbs uphill. I don't think the weaker diesel could handle taller gears. An overdrive transmission would be nice, but they're hard to find at a decent price. So gearing will likely stay as it is. I'll just drive slow.

It will be converted to run on WVO and I'm thinking about an aerocap. Any other ideas? Is synthetic gear oil in the tranny, transfer case and rear end worth it? I'll be plowing snow with it, so I can't lower it or do much with the horrible underbody aerodynamics. Maybe an airdam? Since I'm planning to use the much smaller gas radiator, a grill block is probably a bad idea.

[Frank Lee]

I don't think an airdam will do much behind a plow.

[Gasoline Fumes]

But the plow isn't there all year.

[cleanspeed1]

What are you going to do with the truck most of the time?

[Gasoline Fumes]

I'll let it sit in the driveway most of the time. It's really just for moving things that don't fit in a hatchback. Could be scrap metal or a whole car on a flatbed trailer. And plowing a few driveways in the winter. MPG isn't really even that important considering how much it will be driven. I just like making vehicles more efficient. I already have the diesel engine, so that's a no-brainer. And then I can sell the gas engine for around $500.

[jakobnev]

Will you be driving short or long trips with it?

[Gasoline Fumes]

Mostly shorter trips. 0-30 miles.

[northboundtrain]

Originally Posted by Gasoline Fumes

. . . I already have the diesel engine, so that's a no-brainer. And then I can sell the gas engine for around $500. . .

I did this same conversion several years ago. It can still cost a lot of money, even if you already have the engine. You'll need a different flywheel, starter, exhaust, batteries, glow plug relay, etc., etc. And depending on the condition of the engine, you may need to replace/rebuild things like the injectors, injection pump ($$$), etc. IIRC, the diesel engine has oil cooler lines, so you may need a new radiator too. I remember it nickle and dimed me to the tune of several thousand dollars by the time it was all finished. Perhaps you have more parts than I did to start with, but don't underestimate the cost of all the components to get the vehicle moving.
Then you'll have to figure out how to register it, which may or may not be an issue where you live.
And finally, the old GM diesel is just not a great engine. I saw a very modest mpg increase, and the power for towing or plowing just isn't there. You probably won't ever come close to recouping the cost of the conversion in fuel savings, particularly since you don't plan to drive it a lot.
For a lot less, you could probably tune up and modify the 350 to make more power and be more efficient (headers, free-flowing exhaust, carb rebuild, engine freshen up, towing/mileage cam, etc). It would crush the 6.2 for power and torque.
Then again, the 350 may be worn out and need re-boring, full valve and guide job, etc, but if it's really worth $500, then it should still have good compression and be within wear tolerances.
Anyhow, I'm in the process of freshening up the 350 in a '77 3/4 ton and doing the above-mentioned mods, so when I saw this post, I figured I'd chime in. Hope it helps.

[cleanspeed1]

Originally Posted by northboundtrain

I did this same conversion several years ago. It can still cost a lot of money, even if you already have the engine. You'll need a different flywheel, starter, exhaust, batteries, glow plug relay, etc., etc. And depending on the condition of the engine, you may need to replace/rebuild things like the injectors, injection pump ($$$), etc. IIRC, the diesel engine has oil cooler lines, so you may need a new radiator too. I remember it nickle and dimed me to the tune of several thousand dollars by the time it was all finished. Perhaps you have more parts than I did to start with, but don't underestimate the cost of all the components to get the vehicle moving.
Then you'll have to figure out how to register it, which may or may not be an issue where you live.
And finally, the old GM diesel is just not a great engine. I saw a very modest mpg increase, and the power for towing or plowing just isn't there. You probably won't ever come close to recouping the cost of the conversion in fuel savings, particularly since you don't plan to drive it a lot.
For a lot less, you could probably tune up and modify the 350 to make more power and be more efficient (headers, free-flowing exhaust, carb rebuild, engine freshen up, towing/mileage cam, etc). It would crush the 6.2 for power and torque.
Then again, the 350 may be worn out and need re-boring, full valve and guide job, etc, but if it's really worth $500, then it should still have good compression and be within wear tolerances.
Anyhow, I'm in the process of freshening up the 350 in a '77 3/4 ton and doing the above-mentioned mods, so when I saw this post, I figured I'd chime in. Hope it helps.

+1 with a tool box.

If anything, if you just want something to do, stick the 6.2 in a car to replace a 5.7 Olds diesel.

[jakobnev]

Maybe you can find some eco-friendly way of preheating the drive line.