Big suburban or small jeep

[Tulok]

Hello all,

I've been thinking a lot for the past while since I've had my suburban on how to Eco-mod it. I bought it to use off-road, but I really want to take it to places that are hundreds of miles away without breaking the bank. Ha!

It seems to get pretty good MPG in town and on the shorter trips I take, but I haven't done any mpg tests with it unloaded. I think it does get at least 13 in town, and off-road mixed in.

It has a 40-Gallon tank and I am imagining how amazing it would be to get 20 mpg (straight pure freeway) and to be able to travel so far on a tank.

I often drive between Idaho, Utah, Nevada and California on the I-15 which is mostly flat with some mountains but it's overall net isn't much.

I know the mirrors are just humongous, I can fab up some much smaller ones. and the grill opening is huge. I have trouble keeping it up to temp, so maybe a grill block would help?

Also, there is a Huge mechanical fan that I'll be changing to electric with a thermostat.

I'm to the point where I have to make some changes to the vehicle to get it to go where I want off-road.

One thing, is that I need larger tires 35" and a lift to clear them, and probably a larger heavier rear axle. I know that will murder my MPG. But I was thinking of a way to use a winch strung under the vehicle with some snatch blocks to lower the vehicle for long drives. Do you think that lowering a truck would help mpg on the freeway?


Another option is just converting to a much lighter single cab truck body. Which is very easy and cheap, I have a ton of parts available for that. But I don't have a truck bed, so I would make a flat bed, But that's probably worse aero than a Burban unless I made the roll cage sort of kamm-back shaped and had a vinyl top made for the back. This is doable but I'm not sure if it's worth the work compared to a suburban body in the end.

The last option, and this might be the way I go either way, is to convert to a postal jeep. The oldest really small ones.I can swap everything over to one and be at about 3000 lbs roughly. Much better than 5000 I'm at. I could also keep the smaller 31" tires. I could still put smaller mirrors, and grill block, and do the lowering trick on the tiny jeep.

Do you think venting the fenders on a jeep would help?

I know that's long, but in short:

Much smaller, though slightly worse CD and smaller tires. Or larger and heavier but with better CD, though with bigger heavier tires

20mpg is the goal

[Tulok]

A postal jeep. I would definitely utilize doors

[cRiPpLe_rOoStEr]

At least with a body-on-frame layout you have more flexibility to perform extreme aeromods, but the Suburban being longer allows you to enhance the aerodynamic a little further.

[vskid3]

I think diesel is going to be your best shot at hitting 20MPG with an offroad-ready rig. A guy I work with has an lifted old Land Cruiser with a Cummins 4BT swap and went from 10MPG on a good day with the gas engine to 20MPG. A Cummins B3.3, 4BT, or VW TDI would work in a Jeep. In the Suburban you could maybe do the 4BT, but you'd be best off with a pickup truck diesel.

[cRiPpLe_rOoStEr]

Originally Posted by vskid3

I think diesel is going to be your best shot at hitting 20MPG with an offroad-ready rig.

An uncle of mine used to get 42MPG out of a 4-door Suzuki Vitara with a 50hp 1.6IDI Volkswagen EA827 Diesel.

[carolina guy]

Originally Posted by Tulok

Hello all,

I've been thinking a lot for the past while since I've had my suburban on how to Eco-mod it. I bought it to use off-road, but I really want to take it to places that are hundreds of miles away without breaking the bank. Ha!

It seems to get pretty good MPG in town and on the shorter trips I take, but I haven't done any mpg tests with it unloaded. I think it does get at least 13 in town, and off-road mixed in.

It has a 40-Gallon tank and I am imagining how amazing it would be to get 20 mpg (straight pure freeway) and to be able to travel so far on a tank.

I often drive between Idaho, Utah, Nevada and California on the I-15 which is mostly flat with some mountains but it's overall net isn't much.

I know the mirrors are just humongous, I can fab up some much smaller ones. and the grill opening is huge. I have trouble keeping it up to temp, so maybe a grill block would help?

Also, there is a Huge mechanical fan that I'll be changing to electric with a thermostat.

I'm to the point where I have to make some changes to the vehicle to get it to go where I want off-road.

One thing, is that I need larger tires 35" and a lift to clear them, and probably a larger heavier rear axle. I know that will murder my MPG. But I was thinking of a way to use a winch strung under the vehicle with some snatch blocks to lower the vehicle for long drives. Do you think that lowering a truck would help mpg on the freeway?


Another option is just converting to a much lighter single cab truck body. Which is very easy and cheap, I have a ton of parts available for that. But I don't have a truck bed, so I would make a flat bed, But that's probably worse aero than a Burban unless I made the roll cage sort of kamm-back shaped and had a vinyl top made for the back. This is doable but I'm not sure if it's worth the work compared to a suburban body in the end.

The last option, and this might be the way I go either way, is to convert to a postal jeep. The oldest really small ones.I can swap everything over to one and be at about 3000 lbs roughly. Much better than 5000 I'm at. I could also keep the smaller 31" tires. I could still put smaller mirrors, and grill block, and do the lowering trick on the tiny jeep.

Do you think venting the fenders on a jeep would help?

I know that's long, but in short:

Much smaller, though slightly worse CD and smaller tires. Or larger and heavier but with better CD, though with bigger heavier tires

20mpg is the goal

If you want to raise it and lower it, have you thought about airbag suspension?

[Tulok]

I was under the truck a few weeks ago, and I noticed the transfer case hangs down pretty low, and the hitch was looking like it was in a horrible place for wind. Already took that off! Towing isn't efficient.

I'll probably design an aero-ish skid plate for that.

I think the truck will definitely benefit from tire air deflectors, and smaller mirrors. Both really cheap changes.

I'm going to make some new bumpers and probably get a winch regardless. If it can't be arranged to lower the vehicle some way,

I may just get air bags to provide clearance for the larger tires instead of a traditional fixed height lift. That's actually a great idea!
The truck will have on board air anyways so filling the bags won't be a problem.


My main goal is to extend the range of the truck in pure highway driving between far trails like Vegas, Moab, Colorado and California where it is hundreds of miles of highway between recreational areas.

I don't want to upgrade the engine, though a tune and headers-exhaust have given some people up to 2 mpg

[Tulok]

On another note;
The 4BT would definitely be awesome for mileage! But my truck has a brand new engine right now lol.

And, I figured out that even the smallest jeeps are so bad on gas with a 4 cylinder that I totally threw out the jeep idea.

[Frank Lee]

[The Other Andy]

Originally Posted by Tulok

I was under the truck a few weeks ago, and I noticed the transfer case hangs down pretty low, and the hitch was looking like it was in a horrible place for wind. Already took that off! Towing isn't efficient.

I'll probably design an aero-ish skid plate for that.

I think the truck will definitely benefit from tire air deflectors, and smaller mirrors. Both really cheap changes.

I'm going to make some new bumpers and probably get a winch regardless. If it can't be arranged to lower the vehicle some way,

I may just get air bags to provide clearance for the larger tires instead of a traditional fixed height lift. That's actually a great idea!
The truck will have on board air anyways so filling the bags won't be a problem.


My main goal is to extend the range of the truck in pure highway driving between far trails like Vegas, Moab, Colorado and California where it is hundreds of miles of highway between recreational areas.

I don't want to upgrade the engine, though a tune and headers-exhaust have given some people up to 2 mpg

From everything I've heard regarding GM trucks (based on the 4.3 anyway, which is what my vans had), swapping your belt driven fan for an electric fan will probably be your best bang for the buck.

Actually, swapping out the Suburban with an AWD Astro or Safari might not be a bad idea. You'd have tons of interior room, with a more compact package. They aren't all that frugal, but I was routinely getting 23-24mpg out of a 200,000 mile, 2wd Safari well before I knew of hypermiling. The AWD vans can hold their own out in the wild too.