Four Wheel Driving and Fuel Type

[bigdude101]

Hey guys and girls,

I've decided to pick up Four-wheel-driving as a hobby, but I know that most 4WDs use lots of petrol, and give off lots of emissions. While most 4WDs do have diesel options, it's common knowledge that diesel emits more particles than Unleaded petrol.

Here in Australia, LPG is fairly common, cheap fuel (about half the price of regular Unleaded), and most of the taxicabs run on the gas. LPG also gives off less particles than both diesel and Unleaded. The government offers a relatively large rebate to get cars switched over to gas (around AU$2000), which makes the conversion a lot cheaper.

Converting petrol powered cars to LPG (or at least a dual fuel system) is relatively widespread, (in fact, the Ford Falcon has an optional straight LPG system from the factory, and most Toyota and General Motors Holden dealers convert their cars to dual fuel as well), but I have never heard of it being done to a diesel vehicle.

Is it possible to do this conversion? Or is the diesel engine incompatible with an LPG system?

Would I be able to run the diesel part on vegetable oil (if the engine is modified for SVO)?

Also, what would be a good 4WD to use? I am thinking of the 2nd gen Toyota Hilux Surf (basically a JDM 4Runner with a diesel engine), a Y60 Nissan Patrol or a Land Rover Discovery. Does anyone have any other suggestions?

Please note, here in Australia, the Big Three (Ford/GM/Chrysler) don't have a large selection of 4WDs (Ford had a rebadged Patrol for a while, Holden had rebadged Isuzu Troopers and Rodeos, and Chrysler had the Jeep Cherokee), so a Japanese suggestion would be better.

[sandcruiser]

I've got a toyota hdj80 (turbo diesel wagon) that gets about 20-26 US miles/gallon
I've run it on SVO, and plan to add a second tank and heater system in the future. Biodiesel is also an option.

Depending on your needs, this may be a decent solution for you.

From what I have read, it is not practical to convert a diesel to LPG. But there are folks who are adding propane or LPG into the air intake to make the diesel burn more cleanly. Apparently there is some sort of catalytic reaction that makes the diesel burn more completely when there is propane mixed in. It also cools the intake charge, which allows for higher air density and better performance- which can be made to be more efficiency (or more power).

as with most driving, the nut behind the wheel makes the largest difference.

[comptiger5000]

The best you could do for a diesel is to run it on veggie oil and/or run propane injection. Plus, most newer diesels are actually pretty clean burning to start with.

[TheEnemy]

What kind of off roading are you looking at doing?
Is it going to be back country dirt roads with the occasional washout, rocky mountain trails, mud, sand, rock crawling....

Are you wanting to use it for any other kind of utility?

What kind of creature comforts do you want when you are on the trail?

Are you going to use the rig as a daily driver as well?

Are you going to use it at highway speeds much?


I chose an older Jeep CJ7 (wrangler), It gets most of its off roading on rocky mountain trails, but also sees back country dirt roads, and rock crawling.

It has practically no creature comforts.


Edit: A lot of the competition rigs around here use propane because it will keep running even when upside down.

[TheEnemy]

What we see around here are lots of the Wrangler variants, Grand Cherokees, Toyota pickups(hilux?), and Land Cruisers.

[comptiger5000]

Fuel injected gas runs upside down too. However, even with dry sump, you'll trash the bearings in a few seconds upside down, as they get no oil (wet sump, the pump runs dry. dry sump, all the oil ends up in the valve covers after a few seconds, and can't drain back, pump runs dry).

[TheEnemy]

Originally Posted by comptiger5000

Fuel injected gas runs upside down too. However, even with dry sump, you'll trash the bearings in a few seconds upside down, as they get no oil (wet sump, the pump runs dry. dry sump, all the oil ends up in the valve covers after a few seconds, and can't drain back, pump runs dry).

True, but these are the competition rigs with money on the line. Fuel injection will run for a little while upside down but the in tanke fuel pump runs dry and it quits.

[comptiger5000]

I've seen it run long enough to flip the rig back over under its own power. By the time fuel injection stalls, the engine is probably screwed anyway.

[320touring]

I take it you'd be looking for an early Discovery?

Fair few over here with either the 200 or 300 series TDI engines- they give circa 30mpg (UK) out the box and have plenty torque off road.

Another option would be a v8 4.0 petrol fitted with LPG- lovely lazy big lumps- but need more work to make them reliable if going REALLY offroad- fording etc...

Hilux Surf seems a reasonable option- the 2.4 TD just doesnt give up.

Are you just planning to modify driving techniques to max the MPG? Cant see aero mods lasting a long time offroad!

[bestclimb]

Every toyota truck I have had has been bombproof. Were I to need an suv again a 4runner would be high on the list.