[KKRace]

The US military buys ATV's and other vehicles. I heard they pay a fair bit for them compared to just going to the local Yamaha dealer. One of the things I have heard have spec'd them so they can run "any fuel". Are they saying the same engine can run gasoline or diesel? Anyone know if this is the case and how they acomplish this?

[mk e]

I'm pretty sure that they are trying to minimize the number of fuels, not make everything run on 1 fuel

I found this fuel reg with a quick search
http://www.apd.army.mil/pdffiles/r70_12.pdf

And this:
http://www.desc.dla.mil/DCM/Files/Do...20Jul%2008.pdf


Both are similar and basically say there should be gas and diesel/jet fuel, nothing else.

[Granucci]

I don't see how a gas can run diesel or vice versa. Would take a fair bit of science to pull that off.

I suspect the 'flex' means a variety of either diesel mixes [good idea] or various gas mixes.

[cribbj]

In another life I worked for one of the large industrial engine companies, and we had a family of engines that were called "dual fuel". They were basically spark ignited natural gas engines which could also be run on diesel.

To run on diesel they were first started on natural gas with the SI setup, then diesel was injected with a separate set of injectors, and the flame front from the natural gas then torch ignited the diesel.

Frankly they didn't work that well, especially in cold weather...... but I will say that Uncle Sam was one of our largest customers for them

Probably the technology has come a long way since then (early and mid 80's) so perhaps these things run better now.

[mk e]

I used to have a 1936 J_D tractor. It had 2 fuel tanks, a small one for gas and a big one for kerosene. It was a low compression (flathead) spark ignition engine that you stared the engine on gas and got it warm then open the keno valve and closed the gas valve and turned the mixture screw until it run good again.

When I was younger my sister ran the mower out of gas, grabbed the fuel can in the garage, filled it and finished mowing.....of course it was diesel in the fuel can.

So, it 1936 they knew how to make a dual fuel engine and the "technology" still worked about 1980 in the lawnmower....smoked a bit, but it worked and I'm guessing it still does

[Granucci]

cribbj: In the military we often started emergency diesel generators with compressed air.

MK_E: Didn't know diesel would even combust in a normal gas engine. Guessing the spark must be very intense, and if smoked a bit then the fuel combustion would not be optimal. Also, seems the plugs would foul very quickly.

[mk e]

Originally Posted by Granucci

MK_E: Didn't know diesel would even combust in a normal gas engine. Guessing the spark must be very intense, and if smoked a bit then the fuel combustion would not be optimal. Also, seems the plugs would foul very quickly.

Oh it combusts just fine, the issue is it's like 25 octane so it knocks like hell if you are over about 5:1 compression ratio so it's not a particularly efficient way to go.

I guess the tractor didn't smoke much once the mixture was adjusted and it didn't seem to foul the plugs any worse than they fouled on gas...but they were certainly not lasting any 100k miles between cleanings