The Diesel vs Gas Engine in AATVs

[Breadstain]

Just figured people on here have some experience in form or another with the diesel AATVs in clone form or another, be it an Argo, Mudd Ox, or another modification.

I love my diesel truck. A bit more truck than I need for my ice castle but I love the way it pulls and love the fact that I could also put my Argo in the back of my truck.... if only it fit with tracks. Engine will last a long time as long as I keep it maintained and compared to a gasoline truck of similar size, mileage is better. My question is... since I’ve never owned a diesel in an ATV, do the diesels have any merit?

Does anyone care to share their experience with AATVs and why they would prefer or avoid diesel over standard fuel?

[truckinwagen]

I haven't had a diesel atv, but have plenty of experience with small diesel motors, both automotive and industrial.

I would recommend against going diesel unless you are somewhere that makes gas a hard fuel to get(some remote locations diesel is much more accessible as it is more widley used for generators/heat/etc...)

Small diesels are much more prone to cold starting issues than big ones.
Also the weight of a diesel would be considerably more for a diesel than a gas motor of similar power.
Gearing may be an issue may be an issue as well as the redline on small diesel is often less than 3500rpm.

The other notable issue is that diesel motors careuch more about the quality of the fuel than a gas motor, and the fuel system is much more finicky. It would not take much to make the motor quit from dirt damaging an injector pump, or air getting in a fuel line and killing the engine, would hate to have to prime the fuel system after it gulped some air on a steep climb way out in the bush.

[Noel Woods]

I have a diesel equipped Super Swamp Fox. It is a very powerful 25hp engine. It weighs maybe 15lbs more than a comparable gas engine. In terms of torque however it far out shadows
gas motors up to around and including 31hp. In terms of fuel efficiency it ran on one ride, all day long on 1.5 gallons, while a friend in his gas Muddox used around 10 gallons of gas.
If the engine has glow plugs, as most do these days, the cold weather start issue is negated. In terms of running in hot weather, they run very well. I can touch the shroud around the exhaust pipe on the diesel however on a gas motor it would still scorch the skin. I think with the ethanol blended gasolines these days there is much more chance of the jets in the carb getting clogged than the fuel injectors on a diesel.
The down side of my diesel is, it's loud as all get out and requires ear plugs all the time. Its also kind of smelly and not a pleasure to ride behind.

[allwheeldrive]

My Coot has a Yanmar L90 in it and after running a Diesel I don't think I could ever go back. It's the only small engine I've ever had that has been 100% reliable, it gives you the same level of confidence as your automobile engine.
That said first. I never understood how small diesel engines have "more" torque than their gas counterparts. Torque is simply a mathematical function of HP.
HP x 5,252 / RPM = Torque
A 9 HP Gas engine at 3600 RPM and a Diesel 9HP engine at 3600 RPM make the exact same toque. And varing that max RPM red line usually isn't enough to make much of a difference likewise it can and will have to be augmented with a gear change to keep the machines performance intact. IE a 9 HP Gas engine at 7,200 RPM geared down 2:1 will make the same toque as a 9 HP 3,600 RPM Diesel. (now in our machines it's around 3,400-3,700 RPM and the diesels should be the same as in the industry they are used in the same applications IE generators, pumps, etc.

So no my Coot's 9 HP Diesel doesn't feel more torquey that said it's 211:1 gear reduction does lol.

My engine has no glow plug and is nearly impossible to start under 28 degrees.

Noel is right. These small Diesels are INCREDIBLY loud. There isn't anything you can do about it either. Once you get the mufflers doubled up and packed like I did the engine block itself will expel most of the sound. (tested with a sound meter) I can get as low as 79 Db from the exhaust tip but it's 90 Db at the engine block...at idle. Hearing protection is 100% needed for any usage over a few minutes. The good news is they sound B@D @SS it's a kind of loud you can live with really cool, and the envy of everyone when you have it out.

[Don]

Diesels work fine in my experience. I have a Hustler Bigfoot with a Kubota 3 cylinder that is a great machine: all kinds of power but not a lot of speed. We built an Attex Li'ltruck with a Yanmar clone air-cooled single that worked fine, was a lot of fun to drive, but smoked like a coke oven under power because we had to tweek the fuel to get any power/speed out of it. No problem when you're riding alone but in a group we were always last in line. It really depends on what you want. If you need "right now" power, a diesel may not be what you want. Both the Kubota (glow plugs) and the Yanmar (ether, once) started in the cold, but around 15 or 20 degrees was as cold as we ever tried.

[miller_time]

I have a kubota diesel in my max iv. Noel pretty much nailed it. With my only complaint being the noise but its tolerable.