Pusher/generator trailer idea.

[Stubby79]

There are issues trying to run a diesel engine on propane (I've looked in to it!). First of all, you need to rig up a distributor on something that has never been designed to have one. Possible, but I doubt you'll find off-the-shelf parts to fit.

Secondly, from what I read, propane is best run on low to middling teens CR. I assume this means to go past that, it is going to compression-ignite(which probably won't bother it), or just plain cause knocking(which will).

From what else I've clued in to, it's not just the more modern direct-injection and or common-rail that time the injection at just the right moment. The older, mechanical indirect injection engines do too. They inject it at or a hair before or (as I believe it actually is) after the piston hits TDC, to control when ignition occurs. If it happens too soon, the piston coming up is going to hit all that combustion pressure and bad things are going to happen to the inside of your engine. If it happens too late, well, it might not ignite, or you've just wasted the most efficient time for combustion and lost power.

This explains why the fuel is sprayed straight in to the combustion chamber...if it has to be precisely timed, you can't spray it in advance of said moment. Otherwise diesels would just use a single injector like throttle body injection and be done with it. Probably at a much lower pressure, since they don't have to overcome combustion chamber pressures. All this explains why there's an injector for each cylinder, and why they run the injector pump/nozzles at 1400+ psi.

Anyway, if you introduce another form of fuel before the injection moment, chances are that it's going to ignite before you want it to. And presumably why "they" don't really recommend it. And those who do highly recommend running an exhaust-gas-temperature gauge if you do, as it will help give you warning before you do damage to your engine.

Kubota specifically state in their manual that the introduction of any form of gaseous fuel in to the intake will void your warranty. And, supposedly, it's very easy for a technician to identify that this was the cause of engine failure. Meaning no using ether to help start 'em in the cold. Or any other uses of various fuels. Which has me thinking that if I do run propane on mine, I'm not going to do it to run it as a bi-fuel engine, but only just enough to give me a more thorough and clean burn of the diesel. I'm thinking 5 or 10%, no more. Enough to reduce unburnt fuel and maximize efficiency.

I love the idea of getting a third or more of my fuel/energy from propane, but I'm going to be very careful if I start messing around with it. First I'm going to see how well small spark-ignition engines take to running on straight propane, and take it from there.

Well, those are my thoughts on the topic, after my research. Hope it helps someone else.

[oil pan 4]

I have ran propane on my 6.2L diesel which has 22.5:1 compression. You just can't use a lot of propane.
Alcohol is better.

[Isaac Zackary]

Originally Posted by oil pan 4

You do realize that classical boiler design calls for 8 to 10 square feet of boiler heat exchanger surface area.
Compact boilers that weigh a ton or so make less than 10 horsepower.
Thean reason to use a boiler is so that you can burn something that doesn't burn so well in a piston driven application. Something like coal, wood or bunker oil.

Are we talking a classic design or a modern design? If I do a steam engine I would do a monotube boiler. Here's one that has 80 square feet of surface area, can handle up to 1,000psi, only weighs 350lbs dry and is good for up to 125hp.

Boilers Page of Reliable Steam Engine Co. Maker of Steam Engines, Boilers, and Accessories.

I wouldn't need one that big of course. But yes, by the time I add on a condenser, water tank, fuel tank and an economizer I'd be in the 1,000lb - 1,500lb area. Still not too much to throw on a trailer and pull with a Nissan Leaf though.

[Isaac Zackary]

Originally Posted by Stubby79

From what else I've clued in to, it's not just the more modern direct-injection and or common-rail that time the injection at just the right moment. The older, mechanical indirect injection engines do too. They inject it at or a hair before or (as I believe it actually is) after the piston hits TDC, to control when ignition occurs. If it happens too soon, the piston coming up is going to hit all that combustion pressure and bad things are going to happen to the inside of your engine. If it happens too late, well, it might not ignite, or you've just wasted the most efficient time for combustion and lost power.

It's a lot more complicated than that. You can only get so much fuel sprayed through tiny injector orifices. So the injection period takes a certain amount of time. The faster the engine goes the more that injection timing must be advanced. But just as in a spark ignited engine, changing the injection(ignition) timing not only affects efficiency and even engine longevity, it affects emissions.

Modern common rail diesels not only can precisely control the time the injection begins but can also pulsate and inject a smaller amount of fuel over a longer period of time. This allows for more turbulent air to flow past the injector and receive less fuel, which causes less local enrichment and therefore less NOx and PM formation.

One solution on a mechanically injected diesel that's running at a constant RPM and load is to size the injector nozzles so that they spray a precise amount over a precise time period at that particular RPM and Load. This might be fine for a pusher engine that runs at such a constant speed and load since the EV can easily add or subtract from that load to maintain a fixed highway speed.

[Stubby79]

Originally Posted by Isaac Zackary

It's a lot more complicated than that.

It certainly is! I was trying to keep my explanation...reasonable.

Of course, OTOH, if I had an old VW diesel that didn't cost me anything and I didn't care about, I'd probably go gung-ho on the propane idea. My kubota was a sweet deal...and it's both worth a lot more on paper as well as to me personally than I paid for it. So I'm not about to start wild experiments with it.

Not read a lot about VW's running propane. Truck engines, yes. Guys trying to boost their power and or run a cheaper fuel. VWs and smaller? Can't find many examples of it. Might be a reason?

On the subject of steam engines...from Wikipedia: "In practice, a steam engine exhausting the steam to atmosphere will typically have an efficiency (including the boiler) in the range of 1-10%, but with the addition of a condenser and multiple expansion, and high steam pressure/temperature, it may be greatly improved, historically into the regime of 10-20%, and very rarely slightly higher."

[ThermionicScott]

Steam engines blew up with fatal results often enough when built and operated by professionals. I'd leave it a thought experiment.

[freebeard]

Or use naptha instead of water?

https://en.wikipedia.org/wiki/Naphtha_launch

[Isaac Zackary]

Originally Posted by ThermionicScott

Steam engines blew up with fatal results often enough when built and operated by professionals. I'd leave it a thought experiment.

And diesel engines can spring a leak in the injector lines which can fatally hypodermically inject diesel fuel into your body (which I've gotten injection line leaks twice so far in my diesel.)

The reason that steam engines exploded is from using a tank type boiler. This also remedied by using a monotube boiler. In a worse case scenario a section of the boiler tube will break apart and you'd have a scalding hot stream of steam coming out, but no explosion due to the inability of a large pool of water to flash boil.

[freebeard]

It would be hard to go wrong with a 3D-printed (plus CNC tube bending) 1/2 scale model of the Doble drivetrain.

[Isaac Zackary]

Originally Posted by freebeard

It would be hard to go wrong with a 3D-printed (plus CNC tube bending) 1/2 scale model of the Doble drivetrain.

The Doble Model E had an inline, double expansion (no pun intended), double acting (again, no pun intended), four cylinder engine. It had piston valves. I'm not so sure what kind of cylinder and valve timing it had. Probably like many late model steamers the valve timing was variable. (And we think we're so far ahead with variable valve timing on our ICE's!) it had a steam pressure of up to 750 psi (52 bar) and a temperature of up to 750 °F (400 °C). The acceleration was said to be comparable to a Duesenburg (0 to 60mph in around 8 seconds.) The neat thing about the Doble was the keyed 30 second starting system. It was as easy as, put in your key, turn and go.