Diesel engine and propane

I bought a Champion 3400 watt dual-fuel inverter / generator that I run on propane. I liked the variable speed feature for lower noise, wear and fuel consumption, and the propane for not gumming up with gasoline. Naturally, less than a year later I found something better. Hatz has something similar but diesel and with the option of AC or DC. My question: is there a way to add a measured amount of propane to a diesel generator to reduce diesel consumption? I would think propane would keep the engine oil cleaner and possibly help keep wet stacking / fouling down as well as being cheaper fuel. Maybe this is already being done and my google skills are lacking.

Thoughts?

 

Yes it's already beeing done, search for "diesel LPG conversion". It's not a cheap thing to do, if the manufacturer doesn't offer it as an option I doubt it's economical for a small generator. The kits are specific to the injection type used and have to be installed and calibrated by schooled personnel.

 

Isn't he asking if mixing diesel and lpg is a thing? Sounds insane to me.

 

You might look into methane production from cow manure. Places with lots of cows use the methane to run a generator. I had a dairy and looked into it years ago. There was a guy in South Africa that used a diesel he added spark plugs in place of the injectors and a propane carburetor.

 

No, that's precisely the way it's done, even the big purpose buildt CNG engines still require diesel fuel for the ignition (called pilot jet ignition). If the engine is not purpose buildt for gas fuel only a portion of the diesel can be replaced. The gas side is a multipoint manifold injection as used on petrol conversions, the problems are in convincing the diesel injection to inject proportionately less fuel. Electronically controlled engines are easier then mechanical ones in this respect.

 

I dunno the inns and outs of it as a sole fuel, but pre 2008 diesel standards the hillbillies I knew propane injected their tractor pull trucks on the weekends. Insane was seeing crewcab diesel run past pretty built street cars.

 

The 3400 turns out to be a little large for my application if the water heater is turned off. My idea for the diesel would be to add propane, before plugging in a load, to raise rpm slightly for a cleaner burn. Then when plugged in and house loads cycle the generator would adjust the diesel as before. I'm not very familiar with LPG. I do know leaning out gasoline raises temperatures and eventually to pre-ignition. If there is a minimum air/LPG ratio, I'll have to think of something else.

 

It would not reduce diesel consumption or make it burn cleaner, it would just increase the engines power (as exemplified by post #6). All you will achive is burning out the generating head or the electronics.

 

I've found the lifted pickup crowd are running about 4:1 diesel to LPG on the dyno pulls. I would be nowhere near that, just a trickle to raise the no-load rpm. Looks like I'll have to rent a moving truck to experiment on...just kidding.

 

No, you mix the propane with the air, generally using a liquid propane fuel injector. Most add-ons are throttle body set-ups. For Bigger Engines like Class 8, It's multipoint injection into a custom adaptor plate. Automotive kits run about $6,000 for the engine side and double that for the fuel tank and fuel control system. That's a fleet price if you want 50 of them. A friend of mine is booked three years out now, mostly with utility company fleet vehicles. Class 8 straight CNG monofuel conversions run about +$45K out the factory (Cummins).

 

Has anyone put propane in a small diesel? My thought is taking a regulator off of a BBQ and running a hose into the air filter to experiment with. The goal is better economy / lower operating cost, not more power.

 

For a boat there are some issues you will run into. Propane is denser than air, so it will accumulate in the bilges. That will require a bilge blower. Also, the alternator, relays and all other electrics in the diesel must be changed to spark/explosion protected. As far a lower operating cost, propane is not cheap unless bought in large quantities.

 

Saw this pop back up so texted an old friend who had a system on his old 7.3 power stroke. At some point he also has a propane injected samurai, so figured he'd have some opinions. Ended up having a fun conversation that included actually remembering to ask the salient propane questions.

They uses the propane initially to bring down egts on big hill climbs pulling bull wagons in the mountains. At the time diesel was a little over a dollar and propane was 70 ish cents a gallon. Guys noticed it helped diesel mpg, at the cost of burning a second cheaper fuel. Most only injected with a kit (that seems to still be floating around these days for not much money) when pulling hard. On lighter loads they had pre detonation issues and the engines would ping.

On the gas rig there was a conversion kit available at the time. Late 90s there was a big push for lng and propane to take over from gas much like today with electricity gets pushed now. Was a bit better infrastructure at the time, friends family had an old chevy 3+3 pickup that was propane. The samurai got the fuel conversion as it would stall on heavy off camber trails due to carburetor float issues. It did solve that, but dropped vehicle range so profoundly the kit was removed and replaced with a modern efi system. Solved the off camber solution and the range issue.

Not sure a diesel is gonna be long lived on pure propane, would think the cats that are propane have different cylinder and ring systems and fuel injection. Even the switch to ulsd had cylinder wear problems from lack of lubrication.

Unless propane is substantially cheaper it seems like a hassle. Was at the fuel stop that's one of the cheapest in the state yesterday. On road diesel was 3.75, offroad was 3.49 and propane was 3.78. It would have to be half that for me to bother.

 

A diesel is controlled by a governor that maintains rpm. It does that by either sending more or less fuel to injectors or changing injector settings in mechanical injectors. Propane added in a small amount is like adding fuel and if everything works perfectly, the governor reduces fuel to maintain rpm. But one issue is timing and the ignition temperature of propane. When diesel is injected the cylinder is at high pressure, the air is well above diesel's ignition temp of about 500°F so the spray ignites. Propane's ignition temp in air is about 950°F so should ignite with the diesel. But it could ignite early causing problems.
I use a self built hydrogen generator to produce hydrogen and oxygen from water with potassium hydroxide added using spare amps from my alternators. I add the hydrogen and oxygen to the intake of two Detroit Diesels and see a mileage increase of about 20%. Or I use the same system to ad to a 4 cylinder generator and see about a 25% savings in diesel. When the power is off, the production ends and no explosive gas is stored.

 

The difference is that hydrogen is less dense than air and will not accumulate in the bilges.