Ideas wanted for low speed propane engine

[BruceM]

I'd appreciate some ideas for a low speed (<=1200 rpm) engine to run on propane, about 6 hp.   Something with parts readily available would be ideal.

The intended application is for an off grid homestead, for well pumping, washer, air compressor.  Rarely some battery bank charging. My Listeroid 6/1 is doing this same service admirably, but I'd like to find something to run on propane for some new neighbors that don't want to handle diesel fuel.

Any thoughts?

[LowGear]

Bio-Diesel.

Casey

[Henry W]

Finding a propane engine that runs at 1200 rpm are not abundant.

There are some options.

First is set up the Listeroid  to run dual fuel. Propane and diesel. Use propane as the main fuel source and diesel as a pilot.

Second, Look for a Witte or Arrow engine and rebuild it.

Third look for a Petteroid and convert it.

A question is why 1200. An 1800 rpm engine is much easier to find. And it will run for thousands for hours.

[Tom Reed]

Another good option is a Listeroid spark conversion. It looks fairly easy from some of the pics the woodgas guys have posted. A long reach sparkplug will fit right inside the injector hole and compression can be adjusted via shims under the cylinder. That way you can share a common parts supply with the neighbors too.

[Thob]

Depending on where you live, old oilfield engines may be available.  I have a Witte 98RC, but parts may be hard to get for it.  More common is the Fairbanks Morse engines, available in several sizes (118, 208, 346...).  The 118 and 208 are probably in the size you're looking for, frequently they have been fitted with propane carbs (Impco), low oil and over temp shutdowns, etc.  They are made to run long hours, heavy cast iron, low RPM, etc.  They are frequently replaced with electric motors and either wind up being scrap or sold to folks like us.

Here's an add I've seen, I don't this person or anything about what he has for sale:
http://dallas.craigslist.org/ftw/grd/4754445103.html


If you have lots of cash, go for the Arrow line of engines...

[BruceM]

Thanks for the ideas, guys.  I think you've spanned the gamut of possibilities.  Since my possible new neighbor is also disabled and not too handy, I was thinking along the lines of slowing a gas engine down.  Sound and character of the sound is big issue.  He loves the Listeroid (lack of) sound.  Efficiency is not important.

Is there a rule of thumb for derating an engine HP for reduced rpm? 

[Henry W]

If you can get away with 120 volts take a look at thr Honda EU3000IS inverter generator. That generator is the quietest generator I ever been around. They can be set up to run on propane.

[mike90045]

Thanks for the ideas, guys.  I think you've spanned the gamut of possibilities.  Since my possible new neighbor is also disabled and not too handy, I was thinking along the lines of slowing a gas engine down.  Sound and character of the sound is big issue.  He loves the Listeroid (lack of) sound.  Efficiency is not important.

Is there a rule of thumb for derating an engine HP for reduced rpm? 

"He loves the Listeroid (lack of) sound"   How did you do that? Mine clanks and rattles like a barrel of hammers. I think it's the camshaft and the stuff it drives. But the exhaust, plumbed into something suitable, is very quiet.

"Is there a rule of thumb for derating an engine HP for reduced rpm? "  That's going to depend on the torque curve, as you get below the peak, performance is going to suffer.   What sort of HP do your loads nead, then you look for something that the torque & HP curves can match

[buickanddeere]

natural gas a possibility? simple enough to rig one of them.

[vdubnut62]

I have a Kohler KT17 (17hp @3600 horizontally opposed twin)  based 5500 watt RV unit that runs @1800 rpm and has a remote spin on oil filter, I have seen comparable units set up for propane.  Oh and it does have 12volt starting circuits built into the generator head.
A similar setup might be an option if you wanted something off the shelf.
Ron.

[BruceM]

No NG here.
I'll have a look at the Honda Inverter units.  

1800 rpm may be the best I can do for him, in one of the "quiet" propane RV units.   

Thanks for all the good thoughts, gents!

[mobile_bob]

if it were me, and i have also given it a thunk

you might consider an old style cast iron single cylinder like the 16hp b/s or kohler engines

both would have power down to 1200rpm (6hp is probably about right) and either would likely run forever at that low of a load running on propane.

another option might be a 2cylinder wisconsin,  i have one on an old industrial mower and i run it down to about 1200rpm because i am in no hurry and i like the fact that the db go down appreciably with reduction of rpms   the 2 cylinder is very smooth and the darn things seem to run forever.

my mower is a 65 model and the engine is original and likely never has had any overhaul work done... parts are somewhat of an issue for the old girl, but i bet someone has them if needed... i just can't imagine needing any when you really aren't going to be working it that hard.  i think the engine is rated at 18hp @2600rpm which is flat out on this engine.  so i would expect it is still capable of an easy 6hp at 1200rpm?   after all the mower is swinging a 48inch single blade and also propelling the mower which likely weighs a half ton.

either of these engine's at one point or another had propane conversions for them, and likely there are off the shelf parts available to convert one.

myself i am partial to the kohlers, however each has its strong points and all have proven to be pretty long lived tough units... if not the most efficient engines being flatheads, they make up for that with simplicity and rugged construction.

fwiw
bob g

[Henry W]

The Wisconsin engine you are talking about is a great engine. I believe it is the THD model. It is an even firing 2 cylinder engine. The Pistons move up and down together. There is no counterbalance shaft but they era very well balanced engines. The mad another model the was odd firing. It was designed to run higher rpm's. I forgot about the large one lunger Briggs and Kohlers. They do seem to run for a long time. The thing about all these engines is check out parts availability.

[playdiesel]

I agree with the oilfield engine,,, By chance I have one for sale too   

Witte model B that is in real nice mechanical shape. I think itis 9 HP It is set up to run on well head gas. This is one of the later ones with shut down safeties, Has clutch too.
Just like this one that belongs to a friend.

[Thob]

Henry,

Would that v-twin Briggs that you've started playing with run around 1200 RPM and produce 6 HP?  It seems it would be well balanced, but not even firing.  It should be smoother than a single cylinder engine, however.  Or would need a major adjustment to the ignition timing?