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?
Bio-Diesel.
Casey
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.
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.
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...
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?
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.
Quote from: BruceM on November 21, 2014, 09:48:49 PM
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
natural gas a possibility? simple enough to rig one of them.
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.
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!
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
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.
I agree with the oilfield engine,,, By chance I have one for sale too :P
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.
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?
I would not recommend it. I believe idle speed is around 1200 rpm. i would keep it within recommended operating speed. I believe the lowest recommended speed is 1800 rpm. Recommended max net BHP is just under 7 hp. It seems like it might work.
Log in and look at the charts below.
If you want a slower speed Briggs v-twin than I would try to look for a 14 hp vanguard v-twin. It has more hp than the 16 hp v-twin until they get to 2600 rpm's. Than the 16 hp v-twin starts pulling away from the 14. My understanding is that the only differance between the two engines is carburetors. The peak torque curve on the 14 is at 2000 rpm. The 16 is at 2600 rpm. But I've heard from the Briggs application engineer that I spoke to that the 16hp peak torque curve is closer to 2400 rpm.
It is surprising how quiet these engines are at 2600 rpm's.
Second picture
Here is one similar to the one that I will be building.
http://www.generatorsales.com/order/Slow-Turning-Propane-Generator.asp?page=S6500
Instead of using a two pole head I will be using a four pole. I will experiment running it at 2600 and 3000 rpm's.
Odd they are specing 15w40 in it...wonder if they have cleared it with briggs .....one more thing...i may be wrong but im not sure any of the big manufacturers (briggs,kohler,honda)have certified and will warranty there engines to run on lp/ng ....obviously these guys are doin it but may be taking the warranty/risk on themselves instead....gonna do some investigating...
I was wondering about the oil also. Briggs says only use a 30, 10-30 or 5-30 grade oil. They are also recommending synthetic 5-30 from the start if customers want to use it. I am not sure about LP or natural gas. You could be right that they are taking all the risks.
Somebody is...doesnt look like briggs is or wants too....
http://www.briggsandstratton.com/us/en/support/faqs/alternate-lp-ng-propane-fuel-conversion
Why not use a small Car engine?
Would easily do the HP and torque you want at the revs you are after and LPG kits are available as bolt on's for any engine. You could probably get one cheap at a wreckers and the longevity even on a good used engine would outlast modern stationary engine brands. Would be quiet being water cooled and easy to get any parts for.
Glort,
We are discussing about an engine that will put out around 6hp at lower rpm's. An auto engine would have too much friction loss from the extra resipicating parts and in turn it would not be very fuel efficient. There are some small three cylinder engines available that I would consider for applications near 7kW.
There is a small single cylinder modern stationary engine that Briggs manufactured back in the late 80's. It was a 272 cc, single-cylinder, four- cycle, liquid-cooled engine rated 7.5 hp. The engine ran from 1200 to 3600 rpm. The engine features a 4000-hour service interval and a 40,000-hour life.
Thanks for the continued good thoughts and helping with my engine education!
Air cooled does create a design issue in dumping that heat from the engine shed without leaking sound as well. I've read one author that suggested a pair of squirrel cage blowers to address that since the blower housing acts as a sound baffle. The loss for the blowers just needs to be figured in the total power and overall efficiency, and I don't think it's a show stopper at all.
Here is a design for making a sound resistant generator shed. My Vanguard project will be on a trailer. I will be using the same design principles in the drawing below.
Henry
Quote from: hwew on November 23, 2014, 01:25:55 PM
Here is a design for making a sound resistant generator shed.....
I'd like to see that exhaust take another 45 deg down and away from the eves. The sound traps are very reminiscent of light traps for a darkroom.
Having the exhaust angled down is a good idea. I like it.
http://www.marathonengine.com/
For a senior probably an off the shelf generator that can be bought and serviced anywhere maybe a consideration.
Variable speed inverter generators in particular need to be over sized if starting motor loads while on eco variable mode.
Pressurepro, you beat me to it.
Thanks,
Going to have my new neighbor check out another friend's 2200 rpm propane generator later this week. It's one of those "quiet" park approved jobs. That will give him a point of comparison, anyway.
Veggie sent me some good info on some older 1800 rpm Winco - Briggs direct coupled units. Interesting.
Here is what I was thinking as a possible alternative...
Search ebay for a vintage WINCO generator with the AllCast Iron briggs engine.
(Circa 1970's and 80's)
They run at 1800 rpm and a surprisingly quiet.
The winco generator head was made to direct couple to the Briggs engine and makes for a nice compact unit. Like having an ST head connected to the engine.
The winco heads are heavy cast iron and last forever.
Here is a video of the exact unit I am suggesting.
https://www.youtube.com/watch?v=gMKd4YpwkvM (https://www.youtube.com/watch?v=gMKd4YpwkvM)
I believe some also came with electric starters.
I am in the process of reconditioning one of these right now. I may have found one of the very few left in Canada. However, they seem to be popular on USA Ebay.
I can tell you that the engines are built like a Lister. Heavy cast iron block and cylinder with Stellite valves and replaceable seats. Mine is 25 years old and is still within specs. Should last another 25 years. :D
The reason I wanted one is because the generator is compact and it is a 4 pole unit @ 1800 rpm. Makes for a quiet and long lasting machine.
They can also be converted to Propane or Natural gas.
BruceM, good luck with your search,
veggie
I've built a few 1800 RPM LP generators using a Kubota DF972 engine. You can get about 6 kw output at that speed. If you want a DC output you can run the engine slower. Idle set point on them is 1500. With an electronic governor you could probably go down to 1200 RPM. This engine would outlast any air cooled engine if it is going to run for a significant amount of time per year.
SPSinc,
Is that a Diesel Kubota converted to gas? or a spark ignition (Gasoline) Kubota ?
veggie
It is a spark ignited (dual fuel, LP or gasoline) Kubota. The engine block is the same as the diesel D902. The latest tier models are called WG972 instead of DF972.
Quote from: BruceM on November 23, 2014, 09:09:39 AM
Thanks for the continued good thoughts and helping with my engine education!
Air cooled does create a design issue in dumping that heat from the engine shed without leaking sound as well. I've read one author that suggested a pair of squirrel cage blowers to address that since the blower housing acts as a sound baffle. The loss for the blowers just needs to be figured in the total power and overall efficiency, and I don't think it's a show stopper at all.
Bruce, sorry I missed this post earlier! Some of the RV units I wrote about (mine is one) have a sort of reverse cooling setup. The flywheel has a sort of squirrel cage blower that sucks
air across the engine and is ducted outside the "engine compartment" as it were.
Ron