Engine for natural gas generator

[Procrustes]

I've gotten the mechanical bug a little bit with this Lister stuff.  For my next project I plan to build a natural gas backup generator around 15-20kW.  Ideally I want a water cooled, quiet engine with parts that are easy to find and that is easy to work on.  Weight's not an issue.  I'm assuming that I'll end up converting a gasoline engine.  Any ideas?  Would a slant six running at 1800rpm be a good bet?

[Rtqii]

http://www.cooksengine.com/

http://www.cooksengine.com/product-66-AJAX_E_42-24.html

http://www.arrowengine.com/

I dunno... I still kinda like large flywheels...

[Procrustes]

Those flywheels look plenty big to me.  Seriously though, yes I've looked at the Arrow and Ajax and Witte engines.  They're very expensive and huge.  Part of my goal is to rebuild another engine anyway, not buy a  new one.  Inline sixes are available for a couple hundred or so, so I don't see that I can go far wrong in that direction.

[europachris]

Kohler used a lot of the Ford 6-cyl inline engines on propane or natural gas sets (and probably still does).  I think it was the 300 cid verision, no?

Should be able to find one of those in pretty good shape and be able to rebuild it cheap.  Maybe you'd even be able to find a complete generator that needs fixing up?  That way you'd have the proper governor, etc. already to go!

chris

[fuddyduddy]

Don't know about new, but the  last I heard the used, high quality oil patch natural gas slow-speed engines started at around $10,000 .  Would imagine that the diesel engines would go for thousands more (again, used).

About the cheapest route would be a good used Mercedes diesel and inject propane into the intake. Use idle diesel for iginition. Should get 15-20 KW pretty easy that way.  Try Craig's List.

Slant sixes in good shape are getting hard to find.

Good luck!

[aqmxv]

Something like a slant 6 or a 300 CID Ford would be nearly perfect.  Either would deliver amazing life at a constant 1800 RPM.  A lot of these were used in irrigation country as well pumps back when when natural gas was available cheaply (Texas panhandle).  I know that Caterpillar made a lot of SI engines for gas, but I think most are too big for your purposes...

[rcavictim]

I`ve got an old Hough bucket loader from circa 1950`s that has a huge OHV, 4 cylinder International gasoline engine in it. The block is really tall.  I`ll bet it would be awesome on natural gas running a 1200 RPM (6-pole) alternator.  Tons of slow speed torque. 1800 RPM may be too high revs for it.  If one started with a fresh engine it would probably last at this leisurly speed.  The really long con rod length and stroke of this engine would make for lower frictional losses and longer piston/bore life than a compact car engine.

If anyone can point me to technical info about my engine I`d appreciate it.

[Procrustes]

Kohler used a lot of the Ford 6-cyl inline engines on propane or natural gas sets (and probably still does).  I think it was the 300 cid verision, no?

Should be able to find one of those in pretty good shape and be able to rebuild it cheap.  Maybe you'd even be able to find a complete generator that needs fixing up?  That way you'd have the proper governor, etc. already to go!

chris

Some Onans used Ford industrial inline sixes too.

You're probably right about buying a complete generator.  I've spent a lot of time looking and haven't been able to find one for a reasonable price though.

Does anybody have a clue how many horsepower a Ford 300 inline six would produce at 1800 rpm?  What about a 250?

[mobile_bob]

if i had to guess i would put the 300 at 125 hp on natural gas or propane, and maybe 90 on the 250

bob g

[rcavictim]

I have a gasoline powered Onan 15kW, 18.75 kVA, 3-phase plant that employs an Onan 4 cylinder. OHV gas engine that IIRC is about 115 cu. in.  The alternator is direct drive to the engine at 1800 RPM.  I know that the exact same setup was available with a natural gas carburetor because I`ve seen one. 

A 250 or 300 cu.in. gas engine will be loafing along making 15-20 electrical kW (30-40 hp)..

[Rtqii]

Don't know about new, but the  last I heard the used, high quality oil patch natural gas slow-speed engines started at around $10,000 .  Would imagine that the diesel engines would go for thousands more (again, used).

You guys don't know how to shop 

You need to take a road trip with a truck and trailer down to the permian basin in S. Texas with cash in hand. You pull up to an oilfield scrap dealer, flash a few hundred bucks, and pick up the engine on the spot. There are scrap dealers and used oilfield equipment dealers down there that are using them for parking lot stops, and they will cut cash deals on equipment they know is never going back into commercial service.

Shipping costs are really up due to increased fuel costs, these engines are not going anywhere and there is not enough demand or profit to market them. Most of the permian basin in S. Texas has been electrified... There are electric motors pulling the oil out of the wells today, not gas engines. Hundreds and hundreds of gas engines have been retired, the captial investment put into these engines has been written down to $0 on profit and loss tax statements, and the iron was sold for a buck or two a pound.

Not worth the trip you say? Too much trouble?

How much were you quoting for these engines? How much can you save doing a Texas cash deal on the spot?

I was down there just a few weeks ago, I saw dozens of these engines in several oil field salvage yards, and yes, they were using them for parking lot stops!!!!

[Doug Waggonner]

Its not just south Texas, used oilfield engines are everywhere. Just gotta know where to find them.  I bought 16 Fairbanks Morse engines in Kansas last summer. Ranging in size from 12hp to 30hp.  I've sold them all off except for one, a Fairbanks ZC 18hp 346,  It needs rebuilt but its not stuck, if any of you guys are interested let me know. 

[aqmxv]

When I re-read the original post, I realized how little power we're talking about here - a 300 CI engine (or even a 225 slant 6) wouldn't be making enough power to be happy at only 20KW.  And frankly, anybody not running serious machinery a lot of the time probably doesn't need more than 20KW for a house.

If this is going to be a backup generator, and you only want it for power, and only for 30-35 HP, I am going to risk derision and point out two choices you may not have considered:

1) a type 1-3 VW engine (1600 CC, big oil cooler).  Or a type IV (105-130 CI) up to if you think 100 CI isn't enough to get the job done.  Small, cheap, simple, parts and engines available everywhere, air cooled, so no winter water jacket worries, and easily capable of 40 HP all day long.  IMPCO has made carburetors in this size range forever for forklifts and the like, so gas carburetion is cheap and simple.  Downsides:  They're not really all *that* reliable, require some tweaking, and they have that VW 4-cylinder burble you may not like in the back yard at full song.  Availability of 35 HP at 1800 RPM on the smaller engine might be a bit marginal, so you might have to go belt drive to get up to about 2500 RPM at the crank.  A type 4 coluld easily drive at 1800 all day for that kind of power, but parts are kind of expensive, which leads me to:

2) a corvair engine direct drive at 1800 RPM.  35 HP at 1800 is about right for the smaller (and cheaper) 145 CI engine .  Being a six-cylinder, it has smoother power pulses and (I think) a nicer exhaust note.  Same lack of water jacket advantage as the VW.  Use the 102 HP heads for high compression (good with methane) and run crossover pipe (cheap and common) to a single gas carburetor.  Looking at a stock engine test report, max power at 1800 is about 45 HP, so 15-20 KW should be enough to keep it warm and happy with good BSFC, but not enough to be a cooling problem.  Stock everything should be fine at this power level for this application - I demand a lot more of my mostly-stock van engine.

I've seen several military/industrial/stationary corvair engine installations (it was the prototype engine for the GAMA Goat, among other things).  If this interests you, I can certainly help with details of such an installation.

[europachris]

That brings up a few points:

1)  Find a good engine takeout from a propane forklift.  They should be around.  A lot of the older ones are flathead.  I think Clark was putting flatheads into forklifts into the 80s.  I think Yale uses Nissan engines.  Very nice.  You'll get almost a complete package, except the generator (muffler, air cleaner, carb, regulators, radiator, etc.).

2)  Ford 2.3L 4-bangers were used a lot as industrial engines.  Might be an option.

Only issue with an air cooled engine (VW, Corvair, etc.) is the noise.  They are not nearly as quiet as a water cooled engine.   1800 rpm helps, but neither the VW nor the Corvair is going to be very happy at that low speed.  You won't get much cooling airflow.

You could also find a used Wisconsin V-4 engine and convert it to propane or natural gas.  Kohler made some nice 15-20 kW sets with these engines.  Don't know what shape or cost you could find these.

Chris

[aqmxv]

I did the math on cooling airflow before I suggested the vair.  Given the lower rev limit of the VW, I'm guessing it'd be OK too.  As long as you don't oversize the gen head, you can demand 20 KW all day long from either a little (145 CI) or big (164 CI) corvair generator and not stress a thing.  Noise?  Yeah, it's somewhat louder than a water pumper running in isolation.  OTOH, you may not have the luxury of pumping the hot water into a well or something similar.  A radiator and fan will add a *lot* of complexity and failure points, and some noise.

For a primary system - I'd go with water cooling and a tank.  For a backup - I'll take the air cooling.  Less stuff to go wrong when sitting.