Micro CoGen.

Bruce,

Sorry tht I didn't reply to your #3 question before: I did a lot of "bench testing" with the Generac governor electronics drive.  I was able to use a signal generator at 60 Hz +/- (for testing stepper motor direction and shaft acceleration speed) down to just a few volts with it still operating properly; and, it was spec'd to bettter than 250 VAC for sensing inputs too!  Very wide sense-lead operating range.

I'ts designed to be directly connectable to 120 VAC - maybe even for 240 (check some of the generac drawings to confirm); I'd use'd it directly on the 120 output (with 1K ohm 1-watt [for their 1000 V voltage rating - yes, resistors have voltage ratings!] resistors in series with each of the sensing leads, and a 0.1 uF 300V-rated non-polarized capacitor across the leads at the electronics module (to "filter" for "noise") - just for extra "protection" of the governor electronics.

Hope this helps you (and others).

Regards,   JLB

Horsepoor,

IMHO, several years back, I pondered the same plan to use the mechanical governor, with the electronics as assist, because it seemed as if it would work great.  Never did impement it to try, though.  I'd certainly be very interested in the results of your implementation; as, probably, are many others here.

As previously posted here (above someplace), I used a stepper motor (free) out of an old printer: It just needs to be 12V / two-winding (4-lead), as I recall (haven't looked at it recently - and, many other "irons in the fire").  One of the Generac wiring diagrams should confirm that.

Regards,   JLB

Steve,

Thanks for the continued interest and reply.

I need to point-out, though, that gaseous-fueled (propane / NG) is of higher efficiency when kept cooler (even cold); the drawback is that if "too" cold, condensation problems rear their ugly head in the engine, causing other "issues".  My personal opinion is that about 160 deg F is a good compromise for those fuels.

Regards,   JLB

Michael,

In very general terms: For constant lower-speed engines (such as for 1,800 RPM generators), IMHO, least-cylinder count, large-mass (big flywheel) engines will beat anything else hands-down for fuel efficiency due to much lower parasitic losses.

Most of us "modern" folks are so used to automobile engines, that we don't think about the application.

Auto I. C. engines have historically been designed to provide maximum peak horsepower in the smallest package with "smooth-running" (read that many cylinders with overlapping power pulses), and very quick RPM-change response. This has lead to 8 or more cylinder engines of small individual cylinder displacement (relatively speaking) with very lightweight materials for "economy" and quick acceleraion.  And we all tend to "stick our foot through the floor"!

Stationary I. C. engines used for constant-speed generators are much more fuel-efficient if they are built as the smallest average-horsepower needed, with a large (more massive) flywheel to "average-out" the power pulses; and, to provide "peaking" power when needed for electrical motor starts, etc.


The Geo Metro 3-cyl  engine has a particular attribute of readily-available engines: It's very best fuel-use-to-power-output performance is at about 2100 RPM; and, 1,800 RPM is close to that, so it's actually very good for this generator application.

As for your question about listeroid vs changfa: I don't know. There are a lot better-informed people on here than I to answer that question.

Regards,   JLB

Michael,

Less Cylinders with the same displacement will reduce parasitic friction, thus increasing "efficiency" of fuel use: There are several white papers out on the web specifically addressing this and piston-ring design (one from MIT - I'll try to post the paper during my lunch break here at work). Some really interesting information; one point is that if the compression rings (especially the top one) has a "positive" twist (that is "upward" at the cylinder wall from the piston wall) built-in, this substantially reduces friction without substantially affecting compression and ignition sealing!

Most modern low-friction "european" designs now have this "twist" manufactured into the rings.

More later.

Regards,   JLB

Bio,

F. Y. I: There is a very specific reason I went for the Geo 3-cyl: Less total cylinders means less "parasitic" friction internally (plus it has a "low-friction" piston-ring design).  A lot of folks don't realize that this particular issue can make a very huge difference in the effective fuel "efficiency", as with less internal friction, there is more power available for external use, while using the same amount of fuel.  Put another way, it will use less fuel for the same amount of external power needed.  This can be upwards of 30% difference for the same application!

Regards,   JLB

Bio,

Just "bumping", as I'm curious as to any futher progress with your query here.

Regards,   JLB

Bio,

I was pricing a fuel block only, not the complete kit.  Most of "us" folks usually have access to parts and pieces, and don't need the full kit.  If an CCK generator end is obtained, my assumption would be that it's (probably "blown") engine and attached carburetor would also be available in most cases; and, most of those were already setup in RV's for LP; so, they may also have the fuel system available ( low-pressure regulator, demand regulator, fuel block, etc.  Then, again, maybe I'm assuming too much here.

US Carb's has the full kit for around $170.00, as you say.

Actually, with some precise drilling and a "fab'd" outlet with a control valve, anybody can actually make a "homemade" conversion to most existing carburetors.

Regards,  JLB

Biohazard,

Please note that I used a free stepper motor out of an old printer - it's a standard 4-wire 12 volt, and works just fine with the Generac electronic governor.  It's body is roughtly a 2" cube in size.  I could have gone smaller, but this is what was at-hand.

Most throttle plates are "neutral" mounted on the shaft (that is, the air-stream through the carburetor presents no biased torque to overcome; so, it usually takes only a very minimum-size motor to control it (if the throttle-shaft bearings / bushings are in reasonable condition.

Regards,   JLB

AdeV

The OP wanted something in the $2,000.00 or under range.

Regards,   JLB

Folks,

I did a little research into my back-files, and found the Generac governor part number: 098647.

Hookup information is found in Manual P/N 79699, pp16, Figure 20.

I hope this helps someone.

Regards,   JLB

SteveU,

Please feel free to "spread the word" as you see fit.  My personal philosophy is that that's what these forums are for.

Your comments about woodgas are interesting to me in this conversation because I specifically chose a spark-ignited engine potentially for that very use if (when???) fossil fuels become prohibitively expensive (diesel won't do any good then).

I've been around a bunch of these related forums for years; but, just joined this one.

Spouse and I are totally "off-grid" (though still running too much propane with backup generator!), and slowly moving toward more independence from fossil fuels.

My Geo Metro setup hasn't been used for a while now, as I ran-into a NOS Kohler commercial water-cooled unit for a real steal (under $1K for a unit 10Kw unit with 0.7 hrs on it!).  Absolutely couldn't pass that one up as it also has the "wet" exhaust manifold which will help in recovering even more heat.

If I get a chance, I'll try to I. D. the Generac governor electronics; I bought it from a distributor our of Milwaukee WI - though, I don't remember their name now.

Regards,   JLB

Folks,

Very sorry, don't have any pictures.  Looks crude (as my prototype), but works fine.

Governor is Generac (not particularily "in-love" with Generac); don't have electronics model number handy as was purchased several years back. It's one of theirs that uses the generated 60 Hz to derive control; works with a 4-wire stepper motor.

I have it coupled to the throttle plate via a home3-made "coil-spring" (about ten turns of so of stainless wire) wound slightly tighter than the shaft diameters, then forced onto each shaft.  This kind of coupling helps provide a "cusion" for sudden changes and inherent vibration, and helps with any slight misalignment of the two shafts.

That's about it, except to note that the CCK generators can really take an awful beating with regard to overload and surges: Under room-temperature circumstances, they can usually "take" 150% of rated load for many, many, minutes (1/2 to 1 hr??), and a 200% surge load for up to about 30 seconds (way "overbuilt" according to today's "standards").

For more information on these old Onan's, go to the "Smokstak Onan" forum (easy to search-out).

Must start work now.

Regards,   JLB

Biohazard,

Geo Metro 3-cyl 1 L engine (~$200.00) coupled to an Onan CCK 4KW gen end (~$200.00); use a Generac governor electronics (~170.00) driving a stepper motor (free) on the caburetor throttle-plate, and add an LPG (propane) / Natural Gas fuel adapter (for those fuels  ~$70.00).  Use a stainless swimming pool heat exchanger (~400.00) to run the cooling system water through to capture exhaust heat too.  Have a base and adapter fabricated (~$200.00 ??) Total will be well within your proposed budget.

I've done this.  Had an adapter plate made to match output clutch shaft with generator head; left engine flywheel, clutch, and pressure-plate in-place to provied additional "flywheel" mass for electrical surges.

Regards,   JLB