Build generator with Yanmar engine

thomasinnv · September 06, 2017, 09:40:43 AM

Better to oversize and not need it, going to be the same fuel usage for the same kw output reggardless of the size of the generator head. If it is a 16hp i would probably go with around a 8-10kw head. You need to knlw what the hp is at the rpm you will be setting it at. I would think 1800. You can get a head for 1800 with same size pullys or 3600 with 2 to 1 pullys. Definately go with a cogged belt setup though.

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richard5933 · September 06, 2017, 12:11:14 PM

Belts and pulleys work, but if it's possible to just bolt a generator head to the engine that would get my vote. Certainly more compact, certainly less maintenance. Belts & pulleys seem like just one more thing to go wrong that doesn't need to be there.

The process of mounting the head to the engine took us less than 30 minutes. Would have taken even less time if the guy helping me hadn't dawdled crossing the street to my shop

There are adapter plates and flex plates to fit most common flywheel/bell housing sizes, so it can't hurt to ask about that when you talk to whoever you're going to buy the generator head from.

Richard

Scott & Heather · September 06, 2017, 05:55:20 PM

I agree, bolting direct would be beSt. I'm going to be calling wrico as soon as I get a free moment. I might stop by them when I'm passing by Eugene

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Dave5Cs · September 07, 2017, 08:55:19 AM

Ours is 7KW Kolher head bolted to a 24 HP Kuboda 3 cylinder. It has 9,036 hours and still running strong. Just replaced the Thermostat and change oil every year as well as filters. Blow out the old condenser hole because a lot of road dirt get in there with the air inlet from the bottom.

luvrbus · September 07, 2017, 11:02:05 AM

Do a lot of research before buying a head,I used a M/B engine from a refer trailer one time and bought a 10kw head the the harmonic distortion was so far off on the head a light bulb was about the only thing you could run off it,look for a head under 5% harmonic distortion .A 16 hp engine should run a 7kw head but no more

thomasinnv · September 07, 2017, 11:14:40 AM

Kubota says their 15.6hp 3 cyl will run up to 11.6kw continuous, of course thats going to be at sea level. I would take into consideration hp derating for altitude as well. Higher you go, lower kw output you are going to get from the engine. Definately better to go bigger than you think you will need. Don't want to be camping up at 10k feet and overload on a hair dryer lol.

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Scott & Heather · September 08, 2017, 06:02:36 AM

Ok, so one final quick question. Is there a specific reason for 1800rpm? What would stop someone from running the genny slightly lower RPM, say 1500 and using pulleys and a belt to achieve 1800 on the generator head side? Would this save fuel?

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richard5933 · September 08, 2017, 06:18:00 AM

The generator heads are designed to produce the proper voltage and frequency (60hz in US) at a particular speed. If you're going to bolt directly to the engine, then you'll need to have a way to set the engine speed to the proper speed. Most diesel generators run at 1800 rpm. A few run at 3600, but they are generally much noisier and not ideal. Even with the pretty decent voltage regulator on the new generator heads, get the rpm off just a bit and you'll be producing the proper voltage but at the wrong frequency. You can run an electric motor at frequencies other than 60 hz, but there will be consequences (most not good.)

I suppose you could run the engine at a lower speed and the run generator through pulleys to get the proper speed, but I don't think you'll save any fuel. It will take the exact same amount of energy to produce the desired electrical current and I don't think that there will be any great efficiency different on the engine between 1500 and 1800 rpm. I'm not good at formulas, but I'm sure that there is one which shows how many BTUs of diesel burning are necessary to produce a kw of electricity.

If you go the pulley route instead of the direct bolt-on method, you'll also have to deal with the extra drag and heat generated by the belts and pulleys. That will of course lower your efficiency a tad. You'll also have a larger setup as there will need to be room between the generator and engine for the pulley setup.

I've run a wood furniture business for many years, and whenever someone asks me to build something that is outside the traditional way of doing things I have to ask if there is a reason for things being done the way they are. Usually there is. I think that the same thing applies here. If most of the RV generators use a head bolted directly to the engine running at 1800 rpm, I'd have to start with the assumption that there is a reason. Could someone create something which works equally through some other method? Sure. Would I bother trying? Probably not when the tried and true method works well and is not difficult.

blue_goose · September 08, 2017, 07:56:44 AM

If you are going by Wrinco They will give you all the info you need. If you want they will build the generator for you with your engine. I parked in there lot while they rewired my generator with there safety shut down. They are great people.
Jack

TomC · September 08, 2017, 10:39:37 AM

Most small Diesels have to be tuned to run down at 1800. If you go on site to Kubota, you'll notice special engines that are rated at 1800. Going to 1500 could lug the engine. If anything, run the engine at 2200 and belt drive it down to 1800. Whatever rpm the engine is doing, alternators are made in 60hz mathematical rpms. Like 900, 1200, 1800, 3600. I've seen some 1200 alternators used with slow running Diesels (think Lister 2 bangers) to get rpm-but these are big, noisy, but long lasting-good for home standby use. Good Luck, TomC

opus · September 08, 2017, 11:03:22 AM

I glued these together, which I wouldnt recommend. Works great though, got everything at no cost so I had to do something.

https://youtu.be/-gsQBKDOE2Q

eagle19952 · September 08, 2017, 10:21:38 PM

Quote from: Scott & Heather on September 08, 2017, 06:02:36 AM
Ok, so one final quick question. Is there a specific reason for 1800rpm? What would stop someone from running the genny slightly lower RPM, say 1500 and using pulleys and a belt to achieve 1800 on the generator head side? Would this save fuel?

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load decides fuel consumption regardless the rpm.

TomC · September 09, 2017, 08:56:41 AM

There is a definite difference in fuel consumption from a 1800 to 3600 engine. But these small Diesels are so fuel efficient, that the difference won't be very noticeable. Direct driven 1800 is the best. Using a 3 or 4 cylinder engine-2cylinder engines are rough-Except Onan DJB engine that is the only even firing 2 cylinder I know of (both pistons move up and down together). Good Luck, TomC

Scott & Heather · September 09, 2017, 05:41:44 PM

Ok I've taken the time to read every response and it answers my question. All a learning curve for me. Thank you so much. Opus, I love that genny. Cool project

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Scott & Heather · September 11, 2017, 11:06:05 AM

So I just spoke with Justin at Wrico. I haven't yet determined the style of my engine (will do that this week), but if it's an industrial engine it won't have an SAE bellhousing which is a show stopper according to him. Also, no electronic governor to keep it at 1800 rpm. Also a $1500 add on. He's saying it might be more money to put this together than to just buy one. $6200 for a new unit is a lot of dough tho. I really wish I could find a cheap 1800 rpm governor for this engine along with a proper SAE bellhousing because if I can, I can bring the engine to him and get a head for around d $2000 which i can easily recover selling my hondas. I'm bummed.

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