240D engine to be used for a Generator (info needed) - PeachParts Mercedes-Benz Forum

80's old school · #1 02-11-2009, 12:03 PM

I live on the Gulf coast and have been wanting to build a large standby generator. Now I have located where I can get 15,20,or 25 KW heads.

My question is, what would be the best way to couple the engine to the generator head? I will mount the engine, radiator, fuel tank, and generator head on a skid. I am trying to create the most cost effective way to couple the two.

BTW, the engine is an automatic transmission engine.

jt20 · #2 02-11-2009, 02:11 PM

is the stock trans too much of a loss for you? Determine the most optimal RPM range based off someone's dyno sheet and find the corresponding gear through trial runs kW output.

jt20 · #3 02-11-2009, 03:16 PM

http://www.peachparts.com/shopforum/sitemap/t-102511.html

MBNRA · #4 02-11-2009, 04:15 PM

I don't mean to dampen your enthusiasm, but vehicle engines are not the best type of engine for this! They are meant to provide varying RPM's and power levels and will not hold one constant RPM and be governed well connected to a GenSet. I would seriously look into a Perkins, Yanmar or Hatz. I would look into a Hatz. There are really durable air cooled diesels and this company has been around since the turn of the last century! They make excellent diesels for industrial power service and this is what you are trying to do. I honestly do not think that a 240D engine will do the trick for you if it came out of a car.

What you need is something in the 30 to 42 horsepower range. If you have the time, I would also recommend a Listeroid engine for your project! They are much better on fuel and easy to start by hand! There have been successful Listeroid homemade gensets that deliver amazing results for very little fuel and these are designed to run for long periods at a time and handle varying loads better than a lot of others and no governor is necessary because of their design.

Try this link for some ideas: http://www.listeroid.com/

This link is to a great site called UtterPower and their CD on Lister Engines is worth the $20 bucks alone for offering real practical guidance for the Home Do it your selfer who wants to build a genset. This site and the links at both are worth a read!

http://www.utterpower.com/ Good luck and let us know hiow it turns out!

Stevo · #5 02-11-2009, 08:26 PM

That Listeroid would be the "ideal" stationery gen set, but as a second option I would look for a marine unit out of a fish boat or yacht, someone thats up grading for more KW. One shouldn't be hard to find around a large port.

47dodge · #6 02-11-2009, 08:29 PM

what is your source for generator heads?, and are they 1800 rpms? I have several "Thermo-King" engines, that did have generaters on them and am looking for a 15kw head.

47dodge · #7 02-11-2009, 08:41 PM

Although there are other engines built for generating, I see no real reason that the 240d engine would be not suited, other then not having a governer. You really would need to adapt one to the engine. But other then that you are well within the rated power, and rated duty. I can understand using what one has on hand if it will work, rather then looking for the "right" engine. Depending on the rpm's of the generater a direct drive without the transmission would be best. Do stay away from belt drives, unless side load from the belts are taken by bearings other then the engine. In other words use a short piece of drive shaft to a pulley with a bearing on each side of the pulley to take the load.

jt20 · #8 02-11-2009, 09:37 PM

Quote:

Originally Posted by 80's old school

I live on the Gulf coast and have been wanting to build a large standby generator. Now I have located where I can get 15,20,or 25 KW heads.

My question is, what would be the best way to couple the engine to the generator head? I will mount the engine, radiator, fuel tank, and generator head on a skid. I am trying to create the most cost effective way to couple the two.

BTW, the engine is an automatic transmission engine.

It seems everyone except 47Dodge missed this crucial statement.

As long as this isn't going to be providing energy for a small village, I see no reason to believe that the costs incurred by fabbing some 'perfect' transmission will become overshadowed by the net difference in fuel costs to operate on a lesser transmission such as the stock one you already have.

I would be very surprised if a simple collection of rubber intermediaries and a shaft (as mentioned) could not replace the entire trans.

babymog · #9 02-11-2009, 10:14 PM

The transmission can't be used without a way to compensate for the slip in the torque converter, which would really complicate the governor. You will need a direct-drive.

1800rpm should be fine for that engine.

lutzTD · #10 02-11-2009, 10:14 PM

seems like you could rig the cruise control to be a governor, all those parts are already there

80's old school · #11 02-12-2009, 10:06 AM

I was planning on using a simple Audiovox cruise control system. Run the engine until you get 60 cycles per minute and then set the cruise. When the load changes (increases) the cruise will still keep the RPM constant to power the generator.

Yes I agree there might be other engines more suited to this but hey, I have a ragged out 240D that was just given to me. Besides.....we are all car guys or tinkerers....are'nt we?? I would be so cool to have a Mercedes diesel generator!!

The Generator heads can be purchased online ebay. Just type in generator head.

80's old school · #12 02-12-2009, 10:07 AM

Also on a 1977 240D....what horsepower do you think this engine will make at 1800 RPM directly coupled? Do you think it is possible to make 25 HP at such a low RPM?

Does anyone have a chart showing the HP torque curve vs. RPM???

KCM · #13 02-12-2009, 11:27 AM

The question about the engine speed and horsepower is a good one. I would think a generator that runs around 3600 rpm would be a better match for the Mercedes engine as their maximum horsepower is rated at high rpms (I think 4000 to 5000). You could use a 2:1 speed reducer to run the engine rpms higher, such as a pair of v-belt pulleys. Pulleys would also let you tailor the speed just by changing pulley sizes. But you also may not need the full HP of the engine, so running at lower rpm's would save fuel.

As for attaching it to the generator, you could direct couple it to the generator using a Lovejoy type flexible coupler, but alignment would be more critical. A better option would be to use a short drive shaft with U-joints between the engine and generator, or engine and v-belt pulley for speed reduction. If you use v-belts, you could likely mount the pulley directly to the flywheel. To mount to the engine, I would use a manual transmission flywheel, onto which you can mount an adapter plate for the drive shaft or pulley. Also, I think the manual tranny flywheel would be needed to balance the engine and for inertia as you would not be using the torque convertor, which does that function for automatics. I would not use the flex plate at all as it is just not rigid enough for what you want to do.

For the governor, I would buy a mechanically belt driven unit and install it in place of the alternator. These governors come in fixed speed or variable speed and are designed for power units and generators. You would just need to fabricate a linkage. They are also full-proof. You will not need your alternator since the diesel only needs the battery for starting and all gauges are positive on that engine.

You should also consider installing a safety gauge system. These types of gauges will shut the engine down if it overheats or looses oil pressure. Murphy is one maker of these type gauges.

Bajaman · #14 02-12-2009, 12:07 PM

For maximum efficiency, you need to target the torque peak of the engine in question. Like others have said, the easiest solution would be to get an IP with a variable speed governor.

Other possibilities would be: pulley driven governors on old tractors, also I thought of using the controller from a junk portable welder.

As far as coupling goes, you definitely want a direct drive. A manual transmission behind it would be nice if you want gear reduction 3rd is something like 1.4:1 so you could operate the engine at ~2500 which is close to the torque peak.

80's old school · #15 02-12-2009, 03:08 PM

This is great info. I will be going to get my "freebie" 240D probably next weekend. I will be pulling the engine out of it shortly after that.