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Military MEP and Aircraft Gen-Sets MEP Mobile Electric Power, APU Auxiliary Power Unit and other military surplus generators.

Military MEP and Aircraft Gen-Sets

MEP 003a Engine Repurposed

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Old 09-11-2017, 12:23:22 PM
cnicholls cnicholls is offline
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Talking MEP 003a Engine Repurposed

Hello, I am new here. From what I have found after Googling for 8 hours, this site has the most knowledge about the Onan Genset engines (among tons of other things).

After a impulse buy years ago, I ended up with one 002A and three 003A engines only (no gen set) they look new, with caps on exhaust and inlets the flywheels don't look like they have ever been mated to anything. With fresh(ish) paint.

Has anyone heard of someone using 003A for anything other than a GenSet?

I would love to put this in a low speed buggy or a hydraulic pump driver.
I am always building/recycling old iron for use around our property

If anyone has any input on how to adapt the engines to a straight shaft, pulley/sprocket, or clutch/flywheel I would be very greatfull.

First let me contribute to future googlers, Here is some info that may save you time.

This is what I know at this point about the. MEP 003A Engine based on MIL-STD-1410

MIL SPEC Horsepower: 20 @ 1800 RPM.
No. of cyl: 4 (4 Cycle)
24 VDC electric start
Operating speed: 1800 RPM
140 CI (2294 CC)
19:1 compression ratio
Air Cooled/Naturally Aspirated
5.5 quarts oil
Fuel Consumption: 1.09 gph at rated load.
Environment: Minus 25° F (-31.7° C) to plus 107° F (+41.7° C)
Counter Clockwise rotation
SAE 4 bell housing
Bell housing Od: 15 7/8in
Bell housing ID: 14 1/4 12 studs 3/8 studs
bolt circle: 15in

Flywheel is: I have yet to find out if the flywheel is sae, or custom.
12 3/8 OD
10 1/8in bolt circle - 4 sets of dual bolt holes

Governor: Internal Flyball Externally adjustable.
My understanding is that the GOV HP Rating is:
80% of 1/2 MFG Rating

GOV HP 20 = 80% of 25 (1/2 MFHP)

Making the engine 50HP@1800RPM Manufacture Spec?

Also, advice like "sell the engines and buy something else", I have read enough of those opinions on these forums thanks, I have already read your point of view.
I am a skilled fabricator feel confident that I can overcome the challenge.
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Old 09-12-2017, 07:42:13 AM
dependable dependable is offline
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Default Re: MEP 003a Engine Repurposed

There was a long thread like this on the Steelsoldiers military site a few years back. Suggestions of mini bikes, go carts, but it is a slow revving motor designed mainly for continuous duty at that 1800 RPM, loud, relatively heavy. Good fuel economy though. Lots of suggestions, jokes, but I don't remember if anyone ever actually built anything.

They would be good for running pumps, etc, one of their only other official uses was hydraulics for a type of anti aircraft installation.

They are over speced some, maybe 30 %, but will not make 50 HP. You would get the best money for it selling to a MEP-003a owner, there are quite a few out there.
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Old 09-12-2017, 08:20:19 AM
CharlieB CharlieB is offline
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Default Re: MEP 003a Engine Repurposed

Google "Tapered shaft adapter." Easy fix.
Check engine design to determine if it can support the side loading of a belt or chain drive, or if an external shaft bearing will be needed.
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