converting generator engines.

daveyjones

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I was wondering if it would be possible to take an engine from a site generator, and use it as a power unit for a yacht? It occurs to me that , unlike ex-truck engines, a generator runs under constant load, is usually fairly well maintained, so maybe would be a better proposition than a thrashed-out vehicle engine. As they are air cooled, would it be possible to use them? I have heard of air cooled auxiliaries - wouldn't this be an advantage in terms of avoiding water intake/blockage problems?
 

marina95

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dj, this is a great question. there are numerous brand new diesel engines on ebay at the moment and i was wondering what would be needed to convert this into auxilliary power on a small yacht. I am asumming that they would immediately require some form of flywheel and a gearbox...
 

ccscott49

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They can be easily converted, if conversion kits are available.

Air cooled, well some of the old listers were aircooled and a lot of canal boats have aircooled engines, downside is getting enough cooling air in and out and also they are noisy beasts.
 

muchy_

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One other thing to watch out for on these engines is that some of them maybe set up to run at a constant speed so they dont have the same injection pump as an engine that has to be throttled. No problems putting the right pump on if its available but it just adds to the cost of the thing.
 

TrueBlue

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I haven't looked - but are they air cooled - gensets being compact and need to be quiet, I would have thought they would have to be liquid cooled, but I am probably wrong.

On the other hand perhaps that's why they are on Ebay....

On reflection I have a small 5Kw air cooled lister genset - but it was only intended for traffic lights - presumably in remote locations - it is incredibly noisy, runs at 3,000rpm and is 600ccs. If it's one of those - Forget It.

Edit:
I've just been on Ebay; I searched on "generator" and came up with 10 items, the small low power units are not suitable, the three Paxman V6's will get you on the plane, but the Dale / Perkins unit in Glasgow might even be suitable - how big is your boat....
 

ongolo

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I am not sure what you mean by "power unit", do you like to make electricity or use it to drive the boat?.

The following issues were raised below.

Fly wheel and gear box, all diesels have a flywheel, cannot run without them, but you would need a gearbox . If you attache a marine gearbox, you need to have a drive plate and possibly have to have an adaptor ring made to accomodate difference between gearbox and bell housing.

Injection pumps for stationary engines are actuallt very well suited to marine applications, they can all be regulated. In fact, many truck type regulators would increase revs if the prop stick out of the water.

Tractors (because of power take off) and generator diesels have an RV (Bosch, dont know CAV equiv.) governor in the injector pump. this type of governor/regulator, is much more sutable, because it keeps the set revs almost constant irrespective of load. So if you battle in rough seas and stick your prop out, the diesel will not run away, increase revs to max.

I had a single Lister LT1 500cc 5Hp Aircooled and took it out of my boat, the vibrations of the single were unbearble. I have also an 4 cyl air cooled deutz wih 80HP 3.8 liter. Air intake is not a problem, with a barometer you can check if the pressure drops in the boat when the diesel is running which will be the case if not enough cooling air is available, but the air has to get out and a special duct of adequate seize is needed. In this duct you should also route the exhaust to prevent heating up the boat.

If you add a flap to the duct, you can dump washing in and dry it while the diesel is running, the warm cooling air, you can lead into the cabin to heat up the boat or into the shower cubicle to heat that and dry the place.

One big advantage of the aircooled diesel is that it removes condensation from the boat everytime it runs. Another is the weight, my 80hp aircooled angine is 260kg only, but I know the listers were heavier.

You have no impeller problems but best of all no corrosion in the engine. Noise can be overcome with planning and insulation. You can also forget about water injection into exhaust, just have a dry exhaust going out top.

One better than a generator engine is a tractor engine, they usually have counter balance shafts and these engines are without vibrations.

However, I have hear that now small copies of yanmar diesels made in Pakistan are availble very cheap, now. Apparently 900cc and 3 cyl, that should make for trouble free running, depends on the size of the boat
 

silverseal

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The Perkins 4107 and 4108 diesel engines were produced in large numbers, over 1/3rd of million in total, and many ended up in generators.
The Perkins 4108 manual cites a mechnical govenor, rather than hydraulic, and slightly different injector pump. However, the 4108 is a fine long served marine unit, and was produced as such by Perkins. You can convert Landrover based, Taxi based and even tractor based 4108 engines with heat exchangers from Bowman or Lancing Marine, or try ASAP. Mine has a shaft output of 49 SHP, and if you have a good donor unit, you will have a long lasting lump when converted for less than £1000
 

fishermantwo

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The Kubota 3 cylinder generator motor in my fishing vessel runs at 1500 rpm. It differs from the normal 3 cylinder tractor or propulsion 3 cylinder engines in that the pistons are different weights. The middle piston is different to the two end ones to balance the engine at 1500 rpm. Probably still be fine as a propulsion engine though. Millions of them all round the world.
 

Avocet

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My guess is that a generator engine's valve timing and cam profile(s) might be suited to running at constant speed (or near-constant speed). I guess they might have little or no torque low down in the rev band and be difficult to persuade to idle at the sort of speed that one would have to get down to in order to engage a gear without unpleasant noises!

If I were using one of these types of engine, I'd seriously consider hydraulic or electric drive so that the engine could continue to run at its design speed and turn either a generator or a hydraulic pump. I guess such an engine would be already equiped with a governor set to cope with sudden demands on the engine and optimised to bring its speed back up to the set speed very rapidly. The downside, (apart from cost) would be noise but this has already been mentioned.
 

marina95

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Here's an example of the engine I had in mind...

53_0.JPG

ae_1_b.JPG


Described as:-

# 4 hp half speed diesel engine
# This engine is mainly used in site mixers & is a replacement for most single cylinder hand & electric start diesel engines.
# Output shaft clockwise rotation
# We are the main importers of this engine, so can offer a full & comprehensive back-up service.
# Maximum output 4 hp.
# 20mm output shaft avaliable.
# Recoil & electric start.

340 quid!
 
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