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This is a curiosity question for all you engineer types out there. Are there any other manufacturers that have their alternators driven in oil? I've owned 8 motorcycles, 3 cars, and various lawn tractors, and none of their alternators were driven in oil. Is there an advantage to this? I know Ducati is the only manufacturer with Desmodronic valves but, that is kind of their trademark. Seems to me the alternator would be more efficient running in air. Any insight into this subject would be appreciated.
 

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Oil cooling comes to mind. Although I would normally expect an alternator to run hotter than engine oil temp. So running in oil could moreso be oil heating!

I expect that ducati design their engines with the altenator bolted directly into the crankcase because it's a neat design. Out of the way and clean.

I reckon that would be about it. If it was placed in any other location, outside of the cases, or in an area of the cases that was sealed off from oil. It would either need a different drive (gears or belt) or a more complicatied case casting and the oil seals that go with that.
 

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Discussion Starter #3
Most Ducatis have a dry clutch that runs off the crank on the other side and putting an oil seal there didn't seem to be a problem. But I do see the heat problem. BMWs and Guzzis run theirs on the front of their motors where its in the airstream. The Ducatis would "cook" that alternator inside the case where it is. I quess I answered my own question. It just seems that the alternator would be more efficient not having the drag of oil viscosity.
 

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My old '75 Honda CB750 had a wet alternator. It didn't sit in the oil pan or have an active oil feed but it wasn't isolated either. I can't remember if my '84 vf1000f or my '82 kz1000 had wet alternators and I don't have the bikes or books anymore to see if they where sealed or not.
 

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Oopps!

I just realised I had typed...

"Although I would normally expect an alternator to run hotter than engine oil temp" I meant to say...

"Although I would NOT normally expect an alternator to run hotter than engine oil temp"

I still reckon it's there just because it's an easy place to put it.
 
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