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Author Topic: EFI and liquid cooling  (Read 2469 times)


  • Grand Gearhead
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Re: EFI and liquid cooling
« Reply #15 on: September 25, 2009, 12:52:16 am »
Wikipedia ALWAYS has the answer.  And when it doesn't Google will  ;)

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Re: EFI and liquid cooling
« Reply #16 on: September 25, 2009, 09:31:36 am »
Question:  Why are some beemers called 'oil heads'? Are the heads oil cooled?

The fairings on the Cafe racer featured in the CMW catalog seem very moderate and quite nice to me.  I wonder what they wiegh.  Then we have Ace's newly introduced oil cooler - wonder how much cooling that is able to do.

So we could add fairings and liquid cooling and make our bikes real 21st century - right?

Well, at the speeds I drive at, it is probably overkill.  But then I am still thinking of a bit of fairing, like adding some leg fairings to the front engine crash bar, and a bit of a windshield.  Have to wait on tha ' till I finish other projects, but worth thinking about.

All heads are oil-cooled to a certain extent, even in water cooled engines.
The oil provides some amount of cooling in all engines.
I think in  the beemers, it's just a slang term, and some people say "air-heads" and some people say "oil heads", but I think they refer to the same engine.

I have the Cafe Race fairing here in my spares room. I haven't weighed it, but including all the mounting braces and lower portions and windscreen, I'd bet it comes close to 15 pounds or maybe even more.

My oil cooler has a specification of 1000btu of heat reduction with 100cfm of air going thru it. If there's more air going thru at faster speeds, it can do better.
It is capable of dealing with about 2% of the heat output of a 20hp engine like we have. But the rest of the engine is responsible for most of the heat dissipation, and the oil can only do some of it. In practice, my cooler reduces oil temps by about 10-15 degrees, typically.
The vast majority of the cooling in the Bullet is done by air moving thru the engine fins.
The benefits from cooler oil come from helping to cool internal parts that don't have good contact to the outer fins, and by helping the oil to not overheat, thus retaining its good film strength.
« Last Edit: September 25, 2009, 02:49:35 pm by ace.cafe »


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Re: EFI and liquid cooling
« Reply #17 on: September 25, 2009, 01:16:14 pm »
The Wixipedia citing given by Gearskogul above does clarify this and says that oil was used in the cooling of BMW heads, so it is an interesting adaptation of a not-so-new cooling system.  This would be in addition to the intrinsic types of oil cooling found in all air cooled bikes that you mention, Ace. 

I think one of the advancements of the new UCE, possibly helping it to cope with the higher heat load under EFI conditions, is the larger volume of oil in the crankcase. 
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Re: EFI and liquid cooling
« Reply #18 on: September 26, 2009, 09:48:52 am »
The "oil head" Beemer was the first of the modern boxer engines to use overhead cams. There was a need to provide additional cooling. These bikes also had external oil coolers. On my '98 850 oil head there were two coolers. On some of the later there is just one larger cooler. The difference was is design only, the function was the same.