General topics » 2016 RS-- cooling system question

How much of the above motor is cooled by air/oil/water?

I read somewhere recently [ and can't remember the exact numbers ] that the motor was 80% oil cooled and 20% water cooled?.

Anyone got a definitive answer?

Just curious.

Zitat von azqkr im Beitrag #1

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How much of the above motor is cooled by air/oil/water?

I read somewhere recently [ and can't remember the exact numbers ] that the motor was 80% oil cooled and 20% water cooled?.

Anyone got a definitive answer?

Just curious.

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I would think the motor is essentially water cooled. The oil cooler is to keep the crankcase oil from getting too hot but isn't intended to "cool" the motor.

https://www.cycleworld.com/2012/12/21/bm...r-tech-preview/

Zitat von Bunter im Beitrag #2

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Zitat von azqkr im Beitrag #1

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How much of the above motor is cooled by air/oil/water?

I read somewhere recently [ and can't remember the exact numbers ] that the motor was 80% oil cooled and 20% water cooled?.

Anyone got a definitive answer?

Just curious.

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I could find this but it's far from definitive.

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And in the other link Technically, as BMW like to point out, the GS isn’t water-cooled, it is partially water-cooled. Where the old boxer motor was 22% oil-cooled and 78% air-cooled, the new GS is 35% water-cooled and 65% air-cooled using a technique called ‘precision cooling.

Thanks for the links and replies. I'll remember it's 35/65 [ water/air cooling ]

I think the core engineering need for cooling is two reasons, control (stabilize) the combustion temps in the head to keep combustion emission under control and then keep engine temps stable . under control so the oil is not toasted/ degraded.

So the ratio of air/water/oil cooling is highly variable, depending on the environment (cold-very hot) and how hard you are working the engine.

The oil cooling and water cooling(head) are sized to handle the worse case. Air / environmental does what it wants

This is my best guess.

Zitat von Vtbob im Beitrag #7

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I think the core engineering need for cooling is two reasons, control (stabilize) the combustion temps in the head to keep combustion emission under control and then keep engine temps stable . under control so the oil is not toasted/ degraded.

So the ratio of air/water/oil cooling is highly variable, depending on the environment (cold-very hot) and how hard you are working the engine.

The oil cooling and water cooling(head) are sized to handle the worse case. Air / environmental does what it wants

This is my best guess.

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Zitat von azqkr im Beitrag #8

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Zitat von Vtbob im Beitrag #7

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I think the core engineering need for cooling is two reasons, control (stabilize) the combustion temps in the head to keep combustion emission under control and then keep engine temps stable . under control so the oil is not toasted/ degraded.

So the ratio of air/water/oil cooling is highly variable, depending on the environment (cold-very hot) and how hard you are working the engine.

The oil cooling and water cooling(head) are sized to handle the worse case. Air / environmental does what it wants

This is my best guess.

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If I'm reading this right, you believe the ratio changes based on temp and how one is riding?

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Zitat von azqkr im Beitrag #8

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[quote=Vtbob|p44891]
If I'm reading this right, you believe the ratio changes based on temp and how one is riding?

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Zitat von Vtbob im Beitrag #10

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Zitat von azqkr im Beitrag #8

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[quote=Vtbob|p44891]
If I'm reading this right, you believe the ratio changes based on temp and how one is riding?

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Yes

Also it is typical that there would be a thermostat to turn on/adjust the water temp flow to the cooler and a similar Thermos stat to turn on oil/adjust flow to the cooler.
I do not know if our BMWs have this...
Having these would allow earlier warm up, getting emission in spec sooner (in conjunction with lean gas feed when the choke function is off)

These add expense so if emissions spec do not demand it they may be left off.

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I've no idea what kind of thermostat is used on the RS, but in the old days they were simple mechanical devices- a material that would expand when it got hot, thus opening a valve. I guess if the cooling valve were electronic, there could be a more granular control of operating temperature instead of two choices (on/off).

Thanks for posting the article, Mr. 36654- that was a good read.
Two comments on it- the fins on that engine look larger than what I see on the 2020 RS. I would be willing to bet (no more than a US quarter) that the water cooling proportion has increased. Higher temp is more efficient and less polluting- and BMW is having to follow increasingly tight restrictions.
second- the comments from 2012 have not aged well. Particularly the forecast that the boxer would be a terrible adventure bike. While the GS is not widely used off-road, it is a hugely popular 'all day' machine.

Zitat von jrt im Beitrag #12

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I've no idea what kind of thermostat is used on the RS, but in the old days they were simple mechanical devices- a material that would expand when it got hot, thus opening a valve. I guess if the cooling valve were electronic, there could be a more granular control of operating temperature instead of two choices (on/off).

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