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Was over on ADVrider and rumor has it that the next-gen DOHC Boxer will be liquid cooled.

Thoughts?

Anyone in the know about a possible update for the 12R?

They've been saying that for years and it's never come true yet. As long as they can continue to pass emissions and noise regulations without a water jacket they'll keep them air-cooled - it's a fundamental design feature of the boxer engine and it'd be sales suicide to mess with that.

Yep Honda has tried that for years on the Goldwing with little or no success.

Mark

celticus wrote:Yep Honda has tried that for years on the Goldwing with little or no success.

Mark

What are you talking about? Goldwings have always been water-cooled, BM boxer twins never have. People don't like change. Look how well HD did with their first water-cooled bike even though it was still a V-twin.

basque wrote:Was over on ADVrider and rumor has it that the next-gen DOHC Boxer will be liquid cooled.

Thoughts?

Anyone in the know about a possible update for the 12R?

They have built liquid cooled prototype Boxers since a long time, but nothing has ever made it into production. As everywhere, there are pros and cons. It appears that it's a fact that if they want to continue increasing the power output of the Boxer they will have to think about different cooling strategies.

sproggy wrote:

celticus wrote:Yep Honda has tried that for years on the Goldwing with little or no success.

Mark

What are you talking about? Goldwings have always been water-cooled, BM boxer twins never have. People don't like change. Look how well HD did with their first water-cooled bike even though it was still a V-twin.

Sproggy, See the sly wink?

Mark

I find it strange that BMW would put out a new motor just after releasing the DOHC, but Euro 4 emissions kick in in 2012.

Seems engineers struggle with making air-cooled motors meet those guidelines.

basque wrote:I find it strange that BMW would put out a new motor just after releasing the DOHC, but Euro 4 emissions kick in in 2012.

I'd be very surprised if the current models didn't conform to Euro 4 - 2012 is very close in vehicle manufacturing terms. As you say, with the twin-cam motor released only this year (and then not on all models) they'd have to be reckoning on at least a 3 year life for it, probably double that.

basque wrote:Seems engineers struggle with making air-cooled motors meet those guidelines.

It's not so much emissions regs that large air-cooled motors have trouble meeting, it's noise regs. A water jacket provides a lot of sound reduction and its consistent and controllable cooling effect means the engine can run closer tolerances and therefore make less mechanical noise. That's why BMW boxers aren't simply air-cooled - they're primarily oil-cooled, which allows them to run tolerances closer to a water-cooled motor and therefore keep the noise down. But closer tolerances also improve efficiency so there is some effect on emissions, but I believe it's secondary to the noise issue.

Hex head boxers are very quiet, every bit as quiet as my friends goldwing (valve train noises/whine). High combustion temps are the cause of excessive NOX emissions, I suspect the boxer may need liquid cooling or perhaps an EGR system at the very least.