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Author Topic: Twin Cool or Not  (Read 1016 times)

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Para Bellum

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Re: Twin Cool or Not
« Reply #15 on: August 24, 2018, 11:45:11 PM »

Is oil routed through passages around the exhuast valves luke the coolent is on wet heads?
Yes
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grc

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Re: Twin Cool or Not
« Reply #16 on: August 25, 2018, 08:56:47 AM »

The whole concept of adding coolant to a Harley v-twin, this hybrid air/water cooled engine, is just bizarre (not to mention unreliable).  Either go all in on water cooling (V Rod) or keep it off.  Just seems like an afterthought.

A complete liquid cooled system would be preferable in my opinion, but they weren't willing to alienate the old Harley faithful by doing that.  In that case, water cooling just the hottest part of the engine does in fact make good sense.  The Twin Cooled bikes control head temps so much better than the totally air cooled versions they were able to retune the bikes for better performance and fuel economy without detonation.  You should also expect better reliability from the exhaust guides and valves with liquid cooling.

Once all us old farts are gone, perhaps they will join the 21st century and hang a small radiator on the front of whatever version of V-Twin they use.  You don't need to hide the radiator if it's done right, plenty of other brands have radiators without having to hide them behind lowers.  As always, Harley has allowed style to dictate instead of function.  If they were really good, they could learn how to do both.  So far, I'm not seeing evidence they are even trying.

JMHO - Jerry
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Mark

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Re: Twin Cool or Not
« Reply #17 on: August 25, 2018, 09:25:51 AM »

I think it's time for water-cooling, at least on the touring bikes.  I've evolved.
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scottt

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Re: Twin Cool or Not
« Reply #18 on: August 25, 2018, 10:43:56 AM »

I think it's time for water-cooling, at least on the touring bikes.  I've evolved.
With today's speeds and traffic, water cooling makes sense. Air cooled V-Twin motors were introduced during a completely different era and reality.  Ask yourself, if you were designing a touring motorcycle motor what would it be? I'd bet it would not be air cooled.

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kojak

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Re: Twin Cool or Not
« Reply #19 on: August 25, 2018, 12:14:13 PM »

Twin cooled bikes run cooler and generate a little more power, tested by cycle world.
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kojak
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Re: Twin Cool or Not
« Reply #20 on: August 30, 2018, 01:21:45 AM »

Was poking around in the M8 section to see how things are going with the new motor and I ran across this thread.

I posted a thread in the Twin Cam section related to the water cooled heads on my 2015 CVO SG.  Although the project was about adding a water-cooled oil cooler to my bike the result was I learned a lot about the cooling capability of the twin cooled system.

http://sta-bul.com/projects/OilCoolerProjectPhase1.pdf

The water cooled "Precision Cooling" system actually works VERY well with a lot of unused cooling capacity wasted due to how it is implemented.  When I removed the thermostat from the circulation loop I saw a 20 deg drop on head temperatures.  And even after adding the water-cooled oil cooler into the loop the overall system temp was 20 degs lower at the valves and 10 degs lower in the oil bath.  Not to mention that the system cools off much faster after a high load warm up event.

I was no "sold" on the wet head till I did this work.  And the best thing about it is, if it fails your not stranded.  Just ride on.  It's probably the only good thing about it being a targeted cooling system instead of a 100% water cooled system.

The new M8s that are water cooled I heard have a variable speed motor on the pump.  If you can find a way to get that pump to operate at 100% all the time I suspect you will be surprised at how much more cooling you will see from the system al of the time.

Check out the charts in the report I posted.  You may find it interesting.

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