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When cooler heads prevail

For quite some time the debate has raged on as to whether or not Harley-Davidson will introduce water-cooling on its (non-V-Rod) engine lineup. Most of those who believed it would happen did so for one major reason: emissions. They didn’t think H-D could pass standards any tighter than they already are without resorting to this kind of fix. Most people (like me) dismissed the emissions angle altogether. After all, there is no foreseeable tightening of the standards for motorcycles and H-D has managed to keep pace just fine with traditional air-cooled V-Twins and a little dose of modern technology here and there, like clean-burn EFI, nonexistent overlap in the valve openings and catalytic converters, to name a few. That is where I went wrong. You see the simple fact is, there are at least three other factors that have been quietly, but inexorably, churning to the surface of the “water” issue. To name names, they are rider-perceived heat issues, rarely rider-perceived volumetric efficiency issues, and the department at The Motor Company most responsible for determining what riders do and don’t perceive.

With that in mind, I’ll try to keep this short and sweet. I will wager real money that sometime during the 110th model year of the oldest motorcycle maker on earth, a “special” Touring machine (probably with 110″ engine) will be offered, likely as a limited production CVO/Screamin’ Eagle bike that does, in fact, have water-cooling as one of it’s major features. It’s speculation of course, but don’t bet against it. Here’s why:

1) As of May 19 of last year, Harley-Davidson secured a patent for a “cylinder head cooling system.” Interestingly, that timeframe has given the company a chance to put its patent where its products are… in effect a 2013 machine with this patented feature incorporated into its construction. It would, not coincidentally, be a lollapalooza of a 110th anniversary “surprise” as well!

2) Truth be told—Harley Big Twins have been crowding the acceptable levels of heat radiation for some time and the existing 103″ and particularly 110″ engines have pushed that problem to the limits of what typical riders will or can tolerate. Water-cooling is a natural solution, being able to remove heat consistently and quickly from both crotch and consciousness for the owner/operator—not to mention the engine.

3) Twin Cam engines have never been the poster children for prodigious output per cubic inch. For most riders, as long as there are enough of those cubic inches to offset that inconvenient truth, it’s a non-issue. All the same, The Motor Company has competitors, which the factory watches like a hawk, most of which do better in the power game, inch-for-inch, as delivered. This would lead any sane student of the art to conclude that one way to keep a hand in the game, perhaps even a winning hand, is to improve volumetric efficiency, thus making more power per inch. Alas—this also brings more heat into the bargain. Obviously, water-cooling is a great way to get power up while keeping heat down. Whether that takes the form of more inches, more power from those inches or both. As of now, the factory can play this ace pretty much at will… if and as required.

4) This is where marketing trumps engineering. In its own inimitably conservative fashion, Harley is almost guaranteed to introduce this machine in (initially) limited numbers as a special model to literally “test the waters” of liquid cooling on an equally conservative buying public. Then, once marketing has made it acceptable, or better yet, desirable to the faithful, water-cooled heads will creep across the model range inexorably. The engineering while sound (given that something like 80 percent of the engine heat is in the cylinder heads) is actually most clever in its marketing-derived mandate to keep “The Look” at all costs. Put another way, this speculatively special machine sports a technological breakthrough, yet is well disguised as a normal, familiar touring bike with trick lowers. (If you didn’t look closely, you might never know about the H2O!) Like keeping your light under a bushel (in the words of the old saying) they have literally forced this design to hold its water (Ha!) under a shroud… or two. A win/win for the factory, anyway you look at it. After all—with this patented methodology H-D can address a multitude of current and future challenges very effectively and still have a result that looks like a traditional Big Twin. How cool is that?

There appears to be a bit of a bonus feature in all this coolant coolness, which has as much or more to do with rider comfort as it does with controlling engine heat. If you look closely, you’ll see a fairly large cavity positioned behind the fan coupled with a ported outlet in a low-pressure area at the bottom of the lower that siphons hot air down and away from the rider. A look at the arrows in the drawing gives you a good idea of how this process works… which is most likely pretty well sitting still and “farkin’ fab’lus and fab’luser” as speeds increase. In other words, this patented cooling system cools both engine and rider and makes the whole thing… well… no sweat!

All associated plumbing, hoses and hardware are mostly hidden behind frame tubes, under gas tanks and with covers that make the pump look like a regular oil cooler. What these components might look like when applied to Dynas and Softails (if ever they are) is sheer conjecture and doubtfully half as tidy as this. But by the time we see this cooling applied all across the Twinkie range we probably won’t care, because the results will speak for themselves by then.

Seen a little more clearly here (and in a slightly different iteration), this seemingly simple device (call it the “Coolant Collar?") is the sophisticated heart—the enabling part—of the long-anticipated technology that will allow future Harley engines to improve emissions and power without roasting your tender parts or offending your sensibilities. In a very real sense, this allows the factory to offer the best of both worlds—a truly up-to-date powerplant that works way better, yet still looks like a Harley engine should look. Who says you can’t have your cake and cool it too?

The best part of these water-cooled heads is equally invisible, with internal passages inside the head castings, circulating coolant tightly and directly around and over the hot spots—notably the area around the exhaust valve and its port. By concentrating the coolant on this area, the horrendous heat is contained and evacuated very efficiently—and Bingo!

Look at this! The engine, in profile, shows no evidence of coolant jackets or ugly plumbing. It looks almost identical to the Twin Cam configuration we know and love and that is the best news for traditionalists. Since the radiators and much of the rest of the system is equally well hidden, there’s really not much to object to aesthetically, which just might be where the true genius lies in this whole idea.

Harley has determined that there should be thermostatically controlled dual fans in the design… as it should be! What most excites me about it is the built-in capability to add horsepower to the equation. Since this system controls temperature spikes and prevents detonation—compression and cams (among other things) can be “powered up” considerably over the current state-of-the-Big-Twin-art. Meaning, there’s no reason we couldn’t look forward to emissions-compliant 110" engines that make closer to 110hp instead of the 85 or so we get now, and run cooler at the same time!

A quick read of US patent #20110114044 (which is highly recommended—just Google it) reveals that the key to getting coolant to the hot heads of Big Twins, in an acceptable fashion, has to do with hiding the twin radiators and associated plumbing—in the fairing lowers. Although H-D makes no bones about the idea of transferring the technology to other machines without lowers in the future, that won’t likely happen until the buying public has learned to accept/embrace the idea. A few years from now, visible radiators on Dynas and Softails might be commonplace… for now, however, it seems the plan is a commendably stealthy install on touring bikes only.

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