SEARCH through Harley’s own information about the new-for-2014 touring range and you won’t find a mention of water cooling. But at least some of them are liquid cooled.
The new touring models have their own site, packed with info and videos, at http://projectrushmore.harley-davidson.com/en_GB, and here you’ll find reference to the “Twin Cooled” High Output 103 Cubic Inch engine. It says that “Twin cooling cools the heads around the exhaust ports to deliver at or near peak performance under all operating conditions and temperatures. Higher compression ratio increases efficiency and horsepower.”
So, no mention of water. But the firm’s site also says that the motors are “air and precision-cooled” – and it turns out that in Harley-speak, “precision” is a euphemism for “water”.
In the UK only the Ultra Limited and the Tri Glide get the new engine. Looking at pictures of those bikes it’s clear that there’s a radiator in each of the leg guards, with an outlet air vent towards the back of them. Water pipes also appear to be visible.
A patent in 2011 revealed how Harley was working on water-cooled cylinder heads for its big V-twins, using twin radiators and hidden cooling fans mounted inside the leg guards.
Just as BMW has water cooled the cylinder heads of its latest R1200GS, while still sticking to the line that the engine is mainly air-cooled to keep traditionalists happy, it looks like water-cooling is slowly leaking into the H-D range. Faced with the need to increase performance while cutting emissions and fuel consumption, the more accurate cooling allowed by water, particularly in cylinder heads, is a huge advantage. It allows closer tolerances and better control of combustion chamber and valve temperatures, all vital to ensuring a clean and efficient burn of the fuel.
Harley fans have long since riled at the idea of water-cooled engines, and even a dozen years after its launch the liquid-cooled V-Rod is still largely shunned by Harley traditionalists. So it’s no surprise that H-D is keeping quiet about the precise nature of its ‘Twin Cooled’ 2014 engines, even if the fact that adding water means they’ll actually be better than the ones that went before.