Could this patented W-Triple engine be the next new Beemer platform?

It’s been a decade since BMW cancelled the R1200C, but the firm has always intended to make a return to the cruiser category. Now we’ve seen the first indications as to how it will go about it.

First there were boxers then came the bricks… Recent patent documents suggest W-3s might be BMW’s next powerplant design. This is BMW’s first 75-degree design.

Not only had the R1200C failed to capture the enthusiasm of cruiser buyers, but the boxer twin wasn’t suited to the large-capacity trend that the market has followed. Switching to a V-twin would be too much like following the herd, but the firm has now hit on the idea of using a novel W-3 engine layout—creating a machine that can wear familiar cruiser clothing but which will also be unlike anything else on the market.

The 65-degree layout of BMW’s second design.

So far, BMW has patented two variations on the W-3 engine. Both appear to be air-cooled, which means the engines will have the clean, simple visual appeal necessary for a cruiser and will use pushrods instead of overhead cams, a decision that allows larger-capacity engines in a smaller space. The W-3 layout offers an advantage here, too, since it can fit an extra cylinder (and hence 50 percent more capacity) into much the same space normally taken up by a V-twin engine.

How The W-3 Will Work

There have been previous W-3 efforts, most notably Jim Feuling’s Harley-derived engine (see Fueling W-3 Prototype here), which has powered several jaw-dropping customs over the years. Where BMW’s designs differ is the use of more than one crank throw.

Image: Jim Fueling’s 142-cubic-inch (2,320cc) W-3 prototype (see Fueling W-3, Up To Speed here) with a claimed 150 hp at 5,000 rpm.

In one design, the firm has used a three-throw crankshaft, more like an inline-triple than a V or W where you’d expect more than one piston to share a single crankpin. While the result is wider than a V-twin, it still offers the all-important visual effect and allows the use of virtually any firing order or interval.

Another angle of BMW’s second design, a layout that is much closer to conventional V-twin cruiser engine dimensions.

The second layout is even stranger, with two cylinders sharing a crankpin, in normal V-twin style, while the third piston gets its own crank throw, again, allowing freedom with regard to firing interval. This design is narrower than the first while still gaining the all-important extra cylinder.

Unlike the Feuling W-3, which had a 90-degree angle between the first and third cylinders, the BMW layouts show a total of 75 degrees for the first design and 65 degrees for the second. That’s much closer to a conventional V-twin cruiser engine dimensions, meaning a bike carrying the BMW engine could follow traditional styling cues despite the extra cylinder.

Source: Motorcyclists Online via Peter Dhaese