How does Horex’s VR6 engine work?

BMW likes to brag that the 1,600 inline-six in the new K1600s is just 22 inches wide. But the supercharged six-cylinder engine in the Horex VR6 is three inches narrower and puts out more power. It achieves that by using staggering the cylinders in two rows on a single crank and under a single cylinder head. It’s a design pioneered by VW that’s now coming to bikes.

http://www.youtube.com/watch?v=4DIdD56b4HU

You probably associate the “VR6″ name with VW, who first developed the arrangement in the late ’80s, but it’s actually just a generic name for a monoblock design with offset pistons in rows. The “VR” comes from a combination of “V-motor” and “Reihenmotor,” the German words for a V engine and an inline engine respectively. It’s a uniquely suitable arrangement for a motorcycle, packing six cylinders into a package only slightly larger than an inline-four and considerably shorter than a V6, in fact, VW originally created the design so they could package six cylinders into cars only intended to accommodate four. VR6 engines use a single cylinder head and this one has three parallel camshafts.

The 1,200cc engine develops 197bhp and 110lb/ft of torque with the aid of a supercharger and has to motivate a total package that’s surprisingly not overly heavy at 530lbs/240kg.

The pistons in this motor are offset 15° degree and then each piston’s head is slanted to accomodate for that angle. As a result, all six combustion chambers are on the same plane. the three overhead cams (a first) are arranged so that one operates the two intake valves per cylinder on one side and one cam operates the single exhaust valve per piston on both sides. All this sounds complicated, but was necessary to deliver an engine this compact.

The whole thing kind of makes my head hurt, luckily this video explains it better than I do.

Horex aims to begin producing the VR6 in Germany by the end of next year.

Horex