By Dennis Chung
In April, Motorcycle.com broke the news that Indian is about to introduce a new liquid-cooled V-Twin engine originally developed for Victory Motorcycles. The new engine is expected to power a new fixed-fairing tourer and likely several other models, leaving some to wonder about the future of Indian’s air-cooled Thunder Stroke 111 engine.
A new patent application recently published by the U.S. Patent and Trademark Office suggests the Thunder Stroke may not only be sticking around, it may be getting a variable valve timing system. The patent illustrations show an engine that looks nearly identical to the existing TS111 (see below). From the outside, the only visible difference is a circular plate in place of the Indian logo on the cam cover.
Internally, the engine in the patent is also similar, with two valves per cylinder driven by hydraulic roller-rockers. The four pushrods are matched with three camshafts: two single-lobed camshafts for the exhaust valves and a double-lobed center shaft for the two intake valves. That plate that is visible on the outside of the engine is part of the cam phaser assembly used to vary the valve timing.
A cam phaser is used to alter valve timing by rotating the camshaft forward (advancing) or backward (retarding) in relation to the crankshaft’s rotation. Unlike Ducati‘s Desmodromic Valve Timing (DVT) which has cam phasers for both intake and exhaust valves, Indian’s idea applies only to the intake. This makes it more like the system on the Kawasaki Concours 14 which also varies the intake timing, only Indian’s patent is applying it to an overhead valve V-Twin configuration.
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