Harley-Davidson’s iconic V-twin engines are at the heart of the Harley mystique.
Harley-Davidson sold its first motorcycle in 1903. In 1909, the company introduced its first motorcycle powered by a 45-degree V-twin engine. That engine configuration would be the basis for some of the most famous engines in motorcycle history, and an icon for Harley-Davidson. Harley-Davidson engines are almost as well known for their unusual names as they are for their performance.
Harley-Davidson’s First V-Twins
The first V-twin produced by Harley-Davidson didn’t have a name. The 49.5-cubic-inch, 45-degree twin-cylinder engine produced seven horsepower. Harley-Davidson produced this engine from 1909 to 1911. The F-Head IOE (intake over exhaust) engine replaced that first V-twin in 1911 and remained in production until 1929.
The first Harley-Davidson engine that derived its name from its unique appearance was the 45-cubic-inch Flathead. This engine got its name from the vented tops of the cylinder heads, which were flat. There were no overhead valves in the Flathead. The valves were positioned on the side of the engine. Harley-Davidson introduced the Flathead in 1929, and it proved so reliable, variations of it remained in use until 1973.
When Harley-Davidson introduced the new EL model motorcycle in 1936, it came equipped with a new overhead-valve, 61-cubic-inch engine with a recirculating oil system. The motorcycle and the engine were called Knucklehead due to the shape of the rocker boxes. In 1941, Harley-Davidson introduced a 74-cubic-inch version of the Knucklehead. The engine stayed in production until 1947.
Introduced in 1948 in two sizes, 61 and 74 cubic inches, the Panhead had overhead valves, aluminum cylinder heads and hydraulic valve lifters. The Panhead had internal oil lines, routed through the rocker arms. It took its name from the one-piece cake pan-shaped chrome-plated rocker covers. Harley-Davidson produced the Panhead until 1965.
Harley-Davidson replaced the Panhead with the Shovelhead in 1966. The Shovelhead featured cast aluminum rocker boxes. The cylinder head was enclosed with a curved top that resembled a shovel. The Shovelhead was produced until 1985.
Harley-Davidson spent seven years developing the Evolution engine. The Evolution was introduced in 1984; it displaced 80 cubic inches and came with steel-lined alloy cylinders. It reportedly generated more power, and ran cooler and cleaner than its predecessors. The Evolution remained in production until 1999.
Twin Cam 88 And 96
The Touring and Dyna families of Harley-Davidson motorcycles were the first to receive the new Twin Cam 88 engine in 1999. The Twin Cam 88 was named for its two camshafts. It was rubber-mounted, to help reduce vibration. In 2000, Harley-Davidson introduced the Twin Cam 88B on its Softail line. The 88B was counterbalanced, hence the “B,” and mounted directly to the frame. The Twin Cam 88 and 88B were in production until 2006, when they were replaced by the larger, 96-cubic-inch Twin Cam 96 and Twin Cam 96B. By this time, all Harley-Davidson engines were fuel-injected.
Harley-Davidson made a major departure with its Revolution engine, introduced in 2001. It represented a number of firsts for Harley-Davidson. It was the first to combine fuel injection, four overhead cams and liquid cooling. The Revolution is a 60-degree (as opposed to Harley’s traditional 45-degree) V-twin 1,130-cc engine that produces a reported 115 horsepower. The Revolution was introduced — and is only available on — the VRSCA V-Rod.