A Brief History of Harley-Davidson’s Big Twin

A timeline of Harley V-twin engines from the first in 1909 to the new Milwaukee-Eight.

The First V-twin

The Harley-Davidson Motor Company was six years old when it introduced its first V-twin in 1909. It produced 7 horsepower with a displacement of 49.5 cubic inches.Harley-Davidson

The F-Head

An improved fixed head or “F-head” V-twin came in 1911 and proved to be a workhorse until 1929.Harley-Davidson


The 45-cubic-inch Flathead is introduced on the D model. Variations of this engine are found on H-D models as late as 1973.Harley-Davidson


In 1936, Harley introduces the overhead valve EL, a 61 cubic-inch engine with increased horsepower and uniquely shaped rocker boxes that earned the nickname Knucklehead.Harley-Davidson


Harley-Davidson adds new features to the 61 and 74 OHV V-twins including aluminum heads, hydraulic lifters, and one-piece chrome-plated rocker covers that resemble cake pans. The name Panhead was a perfect fit.Harley-Davidson


The Panhead was replaced in 1966 with the Shovelhead, aptly named again for the shape of the rocker boxes.Harley-Davidson


In 1984, the 1,340cc Evolution was unveiled on five models including the all-new Softail. The Evo was the product of seven years of development and it produced more power across the board, ran cooler and was virtually oil-tight.Harley-Davidson

Twin Cam 88

Harley-Davidson Touring and Dyna models came powered by the new Twin Cam 88 engine in 1999. A counter-balanced Twin Cam 88B followed a year later for the solid-mount Softail models.Harley-Davidson


The Milwaukee-Eight is introduced in 2016 for the 2017 model-year. It is the first total redesign of the Harley-Davidson V-twin since the Twin Cam 88.Harley-Davidson