We just got back from a trip to Milwaukee and the Harley-Davidson Museum. We saw the engine room had a wall filled with their engine platforms going back to the beginning. The Motor Company has come a long way since its first motorcycle prototype built in 1903. The Evolution (Evo) engine is a V-twin engine that has been manufactured and used by Harley since 1984 for a variety of different models, according to a story posted on Lowbrow Customs’ blog.

Tyler Malinky of Lowbrow Customs noted in his blog that the EVO engine design is often credited with saving Harley-Davidson from bankruptcy after the management buyout and subsequent reorganization that the company went through during the early 1980s.

The name “evolution” was likely strategically chosen to coincide with a rebranding process that redefined Harley’s image and helped regain its dwindling market share, wrote Malinky. Harley’s Japanese competition had “evolved” and it was time to show their customers that they could, too.

Here’s a really cool U.S. Patent diagram for the Harley-Davidson Evo motor. (Photo: Lowbrow Customs)

The Evolution’s engine design offered many advantages compared to previous Harley designs, explains Malinky. The most important upgrades improved reliability and durability. A big part of the company’s downfall in the ’70s had been due to outdated engine designs. The competition, especially the Japanese companies, continued to innovate, creating motorcycles that lasted longer and cost less to maintain than Harleys at the time. The little profit Harley-Davidson made at the time was wasted satisfying a growing number of warranty claims.

For more about the EVO engine’s history, head over to Lowbrow’s blog.