Evolution Harley Davidson Engines

The Harley Davidson Evolution engine was an air-cooled, 1340 cc (82
cubic inch) 45 degree 4-cycle V-Twin often referred to as the
“blockhead” for its characteristic rectangular shaped rocker box. This
engine had an oil-bath diagram clutch, electronic ignition, and
aluminum heads and cylinders, rather than the iron of previous engines.
The aluminum parts significantly reduced the weight of the engine and
improved air cooling efficiency. The Evolution was more reliable than
the Shovelhead or Ironhead engines, burned less oil, and required less
maintenance.

Harley Davidson Models

The Evolution engine first appeared on Harley Davidson Dyna,
Softail, and Touring models in 1984 as a replacement for the Harley
Davidson Shovelhead engine and was used until it was supplanted by the
Harley Davidson Twin Cam 88 engine in 1999. A modified Evolution engine
with either 1100 cc or 883 cc of displacement also supplanted the
Harley Davidson Ironhead engine used in Sportster models starting in
1986, and by 1988, the 1100 cc was replaced with a 1200cc.  2010 Harley
Davidson Sportster models are still offered with either an 883 cc or
1200 cc Evolution engine. The Evolution engine also appeared in Buell
sportbikes from 1986 to 2003.