The air-cooled VW engine is one of the most overbuilt small displacement engines ever produced. The basic architecture — flat four, air-cooled, magnesium case, separate cylinders — was designed for simplicity and repairability in any location where a garage might not exist.

The 1600cc variant that powered Beetles through most of their production run makes modest power by modern standards, but it was not designed to be a performance engine. It was designed to run indefinitely with basic maintenance in any climate.

Engine rebuilds are accessible to any home mechanic with a clean workspace, a good torque wrench, and the factory specifications. The parts are available new. The process is documented in extraordinary detail. If you want to understand what makes a reciprocating engine work, rebuilding an air-cooled VW flat four is the best possible classroom.