There is nothing new in the world and it all comes around again, but are we seeing the return of the two stroke diesel engine? This guy seems to think so, Dr James Lemke is a US physicist and entrepreneur who has created the Achates Power engine.
This is an extremely efficient two stoke diesel engine using six horizontally opposed pistons in a design originally pioneered by the Junkers company in Germany before World War Two. The diesel engine was used in some of the Junkers aircraft and the fuel efficiency of the engines gave the aircraft a longer range.
The Australian trucking industry was built on a selection of two stroke diesel engines and the sound of a screaming Detroit coming around the bend at night on our major highways will be a strong memory for many in the trucking game. There is still a deep affection for these engines among the vintage enthusiasts.
Those engines made a lot of noise and did not run clean. As a result, the four stroke gained favour as it allowed more control of combustion and was better able to clean up exhaust emissions.
James decided to revisit the two stroke engine after reading a book on holiday about Junkers and its diesel aircraft. He realised modern computer control and fluid dynamics techniques would be able to make an engine using the same principles, but able to better exhaust emission rules and efficiency requirements.
Here James explains how the Achates engines work:
This is a fuller animated explanation about what is going on in the engine: