What makes a Deltic Engine so different?
Most internal combustion diesel engines used in marine or rail-traction use are of a conventional ‘straight’ or ‘Vee’ configuration, running a four-stroke combustion cycle. Often they will be slow revving (operating at perhaps 800rpm maximum), but with high torque characteristics. In the 1950’s, when the British Rail modernisation plan diesels were being developed, conventional engine designs tended to be heavy, and have a poor power to weight ratio (e.g. the Class 40s and 45s). Engine assemblies such as turbo chargers and cylinder heads were over-engineered to cope with the stresses associated with high-mass engines. Typically, many diesels operated at a power to weight ratio of around 20hp per ton. The Deltic engine was developed by the D. Napier & Sons at Acton and constructed at their works in Liverpool as a compact unit with a very high power to weight ratio. The Admiralty saw the engines potential for use in fast patrol craft however it was the Chairman of English Electric later
