The Griffon has a capacity of 36.7 litres against 27 litres for the Merlin, but is a lot heavier at just over 1 ton.

The Mark 58 can take off with supercharger in high gear if water/methanol anti-detonant injection is used, giving a rating of 2435 hp, rising to 2490 hp at the critical altitude of 3000ft. Maximum fuel demand is 189 gallons per hour, or just over 3 gallons per minute.

The supercharger on this engine is a single-stage, two-speed unit, but two stage Griffons were produced in large numbers primarily for the Spitfire/Seafire and Fairey Firefly, capable of sustaining 2000 hp up to around 15000ft.

Contrary to popular belief, the Griffon was not an enlarged development of the Merlin, nor was the Merlin a development of the famous "R" engine of Schnieder trophy fame in 1931. The Griffon I, a derated version of the R, was first run in 1933, the same year as the first Merlin prototype, and can trace its roots back to the Buzzard engine of 1925. The Griffon II did not appear until 1939, and was a major redesign of the Mk I, all subsequent marks following this design. The Griffon was in production until 1955, and went on to power the RAF Shackleton fleet well into the late 1980s. Although I would call myself a dyed-in-the-wool Merlin fan, I have to admit that the sound of a Griffon Spitfire really is something else, although, of course, the engine really is a bit of an ugly beast!