Rolls-Royce–Bentley L-series V8 engine as the "six and a quarter" litre engine. When new, the Rolls-Royce/Bentley V8 was rumoured to be an American engine design licence-built, but it was developed in-house by Rolls-Royce and Bentley engineers. This can be seen in its design characteristics, with features like an aluminium alloy cylinder block with wet liners, gear-driven camshaft, (initially) outboard spark plugs and porting inspired by the Rolls-Royce Merlin aircraft engine. The bore spacing of 4.75" was unlike any American V8 engine and the firing order was 1-5-4-8-6-3-7-2 something uncommon in any period American OHV V8. The deep skirted crankcase design is also rare with
Rolls-Royce Dart airliner, it powered a number of other European and Japanese designs of the 1950s and 60s and was also used to convert American-manufactured piston aircraft to turboprop power. The list includes: Power output was around 1,500 hp (1,120 kW) in early versions, and close to twice that in later versions, such as those that powered the NAMC YS-11 airliner. Some versions of the engine were fitted with water methanol injection, which acted as a power restorative in hot and high conditions. Rolls-Royce Dart The Rolls-Royce RB.53 Dart is a long-lived British turboprop engine designed, built and manufactured by Rolls-Royce Limited.