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
General Electric/Rolls-Royce F136 program. This marked the first complete engine assembled following US Government validation of the F136 design in 2008. The milestone was achieved one month ahead of schedule. Citing the Weapon Systems Acquisition Reform Act of 2009, the GE Rolls-Royce Fighter Engine Team submitted an unsolicited fixed-price offer for the F136 to the Pentagon on 28 September 2009. The fixed-price approach would cover initial F136 engine production, beginning with the F136 second production lot. According to the GE Rolls-Royce Fighter Engine Team, the proposal would shift significant cost risk from taxpayers to the Fighter Engine Team until head-to-head competition begins between