411A
oxenos is correct. The Rolls Royce Griffon was an exceptional engine, producing some 2,500 horsepower from a V12. Any more power would have resulted in torsional flexing of the crankshaft. Instead of the traditional butterfly, it had a 'Rolls Royce Coreless Valve' in the fuel injector. This is best described as a cylinder within a cylinder, such that at full throttle, there was absolutely no restriction to the flow in the inlet manifold.
The propellors were contra-rotating; the engine drove the front prop which was geared via a rack bolt to the rear prop. The CSU was so efficient that it took just one second to fully restore the RPM following a fuel cut.