You wouldn't have much to complain about 57 RAC HP even now. Other than it's thirst.
2010 Mercedes-Benz CL 600 50 RAC HP 1996 Ferrari F50 GT1 53.8 RAC HP 2010 Ferrari 599 GTO 63 RAC HP Bugatti 16:4 73.4 RAC HPUnless of course they fitted it with a side valve, long stroke, low revving clunker.
The assumptions of 75% volumetric efficiency (VE), BMEP of 90psi (6 bar) and 1000ft/min piston speed were surpassed years ago.
4 valve/cylinder and 1/2 decent induction/exhaust design gives over 90%VE and a turbo gives over 100% VE. BMEP is over 15bar and heading for 30 bar. Mean piston speed for peak power has been around 4000 ft/min (20m/s) for many years but is still lower for Diesels.