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From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Comparative table of various engine specifications, including cylinder head types, dimensions, port areas, mean effective pressures, and RPM.

Identifier  ExFiles\Box 134\2\  scan0041
Date  18th July 1935 guessed
  
[COLUMN HEADERS]
ENGINE, CYLINDER HEAD, PISTON DIAMETER, VALVE OR PORT AREA, RATIO PORT AREA PISTON AREA, M.E.P.S. (at 2500, 2750, 3000 FT/MIN with N.A. [BMEP, IMEP] and 8" BOOST sub-columns), R.P.M AT 200 FT/MIN

[TABLE DATA]
Row 1: Engine: KESTREL, Cylinder Head: STANDARD, Piston Diameter: 5, Valve or Port Area: 3.9, Ratio: .199, M.E.P.S. 2500 FT/MIN (BMEP: 125, IMEP: 147, BOOST: 157), M.E.P.S. 2750 FT/MIN (BMEP: 117, IMEP: 141, BOOST: 142), M.E.P.S. 3000 FT/MIN (BMEP: 111, IMEP: 138, BOOST: 122), RPM: 3275
Row 2: Engine: KESTREL, Cylinder Head: RAMP, Piston Diameter: 5, Valve or Port Area: 3.9, Ratio: .199, M.E.P.S. 2500 FT/MIN (BMEP: 142, IMEP: 164, BOOST: 174), M.E.P.S. 2750 FT/MIN (BMEP: 135, IMEP: 169, BOOST: 160), M.E.P.S. 3000 FT/MIN (BMEP: 126, IMEP: 153, BOOST: 143), RPM: 3275
Row 3: Engine: KESTREL, Cylinder Head: STEEL PENTHOUSE, Piston Diameter: 5, Valve or Port Area: 4.52, Ratio: .231, M.E.P.S. 2500 FT/MIN (N.A.: 143, BOOST: 180), M.E.P.S. 2750 FT/MIN (N.A.: 137, BOOST: 165), M.E.P.S. 3000 FT/MIN (N.A.: 131, BOOST: 144), RPM: 3275
Row 4: Engine: PEGASUS, Cylinder Head: PENTHOUSE, Piston Diameter: 5.75, Valve or Port Area: 5.36, Ratio: .207, M.E.P.S. 2500 FT/MIN (N.A.: 148), M.E.P.S. 2750 FT/MIN (N.A.: 144), M.E.P.S. 3000 FT/MIN (N.A.: 138, BOOST: 161), RPM: 2400
Row 5: Engine: PERSEUS, Cylinder Head: SLEEVE, Piston Diameter: 5.75, Valve or Port Area: 5.60, Ratio: .216, M.E.P.S. 2500 FT/MIN (N.A.: 139, BOOST: 179), M.E.P.S. 2750 FT/MIN (N.A.: 138, BOOST: 165), M.E.P.S. 3000 FT/MIN (N.A.: 135), RPM: 2775
Row 6: Engine: AQUILA, Cylinder Head: SLEEVE, Piston Diameter: 5, Valve or Port Area: 4.8, Ratio: .245, M.E.P.S. 2500 FT/MIN (N.A.: 141), M.E.P.S. 2750 FT/MIN (N.A.: 134), RPM: 3350
Row 7: Engine: KESTREL, Cylinder Head: SLEEVE, Piston Diameter: 5, Valve or Port Area: 4.8, Ratio: .245, M.E.P.S. 2500 FT/MIN (N.A.: 141), M.E.P.S. 2750 FT/MIN (N.A.: 134), RPM: 3275
Row 8: Engine: EXE, Cylinder Head: AIR COOLED, Piston Diameter: 4.25, Valve or Port Area: 2.9, Ratio: .204, M.E.P.S. 2500 FT/MIN (N.A.: 135), M.E.P.S. 2750 FT/MIN (N.A.: 130), M.E.P.S. 3000 FT/MIN (N.A.: 124), RPM: 4500
Row 9: Engine: EXE, Cylinder Head: LIQUID, Piston Diameter: 4.25, Valve or Port Area: 3.37, Ratio: .237, RPM: 4500
Row 10: Engine: BENTLEY, Cylinder Head: STANDARD, Piston Diameter: 3.25, Valve or Port Area: 1.36, Ratio: .177, M.E.P.S. 2500 FT/MIN (BMEP: 117, IMEP: 155), M.E.P.S. 2750 FT/MIN (BMEP: 110, IMEP: 152), M.E.P.S. 3000 FT/MIN (BMEP: 99, IMEP: 145), RPM: 4000
Row 11: Engine: BENTLEY, Cylinder Head: "1 1/2 INLET VALVE", Piston Diameter: 3.25, Valve or Port Area: 1.68, Ratio: .203, M.E.P.S. 2500 FT/MIN (BMEP: 125, IMEP: 163), M.E.P.S. 2750 FT/MIN (BMEP: 119, IMEP: 161), M.E.P.S. 3000 FT/MIN (BMEP: 109, IMEP: 155), RPM: 4000
Row 12: Engine: BENTLEY, Cylinder Head: 2 VALVE RAMP, Piston Diameter: 3.25, Valve or Port Area: 1.68, Ratio: .203, M.E.P.S. 2500 FT/MIN (BMEP: 128, IMEP: 166), M.E.P.S. 2750 FT/MIN (BMEP: 119, IMEP: 161), M.E.P.S. 3000 FT/MIN (BMEP: 110, IMEP: 156), RPM: 4000
Row 13: Engine: BENTLEY, Cylinder Head: 2 INLET HIGH POWER HEAD, Piston Diameter: 3.25, Valve or Port Area: 2.22, Ratio: .268, M.E.P.S. 2500 FT/MIN (BMEP: 136, IMEP: 174), M.E.P.S. 2750 FT/MIN (BMEP: 133, IMEP: 175), M.E.P.S. 3000 FT/MIN (BMEP: 127, IMEP: 173), RPM: 4000
Row 14: Engine: BENTLEY, Cylinder Head: SINGLE INLET HIGH POWER HEAD, Piston Diameter: 3.25, Valve or Port Area: 2.27, Ratio: .275, RPM: 4000
Row 15: Engine: MERLIN C, Cylinder Head: RAMP, Piston Diameter: 5.40, Valve or Port Area: 4.78, Ratio: .210, RPM: 3000
Row 16: Engine: MERLIN D, Cylinder Head: RAMP, Piston Diameter: 5.65, Valve or Port Area: 5.06, Ratio: .202, RPM: 3000
Row 17: Engine: MERLIN D, Cylinder Head: PENTHOUSE, Piston Diameter: 5.65, Valve or Port Area: 5.36, Ratio: .223, RPM: 3000
  
  


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