Rolls-Royce Archives
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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).
Graph comparing the power curves of a B.18 Large Bore unit against a Standard Bore engine.

Identifier  ExFiles\Box 90\5\  scan0086
Date  23th September 1935 guessed
  
POWER COMPARISON.
① B.18 UNIT (LARGE BORE) 6.8 : 1 COMPRESSION RATIO.
1 5/8" DIA. CARBURETTERS & INDUCTION PIPE.
1.600 INLET VALVES. 1.400 EXHAUST VALVES.
CYLINDER HEAD WITH POLISHED PORTS.
④ STANDARD BORE ENGINE 6.45 : 1 COMPRESSION RATIO.
1.400 INLET VALVES. 1.300 EXHAUST VALVES.
Axis Labels: B.H.P., R.P.M.
VALVE TIMING (.020 CLEARANCE)
FOR CURVE ①:
TDC
INL: 4.7°, 47.7
EXH: 49.3, 3.3°
FOR CURVE ④:
TDC
INL: 8.3°, 50°
EXH: 50, 3.1°
  
  


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