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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).
Engine specifications including timing, power curve data, compression ratio, and clearance volume.

Identifier  ExFiles\Box 19\7\  Scan143
Date  11th July 1929
  
To EP.{G. Eric Platford - Chief Quality Engineer} from Hs{Lord Ernest Hives - Chair}/Gy.

X490.

Hs{Lord Ernest Hives - Chair}/Gyl/MJ.11.7.29.

Re. S.S.

X1440
X928
X490.
X381.

(1) Std. Valve Timing.
We attach print V.527, Standard Valve Timing.

(2) Std. Ignition Timing.
This is 12° before T.D.C. with hand control fully advanced.

(3) Power Curve
We understand that the figures supplied previously for a power curve for 6 units are not likely to be obtained on Unit beds, as the exhaust systems are not alike. The silencers arrangements may make 10% difference to the power obtained at high speeds. The nearest conditions to those obtained on your unit beds gave the following figures :-

R.P.M. Load⁺ c/B.H.P.
2750 106.7 122.2
2500 119.5 124.6
2250 126.2 118.4
2000 131.8 109.8 ++ Dyno formula HP = WN/2400
1750 135.3 98.7
1500 136.3 85.2
1250 136.5 71.1
1000 136.49 57.0
750 136.4 42.6
500 135.3 37.8

(4) Compression ratio (actual) is 4.6

(5) Clearance volume = 21.67 cu.inches.

Hs{Lord Ernest Hives - Chair}/Gy.
  
  


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