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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).
Cost and weight comparison between an aluminium monoblock and an existing cast iron engine unit.

Identifier  ExFiles\Box 107\4\  scan0149
Date  24th March 1937 guessed
  
20/25 . 358

COMPARISON ALL ALUM. MONOBLOCK (J.III TYPE) UNIT WITH
EXISTING 20/25 UNIT.

Sp.{Mr Spinney} Gr.{George Ratcliffe} Cast Iron 2.81 times that of Al.

Cast Iron.
Wt. of cylinder block. 62.5
Wt. of cylinder head. 73
Total weight C.I. @ 1d/lb. 135.5.
Total cost of cast iron 11/3.

Aluminium.
Wt. of cylinder block. 22.2
Wt. of cylinder head. 26
Total wt. of aluminium @ 1/4 per/lb. 48
Total cost of Al. 64/-.

Liners basically cannot be much more expensive than the
cylinder bores they replace, otherwise how could the Wolsey Hornet fit
them

Rm.{William Robotham - Chief Engineer}
  
  


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