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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).
Tests using Buick type pistons on a modified Bentley engine.

Identifier  ExFiles\Box 134\1\  scan0060
Date  21th December 1937
  
BUICK TYPE PISTONS.

A series of tests were run on a Bentley head modified to SCT.70, and an open type 20/25. head on a bored out engine to see whether anything could be gained by using a Buick type piston, shown in Fig.1.

Buicks themselves have fitted this piston as standard, and claim an increase in horse power of from 130 at 3,400 rpm. to 141 at 3,600 rpm. for their large engine (bore x stroke = 3 7/16" x 4 5/16"; capacity = 5240 cc.) accompanied by an increase of compression ratio from 5.90 to 6.35. This increase in C.R. only gives a power increase of about 4-5% so that the total gain in power claimed of 8½% is not fully explained by the increase in compression.

The two series of tests run viz.Bentley and 25/30 will be separated until the end of the report when the general conclusions will be summarised.

continued

Fig.1.

Plug.

BUICK PISTON AND COMBUSTION CHAMBER.
  
  


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