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).
Performance graph comparing a large valve cast iron head with a standard aluminum head on a PI unit.
| Identifier | ExFiles\Box 13\2\ 02-page099 | |
| Date | 12th June 1930 | |
| POWER TESTS ON PI UNIT WITH 4.9:1 COMP RATIO A.{Mr Adams} LARGE VALVE HEAD (CAST IRON) B. STANDARD (ALUM) TESTS WITH OPEN EXHAUST RR-CM EAGLE & CARB. 1.800 CHOKE R TYPE 110° CAMSHAFT TO (V.1132) LARGE VALVE HEAD TO E.80170/1/2 V.1169 B.H.P B.M.E.P R.P.M. C.W.S. 12.6.30 | ||