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 showing compression pressures against RPM for an Alfa-Romeo unit with a 5.35:1 compression ratio.
| Identifier | ExFiles\Box 179\2\ img230 | |
| Date | 4th December 1925 guessed | |
| UNIT ALFA-ROMEO COMPRESSION PRESSURES COMPRESSION RATIO 5.35:1 COMPRESSION PRESSURE LBS/SQ IN 170 160 150 140 130 120 110 1000 1500 2000 2500 3000 3500 4000 4500 R.P.M. V12 | ||