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).
Comparing engine power output based on different compression ratios and carburettor setups.
| Identifier | WestWitteringFiles\N\July1925-September1925\ Scan158 | |
| Date | 1st August 1925 | |
| R.R. 493A (50H) (D.B. 175 25-9-24) J.H.D. EXPERIMENTAL REPORT. -5- Expl. No. REF Hs{Lord Ernest Hives - Chair}/TAG/LG26. 8. 25. With the 6.28 to 1 pistons the increase is very slight over the 6.09 to 1 at low speeds and up to 2200 r.p.m. then the lines diverge and at 2300 r.p.m. the increase in power is very large and still continues to rise at 2400 r.p.m. CURVE Vll. COMPRESSION RATIO COMPARISON. The comp. ratios were as in Condor Vl.{V. Lewis / Mr Valentine} (1) and (2). (3) Eagle lX, camshafts. (4) " Vlll. Carburetters and induction pipes. The low speed increase in power over the Eagle lX. carburetters is still shown comparing curves Vl.{V. Lewis / Mr Valentine} and Vll. The increase in power by increasing the compression ratio from 5.27 to 1 to 6.09 to 1 is considerable and the curves for these two are practically parallel with a slightly greater increase at higher speeds. The result of increasing the compression from 6.09 to 1 to 6.28 to 1 is rather peculiar i.e., with the Eagle Vlll. carburetter fitted as will be seen - at low speeds up to 1830 r.p.m. there is a slight increase in power and then it falls below the line of the 6.09 to 1 ratio recrossing it again at 2030 r.p.m. and then rising rather quickly up to 2400 r.p.m. and at 2300 r.p.m. there is quite a large increase over the 6.09 to 1 curve. CURVE Vlll. CARBURETTER COMPARISON. The engine was fitted with :- (1) Eagle Vlll. camshafts (no overlap). (2) " carburetters and induction pipes. (3) " lX. " " (4) Standard pistons 5.27 to 1. contd :- | ||