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 compression ratios and carburetters on different engine configurations.
| Identifier | ExFiles\Box 43\1\ Scan091 | |
| Date | 26th August 1925 | |
| R.R. 493a (50m) (D.B. 175 25-9-24) J.H.D. EXPERIMENTAL REPORT. -5- Expl. No. REF HS{Lord Ernest Hives - Chair}/TAG/LG26.8.25. 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) Eagle 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 increases 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 re-crossing 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. These curves bear out the characteristic shewn in the others, when the Eagle Vlll. carburetters are fitted, of giving better power at low speeds, and that the Eagle Vlll. curves flatten out at high speeds and droops after 2050 r.p.m. has been reached. In the case of the Eagle lX. carburetters the increase at high speeds is considerable. contd :- | ||