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).
Comparison of mechanical efficiency, friction losses, and ignition systems between Lorraine, Goshawk, and Phantom engines.
| Identifier | ExFiles\Box 22\4\ Scan092 | |
| Date | 30th March 1927 guessed | |
| contd :- -6- mechanical efficiency curves. The overall mechanical efficiency of the Lorraine is higher than the Goshawk but actually there is little difference in the power absorbed in rotating the engine up to 2000 r.p.m. although above this it becomes greater. The higher efficiency is due to the greater specific power output. Perhaps a better comparison of the friction losses of these two engines is given on print 12, which shews the H.P. absorbed in rotating the engine per unit capacity and by this basis of comparison we avoid including any advantage resulting from higher compression ratio and other factors. We see for its capacity the Lorraine loses more power in rotating the engine than the 20 HP. above 2000 r.p.m. The loss consists of that due to both friction and pumping. IGNITION AND SPARK PLUG POSITION. Delco dual coil ignition is employed provided with the usual automatic advance. The two spark plugs are symmetrically arranged on opposite sides of the combustion chamber and the times of ignition are synchronised. The synchronisation is not electrical but relies upon the setting of the contact makers in the same way as upon the Hispano. One particularly interesting feature is the small spark advance required to give max: power at full load. This [crossed out] advance is even less than required by the Hispano which we have always considered small compared with our own engines and also [crossed out] less than the best results we have obtained with the new alum: Phantom. The cyl. is of course smaller than these above mentioned engines and would therefore have less distance for contd :- | ||