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).
Analysis of power loss theories related to carbon deposits and a comparison of engine power outputs.
| Identifier | ExFiles\Box 179b\3\ img213 | |
| Date | 4th February 1933 | |
| -23- under certain conditions, remain practically constant in size when the power was fairly constant. It might, however, commence to grow whence the power would gradually decrease and the piston and exhaust temperatures rise. The rise in temperature accelerated rate of growth of the "cone" and the power would fall away at a greater rate. The cone might, and often did, fall off while running when the power would rapidly regain its former value. Carbon deposit also tended to build up in the nozzle hole. Its removal resulted in an increase in power. In the R.R. tests there was no visible carbon cone formed but a deposit might easily have built up at the inner end of the nozzle holes. The three types of power loss mentioned previously could then be explained. (1) More or less steady falling off of power would correspond to slow building up of carbon deposit. (2) A sudden drop in power without recovery might be due to accelerated rate of carbon deposit (as in tests 3b and 3c due to leakage in fuel line) or to a carbon deposit already formed being displaced so as to suddenly interfere with the sprays. (3) A sudden drop in power with immediate recovery would result if a portion of the carbon deposit were broken off and momentarily blocked one or more jets. Such carbon would probably come from a deposit at the inner end of the spray holes. The carbon deposit theory is considered to be the more likely explanation of the loss of power while running. Precisely why and how the carbon builds up is not known. Causes of the Power Output being less in C.I.2 than in C.I.1. At the end of the tests described in this report the steady power of C.I.2 was between 3 & 4 lbs/sq.in. below the corresponding power of C.I.1. The only apparent difference between C.I.1 and C.I.2 is the shape and dimensions of the inlet valve passage. Remembering (1) that the injector and the injection system conditions are the same in both engines and (2) that the secret of successful combustion in the direct injection engine with open type cylinder is correct co-ordination of the air and oil motion and that for the highest B.M.E.P's and | ||