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).
Air flow pressure difference tests conducted on various wooden and standard cylinder head models, with and without cylinder barrels attached.
| Identifier | ExFiles\Box 86\1\ scan0037 | |
| Date | 30th November 1933 | |
| -2- 3. Air flow press. difference curve for wooden model of EB.615 head. 4. Air flow press. difference curve for wooden model of Lec.3673 head. Note. These tests were carried out in the usual manner, with exit from combustion chamber open to the atmosphere - however it was decided to try the effect of a dummy cylinder barrel (attached to the head as it would be in the engine) on the air flow. The difference was so marked in the case of the Lec.3673 head that the following tests were also carried out. 5. Air flow press. difference curve for standard EB.615 wooden model with cyl. barrel attached. 6. Air flow press. difference curve for Lec.3673 wooden model with cyl. barrel attached. 7. Air flow press. difference curve for Lec.3673 wooden model (cyl. barrel attached) with increased valve lift (.450" instead of .400") The results of those tests are shown on graph sheets (1), (2), & (3) attached. CONCLUSIONS DRAWN FROM TESTS. (a) From graph sheet (1) it is seen that the new alum. cylinder head XB.1237 is slightly inferior to the normal EB.615 head fitted with the same size valves (i.e. large valves, 1.5" throat dia.), but still slightly better than the standard head EB.615 fitted with standard valves (1.4" throat) from a volumetric efficiency stand-point. The difference is not large enough to be sure that it is not masked by experimental errors. (b) From graph sheet (2) it is seen that the new design Lec.3673 is very much better from a volumetric efficiency point of view than the standard EB.615 design, the flow for a given press. difference increasing by 20%. | ||