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).
The comparative advantages of a new high power cylinder head design regarding cost, silence, smoothness, and slow running.
| Identifier | ExFiles\Box 148\5\ scan0116 | |
| Date | 1st September 1936 | |
| -3- (4) Cost. The present cylinder head casting is a difficult foundry job. Taub, chief engineer of Chevrolets, was astonished at the high degree of accuracy called for. In a very small space six cylinder studs, two push rods, two valves and adequate water passages have to be incorporated. Owing to lack of space, cores have to be extremely delicate and complicated to get all these parts in. The high power construction enables us to have one valve and push rod only in the head. In America it has been established that a side valve engine is cheaper than an overhead valve engine. Therefore we should save money on the high power head as its cost must be half-way between the two. It is certain that one rocker and push rod are dispensed with. (5) Silence. The side valve exhaust must basically be quieter than the overhead valve exhaust it replaces. (6) Smoothness. A great deal has been written about the advantage of certain combustion chambershapes in getting a smooth engine. Our experience has been limited. If, however, the claims of Mr. Taub can be substantiated, the high power head does permit of his recommended shape being reproduced, whereas with our existing standard head this is not possible. (7) Slow running. It is quite certain that tests so far shew that maximum power output can be obtained with less overlap on the high power than the standard head. This encourages the belief that ultimately the high power head may give a better standard of slow running. | ||