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).
Question and answer sheet regarding the performance, cost, and reliability of an O.H.V. engine.
| Identifier | ExFiles\Box 113\5\ scan0197 | |
| Date | 2nd August 1937 | |
| -3- QUESTION. (3) Can any O.H.V. engine be made as quiet as a push rod engine? (4) How does it compare for detonation with standard? (5) Does the increased power output produce increased roughness, noise and fuss? (6) What is the cost relative to the standard practice? (7) Is the construction of the cylinder head mechanically reliable? ANSWER. the existing preliminary set up a considerable gain in road performance at medium and top speeds has been measured on the road. With the new camshaft that has been designed there is little doubt that the valve gear will be quiet but it has not yet been tried to prove the point. For a given low speed power output it is no worse than the standard Bentley even with the first camshaft. Difficult to say until the correct exhaust and intake silencers have been made for the unit. As the increased power output has been obtained with a lower compression ratio than that of the standard car it is difficult to see why it should be any rougher except at the top speeds. No one has the slightest idea nor is there any machinery at present for finding out. The cylinder head joint of the first design was a weak feature. It can be improved without much difficulty, but in its initial condition it has not given any trouble on the road. If the head were in cast iron, one could almost guarantee that the joint could be made quite satisfactory as the stud centres are less than on many American cars. | ||