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).
Engine development, including superchargers, bearings, and American automotive trends.
| Identifier | ExFiles\Box 178\2\ img127 | |
| Date | 4th April 1934 | |
| -4- Lastly, some of the accoustic work on dash insulation has helped them to keep noise out of the driving compartment. Therefore we know where our deficiencies lie. We were definitely impressed with the Graham supercharger development as being a practical means of improving performance without increase in noise or roughness, except in so far as this may arise with increase of engine speed. At present on the Bentley we throw away a certain amount of low speed performance and a considerable amount of valve gear silence to get a 15% increase in top power. The blower can give us 40% increase in top power without either of the deficiencies mentioned. It has the added advantage that it weighs little and does not increase the length of the power plant. This is the first time we have ever felt any leanings towards a supercharger for a Rolls-Royce automobile product, owing to the crankshaft limitations of a 6-cyl., this blower is more suited to a line 8. It is apparent that in twelve months' time lead bronze bearings will be standardised on the majority of American cars, the cost of production at present is their major disability. The aluminium rod has not yet found many adherents, when utilized it is fitted with a steel cap. Cadillacs have tested this combination experimentally, and have no fault to find with it. Connecting rods are being located sideways directly on the steel. This seems an advantage in several respects. Thin shell bearings down to a total thickness of .050 are being used. There seems to be no hard and fast rule for the number of main bearings giving the best results. We have tried five and nine bearing eights, four and seven bearing twelves, without being able to say that one or the other was necessarily always the better. A lot of research has been carried out on combustion chamber design for smooth operation which we could with advantage emulate. | ||