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 report on the future Wraith, Bentley, and Phantom III models, including various component tests and modifications.
| Identifier | ExFiles\Box 161a\4\ scan0142 | |
| Date | 30th March 1936 guessed | |
| (6) In connection with the future Wraith engine it has recently been agreed that a six cylinder can be made to meet all our requirements as regards smoothness of operation, and Design are preparing a specification for a future engine of this type. It was also considered desirable to obtain some side valve engine data, testing the Packard engine power out-put on the bed originally intended for the Straight '8' Wraith. The Graham 5 port head experiment is now on test, and the results will be applied if favourable to the future Wraith engine. BENTLEY ENGINE. A report is required on the results obtained with running the Bentley engine with six separate fixed choke carburetters to establish comparable conditions with the single cylinder unit test. A development is in hand to the Bentley cylinder head to incorporate the modifications which were made for increasing the power on the Ulster Bentley. It is anticipated that an appreciable gain in horse-power should be available at the standard compression ratio on the peak of the power curve. It has been decided not to pursue this particular development in single cylinder form. Experiments are being continued to reduce exhaust losses in the silencer system. A development is required of the Chevrolet type of coolant jets for concentrating the water flow on to the exhaust valve seats. This would also apply to the 25/30 engine, and would follow the same method as outlined for Phantom III. With regard to valve spring development, it is not proposed to project any design changes on the Bentley until the results have been obtained on the work that has been carried out on Phantom III. Crankshaft and Flywheel Instructions for producing a crankshaft to the four balance weight scheme have been issued to LeC.5139 This shaft has been made and will undergo | ||