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).
Comparing the development of a six-cylinder engine against a four-cylinder version, outlining costs, design choices, and simplifications.
| Identifier | ExFiles\Box 180\M1\9\ img015 | |
| Date | 1st August 1921 | |
| To C.J. from R.{Sir Henry Royce} -2- R3/G29/8/21 Contd. with studs for the head is extremely favourable to a good joint there being plenty of studs in good positions. On this chassis every effort is going to be made to reduce the cost of the rest of the chassis, so as to enable us to give a six cylinder engine, though this will be as simple and inexpensive as possible consistent with perfection of running. It seems particularly desirable that we, as six-cylinder specialists, shall stick to a six cylinder engine. We want you to look at this engine and compare it with the four cylinder one made up of "Goshawk" parts, bearing in mind that this engine will permit of a smaller flywheel and better road clearance, and smaller and lighter clutch and transmission shaft, owing to the more even torque. Against it are the rather large numbers of smaller sized parts, such as valves, pistons, and connecting rods. Mr. Johnson and I have agreed that the approximate Works cost with charges of the four cylinder must not exceed £500 and of the six-cylinder must not exceed £550. It should be remembered also that the six-cylinder engine will be slightly easier for the electric starter. We have already made considerable progress in the reduction and simplification of the gear box and the spring drive for the half time wheels. We do not consider a slipper flywheel will be necessary. We are only fitting a lightly built fan pulley fastened on the crankshaft. R.{Sir Henry Royce} [Handwritten notes below] * 4 cylinder 8½ * 6 cylinder 9½ Blue print attached to Works copy of this memo. [Purple circular stamp on the left side: BEOEIAHPC] | ||