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).
Outlining the requirements and design considerations for twin and 25HP carburetters.
| Identifier | ExFiles\Box 13\3\ 03-page337 | |
| Date | 25th August 1931 | |
| HS.{Lord Ernest Hives - Chair} FROM R.{Sir Henry Royce} X7080 R2/M25.8.31. C. to SG.{Arthur F. Sidgreaves - MD} WOR.{Arthur Wormald - General Works Manager} P.2. CARBURETTERS X.7080. Ct to BY.{R.W. Bailey - Chief Engineer} HS{Lord Ernest Hives - Chair}/LOV.{Mr Lovesey} X.5080. THE TWIN CARBURETTER WHICH YOU HAVE. This has been corrected; what is the best it will do? 25HP. CARBURETTERS. (2) For this we have sent two separate carburetters which can be tried on any existing 'Japan' with a temporary or no silencer. (3) As we do not wish to use a very high engine speed it is imperative that we get a good low speed torque. (4) You will see that if we get good low speed torque we can use it to gear the car higher or to keep the inlet open later and use a higher compression ratio, so we can have better acceleration or higher top speed. (4a) If we can get low speed torque, say 10%, we can gear the car 10% higher for equal top gear acceleration, say from 1000 to 2000 RPM. (5) The following requirements have been laid down, and if they are still true we are forced to make (in the near future) the carburetters either as two separate, or twin. (6) We still understand that for low speed torque we want two carburetters and if fixed throats are used again for good metering there must be 2 carburetters per 6 cyl. engine. (7) For good distribution we must have diffuser main jet. This brings us to a fixed throat. (8) For good slow running and certain starting we must have throttle edge carburation. (9) For snap acceleration we must have pump, with delay action so that this is not excessive or wasteful. (10) Mixture control of both high and low to jet control is agreed to be a necessity. (11) Our scheme of enriching the throttle edge carburation for starting is so good that we ought to protect it if possible. | ||