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).
Increased petrol consumption in 40/50 HP cars with four-wheel brakes, questioning if it's due to the choke valve.
| Identifier | ExFiles\Box 24\5\ Scan043 | |
| Date | 4th May 1925 | |
| To Hs.{Lord Ernest Hives - Chair} from BJ. Copy to...THOR. By H.{Arthur M. Hanbury - Head Complaints} X766 BJ2/H4.5.25. OVERHEATING. With reference to Hs{Lord Ernest Hives - Chair}6/LG27.4.25, concerning overheating on 40/50 h.p. cars, it is stated that when the 40/50 h.p. with four-wheel brakes is run at light throttle, in order to obtain the same amount of power on the road wheels, the carburetter throttle has to be opened more. Therefore, with the car in which the choke valve is in the exhaust pipe for all six cylinders, the driver would use under light throttle conditions, comparatively more throttle. The point, therefore, arises, whether this car is not likely to use more petrol on account of the above conditions. If this is so, can you suggest any way in which we can overcome this high petrol consumption fairly easily? For instance, if one of our inspecting engineers is calling on a customer who is complaining of high petrol consumption, can the inspecting engineer make any adjustment to cure this, or would it be necessary to abandon the choke valve and fit waterheated carburetter? We find that the complaints of petrol consumption are gradually rising, and we therefore want to ascertain what you would advise in such circumstances. We shall of course bear in mind that as there has been such a large number of 40/50 h.p. chassis fitted with the choke valve, we want to prevent starting the rumour amongst all owners that if they come to Rolls-Royce and ask for their carburetter to be altered, we shall fit a new one which will effect a great saving in petrol consumption, as we know what customers are in this respect. On the other hand, where we do receive serious complaints, we obviously want to do everything possible to overcome the complaints and satisfy the customers. For instance, we have the case of Mr. Duncan Patterson, (chassis No. 52-LM), who complained that after his car came back fitted with front wheel brakes, his petrol consumption was "altered from over 13 to something like 11". We asked W. whether they had made any alteration to the carburetter whilst the car was at the works, and they informed us that they made no alteration. Presumably, therefore, the increased petrol consumption is due only to the choke valve. B.J. | ||