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).
6,000-mile performance and condition report on the 24-EX experimental vehicle's Engine Unit No. 23.
| Identifier | ExFiles\Box 11\3\ 03-page223 | |
| Date | 20th July 1930 | |
| To: Hs.{Lord Ernest Hives - Chair} From G.W.H. Hôtel de France, Châteauroux, Indre. 20/7/30. REPORT ON 24-EX at 6,000 MILES. ENGINE UNIT No. 23.- The general performance of the engine for smooth running, good acceleration, ease of starting in the morning, has been very good throughout the mileage. The maximum speed is down, the actual speed timed on Brooklands was 76 M.P.H. with the exhaust system Ex. 5123 fitted. A test on the Montlhéry track with a straight through 2.5" pipe from the manifold to a Phantom II rear silencer was 78.1 M.P.H. The troubles which affected the running of the engine were a failure of No. 3 exhaust valve. This lost .012" clearance in two days' running during the very hot weather experienced. The valve in question measured up proved that the tulip portion had stretched. A new valve fitted has not altered from its first setting. It would appear that the steel of the one that failed is probably at fault. The oil consumption throughout the mileage has been poor, a consumption of 434 M.P.G. being the average. We have not observed any sign of overoiling at high speed or when running light. The oil in the crank chamber got very hot; our gauge which reads up to 100°C. was on the stop on a good many occasions. The engine has been very free from any marked periods of vibration after resetting the low inertia spring drive upon arriving here. There has been no sign of thuds or bus knocks upon acceleration. The acceleration of the car is as follows:- 10 - 20 M.P.H. 4.3 secs. 20 - 30 M.P.H. 4.4 secs. 5-2 30 - 40 M.P.H. 4.5 secs. 10-7 40 - 50 M.P.H. 5.8 secs. 19-0 50 - 60 M.P.H. 7.8 secs. 26-8 60 - 70 M.P.H. 11.5 secs. 38-3 The engine has remained free from any outward bad oil leaks. There is a slight weep from the rocker cover. Signs of pre-ignition were noticed after a hard sustained run. Detonations are more pronounced with the use of the commercial spirit upon accelerating. It is necessary to retard the ignition lever 6 to 8 notches to remain free from them. PISTONS to L.O.P. E.79533.- There are no piston knocks upon starting up from cold, very light knocks can be heard when the engine is hot. There has been no sign of overoiling at high or low speeds. A fair amount of carbon can be observed on the piston tops. | ||