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).
Page 2 of a test report on the Derby Hot Throttle system, detailing performance on a Springfield car and comparing boiler capacities.
| Identifier | ExFiles\Box 50\3\ Scan253 | |
| Date | 27th December 1922 guessed | |
| -2- Re Tests of Derby Hot Throttle, cont'd No. 4 - Springfield standard car Left in yard for 2 hours, bonnet open Air temperature 18° F No water in engine Air temperature at time of test 20° F Engine started within 6 seconds. Due to opening throttle too quickly, engine stopped, making another start necessary. Ran for 1 1/4 minutes on partly open jet and carburetter - it was not possible to entirely close the pilot jet - and examined cylinders at end of run, which were found to be bone dry and no trace of wet gas around valve stems. The rear boiler was emptied and had collected 3 or 4 ounces of gas. The capacity of the Derby boilers is 4 1/2 ounces against 9 ounces for the Springfield type, this being too small to prevent wet pistons, etc. Also the boiler is too high up on the exhaust pipe, and in the event of flange cracking - they do crack - re-flanging is impossible as the union nut cannot be pushed far enough down. The Derby hot throttle is excellent and, so far as my experience with it goes, is an absolute check on loading up. It enables the engine to run well within a minute or two of starting up from cold, and with the engine temperature at 100° F the carburation is so good that one would not suspect the engine of being at anything but the correct working temperature. The power and speed have not been diminished, as 10 to 50 M.P.H. can be done in 22 seconds - 14 x 52 axle enclosed drive body - and 68 M.P.H. is not the limit with cut out closed. The gas consumption has not been altered. Our experience is that the hot throttle does not cancel the boilers, as their chief purpose in life is to prevent indigestion at the start due to the use of bad gasoline, and to watch over the engine in everyday use when the pilot jet will be carelessly used. E.W.C. | ||