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).
Performance comparison experiments for a Bentley II with a standard air intake versus an external air intake, including acceleration test results.
| Identifier | ExFiles\Box 85\4\ scan0195 | |
| Date | 29th August 1938 | |
| 208 To By.{R.W. Bailey - Chief Engineer} c. to Hs.{Lord Ernest Hives - Chair} c. to Da.{Bernard Day - Chassis Design} Rm{William Robotham - Chief Engineer}/GR.{George Ratcliffe}3/JH.29.8.38. BENTLEY II. EXTERNAL AIR INTAKE. Experiments carried out to compare Bentley perform-ance with a standard air intake to the carburetters and with an external air intake. Tests with an external air intake were carried out by reversing the intake pipe between air silencer and carburetters, cutting off the elbow and attaching by means of rubber hosing a two foot length of 3" copper pipe. The latter protruded through the side panel of the bonnet, now replaced by a suitably cut sheet of millboard, and was tied to the headlamp bracket so as to be parallel with the direction of motion. The headlamp was removed, so that air was taken from a spot free from the possibility of eddies. A hole was drilled in the intake pipe midway between the two carburetters, and a thermometer insulated from the pipe by asbestos lagging was inserted so that a figure for air temp-erature at the carburetters might be obtained. Further thermometers were situated under the bonnet to give the temperature at the air silencer inlet, and beneath the front bumper to give external air temperatures. Average acceleration figures were obtained with the two systems of air intake, and special note was taken of any tendency towards flat spots with the external air intake. Summary of tests carried out on 3.B.IV. Acceleration tests. MPH. Standard air intake. Av. time in secs. External air intake. Av. time in secs. % increase in performance with external air intake 20 to 40 6.2 6.0 3.2% 20 to 60 14.9 14.1 5.4% 20 to 80 30.6 29.8 2.6% | ||