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).
The effect of intake air temperature on the power, detonation and carburation of a Bentley III unit.
| Identifier | ExFiles\Box 99\1\ scan0025 | |
| Date | 11th August 1938 | |
| 408 To Hy.{Tom Haldenby - Plant Engineer} c. to Da.{Bernard Day - Chassis Design} c. to Da{Bernard Day - Chassis Design}/JNR.{Charles L. Jenner} c. to Da{Bernard Day - Chassis Design}/Mc Stay. c. to Rm{William Robotham - Chief Engineer}/FD.{Frank Dodd - Bodies} c. to Rm{William Robotham - Chief Engineer}/IMW.{Ivan M. Waller - Head of Chateauroux} RM{William Robotham - Chief Engineer}/CTT.S/JH.11.8.38. BENTLEY III. Intake Air Temperature. PURPOSE OF TEST. To determine the effect on power, detonation and carburation, of varying the temperature of the inlet air over a fairly wide range. METHOD OF TEST. The experiment was carried out on a Bentley III unit, using a normal 2 S.U. carburetter induction system. The normal air silencer shell was used, the innards being replaced by heater coils for controlling air intake temperature. RESULT. Graph No.S.30 shows that as the air intake temperature increases, so slightly more power is lost by retarding the spark to avoid detonation. The tendancy for the higher temperature to increase detonation is in this case therefore of little importance. What is important however, is the fact that our normal under bonnet temperature of 45°C is responsible for the loss of 10 lbs.sq.in.B.M.E.P. at the speed of max. torque. Graph No.S.31 shows this point, and further demonstrates that the difference between the max. power ignition line and non detonating line remains in proportion as the air intake temperature increases. CONCLUSIONS. The experiment of taking the intake air from outside the bonnet should be repeated, because if an under bonnet temperatures are in the region of 45°C, we definitely stand to gain about 10 MEP. at say 30-40 miles per hour. It will be necessary however to adjust the carburation to suit the new condition. Rm{William Robotham - Chief Engineer}/CTT. | ||