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).
Modifications to the Phantom III Induction System for improved breathing.
| Identifier | ExFiles\Box 93\2\ scan0182 | |
| Date | 13th March 1937 | |
| 308. E/PSN.4/MN.13.3.37. To HRS. Copy to- De. BY.{R.W. Bailey - Chief Engineer} Rm.{William Robotham - Chief Engineer} Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} PHANTOM III Induction System. Modifications for Improved Breathing. An examination of the Phantom III Induction System layout from the point of view of restriction to flow shows at once that one main restriction exists at the throttles which are too small in comparison with the rest of the system. It has been our practice on six cylinder engines with one carburetter, to make the area at the throttle 1 1/2 times the induction pipe area. On this basis the Phantom III throttle diameter should be 1.850" instead of 1.687" which they are at present. We have shown them opened out to 1.8" diameter which is the largest we can go, using an existing casting. We also suggest trying a 1.4" bore induction pipe with a view to improving low speed m.e.p. and pick-up. We have opened out the Hot box to suit and retained the horizontal baffle which can be deleted if it is no longer beneficial. We send you herewith a print of LeC.5551 together with the following details which will enable the tests to be carried out. 2 prints. - RS.{Sir Henry Royce's Secretary}462. Modified Induction Pipe Heater. 1 print - RS.{Sir Henry Royce's Secretary}463. Bored out Throttle Body. 1 " - RS.{Sir Henry Royce's Secretary}464. Bored out Insulating Washer. 1 " - RS.{Sir Henry Royce's Secretary}465. New Throttle Spindle. 1 " - RS.{Sir Henry Royce's Secretary}466. New Throttles. - - 2 off. Details of the 1.40" bore induction pipe will follow. Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} will supply the parts to be modified. P/PSN. Att: | ||