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).
Letter discussing modifications to the J.I. engine for a Bensport application, including details on the starter ring, flywheel, and radiator.
| Identifier | ExFiles\Box 3\4\ 04-page111 | |
| Date | 26th October 1932 | |
| To Hs.{Lord Ernest Hives - Chair} from E.{Mr Elliott - Chief Engineer} XC 553. E.6/HP.26.10.32. C.R. Sg.{Arthur F. Sidgreaves - MD} Hsr. Ms. By.{R.W. Bailey - Chief Engineer} re Bensport J.I. We send you herewith a print of LeC.3256 showing the starter ring, rear crankcase flange, rear crankshaft flange, position of starter motor, etc. for the J.I. engine, as modified to suit Bensport. We think there are sufficient particulars on this drawing to enable you to go ahead with the clutch and flywheel arrangement. The diameter of the starter ring and flywheel has been decreased to give a ground clearance of just over 6" with the present transmission line. The rear face of the crankchamber has been moved forward to within 4.625" of No.6. cylinder centre, to enable you to get maximum clearance for the floorboards. As regards the front of the engine, we also attach a print of E.54745 showing the slipper flywheel case and fan pulley that will be used. We cannot reduce the diameter of this case, and it will be necessary to obtain the requisite clearance for the cross steering tube by moving the engine back from where it was shown on our preliminary layout. We are obtaining a blueprint of the underpan which will be sent to you later, but for the time being we think that E.54745 will be useful to you. With regard to the radiator, we have got to ask ourselves if the matrix of the Bensport radiator as designed is large enough for J.I. engine. J.I. engine has a much larger area of water heating surface than Peregrine, although this is counter-balanced somewhat by the difference in temperature, which would result from not being supercharged. The volume of the Bensport matrix is almost exactly half of what we use on the 20/25, but would have a greater relative value if of the Harrison pattern. We can improve the value of the Bensport radiator by dropping the bottom tank some four or five inches until it is level with the bottom of the shutters, thereby extending the matrix the same amount. This may be worth considering if it is agreed that the supercharged engine is a long way off, or may never be developed. | ||