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).
Motoring losses and a development program to address power loss due to injector overheating and air motion changes.
| Identifier | ExFiles\Box 179b\3\ img193 | |
| Date | 4th February 1933 | |
| -3- The motoring losses in C.I.2 at 2000 R.P.M. were 4 lbs/sq.in. M.E.P. greater than in C.I.1 and hence making allowance for this difference the B.M.E.P. of C.I.2 was 90.8 lbs/sq.in. at normal power and 2000 R.P.M. or 11 lbs/sq.in. below the corresponding value for C.I.1. Since the cylinders differed only in the shape of the inlet valve passages and in the cooling of the injector, the loss of power was thought to be due to :- (1) The change in air motion within the cylinder caused by the change in size and shape of the inlet valve passages. (2) Overheating of the injector. Accordingly a development programme was drawn up in which it was proposed to first modify the cooling of the injector by preparing a new cylinder block and boring this out to fit a standard Bosch injector and thus doing away with the bush and sleeve previously used. If the power was still unsteady or the injector still overheating, the cylinder was to be further modified by boring out an annulus in the injector housing and inserting a copper tube so that water could circulate in close proximity to the injector as in C.I.1. The scheme is shown in Fig.9 from which it will be noted that it differs from C.I.1 only in the size of the holes or windows bored through the housing to enable the water to enter and leave the annulus. These holes were made rather small as they weaken the metal taking the reaction of the rocker bracket of the combined pump and injector. C.I.2 would then differ from C.I.1 only in the shape of the inlet valve passages and if the power was still down it could be attributed to the disturbance of the air motion within the cylinder. Having reached this stage it was proposed to modify the cylinder by introducing one by one the special features originally in C.I.2 and thus observing the effect of each on performance. With the exception of the items in the last paragraph this programme is now complete. A schedule of the tests conducted is given in the following pages. This has been arranged to show at a glance the purpose, condition and results of each test. The tests have been divided into four series, the basis of the division being the cooling arrangements for the injector. | ||