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).
Engine performance improvements related to volumetric efficiency and fuel injection systems.
| Identifier | ExFiles\Box 179\2\ img166 | |
| Date | 20th January 1932 | |
| -2- our output at 2000 R.P.M. to 102.8 lbs/sq.in. BMEP at 1447 lbs/HP/HR. We are very anxious for the new cylinder to be pushed on at utmost speed, as we feel confident that its expected improved volumetric efficiency will give us a further improvement in our performance. We have tried ramming pipes of various length in an endeavour to fill our cylinder. While a short pipe (1ft long) increases slightly the compression pressure at 2000 R.P.M., no appreciable improvement in power output is felt. At 1500 R.P.M. a considerable benefit is derived from the use of a 3ft pipe. Tests have been carried-out with alterations to the anti-dribble valve of the Bosch injection pump with a view to finding the most effective displacement of same. Up to double the displacement of the standard valve, no variation in performance is noted; but beyond this amount unsteady running results. If however, the valve is entirely removed and a ball-valve substituted, no decrease in power output is noted. It appears therefore that the anti-dribble feature of this valve is of no importance from a power out-put standpoint. Its effect on slow running and light-load running will be investigated in future tests. More work has been done on the "inverted" or non-return type injector valve, but our performance figures are as yet very poor; viz: 84.5 lbs/sq.in. BMEP at 2000 R.P.M. (normal injection). It will be remembered that prior to our abandoning swirl the behaviour of this valve was promising: a BMEP of 92.6 lbs/sq.in. having been obtained at 2000 R.P.M. It therefore seems that swirl is necessary to obtain good results from this valve, which produces a less-diverged type of spray. Our work for the immediate future includes :- (a) Boosted running, using the improvements detailed above. (b) Still quicker injection. (c) Determination of optimum valve of differential ratio. (d) Improvement of inverted valve injector. Hm{Capt. W. Hallam - Head Repairs}/C.H.Parkinson. | ||