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).
Computed power curves for a 20 HP engine, comparing performance factors with a Lorraine engine and detailing valve and crankshaft observations.
| Identifier | ExFiles\Box 5a\5\ 05-page015 | |
| Date | 30th March 1927 guessed | |
| contd :- -8- POWER CURVES FOR 20 HP. RR. COMPUTED FOR SAME COMPRESSION RATIO AND INDUCT- ION PIPE DEPRESSION AS LORRAINE. On blue print No.9. we have shewn curves calculated for the 20 HP. shewing the I.H.P. and I.M.E.P. we should expect if the compression ratio were raised and the induction pipe depression reduced to the same values as the Lorraine. It will be noticed that the greater gain is expected from raising the compression ratio which should result in an increase of the M.E.P. by 10 lbs/sq.in. The lower induction pipe depression would give about 5 lbs/sq.in. increase in M.E.P. Although these two factors can account for a con- siderable part of the difference in M.E.P. between the two engines there still remains a difference of about 10 lbs/sq.in. It is possible that this difference is partly or wholly accounted for by the lower gas velocity past the valves and the quicker opening and closing in the case of the Lorraine. MISCELLANEOUS DETAILS. The valves were examined up to a speed of 3250 r.p.m. by means of the oscilloscope and no signs of bounce could be detected. The four bearing crankshaft - particulars of which have previously been submitted - possesses a bad torsional vibration at 1950 r.p.m. This is the half speed vibration or one corresponding to six complete cycles per revolution. A light hub carrying the std. 20 HP. slipper wheels having the std. friction setting was fitted to the contd :- | ||