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).
The final test curves for an 8-cylinder car, detailing horsepower losses and performance improvements.
| Identifier | ExFiles\Box 109\4\ scan0110 | |
| Date | 30th June 1939 | |
| 666, 1320 + 1049 By.{R.W. Bailey - Chief Engineer} from Rm.{William Robotham - Chief Engineer} c. Du. c. Da{Bernard Day - Chassis Design}/Ev.{Ivan Evernden - coachwork} c. Da{Bernard Day - Chassis Design}/Jnr.{Charles L. Jenner} Rm{William Robotham - Chief Engineer}12/R.30.6.39. 30-G.VII. We attach a copy of the final curves taken on the test and the dynamometer of the 8-cylinder car before it went to the Continent. The most noticeable features about these curves are:- (1) There is still too much horse-power lost to the exhaust system though this does not matter much to this particular type of car. However, 28 h.p. @ 85 m.p.h. is not economical. We see no reason why the Duplex Exhaust System should not be applicable to the 'Cresta' with similar results to those on the 6-cylinder engine. (2) There is still 15 h.p. lost between the clutch and the hub, and we have not a clear explanation of where this horse-power goes. Having dealt with tyre losses, we are now going to find out where these mechanical losses are located. (3) The exhaust system must be regarded as being undesirably inefficient because it drops the M.E.P. by 10 @ 2,000 r.p.m. or 42 m.p.h., a speed at which the maximum acceleration is always being used. Unfortunately, we did not have the opportunity of taking the car on the Track again with the new engine unit and the petrol flow increased, but from the road wheel horse-power figures it is clear that the lap speed should have been increased from 86.6 to 89 m.p.h. by the improvement in power output. We attach a report by Ey Edwards taken while the car was on the Track, which shows that in its present state the car is exceedingly well cooled. Rm.{William Robotham - Chief Engineer} | ||