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).
B. IV. Bentley engine's performance and modifications after a 7,000-mile test in France.
| Identifier | ExFiles\Box 82\3\ scan0259 | |
| Date | 11th May 1935 | |
| GRY.{Shadwell Grylls} EES FD.{Frank Dodd - Bodies} WHAM X200a Hs{Lord Ernest Hives - Chair}/GWH.{George W. Hancock - Head Chateauroux} 2/JAB. 11.5.35 To Sg.{Arthur F. Sidgreaves - MD} from Hs{Lord Ernest Hives - Chair}/GWH.{George W. Hancock - Head Chateauroux} c to Wor.{Arthur Wormald - General Works Manager} c to P. c to Hy.{Tom Haldenby - Plant Engineer} c to Da.{Bernard Day - Chassis Design} c to Er. c to Sp.{Mr Spinney} c to Lox. c to Hs.{Lord Ernest Hives - Chair} 5. B. IV. BENTLEY - 15,000 MILES IN FRANCE Report on chief items at 7,000 MILES. Specification to Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer} 2/KW 2.4.35. ENGINE. 1) 7 TO 1 CAST-IRON CYLINDER HEAD GIVING 126 B.H.P. With the high compression head, we have had objectionable detonations using the best petrol obtainable on the Continent. The detonations could be deleted by the judicious use of the ignition control. In comparison with a Standard Bentley, the performance is not so much improved to warrant the detonations, and increased roughness of the engine. The half Crankshaft period and 3,750 periods were very noticeable. To eliminate the half period and reduce the 3,750 period to a degree that it could not be heard, the Crankshaft damper load has been increased to 20 lbs. To obtain this load with the use of cotton duck or Ferobestos is not satisfactory, and will not remain for any length of time. We have made friction washers of cork which has a higher coefficent, the corks being held in position by a steel pressing. The chief advantage being that there is no initial or sticking load, a very steady load being obtained. The results after 2,000 miles are good. The following are the comparative results of tests carried out on the Montlhéry Track with the high compression head, Standard head, 19" inch road wheels, 18" inch road wheels small bore Induction pipe, and Standard Induction pipe, also Paris trials Car B.1.CW. WEIGHT. 1 Ton. 13 cwt. 3qrs. 14 lbs. CONDITIONS. 15 gallons of petrol in tank. Driver only. Axle ratio...10 x 43 Rear Wheels..18 inch 5.50 x 18 tyres. Cut-out Closed. Average Lap speed........... 86.25 MPH. Engine revs..............Max. 4,600 Min. 4,300 | ||