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).
Confirming the fitting of experimental raised crown pistons to a Wraith chassis to increase compression.
| Identifier | ExFiles\Box 146\5\ scan0206 | |
| Date | 9th August 1939 | |
| 1245 To Rolls-Royce Ltd. Derby............Rm.{William Robotham - Chief Engineer} copy to Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation} Levallois, Sr/VA.8/HB.{C. E. Harcombe}9.8.39 re: FITTING RAISED CROWN (EXPERIMENTAL) PISTONS TO WRAITH CHASSIS TO INCREASE THE COMPRESSION. ------------------------------------------ (Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation}10/JH.26.6.39) We have fitted a set of the above type of pistons to the undermentioned chassis: Chassis N° Owner Engine N° Type of piston fitted Mileage when fitted Date wh fitted WRB.69 H.H. N.9.WR EB.4740a 4,172 km. 8.8.39 ABBAS HILMI Aerolite High compression (compression raised by one ratio) Sr/VA. | ||