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).
Letter detailing car performance improvements and speed trial results at Brooklands after fitting a Bosch Magneto.
| Identifier | ExFiles\Box 47\1\ Scan054 | |
| Date | 30th September 1921 | |
| COPY. Shotton. September 30, 1921. Dear Capt. Strong, I thought it might interest you to know I have bought and fitted a Bosch Magneto to 39-TW. The result is phenomenal and she pulls dead slow like a pre-war car and has much more life and power. Up a top-gear-struggle hill near here the minimum speed has increased from 15 to 21. Acceleration is at least 30% better. I had the car on Brooklands last Monday with the following results:- Flying 1/2 mile 81.8 m.p.h. ) Flying Mile 80.0 m.p.h. ) All carefully timed Flying lap 79.5 m.p.h. ) with a stop watch. Standing start mile 56.2 m.p.h. ) These speeds were all attained without removing anything from the car (i.e. screen, hood, lamps, etc.) and four passengers were carried. I need hardly say how pleased I am with the results. With your car if you still have the old type Watford Magneto I am willing to bet you will not touch these figures within 5 m.p.h! I am in communication with Derby re an allowance for my old Watford mag. Perhaps you would let them know what records have been reached with the good old Bosch! and do what you can to induce them to buy the wretched Watford machine off me. I hope you will come over and try the car for yourself in the near future. There is just a possibility I might enter my car for a race next year as I understand the B.A.R.C. are organising one for standard cars fully equipped. Could you induce your firm to say whether the engine of 39-TW will run up to 3000 revs? If not, is it because the valve springs are not strong enough or is the valve size purposely limited to prevent such speeds? At 82 m.p.h. I calculate the engine does 2730 approx. revs. For the race I would fit larger rear wheels and run 935 x 135 cord tyres. This would raise the gear ratio by about 6%. | ||