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).
Summary and conclusions of tests to increase the power of an existing 20 HP engine, with reference to the Lorraine.
| Identifier | ExFiles\Box 5a\5\ 05-page038 | |
| Date | 1st April 1927 guessed | |
| contd :- -6- SUMMARY AND CONCLUSIONS. The tests have proved particularly encouraging in shewing us that we can increase the power of the existing 20 HP. to the extent estimated from the Lorraine by :- (1) Using two carbs. to give a low induction pipe depression. (2) Lowering the gas velocity by employing larger dia. valves, and also as shewn previously - (3) Increasing the compression ratio. Although the induction system was not ideal, being so arranged that the two Zenith carbs. could be accommodated under the bonnet of the car and at the same time employ the standard exhaust manifold, the distribution was reasonable at low speeds and quite good at high speeds. The 'opening up' was also good. Factors (1) and (2) above seem to have no attendent disadvantages and it seems if such advantages as are offered by these could be added to the car, the performance would be appreciably improved. We intend xxxx pursuing these experiments further, the next step being to test a camshaft giving a longer duration inlet opening and slightly earlier opening exhaust similar to the Lorraine. It is thought that the longer duration inlet open- ing will increase the volumetric efficiency at high speeds and probably lower it slightly at the low speeds which may be an advantage in lessening detonations and so permit the use of a high compression ratio. contd :- | ||