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).
Performance test results for different carburetter and bonnet configurations at Brooklands.
| Identifier | ExFiles\Box 31\4\ Scan067 | |
| Date | 13th August 1931 | |
| To Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} from F.{Mr Friese} Dodd. 81487. 13.8.31. X.7881 X.1487. X.7080. 12-GIV AT BROOKLANDS. S.U. Carburetter - louvred bonnet (cut out closed). Air Temp. | Water Temp. | Lap Time | Lap Speed MPH. | 1/2 Lap mile Time | 1/2 Lap mile Speed MPH. 21º | 75º | 2-12 | 75.12 | 24 secs. | 73.17 21º | 75º | 2-12 | 75.23 | 24 " | 75 S.U. Carburetter - louvred bonnet (cut out open). Air Temp. | Water Temp. | Lap Time | Lap Speed MPH. | 1/2 Lap Mile Time | 1/2 Lap mile Speed MPH. 20.5º | 70º | 2-10 | 76.27 | 23.4 | 76.92 20.5º | 73º | 2-10 | 76.62 | 23.4 | 76.92 Standard Carburetter - louvred bonnet (cut out closed). Air Temp. | Water Temp. | Lap Time | Lap Speed MPH. | 1/2 Lap Mile Time | 1/2 Lap mile Speed MPH. 19.5º | 73º | 2-18 | 71.97 | 24 secs. | 75 19.5º | 72º | 2.17 | 72.49 | 23 " | 75 Standard Carburetter - louvred bonnet (cut out open). Air Temp. | Water Temp. | Lap Time | Lap Speed MPH. | 1/2 Lap Mile Time | 1/2 Lap mile Speed MPH. 19.5º | 73º | 2-15 | 73.35 | 23 secs. | 77.25 19.5º | 73º | 2-15 | 73.45 | 23 " | 77.25 | ||