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).
Specific gravity of petrol in relation to engine detonation and vaporization tests.
| Identifier | ExFiles\Box 32\1\ Scan053 | |
| Date | 23th October 1920 | |
| X1555 W/S. To Bt.{Capt. J. S. Burt - Engineer} from Hs.{Lord Ernest Hives - Chair} Hs{Lord Ernest Hives - Chair}2/LG23.10.20. X.2451. RE SPECIFIC GRAVITY OF PETROL. X.1555. ---------------------------------------------- With reference to attached note Ref. Bt{Capt. J. S. Burt - Engineer}2/EP{G. Eric Platford - Chief Quality Engineer} 22.10.20, the specific gravity of petrol is no guide as to whether spirit will cause detonation or not, for instance, a mixture of benzol and petrol which will give a very high specific gravity is free from detonations also Shell Aviation "B" which has a low specific gravity (725) is also entirely free from detonation. On the other hand, Pratts special spirit (580 gravity) detonates quite badly. We believe that the petrols which come from America are all bad for detonations - the petrols which come from the East, Sumatra - have a certain amount of benzene constituent which make them free from detonations. We know, that for some time now, the Shell people have been testing thoroughly the petrol obtained from difference parts of the world and we believe that as a result of these tests, they are now blending petrol so that it will reduce detonation. We have lately, at the works, stopped using Mex Spirit and are now using Shell No.1 because with Shell No.1. there is much less detonation. The specific gravity of petrol is useless for a test. The only simple test which is any used for petrol is vaporization test. What we consider is a bad petrol is one which complete vaporization does not take place until 140 or 150°C - as an example we give the following test taken on two petrols which were the same Contd. | ||