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).
Technical memorandum discussing cold weather starting and idling issues in supercharged engines, specifically concerning petrol accumulation and potential solutions.
| Identifier | WestWitteringFiles\V\December1930-February1931\ Scan101 | |
| Date | 6th January 1931 | |
| To R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/LoV.{Mr Lovesey} c.c. to SS.{S. Smith} c.c. to RS.{Sir Henry Royce's Secretary} c.c. to Lr.{Mr Ellor} ORIGINAL x3953 x4550 SUPERCHARGED ENGINES - CARBURETTION. During cold weather conditions we frequently get trouble with petrol accumulation in the volute of the supercharger while idling with a cold engine after starting up from cold. This causes difficulty in opening up by flooding some of the cylinders with wet petrol. We have the volute drain scheme which helps but does not entirely eliminate the trouble. Actually in a frosty atmosphere we get the volute drain venturi freezing up and ceasing to function. We avoid 'building up' to a large extent by running engines at fairly high R.P.M. (about 800 R.P.M.) during the warming up period and have issued instructions to our outside testers to this effect. Although by the above means we are able to avoid the trouble to a degree, we should appreciate that it is a definite cold weather trouble with our superchargers and with bad handling is liable to cause damage to the engine due to wet petrol in the cylinders. An exhaust hot spot at the carburetter would no doubt be ideal but it seems almost impossible to apply in this case. Hispano's use exhaust hot spots on their carburetters but in their case they have the carburetter situated close to the exhaust ports. Hot air intakes would no doubt help to a large extent. [Handwritten note in margin: miseline pipe] The scheme of running the idle running carburetter on the top induction pipe as suggested by H.{Arthur M. Hanbury - Head Complaints} some time ago, would appear the most promising method. It would appear that this could be done fairly easily as suggested in appended sketch. There may even be the possibility of applying a small hot spot after the idling carburetter. The Air Ministry Development Contract No.29793/30 we think covers such tests as this contract calls for tests directed towards "securing greater immunity from weather conditions and operational difficulties". If agreed we should like to have instructions to carry out tests with the slow running carburetter on the | ||