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).
Analysis comparing exhaust heated and water heated induction systems for engine performance, especially in cold conditions.
| Identifier | WestWitteringFiles\S\June1928-August1928\ Scan002 | |
| Date | 14th June 1928 guessed | |
| contd :- -2- without the butterfly choke valve in the down pipe. The curves of the two water heated systems fall far below the exhaust heated and as the actual difference between the exhaust heating with the butterfly valve and exhaust heating without the butterfly is evident to the driver of the car with its present induction system during the warming up period, it is not to be expected that the better of the water heated system would be sufficient. Referring to the curves we should not anticipate much difficulty in making the exhaust heating system without the butterfly choke valve in the down pipe as rapid in its temperature rise as the standard system. We think some form of exhaust heating is the only solution to obtaining rapid starting from cold, particularly so in cold climates and should also consider the intense heat of a suitably situated hot spot, which, when used with the new vertical carburetter and improved induction, may need only to be small, would be a more efficient corrector of distribution under both starting and normal running conditions, than the low temperature of a water jacketed pipe. The high temperature of an exhaust heated hot spot arranged where the fuel would impinge on it - such as at the top of the riser pipe when used with the new carburetter - would tend to give flash evaporation of the heavy fuel without raising the charge temperature whereas the lower temperature of the water heated jacket would result in fractional evaporation and still allow the heavier fractions to flow along the surface of the induction pipe. contd :- | ||