Rolls-Royce Archives
         « Prev  Box Series  Next »        

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).
Engine performance issues related to the induction system and carburetter proximity to the exhaust on the Phantom model.

Identifier  WestWitteringFiles\T\2January1929-June1929\  Scan050
Date  21th January 1929 guessed
  
Hs{Lord Ernest Hives - Chair}/ACL1/T21.1.29.
-4-
Contd.

On the Phantom with the induction system,
carburetter and autovac arranged with such proximity to the
exhaust system, the whole system becomes very hot under normal
working conditions due to radiation and conduction. The fuel
reaches a high temp. as instanced by the boiling or 'gassing'
troubles we have experienced in the float chamber. The
carburetter jets are set during road tests to suit these
average temperature conditions which means that there is a wide
difference in mixture strength between the normal running and
cold engine conditions. This fact accounts largely for the
reason why we require very quick warming up of the hot spot
on the present Phantom; the unstable cold running being due
to excessive weakness more than poor distribution. These
facts are borne out by test bed experience where the temperature
range of the carburetter and intake air is considerably
narrower than when enclosed under the bonnet. It is found under
these circumstances that the cold starting and running immediately
following the start is better than on the car and approaches
much nearer to the normal operation. Our F.{Mr Friese} aero carburetters
in the 'Vee' afford another example of this, where it is found
that their running and acceleration is very nearly as good
during the warming up period as when the engine reaches normal
temperature.

The new S.S. engine certainly scored an advantage in
this respect, having the induction system and carburetter
removed to the opposite side to the exhaust and in this position
  
  


Copyright Sustain 2025, All Rights Reserved.    whatever is rightly done, however humble, is noble
An unhandled error has occurred. Reload 🗙