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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).
Page discussing engine port design and fuel distribution, comparing a six-port engine to a four-port arrangement and proposing new manifold tests.

Identifier  ExFiles\Box 66a\2\  scan0170
Date  13th January 1928 guessed
  
contd :-

-4-

or less a straight path due to its inertia and becoming deposited at the inlet valve of one cylinder during the inspiration of the adjacent cylinder.

For this reason we have favoured the six port engine.

The Hispano which had six ports gave practically particularly good distribution but this engine was fitted with a double carburetter supplying three cyls. each.

We think we should have much better opportunity of providing suitable manifolding to give good distribution on a six port engine than the present four port arrangement.

In order to obtain more information on this point we propose to construct a weir type induction pipe using a vertical carburetter - say a RRCH. - for the Silver Ghost engine. We will carry out some cold distribution tests and report as soon as possible.

SUMMARY:

As far as test bench results go the weir type manifolds are superior both in power and smoothness of operation to the present standard. The comparisons were made with no hot spot heating.

The single cast pipe gives slightly superior results

contd :-

[Text from diagram]
General direction of flow
Wet fuel being deposited at 'A' while 'B' is on induction stroke.
  
  


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