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).
Secret memo detailing instructions for converting the Wraith engine to a larger bore.
| Identifier | ExFiles\Box 6\6\ 06-page031 | |
| Date | 16th August 1935 | |
| GRY{Shadwell Grylls} X4046 600 To WY. from E.{Mr Elliott - Chief Engineer} E.1/HP.16.8.35. c. Sir. HCR. Cr.{Mr Cra???ster / Mr Chichester} Hs.{Lord Ernest Hives - Chair} RHS. JWS. SECRET. re Large Bore Wraith. In accordance with the decision made at the last conference with Sg{Arthur F. Sidgreaves - MD} at Derby, we have issued instructions shown on Lec.4626 for converting the Wraith engine to the larger bore, that is, increasing this dimension from 3 to 3.125". The capacity will thereby be altered from 4168 cc.to 4523 cc. and the tax from £21.18.0. to £24.0.0. on the present rate. These alterations are made without affecting the patterns or castings in any way of the crankcase and head. It is only the machining that will be affected and naturally larger cylinder liners and pistons will be required, and the cylinder head gasket. Actually we understand the main engine pattern is only three quarters completed so there should be ample time to change the instructions before machining is started, and these changes should not cause any delay in the production of the Wraith engine. In the instructions on Lec.4626 the compression ratio has been maintained unaltered mainly by leaving .050 on the face of the cylinder head. E.{Mr Elliott - Chief Engineer} | ||