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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).
The development and performance testing of a 4-stroke compression ignition engine, focusing on cylinder and injector cooling.

Identifier  ExFiles\Box 179b\3\  img191
Date  4th February 1933
  
To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/Ud.
c. Sg.{Arthur F. Sidgreaves - MD}
c. WOr.{Arthur Wormald - General Works Manager}
c. Rg.{Mr Rowledge} M.{Mr Moon / Mr Moore}
c. By.{R.W. Bailey - Chief Engineer} Mr. Jaques

DEVELOPMENT OF R.R. 4-STROKE
COMPRESSION IGNITION ENGINE.

SUMMARY.
At the beginning of the tests the cylinder differed from the original (referred to as C.I.1) in
(1) the shape and dimensions of the inlet ports and
(2) the arrangements for cooling the injector.

At the commencement of the tests described in this report the injector was arranged as shown in Fig.1. The sleeve was removed and water circulated in this space. The performance was then 86.8 lbs/sq.in. B.M.E.P. and specific consumption 0.553 lbs/BHP/Hr. At 2000 R.P.M. and normal injection the power was unsteady and subject to sudden decrease by as much as 7 lbs/sq.in. B.M.E.P.

At the conclusion of the tests using an injector cooling scheme similar to C.I.1 (Fig.9) the performance was 95 lbs/sq.in. B.M.E.P. and specific consumption .480 lbs/BHP/Hr. at 2000 R.P.M. and normal injection. Providing the nozzle holes were clean, the power was maintained. The motoring losses at 2000 R.P.M. were 3 lbs/sq.in. M.I.P. greater than in C.I.1 and allowing for this the B.M.E.P. is 98 lbs/sq.in. which is between 3 and 4 lbs/sq.in. below the corresponding value for C.I.1.

The reason for this difference is believed to be shape of the inlet valve passage which affects the motion of the air within the cylinder disturbing the critical balance of air and oil motion essential for the highest B.M.E.P's and lowest consumptions. The power could probably be increased by altering the shape of the passages or conducting a series of tests on various combinations of nozzle hole dimensions, injection pressures etc. but this might prove a lengthy process and it is not considered that the time and expense is justified.

Considerable trouble was experienced by either sudden or gradual loss of power during running. This has been cured by properly cooling the injector and keeping the nozzle holes clear.

In several tests a B.M.E.P. of 97.8 lbs/sq.in. (equivalent to power of C.I.1) was obtained at the beginning of the test but never maintained. It was felt that if the cause of the power drop could be discovered it might be
  
  


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