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).
Report discussing crankcase dilution, fuel quality, vaporization, and engine performance.
| Identifier | ExFiles\Box 50\3\ Scan133 | |
| Date | 9th July 1921 guessed | |
| Cy2 - G 9721 Sheet #3. Derby pilot jet ...................... 2 min. 20 secs. Springfield choker .................... 2 " 20 " (not so much gas used in this case, as in other two cases the gas is drawn from the extreme bottom of float chamber.) The present heated pipe does not appear to affect very much improvement in crankcase dilution, but a design of heating the pipe just beyond the throttle as shown in recent prints from Mr. Royce would probably reduce it considerably. All cars in this country suffer from crankcase dilution in cold weather to a greater or less extent. The Packard single six, with fuelizer, for example, which runs 1500 miles on one filling of oil in summer, recommends to change the oil every 400 miles or so in winter. Mr. Belnap on Cadillacs changes oil every 300 miles in winter. On our cars the oil is thin as water after 200 or 300 miles of winter running. The Galli-ator improves this considerably. As proof that it is necessary to keep the fuel in a condition of fog as far as possible, for complete combustion, when using low grade fuels, we may mention the care taken in high compression engines of the Diesel or mechanical injection type, to insure complete pulverizing of the fuel and avoid "after drip". Further, we think it is generally admitted, even with European gasoline, that a source of inefficiency in single cylinder engines is that fuel which condenses on the walls of the pipe between suction strokes, enters the cylinder as a "splash" of liquid instead of finely atomized. As shown in distillation curves recently sent to Mr. Hives, while the mixture of Mex. Spirit and kerosene which he is using for inlet pipe experiments, is conservative as far as easy starting is concerned, it is very much better than the American gasolines in the final distillation of the heavy ends. The "end point", that is the temperature at which all the spirit will vaporize, is set at 438º F.{Mr Friese} by the latest Federal specifications, but our tests and others conducted by the Bureau of Standards show that the actual gasolines supplied fall far short of this and actually most of the gasolines will barely boil over at a temperature of 500º F.{Mr Friese} These heavy ends even when vaporized have a tendency to re-condense in the pipe, and unless very finely atomized, they will cling to the walls of the cylinder and piston head and will either form carbon deposit, or work past the piston into the crankchamber oil. | ||