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 using a mixture of paraffin and petrol, comparing different fuel heating and starting schemes.
| Identifier | ExFiles\Box 50\3\ Scan181 | |
| Date | 1st September 1921 | |
| Contd. -2- Hsl/LG1.9.21. in the gauge glass which we assumed was liquid petrol draining into the reservoirs and being immediately vapourized. With this scheme fitted in conjunction with the exhaust heated throttle, we are able to run a car with a mixture of 50% paraffin and low grade petrol and still get very good results. With a 20% mixture of paraffin and petrol which gives the worst distillation curve throughout the whole range than any of those we have received from Mr. Olley, we can get very excellent running. We can never hope to accomplish everything with the exhaust heated throttle because until the engine has been the run for a short time, the throttle cannot be hot. During this process of warming up the cylinders are loaded with liquid petrol which is badly distributed along the engine. With the "Dorris" scheme on, we find that we get wonderful results in getting away with a cold engine. What happens is that when using the Pilot Jet and the first initial starting, a lot of excess petrol must be used. There does not appear any way of avoiding this in order to get enough light spirit to fire. This excess petrol is drained into the reservoirs round the exhaust pipe. As soon as ever the engine fires, these reservoirs very quickly become heated up, and we get back into the engine the fuel that is boiled and vaporized in these reservoirs. The point is, that we get this fuel back at the time when we need it, that is, we get it back long before the engine reaches its normal temperature and before the water is warmed up. We have made a test by leaving two cars out all night; both using the same fuel, 20% paraffin mixture, one was fitted contd:- | ||