Report of the Automobile Research Committee on the Performance of a Converted Petrol Engine with Different Producer Fuels
Authors: Spiers J. , Giffen E. 
Published: June 2010

A six-litre petrol engine has been tested, using six different fuels, in the Government Emergency Gas Producer. The fuels used comprised anthracite, activated anthracite, low-temperature coke, high-temperature (Birmingham) coke, activated high-temperature coke, and charcoal. Starting qualities, variations in power and gas quality during the run, and flexibility were investigated. In addition, some miscellaneous information relating to operating conditions with the various fuels was obtained.

Easiest starting was obtained with charcoal, though low-temperature coke was very little inferior in this respect. Anthracite was somewhat variable, but usually good in starting qualities, and activated anthracite showed some improvement in consistency. High-temperature coke, whether activated or not, was poor in starting qualities, though some improvement was obtained with the use of preheated air and water fed to the tuyère, and it is of advantage to add the water as soon after lighting as possible. Anthracite, whether activated or not, showed serious deterioration in starting qualities when used fuel (“bottoms”) was mixed with new fuel, and this deterioration was also shown, though to a less extent, with low-temperature coke. High-temperature coke showed no change in starting quality after use. In general, the C.A.B. values gave a good indication of the relative starting qualities of the fuels.

Under dry-blast conditions the average power given by 100 per cent new fuel was greatest with anthracite (whether activated or not) and lowest with high-temperature coke, low-temperature coke and charcoal occupying an intermediate position. The use of an air preheater and water addition to the producer tuyère brought the power output with high-temperature coke (both activated and unactivated) up to the level of that given by charcoal and low-temperature coke, whereas admixture of used fuel resulted in appreciable reduction in power with both anthracite and low-temperature coke, the high-temperature cokes were not affected. Thus, in the 100 per cent used condition, high-temperature coke (with wet blast) gave power equal to that given by anthracite, and superior to that given by low-temperature coke. The use of air preheating and water addition had little effect on power output with new anthracite, but gave appreciable improvement with 100 per cent used fuel.

Charcoal and low-temperature coke displayed the best flexibility of any of the fuels tested, while anthracite was the worst fuel in this respect. High-temperature cokes with wet blast were superior to anthracite in this quality, and activation appears to be an advantage. Some improvement in the performance of anthracite as regards flexibility was obtained by the use of wet blast, though it remained inferior to any other fuel.

Hydrogen content varied widely throughout the producer run with both anthracite and low-temperature coke, and, in practice, it would be difficult to obtain optimum ignition timing under all conditions with these fuels. The hydrogen content given by high-temperature cokes and charcoal, on the other hand, remained fairly constant through the run, and such fuels may show to advantage under road conditions, owing to the ease with which optimum timing may be obtained.

The rate of fuel consumption in lb. per hour was very similar with all fuels, including petrol, at the same engine speed, the only exceptions to this being charcoal, which gave high rates, and the high-temperature cokes, if account is taken of the water necessarily used under wet blast conditions. No clinker trouble was experienced with any of the fuels used, but whereas low-temperature coke caused choking of the filters at frequent intervals, the high-temperature cokes used gave no trouble in this respect. Charcoal, on account of its high moisture content, gave wet filter conditions, rendering the sisal difficult to clean. Cylinder wear was not excessive with any of the fuels.