SUMMARY Following the adoption of a suitab, le design of engine anci a tentative procedure for opcrating this engine, the work of the Volunteer Group has covered the $nvestigation of Other methods of measuring ceÍane number 06 diesel fuels looking towards a simplification m:i i mprovement 06 reproducibility of the procedure. Results 06 a second series of COOpe%t'iVe tests are given using the procedure adopted in its last report together with a Series of tests on the same fuels using the critical compression ratio method with an intemial timing conPol device. Results of the firsl series show azr agreement, the grand average deviation on twelve I ' samples being of the Order k 1.9. Resu ts of the critica!, compression ratio tests show improved agreement due to better standardization of details over previous results, tke grand avevagr being now onlir slightly worse than the delay method.
T ests on three dtematiue methods based on the delay method but using dilferent instrum ents for recording th.e d, elny are given. Results on two different types of full scale engine,? a re also presented os an indication of the validit?] of the laboratory test methods.
It is concluded from the results of the pa.st 18 months Work that a direct matching method on the basis of ignition deZa?j is fhe hrst from the point 0% view 0f.pTOdUCtbility o, nd validity, even though this will incolve some sacrifice in sim, pliciiu and speed ot testing. The, progress Ob methods of instrumentation is advanced considerably and it appears that the .bouncing pin type should be dzscarded in favor of a balanced diaphragm OT magnetic pickup type.
Introduction ignition qualities was proposed. In its second report a tentative procedure for operating this engine, a recommendation as to the use of primary and ffiecondary During the past few years the development of the high reference fuels, and the results of a series or coopenative speed diesel engine has been materially assisted through tests using nine different types of fuels, were presented. increasing knowledge of the various properties of diesel In this, its third report, the results of a second series fuels particularly in relation to ai property known as its of cooperative tests using two differmt methods of ignition quality. Standardization of the measurement of operation are given, together with comments on this quality has been in the hands of a small group suitability of either method. Other proposed methods known as the Volunteer Group for Compression Ignition are discussed and some results of tests carried out by Fuel Research and this group now has the honor to these methods given. Results on two different types of present lo you its third report dealing with this subject. 11111 scale engines are (also presented as ali indication of In its first report delivered to this society in Jaauary