A comparison between a conventional capacitive discharge ignition system and a plasma jet ignition system has been performed using a single cylinder test engine fueled with methane. It was found that for optimal engine efficiency considerably less timing advance was required when plasma jet ignition was employed. It was shown that plasma jet ignition significantly reduced the ignition delay time, while the actual burn time remained approximately the same when optimal timing was used for both systems. As would be expected from previous work on gasoline fueled engines the lean misfire limit for the methane fueled engine was extended by plasma jet ignition (beyond #x3BB; = 1.2). The implications of these and previous findings is that an engine using plasma jet ignition and running on either gasoline or methane with mixtures near stoichiometric would not have to alter the timing, when changing from one fuel to another, in order to maintain maximum efficiency.
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