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Lean burn lives. (WIP).

Will "radial squish flow" contribute to a pushrod gasoline engine with two valves per cylinder that will provide fuel economy equivalent to a direct-injection diesel? Dr. Michael Ward, president of Combustion Electromagnetics, Inc. (Arlington, MA) thinks so. He's been trying to convince domestic automakers that his design--which employs two spark plugs per cylinder, a high-energy ignition system, and a modified cylinder head design--can produce 30% better fuel economy than a conventional engine, yet is much easier--and cheaper--to implement than multi-valve/multi-cam engine designs. (Radial squish flow replaces the more conventional fuel mixture tumble: the use of high--energy coil-on-plug ignition and two spark plugs per cylinder create a spark capable of surviving a flow velocity20 m/sec., and running homogeneous air-fuel mixtures as lean as 30:1.)

So far, it seems the response from Detroit has been cordial but cool. Ward has a PhD. From Harvard, not the School of Hard (Engine) Knocks, and is not a member of "the community." Hence, the Not Invented Here (NIH) syndrome. Still he persists. After all, he has 25 years of research to back up his claims, and evidence that companies like Honda are working toward this architecture. One day, he hopes, someone will listen.

"Oddly enough," says Dr. Ward, "the new Hemi, with its twin spark plugs and combustion chamber design, comes closer to our ideal for lean burn than most engine designs on the market today." Of course, the Hemi--which would need an in-head combustion chamber closely coupled around the valves to reach Dr. Ward's ideal--lacks CEI's high-energy coil-on-plug ignition system. The ignition system, he claims, operates on voltages from six volts to 42 volts, has a spark energy of 140 milijoules, is 60% efficient, and boasts a dwell time of 250 microseconds. The coils have 4,000 secondary turns, and use 36 to 38 awg wire. "In order to make this work, you need a high charging current of 30 amps, and until they invented the Insulated Gate Bi-polar Transfer (IGBT) switch," says Ward, "you couldn't do that with a conventional system."

Ward has shown that an engine equipped with all of the items necessary--ignition system, head design, twin spark plugs--is capable of producing 30% better fuel economy and running homogeneous air-fuel mixtures as lean as 30:1 while meeting current and future emission standards. The test engine--a 2-valve, single cylinder unit running an 11:1 compression ratio and fitted with an overhead cam to facilitate valve timing changes--was built from a Wisconsin S-14D industrial motor base, and run at 2,500 rpm to a corrected 2.5 bar BMEP (Brake Mean Effective Pressure) so the results could be compared to published test results gathered by earlier lean burn pioneers like Michael May. At 0.50 to 0.52 lb/hp-hr BSFC (Brake Specific Fuel Consumption), the CEl test motor proved to be 10% to 20% more fuel efficient while producing fewer emissions. In addition, Ward says his engine design can tolerate higher exhaust gas recirculation levels, and is able to ignite less volatile fuel mixtures. The latter would allow refiners to reduce a fuel's cold weather Reid Vapor Pressure (RVP)--in essence making summer blend gasoline year-round-which would reduce evaporative emission levels and fire risk during vehicle refueling.

Oh, and the Hemi? "They're already about two-thirds of the way there. With a retrofit of our ignition and the spark plug design we've developed for this system" says Ward, "the Hemi would have 15% to 20% better fuel economy improvement. Today."
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Author:Sawyer, Christopher A.
Publication:Automotive Design & Production
Geographic Code:1USA
Date:Mar 1, 2003
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