Release 91-06
August 6, 1991
CONTACT:  Jerry Martin
(916) 322-2990

Air Resources Board Approves Nation's First "Soot-Free" Engine for City Transit Buses

        SACRAMENTO - The California Air Resources Board (ARB) announced today its approval of a methanol -powered engine for urban transit buses, the nation's first to meet the state's strict, "soot-free" standards for heavy-duty diesel powered engines.

        The engine manufacturer, Detroit Diesel Corporation, the nation's largest heavy-duty diesel engine builder, publicly unveiled the engine at a press conference earlier today at its national headquarters, in Detroit.

        The new engine, which emits virtually none of the soot-like particulate associated with current diesel buses, was designed specifically to meet the Air Resources Board's stringent new emission standards that took effect on January 1, 1991.

        The engine (6V-92TA), the most widely used in transit buses, is the only engine certified so far this year under ARB standards that limit soot-like particulate to 0.10 gram per mile, 90 percent less than new buses built just four years ago. The California urban bus standards go into effect three years before similar EPA limits nationwide and also will be imposed on "big-rig" trucks, beginning in 1994.

        In addition to low particulate limits, the engine meets emission standards for smog-forming hydrocarbon and nitrogen oxides and carbon monoxide. The engine also meets California's warranty requirements for five years, 100,000 miles or 3,000 operating hours, whichever comes first. In addition, out of special consideration for potential corrosion caused by methanol, the manufacturer's warranty on fuel injectors, critical to elisions, was increased to five years, 150,000 miles and 4,500 operating hours, whichever first occurs.

        The new methanol engine is expected to be used initially in about 100 urban transit buses now on order for Los Angeles and other California metropolitan areas and is also expected to be installed in all newly purchased buses.

        Detroit Diesel Corporation has operated prototype, methanol-powered engines in California for the last five years, as part of a clean air experimental fleet in cooperation with the state Air Resources Board and Energy Commission, and local air quality and transit officials.

        James Boyd, ARB executive officer, said approving the new methanol-powered engine fulfills a major goal of the ARB. "We impose these standards on buses three years earlier than trucks to protect the larger number of people who are exposed to potentially cancer-causing soot emissions in crowded cities and who are especially vulnerable because the ‘stop and go' driving patterns of buses create more pollution.

        "This methanol-powered engine is a breakthrough, with big benefits for air quality. It not only meets the national standards set by the EPA. It also meets California's anti-soot standards -- which for the 1991 are two and one-half times tougher.

        "This engine was developed in an experiment for alternative fuel buses. Now that it's ready for mass-production, this engine shows that the experiment is over. Clean buses, which used to be a contradiction in terms, are now real and something we can count on in our efforts to reduce unhealthy air pollution," Boyd said.

        The ARB adopted new standards for heavy-duty diesel engines in 1986 after scientific evidence showed that particulate soot emitted by diesels can penetrate deep into the human lung and cause long-term, chronic health conditions, including bronchitis and emphysema. Those particles also can be carriers for other highly toxic compounds produced by the burning of fuel.

        The tough tailpipe emission standards are only one-third of the Air Resources Board's anti-soot program for diesels, which also includes clean-up standards for diesels, which also includes clean-up standards for diesel fuel, which go into effect in 1993, and a "Smog Check" style inspection for buses and "big-rig" trucks expected to start up later this year.

        The Air Resources Board is a department of the California Environmental Protection Agency. ARB's mission is to promote and protect public health, welfare, and ecological resources through effective reduction of air pollutants while recognizing and considering effects on the economy. The ARB oversees all air pollution control efforts in California to attain and maintain health based air quality standards.

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