Diesel Tech: Diesel Meets New Regs

Mazda Bongo vehicles equipped with the new diesel engine are the first in their class to comply with Japan’s New Short-Term Diesel Emissions Regulations and the Automobile NOx/PM Control Law.

Mazda Motor Corp. has partially restyled its Mazda Bongo van and truck range with the introduction of a newly developed diesel engine designed to greatly reduce exhaust emissions. The upgraded vehicles went on sale in December at Mazda, Mazda Anfini and Mazda Autozam dealers throughout Japan.

Mazda Bongo vehicles equipped with the new diesel engine are the first in their class to comply with Japan’s New Short-Term Diesel Emissions Regulations and the Automobile NOx/PM Control Law, making them eligible for sale and registration in the major metropolitan areas of Tokyo, Osaka and Nagoya. Moreover, performance and fuel economy show a significant improvement over the previous diesel engines used in the Bongo series.

New Short-Term Emissions Regulations set standards for CO and HC emissions in addition to NOx and PM emissions. They will apply to current production models from September 2004. The Automobile NOx/PM Control Law is effective in major cities with serious levels of air pollution caused by automobile exhaust emissions. This law regulates permitted levels of emissions for all commercial vehicles and passenger cars with diesel engines.

Mazda’s new 2.0L inline four-cylinder, common-rail direct injection turbo diesel engine (RF-CDT type) employs technology that greatly reduces the amount of particulate matter and nitrogen oxides in exhaust gas emissions.

The law applies in Tokyo, Chiba, Kanagawa, Aichi, Mie, Osaka and parts of Hyogo. When introduced in October 2002 the law related only to newly registered vehicles. However, from October 2003 all designated vehicles registered in these regions must comply after a certain grace period. “We developed this cleaner engine in order to clear the stricter diesel emissions standards recently introduced,” says Mazda’s Kengo Matsumura, “There is a significant need for fuel-efficient engines among customers. We are sure that this new engine will satisfy this need.”

The new 2.0L inline four-cylinder, commonrail direct injection turbo diesel engine (RF-CDT type) employs technology that greatly reduces the amount of particulate matter (PM) and nitrogen oxides (NOx) in exhaust gas emissions. The 1800 bar common rail fuel system is supplied by Denso. Based on the MZR-CD engine mounted in the European specification Mazda6, the engine is equipped with an all-new diesel particulate filter (DPF) and an improved engine control unit. As a result, PM emissions have been reduced by more than 75 percent, while NOx emissions have been cut by 25 percent compared to the 2.2L diesel engine (R2 type) previously used in the Bongo series.

In order to reduce PM emissions, the engine employs a diesel particulate filter coated with an oxidation catalyst. The ceramic filter traps PM, and when the amount of PM in the filter reaches a designated level, it is automatically removed through the combined effect of the catalyst and combustion temperature controlled by the common-rail injection system.

Further, NOx emissions are reduced by optimally controlling the combustion temperature with “Cooled EGR” and by improving combustion efficiency with fuel injected at high pressure from the common-rail.

Mazda’s newly developed diesel engine employs a diesel particulate filter coated with an oxidation catalyst.

The new engine employs a common-rail direct injection system with precision-controlled fuel injection pressure and injection timing along with a small, high efficiency turbocharger.

Together these features greatly improve vehicle performance compared to the previous 2.2L diesel engine. In addition, the engine achieves flat torque over all speed ranges, while readily delivering the power required for climbing hills with a load. Maximum output has been increased from 78 hp at 4250 rpm to 74 hp at 3500 rpm. Maximum torque has also been enhanced by around 30 percent from 31 lb.ft. at 2000 rpm to 40 lb.ft at 2000 rpm.

Fuel economy improved by almost 13 percent, the company says. The common-rail direct injection system and small, high efficiency turbocharger work together to deliver an impressive balance of power and fuel economy. Comparing the fuel efficiency (10.15 mode) of a manual frontwheel drive, wide-low long body truck, the new 2.0L diesel engine achieves 9.5 mpg compared to the previous 2.2L diesel engine’s 8.5 mpg.

The new engine is manufactured at Mazda’s Hiroshima Plant in Japan. The initial volume is expected to be 1,400 engines per month. According to Mazda, there are no plans to introduce the engine outside of Japan.

Additional enhancements for the Bongo van/truck lineup include a more powerful gasoline engine, revised seat and door trim fabric and a driver’s seatbelt with pretensioner and load limiter.