TRUCK TRACKS

By: Ken Kelley

Despite the facts that increased horsepower may burn more fuel and fuel prices show little indication of coming down, a horsepower race seemed under way. Many observers were wondering what was up.

Jim Booth, a fuel economy consultant at Caterpillar, said he has studies which show that fuel consumption does not have to soar in high-horsepower engines if they are driven with care. "The beauty of these engines is that extra power is there when you need it," he said.
Truck operators were said to be clamoring for extra power to get their work done more efficiently. Other straws in the wind indicated that big power will get extra attention in the future from several diesel makers and some of their customers. For instance, the Series 60 models from Detroit Diesel, the first powerplants designed from the start for full electronic control, have been moved up to the 500 hp level after making their debut as 400 hp engines.

Volvo's first strong electronic diesel offered here was the VE-D12 which entered this market as a 415 hp engine. Variable-torque versions with horsepower output up to 425 soon followed.
Manufacturers seldom get very specific about future products until introduction time, but Bill Dawson, director of sales and marketing at Volvo headquarters in North Carolina, said current testing "is very likely" to deliver something new in power output soon.

Mack and Navistar, the other two suppliers of diesel engines for big American trucks, have yet to feature models close to or above the 500 hp level. However, they have both added other standout features to maintain their positions in the truck market. Like the four producers of high-power diesels, Mack and Navistar have worked with modern electronics in making some recent improvements. (It can be added that some of the producers of high-power diesels have also taken some of these steps outside the big-power area.)

The newest Mack diesel is the MaxiCruise E7 model which develops 330 hp while cruising but turns out up to 350 hp when more power is needed. The producer said the engine delivers "the perfect balance between lugging power and fuel efficiency." Operation of the engine is managed by the second generation version of Mack's V-MAC electronic engine control system.

The proud boast of the engine operation at Navistar is that none of its powerplants has to rely on a catalytic converter to meet exhaust emission rules. As those rules have become more and more demanding, some engines have needed converters or some other form of exhaust aftertreatment to measure up. Meeting the rules without relying on a bulky or complex fix has emerged as a cherished goal.

Here's a look at what the engine manufacturers have had to say about their recent development efforts beyond the horsepower advances and other moves outlined above: HEUI or hydraulic electronic unit injection fuel systems refer to a concept that is catching on in the medium-duty diesel field. It is not for low power engines in trucks of modest size. Caterpillar offers a 3116 model rated up to 275 hp while Navistar has the 530E with a 300 hp rated system.

Caterpillar said the HEUI system in its 3116 features an electronic control module that handles the injection of fuel using high-pressure engine oil to provide the "muscle," rather than the camshaft. The combination of the HEUI fuel system and the engine electronics provides improved load starting, more accurate and precise governing, improved low speed lug capability, improved serviceability and improved cold weather starting.

A great deal of work is being done to refine existing diesel engines to operate on alternative (nonpetroleum) fuels to curb air pollution and promote national energy independence. Cummins, which has one of the most ambitious programs, has just added horsepower ratings of 280 and 300 to the features of the L10G natural gas engines in its line. The new versions are charge-air-cooled and use water-cooled wastegate turbochargers (in contrast to the jacket water aftercooling featured on earlier L10Gs).

Meanwhile back in the standard diesel field but returning to electronic controls, Cummins has said that it will add those controls to its midrange B and C series diesels over the next two years. In addition to the new controls the engines will be totally redesigned.

In one of the more dramatic alternative fuel efforts, Navistar has reported that it is working with the Amoco oil company and two European companies on a fuel that goes under the name Dimethyl Ether (DME). It is made from natural gas or other feedstocks, such as coal or renewables. Researchers claim that DME can eliminate exhaust smoke and greatly reduce other exhaust pollutants while reducing engine noise. Testing was done in a Navistar engine made for truck use here in the U.S.

Product developers at Detroit Diesel have been doing a lot more than adding that 500 hp model to the producer's Series 60 line. The company has added a third generation version of its patented DDEC Optimized Idle system. It automatically limits engine idling to the times when it is needed to keep battery voltage, engine temperature and cab temperature at the proper levels, reducing fuel consumption and engine wear.

Kelley is a truck writer based in Dearborn, Mich. You may write him in care of the editor.