EGR is A-OK for OTR

| April 07, 2005

Cummins ISX 450 reaches peak horsepower at 2,000 rpm.

Sometimes new technology and the changes it spurs take a while to be accepted by the people who are affected by them. Cooled exhaust gas recirculation is a perfect example.

Many veteran truckers have been wondering whether these lower-emissions engines are up to par with pre-EGR power plants. Drivers worry about power, fuel economy and overall dependability. Pete Huber, former long-haul hand who now drives locally for Schneider in western Pennsylvania, admits his first thoughts about the EGR engines were negative. “The more moving parts, the more problems and the harder it is to fix,” he says.

The regulations that spawned the new engines went into effect on Oct. 1, and more emissions reductions are slated for 2007. So this isn’t the last time you’ll have to adjust to lower-emissions power units.

Drivers will have very little in the way of technique to learn to make the EGR engines perform to their advantage. Having driven the four EPA-certified engines (Cummins, Detroit Diesel, Mack and Volvo) in a variety of terrains, I know they are drivers’ engines. Forget having to compensate for power losses with longer runs at a grade or chugging into traffic to merge after a pit stop.

The key to performance in the new iron is the turbo. All the engine makers using EGR, except for Volvo, have gone to high performance turbos that turn extremely fast and are extremely quiet. Volvo has designed its EGR engine without changing the turbo, although the new system exhibits the same lack of turbo sound as other EGR engines.

So driving EGRs can take a little getting used when there is so little turbo noise compared to what you are used to. What turbo noise there is can fool you. It’s often unconnected to throttle pressure because the turbo is reacting to messages from the engine’s computer, both in response to the EGR system’s needs for exhaust recirculation and because the computer is sensing what the driver’s immediate needs will be. But you can hear a faint rush of air behind the spooling of the turbo as it gulps air in response to throttle pressure.

All the new engines seem much quieter in other respects as well. Part of the reason is because the fan comes on less often and when it does it’s also quieter. Even when I was pulling Fancy Gap out of North Carolina with Volvo’s 435-horsepower D12D and 3:73 rears, the fan was barely noticeable.

Nor is there any noticeable lack of power in these engines. On a 7 percent grade on I-77 out of the Piedmont Plateau you, like me, might have to grab sixth gear pulling 70,000 pounds or so with an EGR engine. If you know that grade, you can appreciate how well the engine performed.

Volvo’s VE D12 465 uses V-Pulse technology to supply plenty of power on steep grades.

The Volvo’s throttle response is quicker than pre-EGR engines. The engine itself performed for me without a hiccup and exhibited strong low-end torque. Torque comes on around 1,100 rpm and stays flat to the top of the shift range. If you shift at 1,500 to save fuel, you will also save it at the other end by letting the engine lug at 1,100 rather than grabbing another gear at the low end. You might notice a slight improvement in shifting over your old engine given the improved throttle response, particularly going down through the gears. There is no hesitation getting fuel to create rpm so that timing is a little easier.

Drivers will appreciate Volvo’s attention to detail when they open the hood. The dipstick has been moved to the cool side of the engine, away from the EGR cooler, to avoid the possibility of getting burned.

Mack has developed two versions of EGR. The on-highway version works a little differently than the I-EGR, which was developed for the vocational market.

Steve Ginter, Mack’s marketing vocational manager, says Mack’s OTR version of cooled EGR is designed for applications where speed and load are constant. The CH 427, like all of the modern engines, has a great deal of torque throughout the rpm range, but it comes on a little more quickly than most, thanks to what is called variable geometry turbo. This, when coupled with quicker throttle response, makes the Mack engine, like other EGR solutions, a strong performer not only when power is needed but in other situations where low-end torque and response make driving easier. Corners where you might have wanted to find a gear with pre-EGR engines can be pulled through more easily and merging into traffic at the get-ons can require fewer shifts.

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