Truck News


Emissions: In their own words – Part 2

With the 10/02 emissions deadline approaching, a vast amount of misinformation regarding the future of heavy-duty diesel engines still exists. This is the second installment in a series giving manufac...

With the 10/02 emissions deadline approaching, a vast amount of misinformation regarding the future of heavy-duty diesel engines still exists. This is the second installment in a series giving manufacturers a chance to explain their solution, in their own words…


Like it or not, the diesel engines of today will forever change come Oct. 1.

And while nervousness and anxiety are the natural consequences whenever technological changes are introduced, history has shown that the trucking industry has been able to cope very well with similar challenges in the past.

In fact, this is the fourth emissions hurdle we have had to deal with over the last 10 years, including those in 1991, 1994 and 1998.

In every case we ended up accomplishing much more than merely meeting the new regulation.

For example, the increased functionality of electronics and sophisticated software programs, which were first developed to meet emissions challenges, have opened the door to a wealth of new customer-valued features on today’s trucks.

If given the opportunity, how many of us would opt for a pre-1991 engine to replace those available today?

I believe very few of us would want to go back.

Therefore, the trucking industry should be looking at the future with their minds focused on how well we’ve done in the past.

After all, the diesel isn’t going to die, nor is the diesel going to become a horrible performer – at least not at Mack.

The October ’02 requirements are a big step, but we have known what we have had to do, we have remained focused, and the product is going to be ready in a very good way for the customer.

At Mack we will employ two distinct strategies that are optimized for each customer’s application – one for highway vehicles and one for vocational vehicles – with the launch of a new family of heavy-duty diesel engines.

The engines will be known as the ASET family, which is an acronym for Application Specific Engine Technology.

This two-part solution represents an industry-unique commitment to meet the new regulations by matching an appropriate emission reduction technology to the specific application of our customers and their vehicles.

We feel strongly that being an integrated manufacturer of both trucks and engines has given us a tremendous advantage in providing customers with the optimum solution for their specific needs.

We see no reason why our customers should have to accept a “one-size-fits-all” approach to engine technology to meet the new regulations.

Highway solution

The Mack ASET solution for highway customers will be based on cooled exhaust gas recirculation (C-EGR) – in which a portion of gases leaving the engine are diverted from the exhaust through a cooling system, and then carefully remixed with air entering the engine for combustion.

C-EGR allows for the best level of performance and emissions benefits in a “steady-state” operating environment – i.e., when the vehicle is operating at relatively consistent speed and load over a significant period of time.

Modifications to the fuel system and software were the initial changes made in developing our C-EGR technology.

The core of the technology, however, is a new EGR valve, electronically controlled by the Mack V-MAC system, to regulate the recirculation of exhaust gases, and a Mack Venturi mixing valve that combines inlet air and cooled exhaust gas prior to introduction into the cylinder.

Also, a new variable geometry turbocharger provides the pressure necessary to drive the re-circulated gases through the system.

Finally, an improved filtering medium is used in the oil filtration system, along with a new oil pan that accommodates an additional eight quarts of oil.

We increased the oil capacity levels of the new engines in order to keep our oil change intervals where they are today.

This is another example of our commitment to introduce the new engines with as minimal impact on the customer as possible.

While these engines employ a number of technological advancements, the underlying process is simple – the exhaust is cooled and burned again to meet the lower emissions levels.

The changes related to the ASET C-EGR solution ensure these engines will meet our customers’ expectations for driveability, performance, durability and maintenance, while at the same time, meeting the new emissions requirements from EPA.

Vocational solution

On the vocational side, we are using a technology called internal exhaust gas recirculation (I-EGR), and much like C-EGR, it also will be customer-friendly.

I-EGR accomplishes emissions reduction by retaining a small percentage of exhaust gases in the cylinders of the engine from one combustion cycle to another.

The exhaust gas is re-burned with the clean combustion air, thus reducing the emissions and meeting the more stringent EPA requirements.

Mack engineers developed the ASET I-EGR solution based on Mack’s in-depth knowledge of typical vocational vehicle operation.

These trucks typically perform in a stop-and-go manner over shorter distances, where operational hours are more relevant than miles travelled.

In response, the Mack engine designers achieved a technological breakthrough by concentrating on optimizing the flow of exhaust gases through the system, in order to make it possible to retain a precise amount of gases in the cylinders for further combustion.

That is principally accomplished through a new camshaft, advancements to the valve system, and precision machining of the exhaust ports to maximize aerodynamic flow.

We believe this is a significant achievement in engine design.

And it came about because we recognized the specific differences in the operating environment of vocational customers versus highway customers and the need for an EPA ’02 solution that is tailored to provide the best performance and emissions benefits for each of them.

So that is what we are going to give them with the ASET I-EGR engine.

Mack, once again, does not believe that a “one-size fits all” solution is the optimum answer for all trucking applications.

Be it our ASET C-EGR engine family for the highway user or the ASET I-EGR engine family for the vocational user – Mack’s primary objective is to bring about this transition as smoothly as possible for the customer.

While there is no hiding the fact the price tag will be higher for these new power plants, Mack remains confident that other issues – maintenance, durability, performance, fuel consumption – have all been properly addressed with our new lineup of ASET engines. n

Special to Truck News, this story was prepared by Steve Homcha, executive vice-president of Class 8 programs for Mack Trucks, Inc.

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Truck News is Canada's leading trucking newspaper - news and information for trucking companies, owner/operators, truck drivers and logistics professionals working in the Canadian trucking industry.
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