by Paul Abelson, technical editor
Perhaps the greatest challenge facing truck and engine builders is not slumping sales numbers. They will bottom out soon and pick up as they have in the past. It may well be the challenge of meeting emissions regulations set by the Environmental Protection Agency (EPA) for January 2004, but moved ahead to October 2002 as part of a settlement for alleged wrongdoing. The enginemakers deny the charges, but who has pockets deep enough to fight the government? If they don’t get their engines certified, they won’t be able to ship them. And if extensive changes to truck cooling systems and under-hood layout are needed, the enginemakers will have to give plenty of notice to the truck makers so they can do all the related engineering and institute production changes, or there won’t be trucks to take the engines.
At the Society of Automotive Engineers (SAE) Truck and Bus meeting last December, exhaust gas recirculation (EGR) was the primary strategy mentioned to meet oxides-of-nitrogen (NOx) standards. Field tests at high altitude and in the desert were held last summer. They showed that EGR raises under-hood temperatures significantly. Engine cooling systems that currently manage 480,000 British Thermal Units (BTU) of diesel-generated heat per hour may be called on to handle as much as 288,000 BTU more, a 60 percent increase. To manage that heat, the water pumps, radiators and fans will need to be enlarged. New materials will be needed for seals and for many under-hood components. All these will add weight and consume power, reducing payloads and fuel economy, and therefore, productivity.
On March 5, Cummins announced its strategies to achieve the government-mandated emissions levels of 2.5 total grams of nitrogen oxides plus non-methane hydrocarbons per horsepower hour. Cummins was able to achieve a 2 percent fuel economy improvement and a significant reduction of the time needed for unaided cold starts – a whopping 80-percent reduction. They used variable geometry turbocharging developed by their wholly-owned subsidiary, Holset. The bad news is that a major part of the emissions reduction strategy is the use of EGR. John Wall, Cummins’ vice president and chief technical officer, said “We … concluded that the only feasible technology for meeting the 2.5 gram level is with exhaust gas re-circulation. No other option provides the benefits of fuel economy, cost, responsiveness and overall performance, and in our view, no other currently available technology can achieve a 2.5 gram (level).” A week later, Mack announced an EGR-based strategy to meet the standards. Both Mack and Cummins also rely on advanced electronics to help manage combustion.
But EGR, with its larger radiators, bigger fans and higher under-hood temperatures, may not be needed to meet the goals, according to Caterpillar. At a rare press conference at their factory in Mossville, IL, on March 6, they presented alternative ways to meet the regulations. Also, the techniques and devices will pave the way for the even more stringent rules for the 2007 model year engines. Cat calls their program “ACERT,” Advanced Combustion Emissions Reduction Technology. It consists of:
- The use of next generation hydraulic electronic unit injectors (HEUI);
- Advanced electronics to better manage the combustion process;
- Improved combustion, possibly due to a redesigned combustion chamber and placement of the fuel injectors; and
- After-treatment of the exhaust, using both oxidizing and reducing catalytic converters, similar to those proven in automotive use.
Caterpillar officials proudly presented the new electronics, which have twice the computing power and twice the memory of current engine management systems, with circuitry that speeds input/output signals by 20 percent. But when questioned about particulars of the ACERT system, John Campbell, director of truck engine products, would only say “We’re here to tell you what we’re doing, not how we’re doing it.”
Caterpillar claims maximum heat rejection increases of only 5 percent. Most cases will be in the 2- to 3-percent range, compared to the 40 to 60 percent reported at the SAE meeting. That, in turn, means simplified installation. Most vehicles can handle the additional heat as they are currently configured. Fuel economy will be about equal to today’s engines, as will durability and reliability.
Engines to be equipped with ACERT will be 50 percent quieter and have 20 percent better engine retarding, according to Caterpillar. Power ratings will be unchanged using Cat’s technologies, while those using EGR may have to de-rate engines to lower power levels. Also, no one knows what effect higher under-hood temperatures may have on reliability and durability, measured as life-to-overhaul.
We haven’t seen hard numbers from field testing yet, and Cat says the technology won’t go into production until model year 2004 engines are shipped, starting in October 2003. The due date for meeting the next round of standards is October 2002, but Caterpillar is counting on using emissions credits built-up over the past few years, to be bartered for the additional time required to get ACERT proven and into production.
How will all this affect you? At the most recent Technical and Maintenance Council (TMC) meeting, many fleets indicated they were considering moving their 2003 purchases up to 2002, ahead of the EPA deadline. But in the world of technology, a great deal can happen between now and then. Eighteen months is half a generation of electronics. We’ll keep an eye on things, and let you know what develops.
Is your engine not performing the same after maintenance?
If your engine has been in for service in the past few months, and you feel it may not be giving you the performance or fuel economy you’ve been used to, it may be due to the enginemakers’ settlement with the EPA. Whether you ask for it or not, the enginemakers’ service shops are obliged to recalibrate your engine management system to conform to EPA emissions standards. This applies to all recent engines deemed in violation, according to the agreement.
The recalibration costs you nothing, and may not even show up on your work order. Each engine builder absorbs charges. You’ll just see the change in miles per gallon, and perhaps in hill climbing and passing power. What can you do about it? Once it’s done, nothing. If you take your truck to an authorized Cat, Cummins or Detroit Diesel distributor, they are under legal obligation to make any changes necessary to get your engine into compliance. Instead, go to an OEM dealer and make sure they will not recalibrate your engine management electronics.
That, by the way, is one way enginemakers earn emissions credits that they can later trade for delays in implementing programs.