What kind of engine will you be driving following Oct. 1, when new exhaust emissions limits go into effect? Most likely the same one you are now, of course. But if you or your company purchase a new truck after then, it will likely have a more complex diesel equipped with some type of exhaust gas recirculation (EGR).

Most domestic diesel manufacturers, laboring under a consent decree forced on them by the U.S. Environmental Protection Agency, will use “cooled EGR” to meet the new regs. They cut two key pollutants by 90%; oxides of nitrogen (NOx) and non-methane hydrocarbons (NMHC) will drop to a combined 2.5 grams per horsepower/hour.

One domestic builder, International, will use cooled EGR in its smallest diesel only, at least for now. Caterpillar will not use EGR at all, even though it will be late meeting the regs. And import diesels were not subject to the consent decree, so they will also not use EGR, until 2007, anyway. EGR development has been costly and the equipment will be expensive; that and larger radiators and other underhood changes will raise the price of a new truck by $2,500 to $6,000.

Some truckers have learned about the upcoming engines and are buying early to avoid them. International, Paccar (Kenworth and Peterbilt) and Volvo are among the builders who are stepping up production to fill new orders. Some orders are from the rumored (if not actual) economic recovery, but some are due to the EGR concerns. We've already heard reports of price boosting by truck builders to take advantage of the new, if perhaps temporary, demand.

Fleet operators are worried about price, and the unknown durability and longevity of the new equipment. Engine builders have not had much time to road-test the new products, but all have testing now under way. Some fleets say they will buy a few of the new engines to try them out, but others say they'll buy late-model used trucks for a while.

Truck builders were worried about higher under-hood temperatures that will come from more heat rejection. This is a function of the EGR system's cooler, which uses engine coolant to extract heat from exhaust gas before sending it to the cylinders. Cooled exhaust gas cools combustion, which reduces the amount of NOx being produced. However, recent testing indicates under-hood heat is not the problem once anticipated.

Here's what each diesel builder has announced about its October engines:

Cummins hosted a press event in mid-March at its Columbus, Ind., headquarters to announce its first emissions-certified engine for October 2002, the 15-liter ISX. EPA formally approved the certification on April 2. The engine reduces exhaust emissions, as the regulations demand.

The ISX, which will replace the non-certified N14, has revised fuel injection timing, cooled EGR and a variable-geometry turbocharger developed by Cummins' subsidiary, Holset. Cummins achieved its goal of being the first to have an engine certified. Between now and the October deadline, engineers expect the EPA to pass on the 11-liter ISM, 8.8-liter ISL and 5.9-liter ISB engines.

Caterpillar will not have a certified engine to meet the Oct. 1 deadline, but will supply interim models until its ACERT (for Advanced Combustion Emissions Reduction Technology) engines are ready. They start in January with a new 9-liter C-9 and in April for other models. Meantime, Cat will have to pay penalties of an estimated $6,000 to $10,000 per engine. But it would rather do that than use cooled EGR, which it claims is inferior to its ACERT approach. EGR will not work past 2007, when emissions regs further tighten, Cat says.

Cat is now trying to get EPA to move back the Oct. 1 deadline, which the agency almost certainly won't do, or reduce the penalties to “sane” levels, which it might. Six to 10 grand is an “insane” amount of money to pay for each engine that will be close to compliance, anyway, Cat declares. It says it will not pass penalty costs on to customers through a higher price.

The Cat advantage over competitors come October is no complex EGR gear (or potential for extra maintenance) and no fuel penalty. The engines will get the same fuel economy, use the same motor oil and go as far between intervals as now. And ACERT engines will be upgraded to meet the 2007 regs. A disadvantage is exhaust after-treatment, which is part of ACERT. These devices are bulky but not very heavy, the company claims.

International will use cooled EGR on a new 6-liter V-8, most of which will go to Ford for its heavy pickups and vans, but no EGR until January '04 on its DT466, DT530 and HT530 inline-6s. The HT already uses a variable-geometry turbo, which improves response. For its heaviest truck models, International will buy larger engines from Caterpillar and Cummins, but not Detroit.

Mack will have two types of engines for the two basic types of vehicles it builds: cooled EGR for highway trucks and non-cooled internal EGR for vocational trucks. Mack's cooled EGR is similar to others, with a waterjacket-to-gas cooler, special plumbing, and a VG turbo. Its I-EGR dispenses with the extra gear and instead uses electronic controls and special valve action to mix small amounts of exhaust gas with inlet air inside the engine.

I-EGR isn't as clean as cooled EGR and uses up to 5% more fuel. Mack has enough Clean-Air “credits” with EPA to allow it to sell this model. Operators of dump, mixer and trash trucks may not suffer a fuel economy penalty, but highway operators would, engineers explained. The cooled-EGR engines they'll buy may do about as well in fuel as today's engines.

I-EGR will be offered only on DM, RD and Granite trucks and tractors. Cooled EGR will go in Vision trucks and road tractors. No, you can't get the simpler I-EGR in a highway truck, engineers said. But some may run primarily on-road if customers buy a Granite or RD tractor to pull lowboy, dump and trash-transfer trailers.

Detroit may be the last to have engines certified, with applications submitted in July and production in August. Its Series 50 and 60 models will also use cooled EGR and a VG turbo. Engineers plan to use the summer months to fine-tune the design and make further modifications. According to one, the new Series 60 is “responsive down to 800 rpm, and far quieter than before.”

The S60 may be lighter, despite the addition of the EGR cooler and piping. However, weight savings may be offset by larger radiators, added engine fluids and cooling system modifications, required for all cooled EGR engines.

DaimlerChrysler-owned Detroit will also sell and service Mercedes-Benz medium- and heavy-duty diesels, available on Freightliner, Sterling and Western Star. M-B engines aren't subject to the consent decree, and won't need EGR until January 2004.

Volvo's Swedish-built 12-liter engines (but not the 7-liter diesels, which are being dropped) will have “V-Pulse” EGR, a simple version of cooled EGR that uses the exhaust's normal pulsing pressures to push exhaust gasses back toward the intake side. There a Venturi effect helps mix varying amounts of exhaust gas with inlet air. No VG turbocharger is needed, so few new maintenance procedures will be required. Except for simple reed-valves, the Volvo system has no moving parts.

Extensive field tests of the new equipment began last July, when V-Pulse was announced. Some of Volvo's 12-liter diesels have covered more than 100,000 miles each and returned to Volvo's labs in North Carolina for teardown. A total of 3 million test miles should be covered by the Oct. 1 deadline, the company said during a press conference at MATS.

Engineers had no fuel economy figures, but expect degradation to be the same 2 to 5% that other manufacturers expect. Underhood temperatures are about 5 degrees F higher with V-Pulse engines compared to today's VD12 engines, they said. Executives estimated the new engines will raise the cost of a typical Volvo truck by $2,500 to $4,500.

Test Drive: Cummins ISX with cooled EGR

It looked ordinary enough, sitting at Cummins' R&D center in Columbus, Ind., but the 1997 Western Star was re-engineered from grille to firewall. It had a high-capacity radiator, an 11-blade fan under a reshaped shroud, and, of course, the exhaust gas recirculation (EGR) devices attached to the new Cummins ISX, now certified by the EPA. The 500-hp, 1,850-pound-foot engine was mated to an 18-speed Eaton Fuller gearbox, 3.70 rear ends and 24.5-inch low-profile tires. That would get us 65 mph at 1,450 rpm.

Loaded to 77,200 pounds plus two Cummins engineers and another writer, we headed west on Indiana Route 46 to find a big hill. Navigating city streets was a breeze with this highly responsive engine. Thanks to its variable-geometry Holset turbocharger, there was no noticeable turbo lag or whine. The new (to the U.S.) turbo provides high boost at low rpm, so acceleration from stops and around corners was smooth, even with revs below 1,000 rpm.

The engine loafed on the highway. At County Line Hill (just shy of 3% for about two miles), I split down and tried to hold 1,400 rpm up the hill at 50 mph. I couldn't. Instead, we accelerated to 53 mph by the time we crested the hill. Coming back down, the Cummins Interbrake was in its highest setting – too much for the grade. I had shifted down to get 1,950 rpm at 50 mph at the top of the hill, and without using the service brakes at all, we shed 3 mph by the bottom.

I had heard a lot about high under-hood temperatures due to the cooled EGR, but the temp gauge stayed fairly steady, barely topping 200 only when we climbed the hill. How the setup will perform in summer, I do not know, but Cummins engineers tell me the ISX has been fully tested in all climates.

They say fuel mileage is down by 2 to 3% from other ISXes but comparable to similarly rated N-14s. If you get 6.5 mpg with a recent ISX, you might see 6.3 with a new model. Fleets will worry about that, but most owner-operators won't, and they'll like the way it drives. — Paul Abelson