What will we see in the engines of 2007? Most diesel makers are reluctant to give us detail, let alone fuel-economy predictions, but we do know a fair bit. Testing is well underway both in the labs and in the field, without the scramble seen before the last Environmental Protection Agency emissions deadline in October 2002. So the engines you buy in an ’07 truck should be much better sorted than they were in ’02.

That said, they will also be more expensive. Best guesses suggest a heavy-duty truck price hike somewhere between US$5000 and $10,000. The lower of those figures was confirmed to us by one truck manufacturer.

This next round of EPA rules demands yet another reduction of both particulate matter and nitrous oxides (NOx). All engine makers will deal with the former through a particulate filter and that will be — with interesting exceptions — the only substantial hardware change.

To avoid clogging these filters, engines will also need to drink ultra-low sulfur diesel fuel (ULSD) with a sulfur content of only 15 parts per million, a tiny fraction of the 500 ppm that’s in fuel now. Oil refineries have to install extra equipment to make the ultra-clean stuff, but the challenge there appears to be in getting it to market.

The new ULSD blend will officially be the standard on June 1, 2006, according to the original EPA mandate, with retailers ready to sell it by Sept. 1. In response to concerns recently raised by refiners, that retail rollout at 15 ppm has since been delayed until Oct. 15, 2006, with 22 ppm being allowed in the meantime. Their concern is that they can’t guarantee 15-ppm sulfur content because the new fuel will inevitably mix with non-ULSD fuel in the pipelines.

Engine makers have had trouble getting supplies of ULSD for their current field testing. Cummins, for example, had tanker trucks carrying ULSD following their test vehicles around the country earlier this year. Yet there was supposed to be, by EPA mandate and refiner agreement, an Interstate corridor of ULSD availability for precisely this purpose.

What follows is a state-of-the-union piece on ’07 engine development as well as a roundup of recent introductions.

Cat Holds Firm on ACERT for ’07:

Caterpillar turned a few heads recently by announcing that its overall compliance strategy for EPA ’07 would include a variation on the cooled-exhaust-gas recirculation (EGR) theme. The engine maker says it will stick with existing ACERT combustion and air-management strategies first introduced in 2003, adding diesel particulate filters (DPF), closed crankcase ventilation (CCV), and ‘clean gas induction’ (CGI) for 2007.

The Cat DPF filter traps soot within a container that also functions as a muffler. The soot is gradually burned away through a catalytic action created by heat from the exhaust gas itself. When light engine loads don’t produce sufficient temperatures in the filter, fuel is injected to accelerate the oxidation of accumulated soot. This process is called ‘active filter regeneration’ and will be a feature of all engine brands using a DPF.

Cat engines with 500 hp or less will require one DPF, while engines with 550 or more will need dual filters.

To meet the required reduction in NOx output for ’07, Cat has introduced what it calls ‘clean gas induction’, which will see a portion of the exhaust drawn from downstream of the DPF recirculated back to the engine in a low-pressure loop. It’s cooled in a water-jacket heat exchanger and returned to the engine in measured quantities. The cooled exhaust gas is reintroduced upstream of the turbochargers and the charge-air cooler.

Cat has long claimed that soot drawn into the engine in the EGR process increases the potential for engine wear. While still relying on exhaust gas to cool the temperature of the combustion event — thus limiting the formation of NOx — Greg Gauger, Cat’s director of on-highway power systems, claims the recirculated exhaust will be soot-free. “This clean gas does not induce the engine wear that cooled-EGR produces,” Gauger says.

Engine makers using cooled EGR, not surprisingly, deny that recirculated air is dirty enough to cause any engine damage at all.

Cat, like the other engine makers, will be forced to add a closed-circuit crankcase ventilation mechanism to eliminate the discharge of blow-by gases from the crankcase — as directed by the EPA’s ’07 requirements — and on-board diagnostic measures to monitor emissions systems performance.

Cummins for ’07: Little Changed from ’02:

A 2007 Cummins engine will look almost exactly like an ’02 model under the hood, according to John Wall, the company’s vice president and chief technology officer. And the same basic EGR technology employed in 2002 will work in 2007, with relatively few changes except for the addition of a particulate filter designed and made by Fleetguard Emissions Solutions, a Cummins subsidiary. Its service interval? They’re aiming for 400,000 miles.

The Cummins ’02 solution is working well, says Jim Kelly, vice president and general manager of the firm’s medium- and heavy-duty engine business. Those ’02 engines have accumulated over nine billion miles to date. Fewer than one tenth of 1% of them –74 out of about 100,000 sold — have needed to take advantage of the company’s ‘Uptime Guarantee’ in which a replacement truck is rented for customers whose engines can’t be repaired in a day. “We got it right in 2002,” Kelly says.

Under the hood, temperatures have not been an issue with ’02 Cummins engines so far and they should be identical in 2007, Wall says. Including filter and muffler changes, he noted that an ’07 engine will weigh about 75 lb more than its predecessor.

Engine design and OEM truck integration are complete for both the ISX and the ISM models. There are presently 75 trucks on the road for real-world testing, split between Cummins engineering, OEM engineering, and end-user field tests (including a couple in Canada).

“Stable architecture allows [us] to focus our field evaluations on optimizing the integration of the proven engine design with the new particulate filter to fine-tune calibrations and certain performance parameters,” says company spokesperson Cyndi Nigh.

The testing process has been a challenge because until recently there was no ULSD fuel available at all in the U.S. Tina Vujovich, Cummins vice president in charge of emissions and engine marketing, said earlier this year she was fearful that oil companies would not be able to meet their commitment to supply the new fuel in time for 2007 because of pipeline contamination by other fuels.

“If we don’t have 15-ppm fuel in 2007, the engine manufacturing industry is in trouble,” she said, because everything has been designed to that standard and it enables aftertreatment. She noted that engine makers had actually wanted 0 ppm, not 15.

Detroit Diesel to Launch the HDE:

While design work continues in preparation for 2007, including an all-new engine platform for worldwide applications, Detroit Diesel Corp. (DDC) isn’t standing still with its existing product line. Its MBE 4000 engine is now available with a rear engine PTO, opening up more vocational applications to the 12.8L engine.

Earlier this year, DDC hosted a preview of its ’07-compliant Series 60 engine, and offered a few hints about its all-new engine set for launch in 2007. It’s presently referred to simply as the Heavy Duty Engine (HDE), to be built at the company’s headquarters in suburban Detroit, and expected to take DaimlerChrysler commercial vehicles worldwide to and beyond 2010.

Production will start in the U.S. with a 14.8-litre version during 2007. Ultimately, the HDE will be the common heavy-duty worldwide engine platform for all DC commercial vehicles, also available in 9.9, 12.8 and 15.6 litres.

During the preview, a few changes to the Series 60 were obvious: the EGR cooler was significantly larger than current editions, and the engine was fitted with a water-cooled Holset turbocharger. Holset is the Cummins subsidiary that makes the very reliable sliding-vane variable-geometry turbo used on Cummins ’02 and ’07 engines. The Holset VGT on the Series 60 (also in use on Volvo’s D12 and D16 engines) is similar to the design Cummins uses. It will replace the current — and in some cases troublesome –Garrett swinging-vane VGT.

So far, DDC hasn’t shared any of its ’07 plans for the MBE 900 or 4000 engines. Both platforms are expected to carry forward beyond 2007. The Series 60 will meet 2007 standards, but DDC is not planning to take it beyond 2010. The 12-litre block will be delisted as the new HDE platform emerges in late 2007, DDC chief Carsten Reinhardt says.

International’s Big Bore Platform:

International Truck & Engine has entered into North America’s big bore engine market. Last year it announced a collaboration with MAN Nutfahrzeuge AG of Munich, Germany on the design, development, and manufacturing of truck and engine components. The new ’07 International engine, based on the MAN D20, is the first fruit of that agreement.

Running in Europe for the last year or so, the D20 is a 10.5-litre engine using cooled EGR and closed-crankcase ventilation. In Europe the D20 comes in 350-, 390, and 430-hp configurations with torque output of 1290, 1400, and 1550 lb ft respectively.

The International version will include the D20’s overhead cam and common-rail injection along with proprietary combustion technology and a new air-management strategy. International has not confirmed North American horsepower ratings, torque output, or even displacement — except to say it will be in the 11-13 litre range and available in late ’07.

Mack Gets New Engine for ’07:

There has been some confusion, and no shortage of speculation, on the future of the Mack power plants come 2007. It’s widely known that Mack’s ASET engine platform — in AI vocational and AC highway configurations — will not be produced for the NAFTA market beyond 2007. The Volvo Group, of which Mack is a part, will have a new family of engines fully commercialized by 2007, when the new emissions regulations take effect. Although the new family will feature some common architecture, such as blocks, cranks, etc., each of the Group’s brands will have distinct engines.

“There will be a period of overlap during which customers will be able to choose between the existing ASET engines and the new ones,” says Mack’s trade relations manager, John Walsh, stressing that although they will feature common architecture, these engines will be customized to meet the unique performance demands of each brand’s individual customers.

“In other words, the differences will be just as significant as the similarities,” Walsh notes. “And more than enough to ensure that our new engines will have the operating characteristics customers have come to expect from Mack.”

Mack officials have told Today’s Trucking that the difficulties some customers have been experiencing with the Borg Warner turbochargers are behind them now, and the redesign has been extensively tested and declared fit for duty.

Volvo’s VN Gets D16 Too:

While we don’t know much about the company’s 2007 plans yet beyond what was written above, we do understand that the ’07 D12 will use a Holset variable-geometry turbocharger as Detroit Diesel is doing. Volvo uses a variation on the EGR theme to meet the current emissions standard, and will continue to do so in 2007, with the addition of a particulate filter.

The company’s recently launched D16 engine is now included in the VN data books. It’s available in the VNL daycab and the VNL 430, VNL 630, VNL 670, and VNL 780 sleeper cab tractors. The D16 is also available in Volvo’s premium owner-operator model VT 880, introduced in early February.

The D16 engine will appeal to drivers who want to run heavy at high legal speeds as efficiently as possible, Volvo says.