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The lowdown on emissions

THE TIME has come.

Starting January 1, 2007, all new engines must comply with the stringent emissions policy enacted by the Environmental Protection Agency (EPA).

Apocalyptic visions — of the intense heat melting pavement, causing out-of-control wildfires, and incinerating anything in sight — have given way to the realities: trucks cost more, weigh more, require more careful maintenance, and, in some cases, require more driver involvement.

There also are a number of changes for bodybuilders, including the knowledge that they won't be able to relocate the diesel particulate filter (DPF) without meticulously consulting with the truck chassis manufacturer. And, in some cases, they won't be able to even think of doing anything.

The emissions standard, signed by the EPA on December 21, 2000, means major changes:

  • The NOx (nitrogen oxides) standard — designed for a 50% reduction — has been revised to 0.20 g/bhp-hr (grams per brake horsepower hour), to be phased in for diesel engines between 2007 and 2010. (The phase-in would be on a percent-of-sales basis: 50% from 2007 to 2009 and 100% in 2010.)

  • The NMHC (no-methane hydrocarbon) standard has been revised to 0.14 g/bhp-hr, to be phased in the same way.

  • The PM (particulate matter) standard — designed for a 90% reduction — has been revised to 0.01 g/bhp-hr, to take full effect in the 2007 heavy-duty engine model year.

  • The certification test fuel sulfur content maximum has been reduced to 15 ppm (parts per million). The diesel fuel regulation limits the sulfur content in on-highway diesel fuel to 15 ppm, down from the previous 500 ppm. Refiners started producing the 15 ppm fuel beginning June 1, 2006.

Sterling Trucks provides its interpretation of what this will mean:

NOx will be reduced by increasing the percentage levels of exhaust gas recirculation (EGR) and, in some installations, with the addition of a diesel oxidation catalyst (DOC). PM, made of soot and ash, will be reduced through the use of a DPF. Both the DPF, and when required, the DOC will be housed in an After-treatment Device (ATD).

The ATD is a canister that replaces the muffler and houses the DPF, a Cordierite ceramic substrate brick and, if required by the engine manufacturer, another substrate brick called a DOC. As exhaust gas passes through the ATD, the DOC oxidizes hydrocarbons and reduces NOx, and the DPF traps PM. Per EPA mandate, the ash must be cleaned from the DPF no more often than every 150,000 miles or 4000 to 6000 hours of service. Soot is also collected in the ATD but is converted to basic elements and a small amount of ash by an event called regeneration.

There are two types of regeneration: passive and active, both of which involve a temperature increase within the ATD.

Passive regeneration takes place inside the ATD when temperatures reach 572° F. It is ongoing when the truck is being driven and exhaust gas temperatures are no higher than normal.

Active regeneration occurs when the inside temperature of the ATD reaches 1112° F. It is achieved by diesel fuel passing through the DOC or by igniting diesel fuel with a burner. The two basic types of active regeneration are: active in-transit regeneration (truck is traveling at speeds greater than 20 mph; discontinued under 10 mph); and stationary active regeneration (truck is parked and in neutral; driver or maintenance technician performs necessary tasks).

Ultra Low Sulfur Diesel (ULSD) fuel and low-ash engine oils will be required. ULSD is 15-ppm diesel fuel that can be used in all diesel engines, has the same level of lubricity, but will have slightly less energy than fuel currently used. Low-ash engine oils also will be usable in all diesel engines. Because burnt oil is the primary source of ash in the exhaust of a truck, low-ash engine oils will contain less than 1% ash.


Greg Saele, marketing manager for the engine group, says NOx reductions require more EGR cooling.

“On the DT, we have two EGR coolers instead of one,” he says. “On the V-8s, there's one larger EGR cooler that sits above the manifold next to the turbocharger. The implication of this is that there is more stuff under the hood. Because you have more EGR cooling, there's more heat going into coolant — that's why the radiators are bigger. They also have larger fans, and some offset from center line of engine.

“For particulate-matter control, we'll have a diesel particulate filter. For active regeneration, we'll be using in-cylinder dosing, so we're not going to have extra fuel lines on the exhaust side of engine. But it does require a diesel oxide catalyst, so that's one more piece to the exhaust system.

“Regeneration inhibitor is an optional feature.

If the filter starts filling up with soot, there's a series of warning lights — yellow, then flashing. That's a signal that you should park the vehicle and push the button, and it'll go through a 20- to 30-minute cycle to burn soot out of the particulate filter.

“The expectation is that it's not going to have any effect on the way the biofuel works. There's no sulfur in biodiesel so it's not expected to cause any problem with particulate filters. In Europe, biofuels are used quite a bit with particulate filters, so there's a good level of experience over there. The Department of Energy is conducting a study to confirm that there are no issues with it, but I think the industry in general is not expecting any new problems with biodiesel.”

He says the temperature out of the exhaust pipe will be 300° F hotter than it is now, with a maximum temperature of 1100° F.

“All engines will have a new engine controller,” he says. “The most important thing for bodybuilders is that today, as most of you know, if you want a remote engine throttle control, you need to buy a remote power module for our trucks. Code 12VCA is the provision for the wiring.

“On the DT, we're going to have a 10-groove belt drive instead of eight, for higher fan loads. We're going to also have a factory option for dual compressor mounting. It's not available in all models.”

Josh LePage, sales manager for product integration, says body lighting is still in the back of cab as it is now, and connection points have not been changed.

“Because of the power distribution channel moving to inside the cab and relocation of the air cleaner, you have two choices to tap into power: battery or in-port side of the air cleaner where you have a power feed you can splice into. If you're looking for a ground, it's on the instrument panel.

“The cluster has more memory and processing speed. Some lights have moved. All are hard-wired circuits.”


Dan Silbernagel, product planning specialist, says that for Sterling's setback axle, the frame rails do not go all the way to bumper.

“This will cause a bit of an issue for bodybuilders who put truck frame equipment on there,” he says. “They're recommended to use front-frame extensions for those applications.”

He says the new radiator is wider, taller, and longer.

“In order to accommodate those large radiators, we're going to splay the frame rails around radiator, which won't cause any degradation in the actual steel,” he says. “We cold roll them at a 90-degree angle out and 90-degree angle back in. It'll be a 47" width. For those who put front-frame extensions and front-end equipment now and are used to 34" width, the mounting equipment will have to change to accommodate the 47" width.

“We chose splayed rail over straight rail and raising the radiator. With splayed rail, we don't have to raise the cab height. That's a concern with people getting in and out of vehicle a lot; they want a lower cab. Also, we're able to maintain current hood profile for the 113 and 122. And on the 111, we're actually able to reduce the hood profile by 11% and provide 11% greater visibility over today's vehicles. One of our competitors chose to do straight rails but had to drastically change the hood to accommodate that, reducing visibility.”

He says Sterling is not losing any cooling capacity with introduction of larger radiators.

“On Acterra, you can go up to 300hp with manual and automatic,” he says. “Automatic, however, requires you to maintain 20 mph random air speed at 8% grade for us to approve that cooling; 350hp is required at 25 mph at 8%.

“On the L series, we utilize 1300-square-inch radiators on the 7500/8500, and 1500- and 1750-square-inch radiators for the 9500. The 1300-square-inch radiators for the L series are for cooling up to 330hp manual or automatic for all applications, and up to 350hp in an emergency. The 1500-square-inch radiator is up to 475hp with manual and 410 with auto transmission.”

He says exhaust configurations are going to affect some of the body installations.

“With Sterling Trucks knowing you won't be able to modify the exhaust system, we've done extensive design work to provide the best solutions to the industry so that the exhaust system would not have to be touched, because it cannot be touched,” he says. “There will be some slight modifications allowed for tailpipe routing. We'll have guidelines by the end of the year.

“In normal operation, it's no hotter than an exhaust system is today, and actually the particulate trap skin temperature is lower than a muffler today. When it's in regeneration, it does peak at up to 1000° F on turbo pipe, 500° on the after-treatment skin, 900 degrees on the aftertreatment device and 1150 at the end of the tailpipe where exhaust exits.

“We also offer a horizontal, frame-mounted aftertreatment device. The Sterling truck will come standard with a diffuser on all horizontal outlets. The diffuser will bring the outside air in to mix it with exhaust gas before it dumps out, so it's going to drastically reduce the exit temperature of that exhaust gas, which will make it safe. We'll also have an under-frame-routed, vertical-cab-mounted tailpipe. The tailpipe comes above the frame rail and will be just 1½ inches back-of-cab protrusion.”

He says Sterling almost exclusively runs air lines and electrical lines down the driver side of rail.

“However, if you do have to go up the right-hand rail, you need to stay about 6" away from all exhaust components,” he says. “It's best if you route the lines back down the left rail and then over the crossmember to the right-hand rail or over powertrain components. You want to use insulated lines up to 125° C and use heat shields for lines that get close to exhaust components.”

Steve Morelli of the corporate EPA '07 team says there will be a manual regeneration switch on the dash.

“We made the decision that it was in the best interest of customers as we move forward to make sure they could do a manual regeneration if need be without having to call a service person out,” he says. “As far as the interrupt switch, that is an available option.”


Nick Vermet, senior vice president of sales, marketing, and customer support, says Japan has required tighter NOx and PM levels than the US law since October 2005. Hino, the largest producer of medium- and heavy- duty trucks in Japan for 32 consecutive years, introduced its 2005 emission changes in May 2005, getting a jump on commercial application experience on the key technology changes that will be used on its J-Series. The 2008 models come out in March.

He says this production experience gives Hino an advantage over US and European engine producers who have not been in production with their 2007 designs. Additionally, Hino's key components such as its cooled EGR system, common rail fuel system, and variable nozzle turbocharger have been in production since 2003. These items, with some modification for 2007, provide a strong base of experience for meeting the new regulations.

“(The technology) is new to a lot of our competitors, but not to Hino,” he says. “There are 80,000 units running, with 60 million miles of operation. If there is ever a stop-and-go duty cycle in the world, it's probably Tokyo. We have proven our system in probably the most severe stop-and-go, light-load duty cycles of anywhere else. If you're driving across one side of Detroit or Atlanta, we believe our system will be able to handle that because of its clean-burn design and its pistons, and its need for manual regeneration is going to be extremely low.”

Hino believes it can meet the emission regulations with four modifications of current components and the addition of one new feature.

The current component enhancements:

  • Common rail injection system, with increased pressure and multiple injection points.

  • Cooled EGR, with increased cooling capacity.

  • Variable nozzle turbocharger, with increased efficiency and surge margin.

  • Piston design, with changes to handle higher pressures.

The new feature:

  • Diesel Particulate Reduction (DPR), with a post-combustion system using active regeneration control and particulate filter.

“High-tech pistons control consumption within the cylinder, so there's less stuff to contain in the trap, which is part of why we're going to have a reduced trap regenerating cycle,” Vermet says. “Our pistons control the combustion process. Our flapper valves or throttle in the exhaust stream are there primarily to control the regeneration process in DPR, but through ECF programming it can also be used as a speedy retardation device. All our ‘08 model trucks as an option have speed retardation. It'll use that exhaust flapper valve to give some exhaust back pressure.

“The DPR system is three-part muffler system with catalyst. All the wiring harnesses going to it — and there are a couple to measure temperatures and pressure — are very securely mounted, and they're mounted away from the DPR for heat control. We ask that you don't modify those components without talking to us first.

“Regarding ground clearance, the DPR filter is 15" from the output pipe to the ground. The exhaust system is 5" longer than in the current model. There are silencers around the inlet and outlet of the DPR. The high-pressure pump has the ability to do five separate injection events — two pre-ignition, one ignition, and two post-ignition — which is dramatically different from what many other engine manufacturers have.”


Ivan Neblett, vocational product manager, says Freightliner not only complied, but took the opportunity to make improvements: a new front frame structure to accommodate larger cooling modules while maintaining light weight; reduced fan “on” time; engine-mounted radiator for heavy-duty engines (12L and over); reduced noise, vibration, and harshness; improved charge air cooler clamping; and improved routing of air lines and electrical harnesses.

Walt Hill of fleet sales application engineering says the passive regeneration requires a temperature of 525° F, can be promoted with fuel injection/engine control strategies and/or catalyzed filters as well as load cycle, and is transparent to the driver. Active regeneration requires an exhaust gas temperature of 1200° F, must have the addition of fuel, in atomized form, to the exhaust to achieve required temperatures, and in many cases can occur automatically, provided the vehicle is in correct operational condition, but may be initiated manually.

When the DPF status lamp is on due to extended periods of low exhaust gas temperature or idling, the driving cycle must be changed, or parked regeneration must be performed. When the DPF status lamp is flashing, parked regeneration must be performed by parking the vehicle in a safe location away from flammables and pushing and holding the regeneration request switch for four seconds. The engine speed elevates automatically and the regeneration event takes between 20 and 40 minutes.

The only portion of the system for which modification will be allowed is the tailpipe downstream of the ATD. Any modifications must follow guidelines for temperatures and back pressure.

Exhaust gas temperatures must be maintained to promote passive filter regeneration and will require insulation in many cases. The distance from the turbo to the ATD must be controlled within prescribed limits. With ACERT during regeneration, temperatures of exhaust gas will be up to 1400° F, and there is an increased need for insulation.

Horizontal tailpipe gas discharge temperatures will be controlled using a mitigation device. If any modification of the tailpipe is performed, the mitigation device has to be left on.

The trucks will be heavier because of the DPF's length and weight: 37.5" and 74 lb on the 210hp-250hp MBE900; 37.5" and 82 lb on the 260hp-280hp MBE900; 43" and 128 lb on the 350hp-450hp MBE4000 and 435hp-515hp Series 60; and 45" and 180 lb on the 515hp HDEP.

The cooling module is about 20% larger in 2007. Frame rail fronts are offset (bolt-on) or splayed (integral) to accommodate the larger cooling modules. Freightliner increased the size of the radiator as much as it could without changing hoods. On the CL/CC 112/120, the radiator is engine-mounted. On the M2-106, it's frame-mounted. Both vocational trucks have the option of extended frames.

Additional wiring harnesses should be routed on the left frame rail. If the wiring harness must be routed on the right rail: avoid routing the harness between the engine turbocharger and the ATD outlet; route the harness across the powertrain components or crossmembers; maintain a minimum distance of 6" from the exhaust system; use TXL/GXL wire insulation with Teflon that is rated to 257° F instead of the standard cross-linked polyethylene insulation; use a heat shield or heat wrap over the harness.

A powertrain PDM is used to house the increased number of circuit protection devices for powertrain components. It provides: battery power to the ECM and transmission control unit (if equipped); ignition power to the ECM, transmission control unit (if equipped), variable-geometry and variable-nozzle turbochargers, aftertreatment device, and fuel heater (if equipped); and a fused-battery sense curcuit for low-voltage disconnect (LVD) system. The powertrain PDM should not be used or modified when installing a body on a vehicle.


Product manager Mike Eaves says GM and Isuzu medium-duty vehicles will have an instrument panel switch to initiate regeneration, but this can be activated only under appropriate operating conditions. GM light-duty vehicles will not have this feature.

The Duramax 6.6L will have a higher capacity EGR cooler, revised cooler circuitry, turbocharger upgrades, extensive software changes, intake throttle, higher horsepower option for C4 and C5 (300hp/520 lb-ft, LRX; 330hp/620lb-ft, LPE), and dual 150-amp alternators added. Production is January 29 for the C4/C5 and February 5 for G vans.

The Caterpillar C7 has Clean Gas Induction, low-pressure EGR post DPF air, variable geometry turbo, CAT regeneration system/auxiliary regeneration device, closed crankcase ventilation, common rail fuel system, and extensive engine software and calibration changes. Production is March 5.

Eaves says ULSD and low-ash oil will cost more. Fuel economy may be negatively impacted — up to 3%, depending on operating conditions. Other system changes can help mitigate the impact, including six-speed transmissions.


Joe Castelli, director of commercial truck sales and marketing, says the duration of regeneration cycle is 7 to 15 minutes and is “largely transparent.” He says he has been “driving these vehicles through Arizona, Utah, and Nevada, and you can't tell when regeneration is occurring. It cannot be manually overridden, except by an authorized service center.”

On exhaust modifications: “Exhaust piping ahead of the particulate trap is not permitted and after the trap is not recommended because regeneration is centered around a pressure differential across the DPF. You can modify it after the DPF if you can maintain that pressure within the same window.”

How to modify truck chassis

Here is a general summary of chassis manufacturers recommendations for installing truck bodies and equipment on chassis equipped with engines and exhaust systems designed to comply with the 2007 emissions regulations:

  • Do not modify exhausts ahead of the particulate trap.
  • Modifications to the exhaust downstream from the particu- late trap are not recommended. If necessary, modifications can be made only if exhaust pressures can be maintained.
  • Avoid running wires near the exhaust system. Use the other frame rail whenever possible.
  • When in doubt, contact the chassis manufacturer.
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