Freightliner releases guidelines
Mar 1, 2008 12:00 PM
To ensure that exhaust modifications by body builders to 2007 Business Class M2 trucks are consistent with requirements of the US Environmental Protection Agency (EPA) and the California Air Resources Board (CARB) and also in compliance with engine manufacturer's requirements for exhaust back pressure, Freightliner engineers have developed guidelines.
The guide is designed to provide more flexibility in performing exhaust-piping modifications downstream of the aftertreatment device (ATD) while staying within the EPA, CARB, and engine manufacturer's requirements.
Freightliner says that EPA '07 exhaust systems must be validated as compliant. Any changes to the turbo outlet pipe and/or the ATD may bring the system out of compliance. Therefore changes must be approved by the engine manufacturer and Freightliner LLC to meet US '07 EPA requirements. Any modifications may significantly alter the performance of the system and invalidate the warranty.
According to the guide, the exhaust heat mitigation device effectively reduces the concentration of exhaust gas heat. All exhaust systems with a street-level, horizontal, exhaust pipe, must use the mitigator. If installed, the mitigator must remain part of the exhaust-piping configuration. Body builder and/or persons modifying the vehicle must ensure that the exhaust gas and exhaust system components are located to protect against damage or injury from high temperatures. Body builder and/or persons modifying the vehicle must ensure that the final vehicle configuration conforms to all pertinent federal, state, and local requirements, including safety, emissions, and noise requirements.
The guide offers a caution to use the same size and material to extend or shorten original tailpipe. Any additional extensions and bends will change the internal gas pressure, which could result in damage to the ATD or other engine components as well as a reduction in fuel economy.
All Freightliner '07 emission-compliant vehicles require elevated exhaust temperatures to effectively remove collected soot in the DPF. The Freightliner exhaust heat mitigation tailpipe reduces the concentration of exhaust gas heat and is required for all horizontal tailpipe exhaust outlets. The mitigation device has been designed to disperse exhaust gas producing distribution representative of active regeneration events for a variety of engine operating conditions, including idling speeds.
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