Freightliner exhaust guidelines
Nov 1, 2007 12:00 PM, By Rick Weber
Freightliner released guidelines to ensure that bodybuilder exhaust modifications to 2007 Business Class M2 trucks are consistent with requirements of the US Environmental Protection Agency (EPA) and the California Air Resources Board (ARB), and also in compliance with engine manufacturers' requirements for exhaust back pressure.
The guide was designed to give bodybuilders more freedom and flexibility in performing exhaust piping modifications downstream of the aftertreatment device (ATD), while staying within the EPA, ARB, and engine manufacturers' requirements.
Vocational product manager Ivan Neblett said EPA ‘07 exhaust systems must be validated as compliant. Any changes to the turbo outlet pipe and/or the ATD could bring the system out of compliance, so changes must be approved by the engine manufacturer and Freightliner LLC to meet US 2007 EPA requirements. Any modifications could significantly alter the performance of the system and invalidate the warranty.
Neblett said 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. Those modifying the vehicle must ensure that the exhaust gas and exhaust system components are located to protect against damage or injury from high temperatures.
Also, those modifying the vehicle must ensure that the final vehicle configuration conforms to all pertinent federal, state, and local requirements, including but not limited to safety, emissions, and noise requirements. Exhaust piping modifications must comply with guidelines and use proper materials. Proper support must be used to adequately support exhaust piping added.
He said that to calculate the pressure loss value for exhaust piping from the ATD exit to the tailpipe exit, go to https://secure.freightliner.com/misc/public/m2bodybuilder/default.asp, then refer to the back pressure equation worksheet (Worksheet A), the component pressure loss value table (Table 1), and the maximum exhaust piping pressure loss value tables (Tables 2a and 2b).
Starting with Worksheet A, fill in the exhaust piping component quantities and multiply by the component pressure loss values (from Table 1) to calculate the component total back pressure. Sum the component totals to get the calculated back pressure for the piping modification. If the calculated value is less than or equal to the maximum value listed in Table 2a or 2b, the exhaust piping should meet engine manufacturer's back pressure requirements.
Neblett said all Freightliner 2007 emission-compliant vehicles require elevated exhaust temperatures to effectively remove collected soot in the diesel particulate filter (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 the thermal distribution representative of active regeneration events for a variety of engine operating conditions, including idling speeds.
