December 15, 2011

Advantages of Removing the Diesel Particulate Filter

At Lawson Industries we get a lot of questions about performance exhaust systems. Recently, I have been asked about the advantages of removing the diesel particulate filter from the exhaust systems of the newer “clean diesel” trucks. When making the decision to remove the Diesel Particulate Filter, here are some facts to consider!

The Diesel Particulate Filter (DPF) is an exhaust filter designed to reduce Particulate Matter (PM) aka soot/black smoke from the environment. This is not green house gas, it is fine dust that settles to the ground.

The DPF is a system consisting of a filter and a complex monitoring maintenance system, to keep the filter operating correctly. The filter itself is made of a special catalyst which, the exhaust from the engine is forced thru, before leaving the tail pipe. The filter collects Particulate Matter. As the Particulate Matter accumulates exhaust pressure builds up behind the filter. The truck computer monitors the pressure, and when it determines the filter is clogged it injects raw diesel fuel into the exhaust system. This ignites in the filter and re-gens (burns), the Particulate Matter out. This re-gen cleaning cycle happens from every 100-300 miles and lasts from 15-45 min. This re-gen cleaning cycle, only happens when vehicle is at speeds above 45 mph.

Long Term Effects:

The Diesel Particulate Filter reduces engine power because of the restriction in the exhaust caused by the filter. Reduced fuel economy, because of lower engine performance, and wasted fuel used in re-gen. Increased wear and tear caused by soot backing up into the turbo and Exhaust Gas Recirculation (EGR) and diesel in the oil. During re-gen fuel is injected into the engine during the exhaust stroke. Small amounts of this fuel leaks past the piston and into the engine oil, thus dilutes the oil, which reduces the oil's ability to lubricate the engine properly, causing extra wear and reduced engine life. This can be prevented by replacing your oil after ever 1000 miles.

Valve Train Component Comparison:

This is a comparison of two identical rocker arms out of two 6.4L engines. Both have been disassembled to show the contrast in the condition of the ball joint after 75,000 to 100,000 miles. The reduced lubricity from diesel fuel in the engine oil, the ball joint on the rocker arm to the right has worn down to the point that it seized causing the rocker arm to break. The rocker arm to the right had a DPF delete pipe installed when the truck was new, thus eliminating the re-gen process that puts the diesel fuel in the engine oil. The ball joint has been lubricated well and does not show the extreme deterioration seen in the rocker arm to the right.