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What is Backpressure

What is Backpressure

Backpressure A key performance factor in selecting the proper muffler is backpressure. For the most efficient engine performance it is important to apply a muffler that minimizes backpressure. 

Backpressure is the force necessary to flow gasses through the Exhaust system, or the resistance to exhaust flow. System considerations include friction and momentum effects - expansion / contraction / elbows, and velocity head loss at outlet. To minimize backpressure, long tube lengths, small tube diameters and sudden contractions should be avoided. 

Backpressure can reduce horsepower and fuel economy. For example, turbocharged diesel engines loose about 0.5% in horsepower and fuel economy per inch Hg backpressure. 

To help you minimize backpressure, our selection guide provides exhaust flow ratings at 1", 2" and 3" Hg (mercury). Conversion: 1.0" Hg = 13.6" H20 Our muffler spec'ing section outlines the steps you need to take for proper muffler selection. 


Another performance factor is the structural durability of the system configuration. Position, mounting support, weight and the type of material that the unit is made from are the key subcomponents of system structure. 

For example, the original OE stanchion or chassis mounting components are adequate for a replacement muffler. 

If you apply a heavier muffler, like one with an emissions device inside, it’s critical to upgrade the hangers, brackets and stanchion with more robust and heavier components. 

Most exhaust system problems encountered in the field service are due to improper bracketing and/or use of clamps – not the muffler or muffler construction.

25th Feb 2020 Daniel Byanski

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