Using the Pressure Drop Graph determin the silencer pressure drop corresponding to exhaust gas velocity and silencing level.
Silencer recommendations are based on 1" Hg restriction and are estimated only. As we have no control over piping system and other variables (i.e. tail pipe loss, flex, sudden expansion/contraction, etc.), we make the following recommendations: Use a size larger silencer or a low back pressure unit* if the back pressure calculations exceed 1" Hg across the silencer or if the silencer back pressure is more then 50% of the allowable back pressure for the exhaust system (be sure to use the smaller of these two criteria in your determination). If components of the exhaust system (without silencer included) exceed 50% of the allowable back pressure for the engine, adjust silencer size accordingly.
*Note: When determining back pressure, velocity should not exceed 15,000 ft/min regardless of the allowable back pressure (10,000 ft/min for spark arresting silencers).
Exhaust Gas Velocity = 1650 = 8,405 ft/min .1963
The Pressure Drop = 9 inches of Water (using Pressure Drop Graph).
*If the exhaust flow rate is not available, it can be approximated by the following equation:
*Note: Use the equation above only when the exhaust flow rate is not available.
Note: All dimensions are in inches