Calculate catalytic converter flow capacity, backpressure, and cell density requirements for engine size and power level.
Input Parameters
Results
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Exhaust Flow Rate
cfm
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Cat Cross-Section Area
in²
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Gas Velocity
ft/s
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Est. Backpressure
psi
Note: High-flow cats use 200 cpsi metallic substrates vs. 400-900 cpsi stock ceramic. For 400+ HP, use dual cats or 4"+ substrates.
Reference
Exhaust Flow = HP x 1.5 (CFM rule of thumb)
Cat Area = pi x (Dia/2)^2
Gas Velocity = Flow / (60 x Area_ft2)
Backpressure = Velocity x (CPSI/200) x 0.004
Higher CPSI = better emissions, more restriction