Engines practise fritter gases which must be expelled in codification to preserve influence Industry and fuel efficiency. Exhaust systems route waste gasses outside through piping and system components. Exhaust testing is required by the department of motor vehicles in many states.
Noise Level Testing
State laws vary on acceptable exhaust noise. California certifies state-run testing facilities to determine if a vehicle's exhaust meets acceptable noise standards.
Backpressure occurs when exhaust pulls back into the cylinder ports. This suffocates the engine, decreases power and lessens fuel efficiency. Normal readings are around 1.5 PSI.
Smog & Emission TestingSmog and emission requirements vary by state. Consult your local department of motor vehicles for state requirements. Exhaust systems will always have some level of backpressure. Excessive backpressure caused by piping obstructions -- or wrongly sized piping -- requires repair. Testing a vehicle's backpressure requires a pressure gauge which reads from zero to 15 PSI. Connect the pressure gauge to the air-pump check-valve and turn on the vehicle.
Smog and emission tests verify a vehicle is not expelling excessive exhaust toxins -- such as carbon monoxide -- into the atmosphere. They verify that exhaust and intake components meet state requirements.