Easy step by step guide on how an automotive exhaust system works, though appearances may vary, the concept is the same for most vehicles.
- Once exhaust gases are generated
from an internal combustion engine
, the exhaust system is responsible for
routing these gases from the engine. The process begins as the exhaust valve
opens and releases hot gases into a exhaust manifold which is connected to the
cylinder head. An exhaust manifold is bolted to the cylinder head,
and is used to gather exhaust gases from the cylinder ports and collected into one location.
Step 2 - After collecting exhaust gases, the
manifold disperses them at the manifold flange connection.
Step 3 - Then, these gases are collected at the
flange as they enter the head pipe which bolts to the manifold flange.
Exhaust Manifold Flange
Step 4 - Exhaust gases then travel to the
Exhaust System Head Pipe
which houses the
. There is a primary sensor located on the head pipe, this device is shielded from the body using a heat shield.
Step 5 - Once the gases are treated by the
catalytic converter and read by the oxygen sensor they are released into the
primary transfer pipes.
Catalytic Converter w/Oxygen Sensor
Step 6 - A backpressure balance collector is
used to help equalize pressures which improves performance, while restricting
engine noise. (Note: Four cylinder engines are excluded from this device.)
Primary Transfer Pipes
Step 7 - Once exhaust gases have been processed
through the balance collector they travel down the secondary transfer tubes
which route over the differential or axle.
Step 8 - Exhaust gases then travel into the
muffler where noise cancelling properties of the muffler help quite engine
Secondary Transfer Tubes
Step 9 - Rubber hangers are used to suspended
the system while insolating engine vibration from the vehicle.
Step 10 - Exhaust gases are released into the
atmosphere through the tail pipe which is connected to the muffler. Usually this
tail pipe is protected by shield which helps defuse the exhaust.
Exhaust System Hanger
Engines produce water and steam with the exhaust gases as a natural byproduct
of the combustion process, which can be observed from the tailpipe in the first
minutes of operation. As the engine heats up the water
is vaporized quickly so the moisture is not visible. Most exhaust systems are made of aluminium or stainless steel to prevent
corrosion. A secondary muffler
sometimes used and referred to as a resonator, which increases the muffle affect.
from exhaust gases are quite harmful and can cause complications including being
lightheaded, blurred vision and death. After the engine has cooled down,
inspect the system for cracks, holes or rust. When a new exhaust system is used
for the first few times, its normal for unusual odors to be produced for a short
There are endless configurations of exhaust systems from the very loud (free
flow, low restriction), to the barely audible depending on application and
manufacturer preference. Performance exhaust systems can vary from a free flow
muffler, to a full system including headers which
replace the more restrictive exhaust manifolds. While standard exhausts are
designed to be cost efficient, a performance
system is usually made from higher grade of materials with more performance oriented
ambitions. Consult state and federal emissions laws before modifying a vehicles
Exhaust Tail Pipe
- Defects or corrosion in the exhaust system cause exhaust gases to be inhaled
by passengers causing asphyxiation.
- When driving long distances the exhaust system can become hot, which can
ignition of dried timbers or grass under vehicle.
Article first published 2016-02-04