Turn the key and ~brumm brummm vrooooooom~ the motor starts roaring like never before! Who would have thought your 4 cylinder engine could excite your ears and heart rate so! As it turns out there’s a good chance you have an issue with your exhaust system.
The exhaust system in your vehicle channels noxious expended gases produced by the combustion taking place inside your engine. The first stage of your exhaust system is the exhaust manifold. Its job is to collect the spent exhaust gases from all of the cylinders and route them all through to the the main exhaust pipe. Unlike most of the exhaust system being fabricated primarily out of steel the manifold can be constructed of aluminum, stainless steel or cast iron. The exhaust manifold leads basically right off the motor itself and into the remainder of the exhaust system. In most vehicles after the exhaust manifold the following pipe is a small pipe unit that houses the flex pipe. The flex pipe is used to absorb and reduce stress and vibration created by the engine. After the flex pipe unit there generally comes in varying order; catalytic converters, resonators and intermediate pipes.
The catalytic converter is easily the most expensive and vital part of the exhaust system. The name given to the unit is well deserved, It catalyses (speeds up) a reaction that converts noxious gases into drastically less noxious gases. It works by oxidising(adds an oxygen molecule) the carbon monoxide(CO) into carbon dioxide(CO2) a gas which all humans exhale, it oxidizes unburned Hydrocarbons(HC) into carbon dioxide(CO2) and water(H2O), and lastly it facilitates a reduction reaction(separates bonded molecules) of nitrogen oxides(NOx) into nitrogen and oxygen. Resonators and mufflers are similar in that they both are designed to lessen the booming sound that a running engine produces.
All vehicles have mufflers, while only some have resonators. A resonator is used for improved noise reduction in conjunction with the muffler. Intermediate pipes are pipes that would fall between any of these systems linking them together and often housing any of the above listed components for added effectiveness. When there is a hole or leak in the system the catalytic converter, resonator and muffler cannot do their respected jobs. The result of a leak or hole will be a noticeably loud noise on start and acceleration. These leaks are most common at pipe junctions and around exhaust hangers where the metal is under the most stress and most likely to hold moisture causing rust and deterioration. The engines natural vibration can wear out its engine mounts. When this occurs it can then send vibrations through to the flex pipe and other exhaust portions also causing leaks and fractures in the system.
Interesting Fact: You can boost your vehicle's horsepower and torque 5-10% by upgrading your exhaust system to a premium exhaust system. The improvement is derived from the increase in diameter of the pipe which promotes a smoother less inhibited passage of the exhaust gases from combustion to tail pipe. Premium exhaust systems are generally derived from corrosion resistant metals like stainless and aluminized steel.