Tuesday, October 1, 2013

Tips for Tuning an Exhaust

Tips for Tuning an Exhaust

Stock exhaust systems designed for passenger automobiles and trucks are constructed for manufacturing simplicity, ease of design and economy. Performance and horsepower tend to be secondary considerations. However, the vehicle owner can tweak his stock exhaust system or invest in some components that can greatly increase performance, horsepower and fuel economy. Changing the dynamics of heat, flow and resistance in an exhaust system can help the vehicle achieve considerable improvements.

Manifolds

    The enterprising do-it-yourself vehicle repair person can tweak his stock exhaust manifold by doing a simple port job. Stock manifolds have irregular internal surfaces due to the rough cast iron seams and ridges. Once the manifold has been removed, a drill with a long-shaft flex grinding cone can be used to grind and polish the inside surface of the exhaust manifold ports. This procedure allows less restriction and the free flow of the exhaust gases, increasing horsepower and fuel economy.

Headers

    The application of high performance headers on a stock vehicle can dramatically increase performance, torque and fuel economy. Headers replace the stock manifold and consist of individual pipes for each exhaust port. They possess very smooth interior surfaces and gentle bends in the tube structure to allow maximum flow without creating back pressure. Most headers have wider diameter pipes and connector flanges. Headers have been manufactured for almost every car and truck available.

Heat Riser Valves

    Many cars have heat riser valves in the end of the exhaust manifold that shut off the exhaust flow for cold starting. The valve opens as the engine engine warms up. Lubricating the valve shaft and making sure it opens and closes properly ensures that there will be no back pressure. Heat riser valves stuck in the closed position can cause extreme back pressure and reduced engine performance.

Catalytic Converters

    High-flow high-performance catalytic converters ("cats") can replace the stock converters. The interior dynamics of the high-performance cats is the same as the regular cats, in that they function as after-burners that reduce emissions. Their components have stainless steel construction and streamlined interior elements that provide less back pressure, less heat and faster and smoother exhaust gas expulsion. Most high-performance cats can bolt right on to the stock passenger vehicle, though some require welding.

Exhaust Pipes

    Replacing stock exhaust pipes with high-quality stainless steel pipes increases exhaust flow because of the smoother, polished tube interiors. They last longer than stock exhaust pipes, since their construction resists water, carbon build-up and raw fuel contamination. High performance exhaust pipes have larger interior diameters that maximize exhaust flow.

Mufflers

    Regular absorption type mufflers can add needed free-flow through their casings, reducing back pressure and increasing acceleration response. A perforated pipe runs through the muffler, with steel wool or fiberglass encased around the pipe. Smaller bullet-shaped high-flow mufflers, known as "cherry bombs" or glass packs have even less restrictive material inside and allow for unrestricted exhaust gas flow. Use of these mufflers does lead to some increased exhaust noise.

Cat-Back System

    The cat-back exhaust system connects to the exhaust at the crossover pipe at the back of the catalytic converter. It consists of two free-flow mufflers designed to muffle the exhaust noise. Installed on dual exhausts, the unit consists of the front pipe necks, two mufflers and the rear tail pipes and extension pieces. The interior of the mufflers contains pre-tuned interior baffles and resonators. The cat-back assembly comes in a one-piece design that can bolt to standard dual exhaust configuration.

Dual Exhaust

    The single exhaust system can be split at the header pipe so it can be joined to a Y-pipe. This allows for the addition of an extra pipe, or dual exhaust setup. This simple modification can allow better free-flow and reduced exhaust system temperature. This increases horsepower, fuel economy and acceleration torque, while the addition of an extra muffler reduces noise.


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