How To Choose the Right Exhaust ?

Modifying our own vehicles were begin viral since the first vehicle invented. All of us keep seeking for something to make our vehicles become unique and eye-catching on the road. As one specific product is just not enough to suit to all need, Max Racing Exhaust offer a vast range of products which allow you to enjoy the passion of modifying and customizing your owned vehicles.

The exhaust system was designed to reduce sound wave pollutions and control the emissions rate of the internal combustion engine (ICE). There are a lot of researches & developments carried out in the term to increase engine performance every moment, including us. Although the exhaust system required complex designs for each different application, the fundamentals never change: absorb combusted gases from the exhaust valve, release it to the atmosphere to ensure the combustion cycle runs properly. The key variable that does change depending on applications are the pipe length, diameter, radius of bends, muffler volume and internal baffle design affect performance.

Choosing the right exhaust can be confusing and time-consuming. Although most of the user select an exhaust system based on only sound and looks, it is important to note that to achieve the optimum performance, the right dimension of pipe must be matched to the engine combination, and most importantly the rpm range of specific horsepower. Therefore, if you are into performance, we, Max Racing Exhaust are here to provide you with a solution of fundamental understanding of the exhaust and the right choices to match your vehicle’s next exhaust system.

For optimum performance, the exhaust system configuration must be matched to the engines induction system, cylinder sizes and camshaft timing. These components should be tuned together as an integrated system for the best peak performance within a specific rpm range. If one component is modified, the entire group of components must be returned to balance the maximum performance.

An optimized exhaust system achieves a balance of pressure between the engine’s intake and exhaust tracts within a given rpm range. Example for the street racer, if you want optimized torque in the low and midrange (2,500-4,500 rpm) for excellent acceleration and highway cruising along with the decent power on the top end. However, every pipe design is a compromise. For example, if a pipe is designed for only bottom end torque, it will give up top-end horsepower and vice versa. meanwhile, for racers, large-displacement high-horsepower engines often design a pipe for top-end power and will lower down the low-end torque, so the vehicle will launch easier, resulting in faster acceleration. An exhaust system is only effective through a narrow range of the engine’s entire rpm band, so priorities must be set and compromises made to achieve the desired performance characteristics.  The major exhaust system components include an exhaust header/ manifold, catalytic converter, exhaust resonator, and exhaust muffler. The diameter, length and overall design configuration of these components will have a major impact on the engine.

Exhaust Pipe Diameter

Pipe diameter is one of the critical parts for optimized the vehicle’s performance because the diameter of it determine the volume amount to flow through which has a major effect on exhaust gas velocity. Together, engine displacement, compression ratio, valve diameter, camshaft specifications and rpm band determine the optimum diameter. Exhaust backpressure will increase if the pipe diameter is too small. Backpressure is the flow resistance created in the exhaust system. High backpressure increases the engine’s pumping losses, resulting in increased pressure on the piston during the exhaust cycle.

Additionally, high backpressure reduces low-lift exhaust flow during the “blowdown” period. Blowdown is the phenomena of expanding exhaust gases helping expel combustion residue from the cylinder and begins when the exhaust valve opens. Blowdown refers to how efficiently combustion residue is expelled from the cylinder by expanding exhaust gases. Blowdown begins when the exhaust valve opens and ends when cylinder pressure and exhaust system pressure are equalized. Using blowdown to help remove exhaust gases reduces the engine’s pumping losses because less physical demands are placed on the piston during the exhaust cycle. The ideal situation is to have a balance between backpressure and exhaust gas velocity. An excessively large pipe diameter will decrease backpressure but also decreases velocity, resulting in poor bottom-end-torque.

Exhaust Pipe Length

Pipe length is determined by the engine’s application (touring, hot street, race, etc.) and rpm range. Pipe length regulates inertia and wave tuning, which establish the effect scavenging has on power production. Scavenging uses a column of fast-moving exhaust gases (inertia scavenging) or a supersonic energy pulse (wave scavenging) to help cleanse combustion residue from the cylinder. Inertia and wave scavenging also can assist the intake charge into the cylinder. During engine operation, positive and negative waves are created in the exhaust system and travel back and forth throughout the length of the pipe. If the pipe length is optimized, the negative wave will be timed to arrive at the exhaust valve during the valve overlap period. A properly timed negative wave will reduce pressure at the valve and help scavenge combustion gases from the chamber. The engine’s most important rpm band must be identified so pipe length can be matched to the proper rpm because pressure waves can only be timed to help exhaust scavenging over a narrow rpm range. A longer pipe length optimizes power at low rpm while a shorter length improves upper-end performance.

The Exhaust Muffler

An exhaust system must have sufficient muffler volume to keep backpressure low at high rpm. Engine displacement, compression ratio, rpm, and horsepower are all factors determining adequate muffler volume. Typically, muffler volume should be roughly 10 times the cylinder volume to make adequate high-rpm power. But keep in mind that as horsepower increases, exhaust gas volume also increases. With increased exhaust gas volume, muffler airflow, and volume must also be increased. That means a 96ci engine producing 100 horsepower generates more exhaust gases than a similar engine producing only 90 horsepower and requires greater muffler capacity for optimized top-end power. Unfortunately, large mufflers are not aesthetically pleasing on the V8 engine, so it is challenging to design an exhaust system for large-displacement engines that satisfies both aesthetics and performance.

Two-into-two exhaust systems use two exhaust mufflers, offering the potential for increased muffler volume. Such designs also are usually tunable through modifications of the internal baffles. Increasing the number and/or size of the holes in a baffle or shortening the baffles reduces backpressure and can help top-end power. Still, remember that increasing flow too much can kill bottom-end torque. Additionally, a tunable 2-into-1 system offers a big advantage over a non-tunable collector system, especially if the engine capacity is large.

Conclusions

Although most drivers buy an exhaust system based on sound and attention-catching looks, remember that for optimum performance, pipe diameter, length and design are critical. Consider the exhaust system an integral engine component that should be tuned to the engine displacement, cam and induction system. Exhaust pipe diameter normally is the most important factor for exhaust system design because it sets the torque curve. Larger diameter improves top-end power at the expense of low-end torque. Changing pipe length moves the torque curve either up or down the rpm band. A shorter length generally improves top-end horsepower while a longer pipe increases low-end torque. Straight pipes typically improve power above 4,000 rpm but reduce throttle response in the lower rpm ranges. Finally, if a key component or specification such as displacement, cam, induction tract or combustion chamber is changed, the engine may require a different pipe design and should be returned for best performance.