exhaust of a road-going car

[piyush123]

Compared with the exhaust of a road-going car, the short but serpentine system in a formula racer looks pretty simple. Each bank of cylinders features a number of artistically twisted steel tubes, with no catalytic converter and no silencer to hinder the flow of the exhaust gases and prevent the engine breathing freely. And yet designing a F1 exhaust system is an extremely complex business that calls for an intimate knowledge of the laws of acoustics if the engineers are to tease the last reserves of power out of the engine. That’s because, like in a trumpet, the exhaust gases vibrate at a specific frequency depending on the speed of the engine. As the valves open and close, they generate a pulsating column of exhaust, with regular peaks and troughs of pressure. To ensure that the 5 cylinders per bank don’t interfere with one another in this respect, all the exhaust pipes must be the same length. And at the end of the collector, the exhaust gasses from each bank exit the car from a single tailpipe.
Racing engines bred for maximum power work with a high degree of valve overlap. That is to say, the inlet valves are opened before the piston reaches top dead center (TDC) while the outlet valves are still open. At this instant, a perfectly tuned exhaust system will ensure that there is already under pressure in the combustion chamber, drawing in the mixture for the next charge. So the induction stroke which is generally triggered by the downward motion of the piston is in this case initiated by the exhaust system . Thus the intake and exhaust system together form an integrated and highly sensitive gas vibration system which influences both maximum power and torque.