As petrol or diesel is burned in a car’s engine known as internal combustion engine hot gaseous waste is ejected through the exhaust. (Formula racing cars do not use petrol or diesel but a special fuel known as methanol.) As exhaust gas is thrown out at a great force under heavy pressure it creates noisy sound.
In order to ‘muzzle’ that noise a silencer is fitted in each motor car. The silencer comprises of numerous boxes separated by thin partitions of perforated sheets. Hot exhaust gas streams through the maze of numerous holes before it is ejected outside. Its torturous passage through the silencer obstructs its force besides reducing the pressure so it is unable to escape with a roar. Ultimately much noise is not produced.
The engine of a modern motor car is very quiet due to such silencer but on the other hand there is a considerable disadvantage also. Efficiency of engine is reduced due to the silencer because the engine has to bear the impact of obstruction caused to the exhaust gas which in turn reduces the speed of the car somewhat.
How can a Formula car which is participating in a race where speed is essential afford any reduction in its speed? In order to see that the speed is not curtailed the silencer itself is not fitted in the exhaust of the Formula racing car. Let there be a roaring noise instead!
Muffler (silencer) (Wikipedia)
Formula One car (Wikipedia)