On the question of F1 noise

An F1 engineer pal of mine (who had best remain nameless) sent me a message about the noise that the F1 engines are likely to be making in 2014.

“The engine noise,” he said, “might be more appealing than that of the current V8s.”

His argument is as follows: at the moment we hear two four-cylinder banks at 18,000rpm. The current engines have two separate exhaust tailpipes, one on each side of the car. This means that we are hearing 600 firings per second per bank of cylinders, which equates to 600Hz (cycles per second) of noise. The mathematics behind this is as follows: 18,000rpm equals 300 revolutions per second; as the engines are four-stroke the rpm must be divided by two, which means 150 revolutions per second, thus a bank of four cylinders creates 600 Hz of noise, which is heard in parallel to its twin bank.

The 2014 rules impose a single turbo, which means a single exhaust tailpipe. The engines will rev to a 15,000rpm, which equates to 750Hz of noise – (15000/60)/2 – which means that the frequency of noise will be 25 percent higher.
GP2 cars currently have a single tailpipe and despite revving to only 9,000 rpm, they sound as “screamy” as the current F1 cars.

The absolute noise level will be lower than 750 Hz because of the energy recovery systems and because of the maximum fuel flow rules, which may have some unusual effects. The rules state that maximum fuel flow allowed will be 100 Kg/hour and that this will come into play at 10,500rpm; so maximum engine speed should ideally be achieved at close to 10,500. In lower gears the engines may rev higher so that the gear changes will not drop the revs below 10,500, however the power will be constant over the rev range between 10,500 and 15,000 (decreasing slightly because of increasing friction), all of which means that the engines will be screaming differently to the current machinery.