Bugatti V-16 Engine Could Reach 9500 RPM In Calculations

I was watching a typically excellent video from Engineering Explained on the new Bugatti V-16, when I realized something interesting. With a bit of math, my ears, and a sine-wave generator, I could figure out roughly how high this remarkable engine revs. The answer? Very.
Bugatti didn’t share too many details on its new V-16, but Engineering Explained’s detective work and images posted by Bugatti Rimac CEO Mate Rimac on Facebook reveal some of the engine’s crazy specs. A teaser clip from Bugatti also features audio of what seems to be the engine running through the gears.

Here’s where we get into some inexact science. The dominant frequency of the engine exhaust sound from the video at its peak is around 1275 hz. You could get an exact figure with a spectrum analyzer, but absent that, I determined that number using my ear and a sine-wave generator, which creates a pure tone. Match the tone from the sine-wave generator and the video, and you’ve got an approximate figure.

You can calculate the dominant tone coming from a car’s exhaust with simple math. Take engine speed in RPM and divide by 60 to get a value in hertz, in this case, revs per second. As a four-stroke engine only fires twice for every degree of crankshaft rotation, you take that number and multiply it by half the cylinder count. For a four-cylinder running at 5,000 rpm, the equation is (5,000/60) x 2, which gives you a value of 166 hZ. 

Working backwards from 1,275 hZ without knowing exact engine speed, you simply divide by 8—half of the engine’s 16 cylinders—and multiply by 60 to convert revolutions per second into revolutions per minute. That gives us a figure of 9,562.5 RPM.

It’s a little hard to determine the exact highest dominant exhaust pitch from the video, and this assumes that the sound clip is the engine running to its redline. It might not be. But if the sound is representative—and there no good reason to believe it isn’t—we can assume somewhere in the range of 9,500-9,600 rpm.

Sometimes automakers can emphasize other exhaust-tone frequencies with clever tuning of manifolds, and the result are other tones that are almost or just as loud as the dominant tone. These are called harmonics, but to my ears, it doesn’t sound like Bugatti is doing that here. There’s one tone ringing far more loudly and clearly than the others, and it’s around 1,275 hZ.

Can I be 100-percent confident? Of course not. But I’m pretty close to full confidence. What is clear beyond any shadow of a doubt is that Bugatti’s V-16 will be like nothing else.