So this may be an odd question but it's something I've been wanting to get to the bottom of for a long time now. I'm a composer and I've been fascinated with the sound of a V10 engine. A few years ago I found that the V10 has a major 3rd interval in its sound. Ever since, I've been wondering what exactly causes this to happen. My guess it has something to do with the order in which the pistons are firing, but I have no idea how.
Let's get to the basics first. I've looked mainly at V6, V8 and V10 engines. I have found that V8 engines have an octave interval
, V6's have a fifth
interval and V10's have a major 3rd
interval (actually an octave and a 3rd). Apparently there's a relationship between these engines and the harmonic series
From the sound of it, a V6 could be a 3 cylinder engine with 2 cylinders firing at the same time. A V8 is very similar to a line 4 (or maybe 2 cylinder?) and a V10 is like a line 5. After some more analysis I found a clear relation between the amount of cylinders and the harmonic series:
V10 and line 5: loudest harmonics are: harmonic 5, 10, 15, 20..
V8 and line 4: loudest harmonics are: 4, 8, 12, 16, 20..
V6: loudest harmonics are: 3, 6, 12, 15, 18..
In all engines I found that apart from these harmonics the octaves would sometimes be pretty loud as well, or very soft. Also, most harmonics would be in every engine, no matter what type. Sometimes the fundamental would be missing. But variations like these could be due to the recording equipent (mics not picking up certain frequencies, pre-amps, even wind). So it's not so much that only the line 5 or V10 have a major third interval, it's more that it is way more prominent in these engines as opposed to 4, 6 or 8 cylinder engines.
For the V10 and V6 it seems to make sense: they're divisible by 2, giving 5 and 3. But 4 is divisible by 2, even though the louder overtones are ever 4th harmonic. Could this mean that in a 4 cylinder engine, none of the pistons fire together?
In any case, I have no idea what exactly causes this relationship. If this has to do with the order in which the engines are firing, how do these frequencies come about? If the pistons fire in an even way in time, you'd have just the frequency of this firing. In all this I just assumed that the firing of the pistons makes the noise, but could there be more?
Hopefully some people here know a lot more about how engines work and could enlighten me on this.
For anyone interested in my analysis: http://v10.basbouma.nl/V10%20harmonic%20series.xls
And I also uploaded some of the spectrums I analysed (the clearest spectrums):
Ferrari F2002 V10
Audi R8 LMS V10
Porsche 991 V6
Alfa Romeo 4C line 4
PS. related to this but not quite the same question. Why does an American muscle V8 sound so less 'tight' from a V8 racing engine?