Crank it up and make some noise, if you have the right V8

A study commissioned years ago by Hiscox insurance company in the UK asked, and I'm paraphrasing, whether the sound of more exotic (ie. more expensive) cars had an effect on the human libido.

They might have used the word arousal. And I'm not sure if they were just trying to get some attention with the inevitably sexist-sounding headlines after the study found there was a greater effect in the "primeval physiological response" for women than men (for example, "Study: Women Aroused by Big...Engines" on cars.usnews.com), or if they were hoping the findings would show that there's something other than the financial status symbol of an expensive car that makes its owner seem more attractive.

A dual-plane crank is why production V8s give a better aural sensation. Photo: Shutterstock.

A dual-plane crank is why production V8s give a better aural sensation. Photo: Shutterstock.

For me though, it was the wrong question from an engineering standpoint (and very limited from a scientific standpoint for that matter, with only 40 participants listening to recordings of a Ferrari, a Maserati, a Lamborghini, and a VW Polo).

You see, while they found that 100 per cent of female participants, and about half the men, had a significant increase in testosterone as measured in the saliva (an indication of increased arousal) after listening to the Maserati, the folks doing the study got a bit confused when they didn't get a similar result from the Ferrari, even though these cars used the same family of V8 engine (meaning it shares a significant portion of its design, with many parts being extremely similar or exactly the same).

The answer that I wish to offer you is the one major part they do not share; the crankshaft. Ferraris all tend to use a single-plane (or flat-plane) crank, whereas the Maserati uses a dual-plane (cross-plane) crank.

What's the difference? Well, for that study, it was the firing order that mattered, because it dramatically affects the sound.

If you think of the conrod journals (the bit on the crank the conrods connect to) as going around a clock, with a single-plane crank you can put half of them at the 3 o'clock position, and then the other half will be in the 9 o'clock position. Like two clock hands in those positions, they appear to be in one flat plane, hence the alternative name, flat-plane.

With a dual-plane crank in a V8, when you put a quarter of the conrod journals (and they are usually in pairs, one for each bank of cylinders) at the 3 o'clock position, the rest will be at 6, 9 and 12 o'clock, occupying two perpendicular (or cross) planes.

The benefit of the dual-plane crank is that it's much easier to reduce vibration, so most road car V8s use it. However, it creates firing order options where it's impossible to avoid having two cylinders on the same bank (side of the engine) fire one after the other.

The Maserati V8's firing order around the time of the study was 18436572, where 1 to 4 are on the right (our driver's side), and 5 to 8 are on the left (with cylinder 1 at the front, and cylinder 5 at the back of the engine).

With this firing order, cylinder 8 can fire off its note individually, but then 4 and 3 go one after the other in the same exhaust manifold (or extractor, or header) so their sound combines into one deep note. 6, 5 and 7 combine for another even deeper note, then 2 and 1 combine for a deep note. In terms of sound pattern, it's normal, then deep, then very deep, then deep. It's quite distinctive.

However, with a flat-plane crank this cylinder firing order pairing is avoided, which helps exhaust flow (for reasons we'll go into another time), but all cylinders will make pretty much the same higher note.

What that means is, with its single plane crank the Ferrari sounded like two (evenly-offset) four-cylinder engines singing in unison, whereas the Maserati sounds like it's shouting with a raspy voice. And therein lies the key. It's a more guttural sound, which is associated with being higher up the male dominance hierarchy.

To explain why that matters we need to start delving into other psychology studies and lectures. But the ultrasimplified version is this. Psychology professor and clinician Jordan B Peterson has said in his lectures at the University of Toronto that heterosexual human females will normally pick a male partner from as high up the male dominance heirarchy as they can. And, there can be primal sounds associated with at least one dimension of that dominance.

This story Crank it up and make some noise, if you have the right V8 first appeared on The Canberra Times.