The pros and cons of 10-cylinder engines – Jalopnik

Ten-cylinder engines, especially V10s (the most common layout for 10s, although there have been attempts to use flat 10s and even W10s), have some interesting quirks in engineering, packaging and power delivery. But that can all wait, because listen to this:

That’s the exhaust note of the V10-powered Lexus LFA. If you’re not familiar with that car, oh, lucky you, you’ll discover what is perhaps the most astonishingly sonorous, sensual, spine-chillingly sweet-sounding cylinder count out there. Yes, the Lexus LFA had help tuning the exhaust notes from Yamaha (both the one that makes motorcycles and the one that makes pianos), but there’s something inherent about V10s that just tickles our brains.

Scott Mansell, former EuroBoss racing champion and founder of YouTube channel Driver61, did a deep scientific dive into why V10s sound so good, especially the Formula 1 V10 at 20,000 rpm. He showed that as engines gain more cylinders, new frequencies are accentuated. My fellow musicians can already see where this is going: as soon as an engine hits cylinder five, you get a big third interval, which sticks around as the number of cylinders doubles to 10. People generally like big intervals to sound, so it can be scientifically proven that V10s please our ears. Even a diesel version, like the one found in the nightmarishly complex Volkswagen Touareg V10 TDI, can sound great:

Okay, enough talk about how V10s sing – now about brass heads. Another thing Mansell said about V10s is true, and that is that they involve a lot of compromises. Anyone who’s ever compromised knows that you have to give something up to get something, and V10s are both give and take away.

Let’s compare them to V8s first. Obviously, more cylinders mean higher possible power. In addition, V10s can run faster. Compare a 5-liter V8 to a 5-liter V10, and you’ll see that the V10’s pistons and rods are smaller, allowing it to spin more freely thanks to its lower reciprocating mass per cylinder. While higher revs don’t automatically mean more power, the potential is there with more breathable hardware. And with power strokes every 72 degrees of rotation, evenly fired V10s can be quite smooth (more on even and odd firing, temporarily).

Now for V12s. V10s tend to be smaller and less fuel-thirsty. Smaller makes sense, as 10 is a lower number than 12, and the complexity is also obvious, as V12s have 20% more cylinders than V10s. But the difference in fuel consumption is more complicated. Sure, more cylinders use more fuel, but there’s another efficiency enemy: friction. Those extra two cylinders require lubrication for their associated parts, including the crankpins, journals, pistons, valves, lifters, etc. V12 cooling systems need to be sturdy to keep everything from melting down. Let’s also say you have a V10 and V12, both with a 4-inch bore and a 3-inch stroke. The V10 will displace 377 cubic inches and the V12 will displace 452 cubic inches, but the V10 will have less reciprocating mass (two fewer pistons/rods) and less rotating mass (shorter crankshaft), meaning it can spin faster.

V10s can also “shoot strangely”, with power strokes ping-ponging between 54 and 90 degrees (as in the Dodge Viper):

Typically, even V10s use 72-degree V10 angles, while odd V10s use 90-degree V10 angles, although split 18-degree crankpins can make 90-degree V10s fire evenly (as in the Lamborghini Gallardo, which is old enough to be restomodded now). So here’s the first V10 problem: balance.

Although even-firing V10s have good primary and secondary balance, they wobble due to torque fluctuations. For example, in a Ford Triton 6.8-liter V10, after cylinder six ignites, the next cylinder is five, on the other side, on the opposite side of the engine. Open the driver’s side valve cover of that Ford V10 and you’ll see a huge balance shaft to combat those vibrations. And while odd-firing V10s don’t need balance shafts, they have another source of vibration: that perpetual switch between 54 and 90 degrees of firing. You can combat the harshness of odd-shooting V10s by installing out-of-speed counterweights on the crankshaft, adding vibration dampeners, or ignoring them and turning up the radio.

Finally, this is where the Goldilocks zone is turned on its head. V10s are bigger, more complicated and thirstier than V8s, which you can simply turbocharge or hybridize for more power. As for V12s, they are inherently much smoother than V10s. This is the real crux of why V10s have disappeared from passenger cars. Automakers would rather hybridize or turbocharge a smaller engine and get better EPA fuel ratings with less size, weight and technical complexity. Sorry, V10s, we will always miss you.