A Dodge Viper and a Lexus LFA both use a V10 engine, but a Dodge Viper has a very “deep” sound, but a Lexus LFA has a very high pitched whining sound?
What makes a car like a muscle car like a Mustang or Viper have such a different sound than a car like a Lamborghini or Ferrari when they use the same kinds of engines?
In: Engineering
gasoline engines harness the power of small “explosions” of gasoline and air to create movement. the order each cylinder “explodes” is different for different engines. the pipes the exhaust flows through where they all meet together can also be different lengths, so even if the cylinders all fired with equal time between each one, they come out of the exhaust with some closer together than others, which changes the sound
subaru wrx cars have traditionally had unequal length headers (the pipes that collect the exhaust together into one pipe to go out the back of your car), which made two cylinders’ exhaust pulses meet almost at the same time, which makes it sound more like a 2 or 3 cylinder engine
[unequal length example](https://www.youtube.com/shorts/ca0mk-xwABE). notice it doesnt’ sound smooth. it sounds choppy and you can hear the pulses
in the newest models, subaru switched to equal length headers like normal cars, and that made the iconic sound go away, so the exhaust sounds smooth like a normal engine. the rest of the engine is the same though. same order of “explosions”. same engine size (as the jdm market ones, before a subby fanboy comes to argue me on this lol). and yet, they sound completely different. [have a listen](https://www.youtube.com/watch?v=OnT5Smp_5W8)
also, sound travels in waves. you can think of those visualizations you’ve probably seen of sound waves. if someone claps their hands or some quick sharp loud noise happens, you can see a spike on the wave. each “explosion” of the engine is like a single pulse. [the higher pitch a sound, the more frequent those wave peaks are. the less frequent they are, the lower pitch the sound.](https://youtu.be/0j0rKNhmtIQ?si=bjolbzhMirFL4THT&t=255) so if you compare a 2 cylinder engine and a 10 cylinder engine, both having the same “size” per cylinder, the 10 cylinder has 5x more “explosions” when both engines spin at the same speed. this is what makes the exotic cars with v10 and v12 engines sound so high pitched. also, since i mentioned how frequently these “peaks” happen is what affects how high pitch a sound is, revving to a higher rpm also does this, so even if you only have 4 cylinders, like a sports bike (crotch rocket, whatever you prefer to call them), since they rev to 2-3x the max rpm that a normal car’s engine does, you get a much higher pitched sound. the size of the explosions also affects the pitch. the bigger, usually the deeper. smaller, higher pitch.
speaking of bikes, that’s another good real example. some motorcycles have 2 cylinders. those are usually called v-twins. (like a v-8, but with 2 cylinders) some bikes, usually japanese ones, have 4 cylinder engines like a small car. the v-twins usually have much larger cylinders, which means they have to have a lower max rpm. the sport bikes with 4 cylinder engines have tiny pistons and they have a very high max rpm (most can do like 10-13k+, depending on the bike. so the v-twin has bigger “explosions”, which means lower pitch, and it also has a lower rpm, so that also means lower pitch, and it has half the cylinders, so that also means lower pitch. that’s three things that all make it lower pitch. [have a listen](https://www.youtube.com/shorts/1fpv9nm1RVw). that’s a 650cc engine. now hear a 600cc engine (meaning nearly the same overall “size”), from the same brand (suzuki), but in a high-revving 4-cylinder. smaller cylinders (smaller “explosions”), twice the cylinders, and higher max rpm, all mean higher pitched sound. [have a listen](https://www.youtube.com/shorts/HlGS0dFFG6g).
it’s a lot of physics, so i overly simplified some things, which is why i put some words in “quotes” to let the armchair engineers know that i’m oversimplifying for the sake of ELI5
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