The Surprising Reason Cars Sound Different | WheelHouse

The Surprising Reason Cars Sound Different | WheelHouse


– [Nolan] An American V8. A 12 cylinder Italian stallion. Or a Japanese inline 6. Everyone’s got at least one engine sound that gets them going. But what makes them sound different? It’s not just the exhaust pipe. Hey James? (door squeaks) (upbeat dance music) – [Man In White] Looks like Nolan got into the Nos Energy stash again. – [Man In Blue] Those
dance classes are really paying off though.
– Sick moves. – So many parts of the
car can have an impact on how an engine sounds. And car companies pour millions of dollars into developing those sounds. Sometimes they (bleep) up. To understand engine sound,
you must first understand the fundamentals of sound itself. Yep, it’s gonna be one of those episodes. The reason we hear at all, is thanks to waves of different pressures traveling through the air. Our ears interpret these waves as sound. How fast the wave oscillates
is called frequency and it’s measured in Hertz. The frequency of a wave
determines the pitch. So if the wave is slower,
you hear a lower pitch. If the wave is faster,
you hear a higher pitch. That’s easy, right? You are now a certified
audio engineer, like Joe. Engine sound is produced
after a cylinder fires and sends the exhaust in
the form of pressurized air into the exhaust manifold. These are called pulses. And the rate of pulses per
second coming out of an engine is what dictates frequency or pitch. Sounds are made up of a bunch
of different frequencies. (engine revs) The frequency with the
largest amplitude, or volume, is called the dominant frequency or root tone. The pitch is directly linked
to the revolutions per minute which is what gives us tone change when we’re revving the engine. (engine revs) Everything that makes
noise has a root tone, and in the case of cars, that
frequency can be calculated. Okay this is where it starts to get a little more complicated but stay with me here. I’m pretty bad at math too, but trust me, this is how you do it. Engine speed can be converted
from revolutions per minute to revolutions per second then to Hertz. 60 revolutions per minute equals one revolution
per second or one Hertz. To make it easy, let’s
start with a V8, okay? An eight cylinder engine
idling at 1,000 RPM should be about 17 Hertz. But this only accounts for one cylinder. Four stroke engines, like
V8s, fire two cylinders once every two turns of the crank shaft, so only half the cylinders in an engine are firing during one revolution. Still with me, that make sense? Great. In a V8, because only
four cylinders are firing during one revolution, we’re gonna multiply four by 17 Hertz giving you a dominant
frequency of 68 Hertz. This is called the fourth engine order and it’s specific to
eight cylinder engines. Take a V10 for example, one of
the coolest sounding engines. We did a bumper to
bumper on the Lexus LFA. It has one, it sounds great. To figure out the dominant
frequency of a V10 at 6,000 RPM, it’s 6,000
divided by 60, 100. Multiplied by half the
amount of cylinders, five. Which gives us a dominant
frequency of 500 Hertz at 6,000 RPM. This formula just gets
you the dominant tone that the engine produces. There are also quieter frequencies that complement the sound. These quieter tones can
be caused by anything from the resident
frequency of the engine bay to the thickness of sheet
metal used in the car or the diameter of piping used. Much of the sound we hear from an engine has to do with the cars
exhaust system as well. A big fart can exhaust lets out a lot more air at one time, which gives us a bass-ier tone. That’s why you see cars
like Sentras or CR-Xs with huge exhausts trying
to beef up the sound of their little four banger. (engine revs) (farting) There are engineers at
every major car company that focus on just the sound alone. They work in the NVH or noise vibration harshness department. A completely unaltered engine sound has some abrasive tones. These engineers experiment with different diameter
pipes, mufflers, bushings, and other insulation material to mute those unwanted frequencies and shape the engine tone
to the company’s liking. – [Voiceover] Computer,
computer, yep, yep, yep, yep, yep, yep, yep, yep. – One super recognizable sound is the good ol’ American V8. It’s a really throaty, gurgley
sound that everyone loves. (engine revs) But why does it sound so much different than an eight cylinder European engine? (engine revs) – Let’s ask some people at donut. – American and European
cars probably just (bleep). – Just, probably just like
different exhaust manifolds. – The passion involved
with the production. – [Voiceover] Round two. – Probably all the cats
and all the EGR valves and stuff like that we
have to have in America. – Probably just the firing
order in which the pistons are going up and down. I’m a VQ type of guy. – [Nolan] Most European
eight cylinder engines use a flat plane crank. Which means the lobes on crank shaft are separated by 180 degrees. This makes the firing
of the cylinders happen in a balanced way. Each cylinder fires from the
opposite one across from it. A very consistent and
uniform firing order. American V8’s on the other
hand use cross plane cranks which have lobes at very
90 degrees from each other. This makes the firing seem
a little more sporadic and unbalanced. It also creates moments when two cylinders on the same side of the block fire at the same time producing a lower, guttural noise which
adds to the ragged sound. (engine revs) Sometimes the intake can
form an exhaust sound just as much as the exhaust
or engine block itself. Cars like the Lexus LFA
have a two intake sound. (engine revs) It has surge tank under the hood that engineers from Yamaha tuned in order to generate the
sound angels would make if they were in cars instead of in heaven. Not only that, they tune
the exhaust as well. How Yamaha went from making
pianos to side by sides to saxophones to building
and tuning Lexus engines I’m not really sure. You all know that (engine revving) of rotary engine, right? Without getting too technical, a rotary engine has three firings per rotation of the Accenture shaft. When the exhaust phase and
the intake phase overlap, some of the exhaust seeps
into the intake chamber and that’s when you hear
that (engine revs) noise. It’s a really distinctive
and kind of polarizing sound. I love it. Our friend Aaron Parker
has a heavily modified RX7 drift car that I think sounds amazing. Check out the bumper to bumper on it here. I love rotaries, I need to get an RX7. One engine that gets
some flack for its sound is the boxer engine. But I just think they’re
being Subie haters. This type of engine has
horizontally opposed pistons and a unique firing pattern. Subarus are famous for
having boxer engines and same with Porsches. But why do people love how Porsches sound and they hate on Subarus? The reason is because Subaru boxer engines have unequal length headers, which means that they exhaust coming out
of cylinders one and three has to travel a different distance than the exhaust coming off
of cylinders two and four. This is effects the sound,
producing a lower base tone and a distinct rumble. I love how boxers sound,
I love how Subarus sound. I think they’re awesome. The older 2.5 liter WRX STI engines have unequal length Heathers. Heathers, Heathers, (bleep). Headers, headers, Heathers. How many takes is this gonna– The older 2.5 liter STI engine
has unequal length headers. But the new two liter WRX
has equal length headers. Which is why it sounds so much smoother. Ever since Porsche
switched from a flat six to a turbo charged flat four, people have started
comparing the engine sound to a Subaru. This is because the new Boxster also has unequal length headers, resonators, and an asymmetrical muffler that add to that ragged sound. Don’t believe me? Listen to this. (engine revs) (engine revs) Of course there are a million other sounds that come from a car’s engine. They’re all music to my ears. I could go on forever. But we’ll save that for another video. Let us know in the comments
which engine you think sounds the best, and while you’re at it, hit that like button so we can
keep making videos for you. (jazzy upbeat music)