How are regular car engines so quiet?

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Racing cars like Nascar and Formula 1 have loud engines but how are normal road car engines quite quiet?

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3 Answers

Anonymous 0 Comments

A lot of requirements is focused into acoustic insulation.

For any type of race cars, acoustic insulation is not of importance. Even moreso, sound may be a requirement for audience and advertisement.

Anonymous 0 Comments

Regular cars have mufflers and are designed to be used in neighborhoods and around people.

Race cars are made to be as fast as possible. That’s it. So noise levels arnt a consideration. Mufflers are adding weight and I don’t think that’s a good idea for a race car. I’m not really a car expert but I’m pretty sure a muffler can restrict the airflow and hurt engine performance.

Anonymous 0 Comments

Mostly intake and exhaust systems, along with mild cam shafts (for low end torque, a limited rpm range, and a flat power curve), along with engine covers designed together to reduce noise. The muffler and intake were the first way to reduce engine noise. The next is a well designed engine bay and lots of insulation, including engine covers and sound reduction mats.

The two most popular mods are a hot air intake (aka “cold” air intake) and a big muffler. These mods do little to produce overall power, but they do make a lot of noise and turn that nice flat power curve into one with valleys and peaks. This fools the butt dyno into thinking you’re making power two ways; by reducing low end torque and with the added noise. You will likely make your car slower with these mods, but it will feel faster cause once you get over your low end losses, you’ll feel the power picking back up. Think of the Honda Civic DX in the middle of the night droning with a loud exhaust that sounds terrible.

Less popular mods include turbos, superchargers, cam shafts, internal engine work, transmission flywheel or torque converter, and final drive ratios that are street legal versions of actual race cars use. These will make your car faster and make up for the low end torque by allowing you to launch at a higher rpm and get into the vehicles power band quickly. Adding a high flow air filter isn’t necessary until your tripling the original power of the OEM engine. A free flow exhaust is preferred with a turbo, but isn’t necessary in most cases. These mods will make your car sound like a race car, but not as loud. Think of it as cars that sounds like a race car or motorcycle screaming down the street, but not as loud (usually).

A full on race car has a very open intake and exhaust system. Most racing classes require a muffler of some kind. They run very aggressive cam shafts, large turbos or superchargers, and are designed to run at very high rpm’s, often double or triple the rpm of most street cars. They’re designed to last anywhere between a quarter mile to an entire season and are inspected or rebuilt frequently. These make the most noise. Place twenty of them on the same track and it sounds like music.