Summary:
An exhaust note contributes significantly to a car’s personality, with its characteristics largely determined by the engine type. Toyota explains that the engines cylinder count and configuration are crucial in shaping the exhaust sound.
The number of cylinders impacts the frequency and consistency of the sound. a four-stroke engine produces sound every two crankshaft revolutions, so engines with more cylinders generate sound more frequently, resulting in a smoother and fuller tone.
Cylinder configuration also affects the exhaust note. Inline-6 and V-12 engines are well-balanced because their cylinders work in pairs, which cancels out vibrations and enhances sound quality. The balanced design of these engines allows for better exhaust system design, maximizing the auditory effect without interference from exhaust gases.
V-8 engines, another common configuration, vary in sound depending on their crankshaft design. Cross-plane crank V-8s, typical in muscle and NASCAR cars, create a distinctive rumble due to uneven firing impulses that cause choppy exhaust flow. Conversely, flat-plane crank V-8s, like those in the C8 Chevrolet Corvette ZR1 and Z06, produce a smoother, higher-pitched sound due to their more even exhaust gas flow.
Turbocharged engines introduce additional sound elements, such as hissing and whistling, caused by the air moving through the turbochargers. Mufflers, which road cars require, play a role in modulating these sounds. They use chambers to slow and absorb exhaust gases, which can also be designed to enhance the sound quality.
Toyota is exploring ways to preserve the appealing exhaust notes of combustion engines. This is despite stricter emissions regulations pushing the industry towards electric vehicles (EVs). To achieve carbon neutrality, Toyota is collaborating with Subaru and Mazda to improve fuel efficiency. As well as develop carbon-neutral alternatives like synthetic fuels and hydrogen, aiming to continue delivering enjoyable engine sounds while meeting environmental goals.
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