The Ford Mustang: Engineering Sound

May 29th, 2018 by

Mustang Performance Pack I

Most people assume that a given car’s exhaust note is just an accidental product of the engine. The parts of an engine are designed with certain criteria in mind. These include durability, efficiency, heat resistance and so on, but they don’t include sound. So the engine produces a sound roughly commensurate with its size and the exhaust tries to limit it, right?

An Inexhaustive Guide to Exhaust

Your exhaust system performs two functions. The first is to release exhaust fumes, the wasted byproduct of combustion. Passengers don’t want to breathe in toxic fumes, so the exhaust directs it out the back of the vehicle. The exhaust system’s second function is to control noise. In most vehicles on our roads, controlling noise means reducing it. Your Toyota Camry was not designed to let out a terrifying exhaust growl. But, in performance vehicles, the objective is a little different.

You see, Mustang engineers take the exhaust’s noise-control responsibility seriously. These are connoisseurs of sound who connect exhaust notes to autonomic responses embedded in our DNA. These responses keep us alert when we exposed to dangerous stimuli like the growl of an animal or the sound of thunder. Hani Ayesh, a Ford exhaust engineer, claims an engine growl provokes a similar response: “We’re probably the few engineers here who do not have to design to a number or a specification. Instead, we work to identify that signature sound DNA that connects drivers to the emotional expectation they have for a specific car.”

2018 Ford Mustang

In the new Mustang, all of these factors are taken into consideration when designing the exhaust system. And that shouldn’t be too surprising. If you’ve ever listened to a GT peel out from a red light, you’ll know just how aggressive it can sound. That’s partly because the system is more efficiently expunging exhaust fumes from the engines (which benefits performance). But it’s also because Ford engineers, like sound engineers, are carefully tuning the exhaust note to evoke an emotional response.

Active Valve Performance Exhaust

The Mustang uses a feature called Active Valve Performance Exhaust. It allows drivers to alter the exhaust sound by simply pressing a button on the center console. Track and Sport mode will give you the high performance whine, growl, and rumble. Quiet mode, meanwhile, helps when trying to be a good neighbour or skirting past a police cruiser. Ayesh explains the exhaust modes with an analogy to the guitar, “Strum a chord on an acoustic guitar, and you get a clean, simple sound wave – that’s your quiet Brahms’ Lullaby kind of mood. Plug that guitar into an amp and crank it up to 11, and that’s your aggressive, crackling sound that really rocks your soul. We call that track mode.”

When you think about the detailed engineering that goes into performance vehicles, you probably think about the engine, chassis, and aerodynamics. In reality, a great car is a system of deeply entwined components. In the Mustang, that means the 10-speed, SelectShift transmission; MagneRide Damping System, and even the exhaust system play an important role in delivering a great driving experience.