Sound. One of the most important players in communication. It can trigger fight or flight responses, stir curiosity and provide us with information about the surrounding world. Loud rumbles, cracklings or screams may hint at danger – causing fear and excitement to rush over us. This is exactly what you experience when you turn over the engine on a 911. The 911 has had a distinctive sound since its public release in 1964. Porsche engineers have worked hard to maintain that distinctive growl of the engine all the way up to the current 991.2 generations. But what makes that sound so distinctive? Could one just buy a six-cylinder car of any make and get the same effect?
Before we get too deep into the distinctive flat-six sound, it is important to understand what sound actually is. Sound originates as vibrations that cause air-pressure disturbances that hit our ear drum. With cars, it is the combustion of each cylinder that causes these vibrations. So why is it that a flat-six cylinder 911 has such a distinctive sound in comparison to any other 6-cylinder cars out there?
A Porsche engine is a symphony of sounds which come together in a unique manner. To start, there is the firing sequence of the cylinders which create a distinctive gurgling rumble. Most sports cars have double the firing frequency which produce the aggressive tones of a sports car, or in this case a Porsche engine. The valves, belts and other componentry are introduced as the orchestra comes together. The most crucial aspect however is the exhaust system through which all of these vibrations are filtered and magnified. Different exhaust materials will change the sound of a car; the direction of the tubing, the diameter, for example, all play critical roles in how the car will sound. Modern Porsche models have a sport button which you will notice makes the car distinctively louder, as well as maximizing the performance of the car. The additional sound comes from butterfly valves located at the tip of the exhaust which have the ability to alter sound as they open and close. Closing the valves will limit the cars sound for a more civil commute while opening them unleashes the full potential of the exhaust system. If you want to hear more of the engine, you can opt for the Sport exhaust. This uses a more “open” exhaust layout and allows a larger amount of vibrations to escape the engine, giving it a greater sound.
The sound of a car is very similar to that of a music. You can never pinpoint why ACDC sounds the way they do, but rather it is a combination of unique tones that create the finished product.
While idling a Porsche, the flat six sounds annoyed, agitated almost - growling at you to unleash it as it rumbles at a low RPM. A mechanical scream kicks in at higher RPMs and at around 3500-4000 RPM you will notice a distinctive change in tones. Get closer to the red line and the engine sound is incredible, screaming at the top of its lungs. Lift off the gas and the crackling exhaust is distinctively heard as the engine takes a break. The crackling is caused when you have a hotter high velocity exhaust suddenly followed by a cooler low velocity gas. The pressure difference between the two crackle while they equalize. Experience the thrill in person and stop by Downtown Porsche to hear it for yourself.
Date Posted: August 10, 2017