Calibrating a "controlled misfire"
"'Theater' is a great word," noted Kevan Richardson, Program Manager for Jaguar sports cars. “We want the car to be entertaining. That’s why it has pop-up [HVAC] vents, a lighting cascade on start-up and a pop-up rear spoiler. It is all part of the show."
"All of those little noises are usually the kinds of sounds engineers spend months trying to dial out," he acknowledged. "Because this is an unashamed sports car, we’ve recognized the noise the exhaust makes is part of the experience and something customers want."
Jaguar engineers achieved this by defying convention. "Usually you’d cut the fuel to the cylinders, when the driver lifts off the accelerator," explained Andrew Lowis, the Gasoline Calibration Manager for the car. "We are delaying the point when we do that and igniting later than we might in normal circumstances. It produces a controlled misfire."
Obviously, the car must still meet emissions regulations despite the intentional introduction of pollutants to the exhaust stream. "It is a challenge, but it is one we can achieve by careful calibration," said Lowis. In fact, Jaguar has more stringent internal emissions limits than the government applies, he said, and the car meets those, too.
Regardless of the difficulty, it was necessary work, Lowis insisted. "The powertrain sound quality of this car was absolutely fundamental to the character of the F-Type."
The burble through the pipes is made more audible by the use of muffler bypass valves that open to send the glorious noise directly out the back when the driver selects the appropriate drive mode and stands hard on the gas or lifts off abruptly. The bypass is standard equipment on both the V6 S and V8 S, and is an option for the base V6 car.