How Bentley Gave Audi's 4.0-litre V8 A Classy 'Woofle'

We recently found ourselves on the delectable quilted leather seats of the new Bentley Continental GT V8. One of the first things that struck us (after we’d stopped ogling the gorgeous Alpine Green paintwork) was the noise it made; although it uses the same Audi-Porsche developed 4.0-litre as a huge range of other cars including the Panamera Turbo and the new RS6, it doesn’t sound like any of them.

It’s a more restrained, classy exhaust note which gives off a delicious, old-school ‘woofle’. It sounds more like the company’s soon-to-be-departed 6.75-litre V8 than something like a Cayenne Turbo. But how? We contacted Bentley to get the science behind the woofle.

There isn’t one trick behind the noise, there are a variety of ingredients that go into Bentley’s secret exhaust sauce. The company’s bespoke system sends the V8’s exhaust gasses down two different pipes; one smaller pipe with a focus on refinement, and a larger pipe that “gives a richer, more performance orientated sound”.

The old Continental GT V8 used pneumatically-actuated valves to control the exhaust flow, but now they’re electronically-controlled, allowing for continuous variation rather than them simply being fully opened or fully closed.

It is possible to close off the larger bank entirely for a more discrete sound, but when noise is wanted - for instance if you’re giving it some in Sport mode - the two are mixed to give a more offbeat thrum. In Bentley’s words:

“The valves operate asymmetrically. The left and right systems work independently. This is where the distinctive sounds comes from, by making each bank sound different. When they’re combined, some parts of the audio profile are enhanced and some are cancelled, meaning much more variability and control over character of the exhaust. The burble at idle in sport is due to the asymmetric valve operation.”

Even with some extra pops and crackles, it’s not the rowdiest of cars. We thought that might be down to the use of gasoline particulate filters, but it turns out the Continental doesn’t use them. It’s just a little more demure in the volume department compared to some other V8s we’ve tested recently.

As such, the distinctive burble isn’t the easiest thing to to relay via a video; in the launch control shot above, the sound of the V8 quickly disappears into the wind. In person, though, Bentley’s exhaust fiddling really does work.

Stay tuned for our full verdict on the Continental GT V8.