Toyota releases three-hour ASMR-style video; Subaru boxer engine sounds with STI aftermarket exhaust

Having committed to a renewed effort towards developing next-generation internal combustion engines, together with Subaru and Mazda as part of its multi-pathway commitment to carbon neutrality, Toyota has turned the spotlight – or rather, cameras and microphones – to the boxer engine that is commonly associated with Subaru.

Toyota Times has published a three-hour video clip dedicated to the sights and sounds of a horizontally-opposed four-cylinder engine that is the Subaru CB18 unit in the Levorg Layback STI that stars in this video. The CB18 1.8 litre, direct-injection turbocharged petrol engine made its debut in 2020 with the second-generation Levorg, and produces 177 PS from 5,200 rpm to 5,600 rpm and 300 Nm from 1,600 rpm to 3,600 rpm.

Upon listening to the audio in the video clip, this features the classic Subaru boxer-four cylinder throbbing sound signature, which had been a characteristic of Subaru engines from the manufacturer’s early models.

“From the original Leone to the Legacy, Impreza, and Forester, we always used the unequal-length layout, but for the fourth-generation Legacy and the second-generation Impreza, we changed to a uniform length to create a more powerful engine with better response. In doing so, we lost the distinctive sound,” said Jun Hirano, Subaru project general manager at the carmaker’s vehicle environmental development department.

The switch to equal-length exhaust manifolds was brought about also by tightening emissions regulations, though with advances made for the CB18 engine, Subaru returned to the unequal-length exhaust manifold layout, enabled by a quicker-responding turbocharger and improved exhaust gas performance.

In horizontally-opposed cylinder engines such as those used by Subaru, separate cylinder banks see that exhaust gases are expelled through separate rows, albeit in roughly equal distances from both sides.

“The turbocharger is positioned where the two sides come together, but instead of placing it dead-centre at 250 mm, we gave the left and right pipes different lengths, one a little over 100 mm and the other at 350 mm or 400 mm. As a result, the turbo spins faster. In addition, the catalyst that cleans exhaust gases can also be placed close to the engine, which is why we chose this as the optimum layout,” said Hirano.

Though the second-generation Levorg saw the return of the classic, boxer engine sound, noise regulations dictated that the changes to bring back the throbbing sound were barely audible to the average customer.

“Personally, I wanted to keep the boxer sound, and ultimately we were able to do so in mass production,” said Hirano, and thus a Sports Muffler offered by Subaru as an aftermarket component is key to more of the sound, as fitted to the car in the ASMR video.

Below is the video with audio for the Subaru Levorg Layback with its standard exhaust:

Next, a video with audio for the Levorg Layback with the STI aftermarket exhaust:

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