One of the talking points of the new-generation 2018 Honda Civic Type R is its three-pipe exhaust system, which you may have thought was just a (further) styling exercise for the Japanese hot-hatch. But there’s more to it than that.
The three-tip system has a clever noise-lowering function when the Honda‘s 2.0-litre four-cylinder turbo engine is hoofing it on the highway. But, bear this in mind: it’ll only be useful on an Aussie highway if you’re in a rush to lose your licence.
The middle pipe is a different diameter and sits slightly askew of the outer two pipes. That pipe is essentially a resonator, while the other two are straight-through exhausts. However, the centre one can, at certain speeds, act like an intake – due to negative pressure – and thus lessen the booming noise you might experience inside the car at high speeds.
Honda spokesman Kotaro Yamamoto said the aim of the elaborate triple-tailpipe system was simple.
“We’re trying, basically, to enhance the good sound and eliminate the bad noise,” Yamamoto said.
“Many people think that it’s just a design feature, but it’s not the case. There is a very important function of this triple exhaust system – at low and mid RPM or engine speed basically exhaust gas is emitting from all three tail-pipes, which is creating a distinctive and sporty engine sound,” he said of the resonator pipe when it’s in action.
“But at high RPM, we managed to create or generate a negative pressure on the centre tail-pipe, just by thermodynamics, without using any flaps or valves – just by the layout and the diameter of the pipes, by the location of where they’re attached,” he said of the Civic Type R‘s tail-pipes.
“At a high flow rate of exhaust gas we can turn around the pressure around the centre tailpipe, and that creates a negative pressure which basically leads to air being sucked into the exhaust system by the centre tail-pipe.
“Why did we do this? The exhaust system tends to resonate within the cabin, because they are emitting a certain frequency,” Yamamoto explained, suggesting customers had complained about this in the previous-generation car.
“This resonance causes what we call a booming noise or a droning noise, which is not very convenient when you’re travelling long distances, for example here in Germany on the autobahn for hours,” he said. “By creating a negative pressure in the centre tail-pipe, we can shift the frequency to another band so that it will not resonate within the cabin, and by this measure we can reduce the booming noise.”
It was noticeable – at 120km/h there was still a fair amount of exhaust noise intrusion into the cabin, but at 200km/h on the autobahn the more noticeable noise was wind around the A-pillars and mirrors, with the exhaust seemingly silencing itself, to a small degree.