McLaren's Top-Exit Exhaust Has Real Performance Benefits

It's lighter, creates less back-pressure, and doesn't disturb aero. Every mid-engine car should have top-mounted exhaust exits.

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Beadyeye

If you haven't already heard, the McLaren 600LT uses a top-mounted exhaust. In addition to looking cool and sounding great, there are some actual performance benefits to having the exhaust exit at the top rather than the bumper. Jason Fenske of breaks down those benefits in his latest video.

In the 570S, the 600LT's more pedestrian sibling, the exhaust exits at either end of the bumper. Because the car is mid-engined, the exhaust has to travel from the engine, over the transaxle, then back down to the bumper to exit. That's a lot of piping. A top-mount exhaust fixes that by simply exiting over the transaxle without having to travel back down to the bumper. Here's a gif showing the difference in how the exhaust air travels:

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Engineering ExplainedYouTube

This means less piping, which means less weight, less back-pressure, and better cooling. And because there's no exhaust exits at the bumper to disturb air flow, McLaren can incorporate a bigger diffuser to produce more downforce.

Some of you might be thinking: Does the top exit exhaust disturb airflow to that big rear wing? Fenske had the same concern, and asked a McLaren engineer, who explained that most of the wing's downforce actually come from either side of the wing, not the center portion where the exhaust is. The car's body work sends clean, undisturbed air to the wing's sides, while the cabin structure sends dirty air to the wing's center, which isn't as effective. That's why you see cars like the Ferrari FXX K with two winglets on either end rather that one massive piece.

Check out Fenske's full video below if you want to learn everything there is to know about top-exit exhausts.

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