Honda's New Spiral Exhaust Design Will Improve Efficiency

Technology / Comments

Honda is taking efficiency to extremes with a new tailpipe design.

In the never-ending pursuit of efficiency, Honda is proposing spiral exhaust pipes that look like curly pigtails on future cars. Weird as it may sound, there is at least some merit to a patent CarBuzz discovered filed with the United States Patent and Trademark Office (USPTO).

Published on March 30, 2023, Honda proposes a section of the tailpipe aft of the muffler that spirals vertically upwards before exiting out the rear bumper. The muffler itself is positioned wide of its traditional central position under the body, which in the patent sketches looks fairly odd. But the reasoning is sound - it's all about saving weight in anything from a Honda Civic to the Ridgeline pickup truck.


Long exhausts are not uncommon. The exhaust is an important part of a car's powertrain, and its diameter, length, and even shape can all impact how much power a car makes and how efficient it is. Very often, a longer pipe - provided it's the right diameter to maximize flow, for instance - can improve gas mileage. Traditionally, the final length of tailpipe aft of the muffler is relatively long, with the muffler located centrally.

But Honda's new design proposes the muffler being located far to the outboard extremities of a car's undercarriage. That's because Honda wants to ditch splash shields on the exhaust and instead let the muffler double up as both an integral element of the exhaust system and a shield for the tailpipe to prevent water being sprayed up from the rear wheels, which could result in the hot exhaust pipe cracking as it comes into contact with cold water.


Traditionally, an automaker would simply install a splash guard over the section of exhaust at risk. But Honda alleges that such a shield is too heavy and that "in order to suppress natural disasters," the cost and weight of such a shield should be done away with.

It's a little melodramatic on Honda's part, but lightness has long been one of the easiest ways to improve efficiency. Some lightweight automakers, like Donkervoort, even go so far as to say building lightweight gasoline cars is more efficient than building heavy EVs.

Honda is, of course, investing in the latter, too, and is planning two new EVs with an imminent reveal. But perhaps, if it can string together enough incremental weight savings and efficiency gains through innovative aerodynamic developments, it may help combustion cars live a little longer.


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