Honda Accord buyers may think they’ve outgrown cars like the Civic Type R, but for 2018, the Accord sedan shares more engine parts with that millennial-baiting hot hatch than with anything else in the Honda lineup.
Lift the hood of the 2017 Civic Type R and the 2018 Accord 2.0T, and you find nearly identical turbocharged 2.0-liter inline-fours, both part of the new Earth Dreams family. Granted, they may not look the same: One has an engine cover in snazzy red and carbon fiber, with HONDA proudly embossed in contrasting silver letters; the other is generic black plastic. But beyond their displacement, nearly everything that makes up a modern engine is shared: the exhaust manifold built into the cylinder head, the air-to-air intercooler, the sodium-filled exhaust valves, variable exhaust-valve lift and timing (VTEC), intake and exhaust camshaft phasing, a two-piece water jacket, the turbo’s electric wastegate, and pistons with internal cooling channels. The 9.8:1 compression ratio is equal on both cars (the Accord’s engine runs less boost, thereby avoiding devastating knock when burning regular gas).
How, then, can the same engine feel snappy and high-strung in the world’s fastest front-wheel-drive production car around the Nürburgring, yet refined and smooth in a mid-size family sedan?
Chief powertrain engineer Terunobu Kunikane told us that a major differentiating part is the Accord’s smaller-diameter turbocharger. While this lowers the relative peak pressure, the Accord’s turbo spools quicker because there’s less inertia. The charged air also hits the turbine vanes at a sharper angle, which increases the amount of force on the vanes, helps provide quicker throttle response, and increases torque at lower revs.
Indeed, low-inertia turbos work magic. The Accord 2.0T maxes out its 273 lb-ft at only 1500 rpm, at which point the Type R is generating about 115 lb-ft. At 2500 rpm, the Type R reaches its 295 lb-ft peak following a dramatic surge (thank you, turbocharger) between 1000 rpm and 2500 rpm. But whereas the Accord’s torque fades after 4000 rpm, the Type R’s four-cylinder hangs in until 4500 rpm and then floods the driver with horsepower. At just above 4000 rpm, both engines churn out more than 200 horsepower (208 in the Accord and 225 in the Type R), and both reach peak power output at 6500 rpm. The Accord’s peak of 252 horsepower, however, is no match for the Type R’s 306. And for extra fun, the Type R’s 7000-rpm redline is a few hundred higher.
Turbos aren’t the whole story. The Type R has higher-flow fuel injectors that Kunikane said are designed primarily for a “heavy spray,” whereas the Accord injectors have a wider range of flow rates. With less oxygen in the cylinders due to the lower boost pressure, the Accord’s engine sips less fuel, hence the Accord’s estimated highway rating of 30-plus mpg (with the manual transmission) versus the Type R’s 28 mpg. Aggressive software tuning and required high-octane fuel are the Type R’s finishing touches. Honda also added a balance shaft to the Accord’s engine to quell second-order vibrations. Presumably the Type R driver likes the extra vibrations.
Naturally, these similarities and minor changes had us wondering. Could, or rather, should there be an Accord Type R? Kunikane smiled and offered no further explanation. We hope that’s an engineering feat he’ll tell another day.
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