Auto Tech: Honda’s Hayato Mori about Revs and Redlines

JP: Honda has, and has had, a number of high-revving engines loved around the world. I’m thinking of the Acura NSX, Honda S2000, Honda Civic Si and others, some of which rev to 9,000 RPM or more. What are the benefits? What does a high-revving engine add to the driving experience?

HM: Honda is an engineering company, and our specialty is engines. We’ve learned a lot about engine tolerance through our many racing programs including F1, Indy and Moto GP, and as a result, have the ability to create small displacement engines with good fuel efficiency, which can be spun high to wring out every horsepower we can get.

The initial Honda S2000 models with the 2.0L normally aspirated engine was able to wring out 240 hp. That’s 120 hp per litre! And without sacrificing fuel economy like some large V6 or V8s. The result was a driving feel like an F1 car, in terms of driving feel and linear acceleration with no turbo lag, even for a novice driver. “Fun to Drive” is one of Honda’s traits and many of our vehicles give you this kind of thrill through their efficient engines.

JP: Do you have a preference? Do you prefer an engine with a high redline, or more low-end torque? Does one always mean compromising the other?

HM: It’s a matter of taste. Do you like the sound of a F1 race or NASCAR? If you are looking for pure acceleration from a stop, large displacement with lots of torque for more power at low RPM would be the way to go. This will eat up fuel, however. If you are looking for something that’s efficient in normal driving but when asked, can involve the driver more by wringing the engine to high RPM and using manual transmission to maximize the RPM to get all the power from each gear, a high revving small displacement engine is ideal. I personally drive a Civic Si and there is nothing like the sound of the engine nearing the rev limiter at each shift point.

JP: How does Honda’s much-loved VTEC system play into the equation?

HM: By varying the lift and duration of engine intake valves, you can help the engine to maximize taking on air at any RPM. This is especially helpful in the high-RPM range, where the engine demands more air than the valve opening can allow in a non variable lift engine.