Honda has announced a new line of engines for the Civic for the upcoming model year. Based upon their successful K-series of engines, the new Civic engine will expand in displacement from 1.7 liters to 1.8 liters, gain an increase in horsepower and fuel efficiency, all while reducing engine parts by about 10%. Wow! What a break through in engine design. How did they do that? Maybe Honda did it by rediscovering an engine design from nearly 20 years ago.
We do not have any hard details at this time; Honda prefers to withhold the specific information until the new engines go on the market. But I have a pretty good idea how Honda increased engine efficiency while decreasing the number of parts required to put the engine together. And I expect that the Honda marketing folks are going to be challenged to make the public understand how less is more.
The current Honda K-series engines are a double overhead cam (DOHC) design with electronically controlled variable valve timing. An excellent design and one that appeals to consumers who desire the prestigious DOHC design; but there is room for improvement. The two cams per cylinder bank and the four valves per cylinder of the DOHC design allows great flow through the combustion chamber, particularly at high rpms. But the parasitic loss of having to spin two cams and open four valves costs the engine some efficiency, particularly at lower rpms where the typical street car operates.
Back in the early 1980's, Honda offered a D-Series Overhead Cam (SOHC) engine that had three valves per cylinder which was considered unusual for its time. The two intake valves gave great breathing characteristics and the single large exhaust valve created just enough backpressure to build great low end torque for stop and go driving. Engineers loved the engine, but the public greeted it with a yawn. It did not have the "sexy" DOHC design and was not easy for consumers to grasp its unusual design.
Honda eventually dropped the three valves per cylinder, SOHC engine design as the public voiced a desire for DOHC engines. Honda happily supplied the public with what they wanted and has sold hundred of thousands of DOHC engines around the world.
Recently Ford has introduced a successful series of SOHC, three valve engines that power the new Mustang amongst many other cars and trucks. The inherent efficiency of this design is too great to be ignored and I expect that more manufacturers will seriously consider bringing similar design to market.
And with this in mind, I expect that the new Honda Civic engine will also feature the SOHC, three valves per cylinder design. And those of us who always like the quirky design of the old Honda engine will be vindicated after all these years.