Ward’s 10 Best Engines competition has recognized outstanding powertrains for 20 years. This installment of the 2014 Behind the 10 Best Engines series looks at the development of Honda’s 3.5L SOHC V-6.

Previous versions of Honda’s SOHC all-aluminum 60-degree V-6 were Ward’s 10 Best Engines winners in 2005, 2008 and 2009, and this new one already is a two-time awardee for 2013 and 2014. Tested by WardsAuto editors in a ’14 Accord sedan equipped with a 6-speed automatic, it pumps out 278 horsepower and 252 lb.-ft. (342 Nm) of torque while delivering segment-leading EPA-rated fuel economy of 21/34 mpg (11.2-6.9 L/100 km) city/highway.

The Ward's 10 Best Engines jury collectively averaged more than 28 mpg (8.4 L/100 km) over 837 miles (1,347 km) of driving, well better than the 25-mpg (9.4 L/100 km) combined EPA rating. "Turbocharged 4-cyl. engines, fast becoming the standard in this segment, struggle to post numbers like that," one WardsAuto juror wrote, “as did some naturally aspirated I-4s in this year's competition.”

The most significant difference between this V-6 and previous versions is the first-ever marriage of Honda’s intelligent variable-valve timing and lift electronic control (i-VTEC) to variable cylinder management (VCM), which is Honda's clever cylinder-deactivation system. General Motors and Chrysler deactivate intake pushrods to shut down cylinders in their cam-in-block engines during light-load conditions, but Honda was first to use its (patented) zero-lift cam lobe technique to accomplish that in an overhead-cam layout.

Honda's i-VTEC hydraulically shifts the camshafts back and forth between two intake valve lobes. The first one optimizes valve timing and lift for low-rpm torque; the second is a high-lift, longer-duration profile for increased power above 5,150 rpm. Then this engine's VCM adds a third lobe with a zero-lift profile to the rear-bank cylinders only, which deactivates those three cylinders by keeping their intake valves closed.

While Honda's previous-generation VCM shut down two and sometimes three cylinders to save fuel, depending on driving conditions, this new system transitions between 6- and 3-cyl. modes only. And that simplification enables the addition of i-VTEC.

“We can only have three lobes and three oil circuits to control that,” Honda R&D Engine Design Group Manager Mike Dunn explained in a 2013 interview. “So taking away the 4-cyl. mode allowed us to add the high valve timing.”