Variable Cylinder Management for New Honda Engine

Variable Cylinder Management for New Honda Engine

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The concept of running on less than all the combustion chambers available in an engine to save fuel is not new. Back in the early 1980s, Volvo had a prototype 760 with an engine which could cut the sparks to some cylinders and GM also introduced some Cadillac models with engines that ran on less cylinders sometimes. However, the technology was still in its infancy and motorists experienced problems and roughness with such engines.

During the 1990s, technological advances in engine design enabled the concept to be more refined and it is slowly being offered with some engines. The latest company to offer this ‘cylinder cut’ idea is Honda with a V6 i-VTEC engine.

Through new ‘Variable Cylinder Management’ technology, the V6 3.0-litre i-VTEC engine runs on all six cylinders during acceleration and when high output is required, but employs only three cylinders during cruising and at low engine loads. The ‘Variable Cylinder Management’ system analyzes throttle opening, vehicle speed, engine speed, and gearing to determine that the car is cruising, and then idles the intake and exhaust valves of the three cylinders in the rear cylinder bank. With zero valve lift, the cylinders are sealed, and no fuel is injected. Pumping losses are thus reduced by as much as 65% and low fuel consumption is realized.

When operating in 3-cylinder mode, engine vibration is reduced by extrapolating vibration from the change in crankshaft rotation speed and sending the information to the ‘active control’ engine mount, which compresses / extends an actuator in same-phase, same-period motion to dampen the engine mount. Similarly, a speaker creates an opposite phase sound or ‘active noise control’, to provide a cancelling effect, for a quieter interior which leaves the driver unaware of changes in cylinder activation.

The new engine thus combines the powerful performance of a 3.0-litre engine, while offering superior fuel economy claimed to be 11.6 kms/litre (Japan 10-15 test cycle) – comparable to that of a 2.4-litre 4-cylinder engine.

In addition to its low fuel consumption, this new V6 i-VTEC engine also significantly reduces exhaust emissions to a level where it meets Japanese Ultra-Low Emissions and 2010 fuel consumption standards, making it eligible for preferential ‘Green Tax’ treatment.

The new engine achieves its superior cleanliness by combining high-density catalytic converters located directly below each cylinder head for further improved exhaust gas processing at low engine temperatures with exceptionally fine air/fuel ratio control.

The adoption of a variable intake system, oversized intake valves, and low back-pressure catalytic converters further improve engine respiration efficiency, helping deliver maximum output of 184 kW (250 ps) and maximum torque of 296 Nm.

The first Honda model to get this innovative new engine is the latest generation of the Honda Inspire sedan which started off in 1989 as a more luxurious variant of the Accord. It is sold only in Japan.

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