Honda V6
As far as we are aware, there’s only one mass produced Japanese engine that employs cylinder deactivation – the Honda J-series V6.
For the 2005 model year, Honda introduced its Variable Cylinder Management (VCM) system to the 3.5 litre Odyssey and 3.0 litre Accord Hybrid. For the 2006 model year, VCM is also likely to appear in the Honda Pilot soft-roader.
Honda’s VCM system deactivates an entire bank of cylinders at light load – the engine switches from 6 to 3 cylinder operation. Road speed, rpm and throttle position are the major factors used determine when the engine switches to 3 cylinder mode.
Deactivation of cylinders is achieved by releasing a synchroniser pin that normally interlocks the cam follower and rocker arms. The synchroniser pin is released using hydraulic pressure which is controlled by a dedicated solenoid. Once the synchroniser pin is released, the cam follower continues to move against the camshaft but the rocker arms and valves remain in a closed position.
It is said that 3 cylinder operation remains smooth (though not quite as smooth as in 6 cylinder mode) and Honda has done a great job calibrating the electronic throttle system for a seamless transition. Actively controlled engine mounts are also employed to reduce the sensation of cylinder switching.
Interestingly, the VCM-equipped Odyssey and Accord Hybrid also feature an Active Noise Control (ANC) system that uses the audio system speakers to cancel undesirable engine boom during 3 cylinder operation. The ANC controller uses 2 microphones inside the cabin and generates an out-of-phase signal to cancel out the sound waves. ANC is not used during 6 cylinder operation.
The J30 3.0 litre VCM engine of the Accord Hybrid generates 179kW (plus 12kW from its electric motor assist) and delivers 23 – 43 percent better fuel consumption than a conventional Accord V6.
The Odyssey’s J35 3.5 litre VCM engine puts out a considerable 190kW and returns fuel consumption around 11 – 12 percent better than the non-VCM version.