Variable Cylinder Management; when the computer detects that speed can be maintained on 3 cylinders instead of 6, and shuts them down

VCM has been around for a long time (most notably in the Cadillac V8-6-4 system in the 80's, which worked badly - you'd be cruising in 4cyl mode, but it would take forever to get all 8 fired up again if you needed it).

In Honda's version, here's what happens:

- fuel cut on the rear fuel rail

- spark is maintained, which minimizes plug temperature loss and prevents fouling induced from incomplete combustion during cylinder re-activation. Sparking in air alone results in higher voltages than in a fuel-air mixture because of the higher insulation resistance. Thus, Honda used iridium-tipped spark plugs are used because of their high resistance to wear at high voltages.


- Intake / exhaust valves sealed on the out of service bank of cylinders (the rear, in this case, because the catalytic converter gets to remain at an optimal temp, and because the front bank gets the best cooling efficiency)

Sealing the valves cuts the inefficiency of pumping intake / exhaust out of idling cylinders (and improves FE in the process)

To improve the ergonomics, Honda also employs a noise-cancellation system through the audio speakers, because normally, an engine running on half it's designed capacity produces an annoying booming noise. The noise still persists, but by introducing a complementary tone at just the right frequency, the noise is 'cancelled', and you don't hear it (it still works if you have the radio off).

Honda also has this system in their upper-end trim on the Odyssey van, with the 3.5L V6. Given that the J30 and the J35 are Honda's V6 workhorses, I'd like to see this adapted to every V6 in every carline (Honda *and* Acura). Or at least make it an option in every carline. Only works well w/ V6 engines, though...Wayne reported that the Honda engineers tested it on I4s and found that it just wouldn't pass muster with consumers (not enough power on demand, fast enough).

Mark

Sometimes we could all use a little less

My hybrid automobiles:

Current:
2006 Honda Civic Hybrid (CVT, w/o Nav)
Magnetic Pearl / Blue - 008661, born 12/28/05
Mods: Neck pillows, Garmin C330 Nav, Draw-tite 1.25" hitch (for bikes, not towing!), Pioneer Inno XM receiver via Aux jack, OEM mud flaps, more to come!

Hypermiler status on 3/12/06 @ 3077mi.

Previous:
2005 Honda Accord Hybrid (5AT/Navi)
Desert Mist / Ivory - 001254
Retired 1/21/06 - LMPG 34.1

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