Variable Cylinder Management (VCM)
Variable Cylinder Management (VCM) is Honda's term for a variable displacement technology. It uses the i-VTEC system to disable one bank of cylinders during specific driving conditions (for example, highway driving) to save fuel. The 2008 Accord takes this a step further allowing the engine to go from 6 cylinders, down to 4, and further down to 3 as the computer sees fit. Honda's VCM uses overhead cams as opposed to DaimlerChrysler's Multi-Displacement System and General Motors' Active Fuel Management pushrod systems.It uses a solenoid to unlock the cam followers on one bank from their respective rockers, so the cam follower floats freely while the valve springs keep the valves closed. The engine's drive by wire throttle allows the engine management computer to smooth out the engine's power delivery, making the system imperceptible. Vehicles equipped with VCM are equipped with an "ECO" indicator on the dashboard which corresponds to the VCM system's operation. Vehicles equipped with VCM also include Active Noise Cancellation (ANC) and Honda's Active Control Engine Mount (ACM) system. The ANC and ACM systems work in cooperation to cancel both noise and vibration that could occur in relation to the cylinder deactivation process. The ANC system uses the audio speakers to cancel out noise by using an opposite phase sound.
Vehicles equipped with VCM
Hot off the presses, Honda are making moves to increase their stake in the V6 Family car market. The updated Honda Accord is to be unveiled to the Australian market at the Melbourne motor show.
Lets be honest, the styling is same old same old. This is the four door family car market, so no-one is expecting a revolution. The Accord is tidy and neat, a car that looks appropriate for any situation and that’s exactly what its supposed to do.
So where’s the kicker? What is going to make this car something special?
Its all in the engine. A 3.5 litre V6 is going to be fitted, but its party piece is its VCM, or Variable Cylinder Management. Similar to systems fitted to the Chrysler 300c, Honda’s VCM works by sealing off cylinders when the car doesn’t need its full power. In other words, most of the time. The power is there when you want it, but you don’t have to keep paying when not using it.
Holden and Ford take note, if you want to claw back market share from the smaller more economical rivals, here’s your answer right here. GM already have a successful version of this technology but so far have only fitted it to some of their American pickup range.
Honda have made a brilliant maneuver by being the first to introduce this technology to the Australian market. This is the kind of fuel saving technology that will work here, I look forward to getting behind the wheel of the car.
It looks like its going to have the right stuff. Well done Honda.
This paragraph is going to be a little technical, so if its not your scene just mosey along to the next one. The engine will switch between 3,4 or 6 cylinders, depending on the power needed. This can result in the economy of a four cylinder engine. The pistons still need to be moved through the cylinders even if they aren’t actively firing, but by sealing the valves an air spring is created in the cylinder which assists. The real economy comes from the remaining pistons however. When running at part throttle, large capacity engines drop pressure within all cylinders, this results in poor performance and reduced fuel efficiency. By completely sealing off some of the pistons, those remaining have greater internal pressure and better fuel efficiency.
Honestly in hind sight I cannot believe it has taken so long for engines like this to hit the Australian market. We have a lot of highway driving and systems like this will result in better fuel efficiency than that of a hybrid. Hybrid cars are very good for stop/start inner city driving due to their electric motor being able to stop completely when the car is stationary and recover energy when the car is slowing down. However, when cruising at highway speeds the efficiency of hybrids drops dramatically. The drain on the electric motor is constant, requiring the petrol engine to constantly keep topping it up. With the added weight of having to carry both an electric and petrol motor as well as battery packs, a lighter car with just a petrol engine is capable of much better fuel consumption. In the case of the Honda, the car has your regulation V6 engine, there’s no electric motors or battery pack weighing it down, they simply use the V6 smarter.In Australia the majority of the population don’t have to deal with traffic jams and stop/start inner city driving. They live in suburban area’s and instead commute along highways. The fact of the matter is, technology like VCM is far more fuel efficient and environmentally friendly than hybrids, while still letting you have the power of a V6 engine when you want it.
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