[Piwoslaw]

I there was an article on VW's cylinder deactivating TSI in a magazine (Serwis motoryzacyjny, 11/2011) and it had the following BSFC graph, illustrating an example of how cylinder deactivation can help reduce fuel consumption:


The red line '1' graphs constant engine power, in this example 30kW. By going to an rpm and load closer to the BSFC sweetspot the fuel consumption can be lowered by 20%. Deactivating half of the cylinders helps to increase the load, but among the things the article didn't state are:

• Is that BSFC for the engine in 4-, or 2-cylinder mode? Or maybe combined?
• What would be the effect of only shifting gears?
• What would be the effect of only deactivating 2 cylinders?

Anyhow, the article claimed that only deactivating the cylinders reduced fuel consumption by 0.4 l/100km in the NEDC cycle, while with the Start/Stop system 0.6 l/100km. At steady, low speeds and loads the fc can be reduced by 0.7-1.0 l/100km. The cylinders are deactivated when engine speed is between 1400 and 4000 rpm, and torque between 25 and 75 Nm (the max torque is 250 Nm).