Cylinder deactivation

[Ryeman]

VW already have a 1.4 with it but Bosch are intending more small/medium fours will have it for ~ 4-5% economy improvement.

To me just more complexity for a 'placarded' but not real life gain when lifetime reliability is taken into account.

Another straw on the back of the reciprocating engine for me.

[Yeti_Man]

Like any technology, only time will tell if it's reliable but there are certainly real world economy gains with going COD/ACT imo. The Leon 150ps ACT gave me the best petrol economy I've had in a c segment petrol car recently (compared to the older 140ps non ACT version). It's also been around since early 2005 in other markets - iirc Chevy first used it and it's a excepted in the US as a reliable technology. And if they think it's profen, it's probably good enough for me, unless of course, VW kill it's reliability with a bad/penny pinching design.

[Huskoda]

Its not that complicated a piece of kit. Its basically just a pair of sliding cams, which is not new and has been used for a very long time to adjust valve timing except they're shaped to never let the valves open when the engine doesn't need those cylinders. Given that petrol engines are particularly inefficient when idling (compared to diesels) its something I'd like to have.

[Ryeman]

They claim 4-5% but from my perspective it's just more problematic complexity for particularly out of warranty owners.

It would require v high kms to cover the potential outlay in the event of an actuator/sensor/? issue.

To me it just adds to the cheaper cars but more expensive motoring equation.

[weasley]

I am a big fan of the COD/ACT that VW have implemented. It is relatively simple and gives real world benefits, since it activates under significant portions of normal driving (unlike stop-start systems, which benefit only if you stop).

Plenty of stuff we take for granted now was once new-fangled.

[Ryeman]

Hopefully I'll live long enough to one day have a next gen battery powered car.

When you consider every convenience/comfort item in a conventional car is electrically driven whereas a reciprocating engine burns fuel to drive an alternator to provide the electricity.

Batteries do all that in a simple plug-in way plus max torque from zero revs and b all servicing costs.

[leaky5]

Like any technology, only time will tell if it's reliable but there are certainly real world economy gains with going COD/ACT imo. The Leon 150ps ACT gave me the best petrol economy I've had in a c segment petrol car recently (compared to the older 140ps non ACT version). It's also been around since early 2005 in other markets - iirc Chevy first used it and it's a excepted in the US as a reliable technology. And if they think it's profen, it's probably good enough for me, unless of course, VW kill it's reliability with a bad/penny pinching design.

I first heard about this nearly 30 years ago, one of my friends dads worked at the Ford techincal centre near us and had a test Mk2 Granada with this fiited. It was on a 2.8 V6 engine

[weasley]

The difference with VW's system is that it is two cylinders being deactivated in the same 'block' as the remaining active ones. It is relatively easy to switch off one bank of a Vee engine.

[Urrell]

This explains it pretty well

 

https://www.youtube.com/watch?v=qzYK5WeFvr8