IAA 2011: Audi's New V8
Audi from the Frankfurt Motor Show

Audi has developed a new engine that can be a V8 for high-performance driving and a V4 when cruising, to help reduce fuel consumption and emissions.

It will replace the V10 used in the previous Audi S6 and S8 when new versions ofboth cars arrive in the UK early next year, and also go into the new S7 Sportback.

Cylinder cut-off - Audi prefers to call it ‘cylinders on demand' - is not a new idea. It was last seen on the Mercedes S-Class about 15 years ago, and is again being developed by Mercedes for its new 5.5-litre V8 engine , but Audi believes this application is new.

It includes active hydraulic engine mounts to reduce vibration and active noise cancellation. There are also variable camshaft profiles, based on a system in use in other Audis, to isolate four of the cylinders when the car is running under light loads.

The engine takes its readings from the amount of effort the engine is being asked to do, and can therefore run as a four-cylinder unit over a wide area of the rev band. ‘It will be able to run as a four-cylinder at 130 to 140 kilometres an hour (80-90mph) on a flat road with the air conditioning working,' says Axel Eiser, the head of Audi powertrain development. The fuel savings with the new V8 can be close to 20%, says Eiser, and it is much less costly that developing a hybrid powertrain. It will also be a big contribiutor to the weight-saving programme Audi is undrtaking with all future models.

There is no reason why the idea could not be carried over to engines with fewer cylinders, and Volkswagen is developing the idea for four-cylinder units, but the savings would not be as great, he says. ‘It depends on the size and weight of the car and its aerodynamics.'

Technically, it would also work for diesels, although the exhaust gases would then need more after-treatment to meet emissions targets, so the advantage would be reduced.

The new V8 develops 415bhp for the S6 saloon and Avant and the A7 Sportback and 514bhp for the S8, but its arrival does not signal the end of 10- and even 12-cylinder engines at Audi. ‘We will still have them in future,' said Eiser.

Source [Headline News]

 

You can barely differentiate them if both of them would be finished in silver.

 

Didn't GM use cylinder on demand a few years ago? I think I remember some of their suv's using it. No?

I likey the S7.

edit: Found it. GM's version is called "displacement on demand" and they use it on their larger truck engines, like the 5.3 liter.

 

Wow, I really really like both a lot.

 

the wheels on the S8 are hot

 

Yes, displacement on demand cut your 8 down to a 4 saving gas. I have never owned one, but I think it is pretty cool for those who drive their heavy duty truck long distances. I'm not sure how I feel about it in a performance car though.

 

S6 or S7 for me. S8 isn't aggressive enough.

 

Is that red car in the first pic the S7??? She looks greattt in red!!! Does anyone have more pics of it?

 

yup - I've got this in my 06 Envoy Denali 5.3L. You never feel it change over or anything.. it's pretty decent technology.

 

Cadillac had it way back in 1981 and it was called V8-6-4.