Much better

[t_urbo]

There is no risk of damage, its only an exhaust. What is really surprising about the RS4, is that with them disconnected (i.e. valves remain fully open at all times) the car drives much more smoothly and progressively, gives better MPG and doesn't sound much louder (certainly from within the cabin). It just sounds more characterful and fun.

That's what's really daft about it, with valves disconnected it feels a much better all-round car - with no downsides whatsoever.

p.s. EVO's long termer used a standard exhaust, and now my car behaves 'exactly' as it did. I'm really glad I chanced upon this discovery.

It there was a difference in MPG then it must be so small i can't see how you could ever carry out a test accurate enough to tell.

[t_urbo]

I don't believe that opening the flaps at mid-rpm ranges will affect AFR enough to make a difference. Not with the stock exhaust. Any pros willing to venture more conclusive evidence?

There is a 10Nm difference in power when the flaps open so there must be a shift in the Air/Fuel Ratio.

[Mori]

How do you know this? Any dyno sheets to prove that t_urbo? Just asking because I have not heard of anything of the sort.

[audijohn]

There is no risk of damage, its only an exhaust. What is really surprising about the RS4, is that with them disconnected (i.e. valves remain fully open at all times) the car drives much more smoothly and progressively, gives better MPG and doesn't sound much louder (certainly from within the cabin). It just sounds more characterful and fun.

That's what's really daft about it, with valves disconnected it feels a much better all-round car - with no downsides whatsoever.

p.s. EVO's long termer used a standard exhaust, and now my car behaves 'exactly' as it did. I'm really glad I chanced upon this discovery.

I am very interested in the "Improved fuel consumption" figure you got, just what in terms of miles per gallon benifits have seen?.

[DoctorD]

It there was a difference in MPG then it must be so small i can't see how you could ever carry out a test accurate enough to tell.

The difference in MPG has nothing to do with any change in the engine, but 'everything' to do with how you therefafter drive it. If the torque is more accesible, then smaller throttle openings will achieve the same end result.

[DoctorD]

I am very interested in the "Improved fuel consumption" figure you got, just what in terms of miles per gallon benifits have seen?.

More consistently above 20mpg than below (before I was getting more like 18-19mpg)

[audijohn]

I am very interested in the "Improved fuel consumption" figure you got, just what in terms of miles per gallon benifits have seen?.

More consistently above 20mpg than below (before I was getting more like 18-19mpg)

OK thanks. It would seem then "Bottom end/ slow " running is better with improved breathing, this is pure guess work.

[DoctorD]

I am very interested in the "Improved fuel consumption" figure you got, just what in terms of miles per gallon benifits have seen?.

More consistently above 20mpg than below (before I was getting more like 18-19mpg)

OK thanks. It would seem then "Bottom end/ slow " running is better with improved breathing, this is pure guess work.

Yes, precisely. It just feels like the engine has been 'released' and is now able to operate as intended, whereas it was really uneven and stifled before. The S5 I had also felt free to breath (at the bottom end), which is why I started exploring ways of achieving similar with the RS4.

[audijohn]

More consistently above 20mpg than below (before I was getting more like 18-19mpg)

OK thanks. It would seem then "Bottom end/ slow " running is better with improved breathing, this is pure guess work.

Yes, precisely. It just feels like the engine has been 'released' and is now able to operate as intended, whereas it was really uneven and stifled before. The S5 I had also felt free to breath (at the bottom end), which is why I started exploring ways of achieving similar with the RS4.

I will give this a try later today, run it for a week and see what happens,

[ChrisRS4]

I did mine last night, and I'd have to agree with DoctorD. The engine definitely feels like it flows better at low rpm and the noise is much better

[audijohn]

I did mine last night, and I'd have to agree with DoctorD. The engine definitely feels like it flows better at low rpm and the noise is much better

Nice one Chris.

[ChuckUK]

Wow this is such an interesting subject.

Is there any way you can get 100% power when you want it? VAGCom change etc or would it require a remap? Why would they reduce the power to 50-60% in gears 1-3 below 5.5k? does version 80 of the software solve this as some folks are saying the surge at 5.5k has gone?

[DoctorD]

I am assuming mine has version 80 of the s/ware since its a brand new car and it still felt like it was restrained in those first few gears. Now it doesn't.

This adjustment really is a no-brainer IMO, I cannot see why anyone would not do it since it doesn't make the car feel any less civilised, but adds back a bucketload of character and smoothness that was being hidden.

It's really quite a bizzarre difference from 'only' opening up the exhaust valves, I would have predicted from past experience that it would only improve the noise.

[Scoobysnack]

If I can on Sat i will ask the dyno guys to use a sniffer or AFR meter on my car to see what the ratio is on flap and open flap....... will really try to get this done on sat using all gears.

Anyone else already done that?

J

[Mori]

Waiting for some data.