XKR Active exhaust

[bass2rez]

Hi,

Does anyone know whether all 5 litre XKR's have the active exhaust (where you can remove fuse 19) or was the active exhaust an optional extra? If it is an optional extra, how would you know if an XKR has it fitted?

Thanks,
Steve

[Triple7]

I believe it was from 2013MY that the exhaust became the ‘Performance active exhaust’. Mine is a 2012MY and you can still open the exhaust valves in ‘dynamic’ mode or pull fuse 19 and have them open all the time.

PS ask a Jag dealer for the ‘build sheet.’ Obvs if it is a XKR-S or Dynamic R it will have the Performance active exhaust as standard.

Edited by Triple7 on Tuesday 29th May 15:06

[The Bodyman]

Stick your head under the back of the car and look at the rear box. Your looking for a valve on one of the pipes.

If you can see this



then yours has the active valves fitted.


Jon

[bass2rez]

Many thanks for the replies.

I believe mine is 2013MY (the tenth digit of the VIN is "D") though it is a "12" plate vehicle?

I just had a look underneath at the back on my car and there are two devices that look like solenoids with a lever to a valve as in the photo above.

So, I can conclude that mine has the active exhaust.

Cheers,
Steve

[8bit]

All XKRs (alloy body ones, aka X150 certainly) whether 4.2 or 5.0 have the active exhaust valves which are operated by the ECU and powered through Fuse 19 in the box behind the panel between the rear seats. This came with the first 4.2 XKR in about 2006 right through until they stopped production of the 5.0 XKR in 2014 or thereabouts. If you have an alloy-body XKR then you have the active exhaust (assuming you have the original exhaust fitted).

The change in 2012/2013 or so was that an option appeared for the somewhat confusingly-named Performance Active Exhuast. This is essentially the same back box with the vacuum-operated active valves, but the mid section between back box and cats is different; there are no smaller silencers/resonators in the mid section but there's a cross-over section instead. This is a little louder than cars without it. That part was standard on the 5.0 XKR-S, XK Dynamic R and a couple of the special editions such as the XKR-75.

[a8hex]

I think all 5L XKR's have the active exhaust, at low revs it runs in quiet mode at higher revs with enough throttle opening it needs to be able to breath out more, so it opens up the exhaust. Without the open exhaust it wouldn't be able to make 500+BHP. Being able to manually select the noisy mode at other times might be optional, but the basic functionality should be there.
One think I've noticed on mine is that if you've been driving gently in normal mode on the gearbox and then try and accelerate quickly I've often got to the maximum speed I'm aiming for before the revs have risen to the point the exhaust opens up and goes into noisy mode.
I've not driven a X150 4.2XKR since the launch, I think these did the same, but I'm not certain.

[8bit]

a8hex said:

I think all 5L XKR's have the active exhaust, at low revs it runs in quiet mode at higher revs with enough throttle opening it needs to be able to breath out more, so it opens up the exhaust. Without the open exhaust it wouldn't be able to make 500+BHP. Being able to manually select the noisy mode at other times might be optional, but the basic functionality should be there.
One think I've noticed on mine is that if you've been driving gently in normal mode on the gearbox and then try and accelerate quickly I've often got to the maximum speed I'm aiming for before the revs have risen to the point the exhaust opens up and goes into noisy mode.
I've not driven a X150 4.2XKR since the launch, I think these did the same, but I'm not certain.

As per my post above, all the X150 4.2 and 5.0 XKRs have active exhaust valves. It's not about performance, it's just about noise, the valves are opened above certain engine RPM and/or throttle positions to slightly increase the noise. The 5.0 cars eventually had the optional "Performance Active Exhaust" which has the upgraded mid section but power output is quoted as the same, the exception being XKR-S which gets extra power through various other improvements.

[a8hex]

8bit said:

a8hex said:

I think all 5L XKR's have the active exhaust, at low revs it runs in quiet mode at higher revs with enough throttle opening it needs to be able to breath out more, so it opens up the exhaust. Without the open exhaust it wouldn't be able to make 500+BHP. Being able to manually select the noisy mode at other times might be optional, but the basic functionality should be there.
One think I've noticed on mine is that if you've been driving gently in normal mode on the gearbox and then try and accelerate quickly I've often got to the maximum speed I'm aiming for before the revs have risen to the point the exhaust opens up and goes into noisy mode.
I've not driven a X150 4.2XKR since the launch, I think these did the same, but I'm not certain.

As per my post above, all the X150 4.2 and 5.0 XKRs have active exhaust valves. It's not about performance, it's just about noise, the valves are opened above certain engine RPM and/or throttle positions to slightly increase the noise. The 5.0 cars eventually had the optional "Performance Active Exhaust" which has the upgraded mid section but power output is quoted as the same, the exception being XKR-S which gets extra power through various other improvements.

Sorry, I was in the edit screen for ages, so I was writing my drivvel before you posted your info.
I was just recalling what I'd read in the blurb when the cars were launched.

[Triple7]

As 8bit correctly deciphers the difference between active and performance active exhaust.

[8bit]

No worries - yes it is confusing, Jaguar could have picked a better name for that option when they introduced it, given that all XKRs already have active exhaust valves...

[6Grimreaper]

Well here is what & how the active Exhaust valves work on flow in system.



Also chart to see when valves open on 5.0L. But if you use flappy paddles or Dynamic mode button valves will stay open.




Last chart is for X150 4.2 L as operation is different.



On a 5.0L if you hold the rev’s just above 1,100 while stationery & push Dynamic button you can hear Exhaust note change. As you can see on 5.0L Exhaust flap control chart when they open & Close.

Have a play

[bass2rez]

6Grimreaper said:

Well here is what & how the active Exhaust valves work on flow in system.

...

Have a play

Many thanks for that detailed explanation, 6Grimreaper. I will indeed have a play, particularly the last sentence on how to test.

Cheers,
Steve

[a8hex]

OK, so cross thread quoting from the thread about rev'ing at start time.

a8hex said:

6Grimreaper said:

It’s normal.
Have aXKR 5.0L & does the same.
Done research & found that this is done to save over stressing cam chain apparently. I also wait till idle before selecting drive. About 30 seconds when cold to save it lumping into gear.

I've always assumed that my XKR did this because some 5 year old was left in charge of the marketing dept. at some point and thought that rev'ing like that was cool. It's probably the thing I like least at the car. I was tempted to say that's it's the only thing I don't like about the car, but I'm sure there must be something else, I just can't think of it at the moment.

6Grimreaper said:

Also chart to see when valves open on 5.0L. But if you use flappy paddles or Dynamic mode button valves will stay open.

JaguarsTechDoc said:

At startup the exhaust valves are always open, to enhance the exhaust sound

Seem I was right, they make a noise at startup coz "some 5 year old was left in charge"