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Easy. Long winded but easy. A resonator is a sound control device. On the XK/XKR both pipes enter a common chamber inside the resonator so the gas is mixed and the exhaust pulses are dampened. An X-pipe merges and combines the exhaust pulse waves to better scavenge the cylinders without regard for sound control. We all know the XKR has two resonators installed on it's mid-pipe. Removing one resonator and installing an X-pipe in it's place is a waste of money because the remaining resonator will ruin the scavenging effect the X-pipe might otherwise contribute. The exhaust will only flow as much as it's most restrictive point. The XKR-S has no resonators, only the X-pipe in it's mid-pipe then straight to the muffler which is bypassed under WOT. This is why it can be more aggressively tuned...if you can live with the noise.
Burns collector:
Same work of art on the interior of their x-pipes.
You can see how beautifully it would divide and flow the exhaust pulses. Pulse from one cylinder travels down the exhaust to the x-pipe where it joins the other pipe from the opposite bank. This creates a vacuum which pulls the exhaust out of a cylinder from the other side or perhaps another from the same side. It's more efficient at moving more of the exhaust out of the cylinders than a back pressure design and improves volumetric efficiency (VE). More fresh air and fuel in the cylinder equals more power. Older cars with flapper air flow meters would adjust automatically but today engines are tuned using speed/density systems. These use manifold pressure and temp sensors which assume constant volumetric efficiency. Change anything on the car that changes VE and you have to change the tune. Hence the reason the XKR-S tune won't work on an XKR. Match the VE and it'll work.
Common dual exhaust resonator:
Definitely NOT for performance. Most of the exhaust scavenging energy is lost in the mid-chamber.
The performance active exhaust was an option for the 5.0L XKR. This was the X pipe and no resonators.
The performance active exhaust was an option for the 5.0L XKR. This was the X pipe and no resonators.
Did you phrase that correctly? It reads like the resonator isn't installed with PAE. My PAE has the regular ole resonators, but the rear box has the active valves to open it up. I'm probably just reading your post wrong.
Did you phrase that correctly? It reads like the resonator isn't installed with PAE. My PAE has the regular ole resonators, but the rear box has the active valves to open it up. I'm probably just reading your post wrong.
We may need to find the Jaguar literature but as I understand it the PAE is only an X pipe and active rear muffler. The standard exhaust has 2 resonators and an active rear muffler. I also think the rear muffler is a different part number for the PAE vs the standard exhaust. Maybe someone else can chime in here but I recall the PAE for my 2012 XKR was a $1400 option. The XK rear muffler does not have the external valves whereas the XKR does.
My 2010 XKR with PAE has the active back box with controlled valves. It also HAD resonator(s) and no X-pipe. I did get a shop to make up the X for me and I have the resonator(s) in my shop.
Only the XKR-S came with the X-pipe, or so I've come to believe.
My 2010 XKR with PAE has the active back box with controlled valves. It also HAD resonator(s) and no X-pipe. I did get a shop to make up the X for me and I have the resonator(s) in my shop.
Only the XKR-S came with the X-pipe, or so I've come to believe.
The PAE came out after your car was built so you had the standard active exhaust (as opposed to the semi active exhaust on the XK).
The PAE had the same mid-section as the XKR-S (note the VIN):
jagtoes, do you have any sound clips of your setup? It's very similar to the setup I will be running. Debating doing away with the cats altogether, and running an x-pipe. Seeing exactly how loud it is (I like loud as long as it's not obnoxiously drone"y"), and if its too loud for my taste, throwing some 200 cell cats back on.
Sorry no sound clips. If you like loud then you can just remove the back box. Leave the resonators and give that a try. Then decide if you want an X pipe or different cats.
Well im 98% positive both my stock cats are pretty clogged up, as both are throwing the catalyst below efficiency codes and car is lazy/hesitant acting at low rpms. So im going to do away with them, add the x-pipe, and see how she sounds. IF, its too loud, then I'll have some 200 or 400 cell cats re-installed.
Originally Posted by jagtoes
Sorry no sound clips. If you like loud then you can just remove the back box. Leave the resonators and give that a try. Then decide if you want an X pipe or different cats.
I don't know what the 5 litre sounds like with no catalysts but I took both cats off my '07 4.2 litre XKR after one failed a couple of days before Xmas and it was obscenely loud. I had to get special resonators made up to replace the central ones to try and quieten it down plus get my tune changed to alter when the valves opened on the back box so that it only opened at high revs.
I also got sick and tired of the rotten egg and fuel smell that permeated my clothes after parking the car in the garage so put some high flow cats in place eventually.
It doesn't really do it justice but this is what it sounded like with no-cats:
The XKR-S rear muffler is very different internally and makes a significant change to the tone of the exhaust, the x-pipe on it's own not much difference at all.
The XKR-S / PAE rear muffler can certainly be described as throatier, louder and deeper.
A friend of ours here in Sydney (unknowingly) got an XKR-S / PAE rear muffler from a wrecker, he just wanted quad tailpipes on his 5.0L XK, they pulled the rear muffler off an XKR in the yard, nobody knew it was a PAE car, when he showed me pics of what arrived I nearly died...
On the 5.0L XK it sounds outrageous, huge deep ballsy tone. I think it sounds better than anything short of an F-Type V8.
Only thing is they cost a fortune if the seller knows what he has.
I seem to remember someone posting pictures of the guts of some mufflers, but that was awhile ago. I'm thinking about cutting mine open and changing stuff around IF I can find some sort of plan/diagram to do so.
No, I'm not an idiot... The bottom skin on my rear box was dented up when I got it CPO. Dealer said since it was in one piece, didn't leak and didn't affect performance, they wouldn't fix it. I think someone tried to lift the rear with a floor jack on the box.
Anyway, I'd like to cut the skin off, straighten it up and reaffix it. Since I would already BE inside, a few more welds and cuts wouldn't be any sort of deal.
I figured you wouldn't be so goofy as to forget the actual post, so I opened the page on Edge instead of Firefox, and I got it. Thanks, man. A bit difficult to see much as so small, but I'll take a closer look later.
SO, anyone using Firefox on a PC may miss things in here! Don't know why, don't know how.
03-28-2020, 08:10 AM
