I'm looking into exhaust upgrades for the 07- UP XKR's.

Only published dimensions I'm finding are the following:

Milltek
2.25" Sport Cats (Assuming O.D)
2.36" Cat-Back

Paramount Performance Cat-Back:
?

Quicksilver:
2.1" I.D

These are the only ones I have located currently. Does anyone know of a manufacturer that is fabricating 2.5-3" Cat-back systems?

Per my engineering knowledge and fabricating history with race cars, The 2.36" Cat-back system would be a little restrictive if my goal is 500-hp.

I'm currently building a 2.5" 200 Cell Cat kit, that will lead into a 2.5" X-pipe. The plan is to venturi out to 2.75"-3", depending on supplied kits or fabricate my own.

Any input is appreciated.


Regards,
D. Fricke

 

I recently bought a 2013 xkr from a woman who is an engineer that was often on this site.

she designed her own exhaust. I acknowledge her to be the expert on exhausts, considering that the car I bought put out 680 hp at the rear wheels, on a dyno.

The car has a scream to it that I have only heard from cars that cost 350,000 dollars and higher

I also consider her an expert at engine modification and aerodynamics.
She posted as "SoCal Babe".

I encourage you to look in the archives for pics and the specs of tubing size and other details that will help you

 

Md_plasticss......Do you have proof to back up those claimed dyno numbers?

I also would like to see alot more input into this thread, im currently in the process of building an all 2.5" 304 SS exhaust system from the manifolds back. Started making the X-pipe today, I will post pics as the project progresses. All ive been able to find from the few others that actually list the pipe size is already listed in the first post here. I believe the Spires stage 1 is 2.25" as well but dont hold me to that.

 

Thanks for the input.

bigdhenderson, 2.5" Is a good approach. Depending on your end goal of hp, I would consider at least this diameter. Which is approx I.D. 2.37" I.D. in 16 gauge.
4.41in^2, which should flow about 507 CFM or 1014 CFM for 2 pipes.

The rule of thumb is you need approx 2.2 CFM per HP for exhaust.

Standard steel pipe assuming standard frictional losses will flow about 115 CFM per in^2.

Other piping options:

2.75" 16ga I.D. 2.62" or 5.39 in^2, flow about 620 CFM or 1240 CFM for 2.

3" 16ga I.D 2.87" or 6.46 in^2, flow about 742.9 CFM or 1485.8 CFM for 2.


Since my end goals will be to push close to 600-650 bhp Im going to build the rear from 3", the cat system will consist of 2.5" and run into a 2.5" x-pipe center. I will then venturi from 2.5" to the 3" rear.

For a stock motor setup, the supplied Milltek, quicksilver and other systems seem to be okay. For those that are upgrading pullies etc, anything smaller than 2.5" may be a little restrictive.

I'll look forward to seeing your photos. I'll post some up of my cat system next week.

 

The stuff that I'm using is 2.5" "sanitary" tube. 304ss sch 5 I believe, I'm a Pipewelder so I have access to parts and pipe so hoping to have all mandrel bends even if I have to do a lot of welding.

 

A little progress so far....

 

Didn't have much argon left so tacks are pretty brown, will be grinding them off and purging when final welding is done. Then a full sanding and polishing for the nice seamless look.

The pipes are so close together I'm a little concerned about proper flow through the x-pipe I made, I wish someone had the dimensions and location of the xkrs/aftermarket x-pipes

 

This is a photo of the XKR-S pipe section below.

You are merging closer to the trans and I would feel this is a better approach than the XKR-S System. Typically, the rule of thumb I've used with hotrod / race car projects is to mount the x-pipe as close to the trans as possible.
You want the x-pipe positioned in the exhaust where you still have pulsing and scavenging effects. So you are at the ideal location.

I'm attempting the same with my setup.

Attached are some options on mounting depending on size of muffler (18.5 x 4") in photo. I'm opting to do as minimal bends as possible and have decided on the 150 deg approach in "Exhaustdim2" pdf.

Regards,
D. Fricke

 

Hi Chaps,

Very intetested in this thread as i'm in the process of having a custom center section made for my 2010 XKR out of 2.25" pipe. I was going to get the shop to do a direct copy of the XKRS center section with X pipe........intetested on your point about the X pipe position......so closer to the front of the car the better or is there an optimal position? Also what about the entry/exit intersection of the x pipe? Is 90deg optimal? A
so intetested to know how it effects the exhaust note........a very interesting thread has been born!!!

 

Did you find her dirty underwear? https://www.jaguarforums.com/forum/x...me-gag-116612/

 

+1

I too will be working on this modification next. Want to replicate the XKR-S exhaust center section, retain stock muffler set up but remove stock tips and add Mina tips given to me by a very generous fellow member TBerg. My goal is simple, to get a better sound and look without spending a fortune.

Knowing if there is a way to improve this part before I begin would be great!

Bob

 

Perfect pictures Bob......very useful to see those renderings.

i'm now debating to move the x pipe nearer to the front of the car to go where the first silencer is......my cars going in for the work on the 22nd of December.........need some informed input.......or i may just go for it!!

Need to engineer a way to be able to slide the X pipe along the center section!!

 

I'd almost bet that the reason they didn't put it up further is because of the center lines, its a very tight fit to fit an x-pipe there because of the 3" centers. Further back it turns to 4" centers, which appears to be where its located on the xkr-s.

 

Here is a close up of a Performance Active Exhaust, which I believe is the same as the XKR-S exhaust. BigH, yours looks nicer!

 

GrtShrk or anyone can you answer this. Some rear boxes made by performance exhaust manufactures have no valves that open or shut to create more noise. Number 2 on the pictures are the valves one each side of the original . When these are not used are the air pipes blocked or just left open.
The picture i show is a quicksilver system and has no valves, so if fitted the old valve pipes would not be used, so would it be better to block them or leave open.

 

speaking of the valves, Ive been considering putting some in, but what im unsure about is the vacumm/pressure range they have to work in. Anyone have that info?

 

Hey Mate,,,
Is that a 1st gen (65-66) mustang roof line, I spy there?

 

A little more progress..I've also decided to build the cats while I'm at it. And still trying to decide on what mufflers to use. I really like the sound of Dom's xkr-s with the magnaflows so more than likely going with those mufflers but also open to suggestions.

 

Good looking job bighenderson, nice to see a good bit of engineering. In your picture there is a black rectangular plate that the pipes go under, mine seems to be missing, has yurs a part number on it , maybe some one can tell me where to get one

 

Just posted this in another thread but it may be worth putting in here too...

Is the performance active/XKR-S back box also different to the standard XKR? I've read a couple of times now that just replacing the centre section and secondary cats with an X-Pipe actually seems to make the standard exhaust more refined on the XKR/XFR; slightly louder with a different tone, but stops the pops/bangs on the over run, this is the opposite of what I'd expect to happen?!

I'm weighing up options for a new exhaust on my XKR at the minute, I was thinking about just doing the X-Pipe, but I wouldn't bother if it meant loosing the popping etc as I think that's part of the fun.