As I stated before I guess I was lucky with my 2012. It came with the performance exhaust feature (X pipe) and I find it the best of both worlds. When I drive in the DSC mode you still get the burble while downshifting which I still enjoy as it reminds me of my old Ferrari. While driving with my bride I use it in normal mode and she is comfortable with that. Long drives are a pleasure and other then the tire noise (Dunlops) it is quite pleasant. This is my opinion but I enjoy the sound.

 

bigdhenderson,
Pertaining to the vacuum. You do not have to be concerned about the range in which they function. They are controlled by a vacuum that is based off of a relationship of throttle % and RPM. Above 4000rpms they open regardless of throttle angle.
They are activated open or closed. No in-between range. You can use these valves on the system you are building to help adjust your low range torque. That is one benefit of a variable valve system. By having one exhaust exit closed, this allow the engine to build more torque on the lower end. When open it allows for more HP in the top end.
I'm bypassing this system and opting for the overall HP myself.

I would be curious to see if someone has conducted some Dyno pulls with Fuse 19 pulled (leaving valves open) and without, to see the difference in the torque curve on the lower end.

From my experience with mufflers and engineering knowledge, there are many options out there for muffler design. Sound vs performance seems to be the basic battle.
Some of the best performing mufflers HP wise would be BORLA, MAGNAFLOW, BASSANI etc. I run the Magnaflow on my mustang and love the sound. I have run Borla on my other and those were quite nice too.

Depends on how much you want to hear it and the type of sound you are going for. Magnaflow straight through designs have a great tone and are good for cruising without too much cabin noise. As are the BORLA-XS (Which i favor for Low-end Torque. There are many other options too, these are just a few. Keep in mind, sound is dramatically impacted by the type of CAT you are running.
A good car for comparison would be the 03-04 Cobras, similarly designed engine and I feel it is a similar sound to our XKRs.

Take a look at the attached images from a Mustang and Fast Fords article by Steve Turner. Includes db readings and avg HP /Torques. I believe this is for a 2.5" exhaust. You may see a larger difference in HP with larger piping. Seems we are looking at a 2.3% variation in power from a decent flowing muffler to a great flowing design.

Regards,
D. Fricke

 

Need sound clips when the zorsts are complete!!!!! Some great work!!

 

Powerhouse, I bet the manufacturer can give you your answer. It's interesting that some aftermarket exhaust builders offer their exhaust with the active valves or without. Spires is one: Sports Exhaust : XK 5.0 XKR Stage 2 Active exhaust. FrickenJag gives a good reason (See post #22) to keep the system operational if you can.

 

I'll check next time im back out in the shop and let you know. I need the heat shield that goes right there but I cant find anything anywhere even using the part numbers off the old heat shield. If anyone has that info I'd greatly appreciate it.

As far as the mufflers are concerned, Id like to do the magnaflow 11148 like Dom's, but I want a 3" inlet and dual 2.5s or 3s out. Still debating on doing the valves too.

 

Exhausts exhausts exhausts!!! Was swatting up today on X pipes vs H pipes.......has anyone done a H pipe on an XKR.......reading some of the Hot rodders takes on H pipes they seem to prefer the sound as they produce that thumpy low end burbble........i love the old school American muscle car sound so tempted now to go with a H pipe instead!!! Oh man .......choices!!

 

H pipe would be much easier to build if one was doing a diy build like I am, I built 3 different x-pipes before I settled on the one I liked the best. What im really after in this whole build besides the power increase is I want a really raspy sound, something that sounds like a mean v8 but an exotic, "what is that!?!" sound.

 

This is EXACTLY what I am after. Before purchasing my 2012 from a private seller I test drove a 2013 XKR at my local dealer that had a great sound. I incorrectly assumed all 5.0 XKR would sound the same. NOPE. My car is way too tame. Looking back I suspect the '13 had the Performance Active Exhaust option (standard on the XKR-S). I've learned a lot since then...

Now if I could just locate a good fabricator to build me a replica of the Performance exhaust I'd be thrilled. I'm about ready to call the dealer and inquire about purchasing one from them and install it myself - yikes! Has anyone gone this route??

 

Check out the Spires systems, if budget wasnt a concern I would have gone with their system or an Arden system if I was really feeling rich

Heres some more progress pics. First pic is the way I want to route it, second is the original way I had planned but I think the way I have it in the first picture will flow better...let me know what you guys think.

 

Bigh........Looking good!!!! One thing i may have missed.....are they screw in bosses for oxygen sensors in the middle section??? Whats the time frame for completion?? Cannot wait to hear it!!

Something else i'm looking at is deleting the intake silencers on the intake pipes......looks like a case of cutting them off and doing a bit of plastic welding........would love to hear a bit of the supercharger whine!!

 

Thanks! Im still trying to decide on what muffler to use, after some research Im now leaning towards the Aero Turbine AT2525. Cant make up my mind between that or the Magnaflow, Ive been scouring youtube trying to listen to many different systems and I just cannot decide. I also decided to order some 100 cell cats and fab the cats too. Parts are on order for that, along with stainless hanger rods, and flanges and clamps so Im hoping to be all finished up with this in the next couple weeks.

Those o2 sensor ports I put in myself because I had been running the cat delete pipes I made, so I tried to locate the sensors as far back as possible. Even though I've decided to run cats now (100 cell), Im still going to locate the new sensor bungs as far back as possible and then I still may have to run the bigdaddiesgarage mini-cats or get a re-tune and have the sensor range adjusted like Max did. That would be ideal, but the whole point of this build was to be sort of a budget build, just to see how cheap I could actually do this and compare it to the sky high prices of some aftermarket manufacturers out there.

 

Good man........its always frustrated me that the amount you appear to pay for an aftermarket exhaust is proportional to the cost of the car........what a load of bull. Same or very similar parts, same amount of research into optimising performance gains and same manufacturing process weather its a XKR or a Honda Civic type-r..........

 

I agree, and especially when it comes to the high flow cats. They range from 2k$ on up for our cars and if you look at high flow cats for say civics/eclipses etc they are around a couple hundred bucks.

Im actually considering offering this forum some fabrication services, ranging from 'you send me your existing parts and I modify them' to 'off the shelf' type parts and custom requests. Like for instance if someone wanted cheap(er) high flow cats, but didnt care about being new polished stainless steel etc, they could send me their stock cats, I could cut them out and weld in place a new high flow cat and ship them back to them for a considerable savings. Also I could build x-pipes, etc etc.

 

Have you heard the quick silver XKR on youtube?? Its a single resonator system with a H pipe........sounds nice and deep but kind of looses the metalic rasp at the higher end which i kind of like.

 

The H-pipes are nice for that traditional muscle car sound, however become less efficient in the higher RPM's. This is where an x-pipe works nicely.
For the hp, I'd go x-pipe and for high-end sound. For a nicely cammed setup, h-pipes sound great. (I'll be looking into working with Comp-cams for some custom ground cams).

Pertaining to decision on muffler, just order both and clamp them in. They should be roughly the same dimension. Sell which ever ones you don't like, and get your money back....just a thought.

Henderson, do you have any baseline dyno numbers prior to your install?
Everything is looking great.

I'm taking mine in tomorrow for some base pulls. Then its on to build. I have all the piping in and I'm ready to get to tigging everything up.

Next step, investigating how I can get into the ECM and do some MAF transfer function adjustments for a/f ratio. Tuning surely will be another thread, but I'm considering all options. Seemingly a piggy-back may be my best approach.

 

I'll add this, I run a "cammed" setup in my 331 stroker (289 base) that makes 392 RWHP at 6200 Rs, I run a set of 40mm WEBERS and a 2.5 exhaust (includes a "X") system. Once the engine comes "on-cam" (approx. 3500) the "pitch" increases dramatically. It's a sweet sound.
As far as our "cats" go, I'd like to experiment with a muffler system I have on my E-Type that i custom fitted. They are, what's called "Power sticks". These are cylinder shaped chambered mufflers that originally were designed for the off road systems typical of the 427 Cobras and the 427 vettes. They have an awesome sound, if you like the rubbly, guttural type sound. My E-type 6 cat purrs with a beautiful melodic rumble running this system. They can be custom cut to length too.
When I get to the XKs exhaust, I'll be going with the "X". Not yet sure on the rest of the system.
This is the system on the E...

 

So the standard system i guess has no cross over at all of the two V8 banks?? Got me thinking in that case why not just run straight pipes in the center........ should surely improve exhaust flow velocity......although no scavenging of opposing banks.........as its cutting out some back pressure this should also increase power a wee bit further up the rev range........

 

That is correct. By just adding in straight pipes for the mid section you would surely see some benefit and more tone out the rear.

Power sticks have always been a great add-on. I was just at the Dyno shop and they were bolting some onto a 2015 Mustang. Per my experience they have a great sound. Im not sure of the overall performance but seem to flow pretty decent CFM. Definitely a good suggestion.

I put my XKR on the dyno today for some base numbers for before and after (Which were within expected range). I will be working on the exhaust this coming week and will report out final numbers. I'm going to tig weld up this first system and I will have mandrel tubing bent after I scan the stock piping. I'll replicate the cat bends, however with the different rear configuration of mufflers, I'll only have two 20 deg bends for optimum flow.

I'll be scanning the manifolds as well and building a set of equal length shorties. If anyone has a set I can use to scan let me know.

Regards,

D. Fricke

 

Thanks for the compliments. Im waiting on more parts to show up, ended up getting 50 cell cats, all new flanges and parts to build the cats, and SS hanger rods (freekin expensive, but I wanted an OEM look)

I also tried to minimize the bends as much as possible, I think by tweaking things just a bit I eliminated the bends in the middle kind of by that black plate, but back where it meets the rear subframe/differential the bends couldnt be avoided back there. I also cut up the stock muffler a bit, I modified it to accept 2.5" inlets and outlets, and Im going to see how that goes for the time being. I'll eventually sell the whole setup and build new with Magnaflows.


So how did your dyno pulls go? Also, I was beginning to collaborate with a company in the UK about prototyping some headers, but they seem to have forgotten about me. Im glad you are taking the steps to get some forward progress in this area as well. I think for the time being (this winter) Im just going to give the manifolds a bit of a port job on the outlet while they are still on the car. I really need to find a dyno local and start getting some data, and any data you can share in your venture would be much appreciated! Been an interesting thread so far....

 

I highly recommend getting dyno data with your journey. Really allows you to understand what is happening as you adjust. Where did you get your hanger rods? Summit racing has some nice quality ones.

I'll be scanning the entire exhaust system and mandrel bending in large segments seamlessly just as factory did. Less bends and only a small 30 deg (150 deg) bends at the back. I will do some testing on sizing, I'm starting with the 3" from base of cat back.

The dyno data was good and consistent. I'll toss up graphs with a/f of before and after. This engines seem to be quite fat around 10:1 at WOT. Once I figure the best method on tuning the Maf and timing we should see a nice improvement. For comparison, 03-04 Cobra M112's usually put down 340rwhp, with 21 deg timing and corrected a/f they can put down 415rwhp. Im assuming similar percentage gains can happen with this engine with the proper tune.
If anyone has ideas on how I can get into the ECM and adjust these parameters let me know. Does IDS SDD allow for adjustments?

If you want help with the headers, I'll be scanning and designing jigs soon. I just need to order an additional set to scan. I plan on designing an equal length shorty style. You wont see huge improvements with shorties but every little bit counts. The factory cast design seems to love soaking up heat and has plenty of room for improvement. I'll see what I can do. Keep an eye out for a spare set and let me know. Bare in mind, as I design the equal length I'll perform flow simulation on them and make sure these are engineered and not just fabbed. Many after market header companies and builders stick to the rule of thumbs and do not fully get into fine tuning the flow characteristics. This is where I plan to play.
As the exhaust, I plan on building these from 304ss.