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STOP!! Read This Before You Remove Your Center Muffler.

XK8 / XKR ( X100 ) 1996 - 2006

STOP!! Read This Before You Remove Your Center Muffler.

 
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Old 07-02-2014, 07:46 PM
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Default STOP!! Read This Before You Remove Your Center Muffler.

Well, went and done it. Had my center muffler removed and installed an x-pipe. The sound is slightly better and I am happy with that, but it backfires sometimes on a quick rap down in RPM. The muffler guy says he has seen that happen when the center muffler is removed. He also showed me that the center muffler is a straight through with no restriction(see pic). It has some perforations like a glass pack where the exhaust sound from both sides can mix. (similar to an H-pipe). I just removed a Slightly muffled H-pipe back fire arrestor. He also told me he would have removed the before axle mufflers and replace the factory crushed over the axle pipe for the same price as the center muffler delete. I asked him Why he did not suggest this before. and he said I sounded so sure of what I wanted. Live and learn.
Knowing what I know now I would have left the center muffler because it does just what an H pipe does and has no restriction.
Has any body removed just the before axle mufflers?
 
Attached Thumbnails STOP!!  Read This Before You Remove Your Center Muffler.-img_3373.jpg  

Last edited by bigk9863; 07-02-2014 at 07:51 PM.
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  #2  
Old 07-02-2014, 09:20 PM
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Whoa...never ever had any backfire with my center muffler delete to x-pipe. Ever.
 
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Old 07-02-2014, 09:34 PM
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I probably exaggerated a little. It s not like a gun going off but muffled gurgled pop that I didn't hear before. It only does it in park, free rapping the engine to 3500 rpm and letting off accelerator quickly. It might have been there before but I did not notice it.
 
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Old 07-02-2014, 11:24 PM
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Ok, that makes more sence. Had me worried as I'm about to do the same. I believe the perforated pipe inside the center box also acts as a resonator to help quite the sound.


Any chance you can post a sound clip of your setup?
 
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Old 07-02-2014, 11:43 PM
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I will try to get that done. I am wondering if anybody has removed the small before axle mufflers. It might be the sound all of us our looking for. The center muffler does silence some of the sound and connects the sides together like an H pipe and it is a straight shot through it. From what I have been reading. the members that end up removing the small before axle mufflers also change the back mufflers to after markets which would be way to loud for me.
 
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Old 07-03-2014, 01:56 AM
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Aren't the mid or rear ones just resonators as well? Would be great if someone could confirm
 
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Old 07-03-2014, 08:17 AM
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UPDATE: After driving the Jag around, the small backfire went away. I guess the car adjusted to the change.
If I had to do it again I would get rid of the small mufflers only and replace the factory flattened pipe.
I think it would be just a little bit louder (which would be acceptable) and it might even run better.
I hope someone has already done this and will chime in.
 
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Old 07-03-2014, 08:34 AM
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Your picture is worth a thousand members reviews. I was about to remove the center muffler and your picture saved a needless learning curve. Looks like the before axle boxes will get chopped instead.
If my ear says the rear resonators need to go as well for me to get a bit more audible aggression out of Jaguar's extremely quiet exhaust system a Saws-all and a pair of inexpensive aftermarket mufflers or resonators can easily be added at home.
RB
 
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Old 07-03-2014, 10:35 AM
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Everything I've read says not to fool with the small before axle boxes. These keep the low, cruising rpm drone down. All the posts I've seen say without these the drone on longer trips gets unbearable.
 
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Old 07-03-2014, 11:09 AM
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Hey East,
Even if you left the small mufflers alone and played with the last larger mufflers you would still be money ahead if you were going for more aggressive sound. The center muffler has gotten a bad rap and knowing now how it works I wish it were back on (The muffler guy cut the flanges to the center muffler off flat to give him more material to weld to) so I could experiment with the other mufflers. Good luck in your choice and keep us posted.
 
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Old 07-03-2014, 11:34 AM
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I think there is an over exaggerated mystique to exhaust system mods. Similar for things like increasing the size of things on the intake end like throttle body bore. The argument is always that if you make things larger with less restriction you will get all sorts of benefits. Maybe so if you are going all out and creating a drag machine but not so much for the daily use that I expect 99% of folks do.

The appeal of these types of mods is that they are relatively inexpensive and easy. When I was on the Corvette forum I remember all sorts of guys swapping out their throttle bodies with larger ones and then being disappointed with decreased performance (or at best no discernible improvement). Then someone with smarts would eventually come along with an air flow calculation demonstrating that the OEM throttle body was MORE than sufficient for the cubic inches of the stock engine and that you would have to be doing all sorts of other mods (bore heads, etc.) before you needed the bigger throttle body. Same thing for the exhaust--the stock system was just fine for the way the car was typically driven and when someone did some exhaust "upgrade" 9 times out of 10 it would be followed up by complaints of unpleasant drone in the cabin and LESS responsiveness at low rpms (where most folks spent their time).

Sure the Jaguar pipes look ridiculously restrictive where they pass over the rear axle but I wonder at what point of the rpm range will this make a difference.

Doug
 
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Old 07-03-2014, 12:35 PM
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Well said, with a stock engine you probably wont notice any improvement until the extremely high RPMs, and who likes to hang out there. That being said if you are going for a more aggresive sound, the easiest mod would probably be the rear mufflers. I am going to get some measurements on that aledged restrictive section of pipe to get a cross sectional view. It probably has more area than It looks.
 
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Old 07-03-2014, 01:51 PM
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Here is the O.D. of the round exhaust pipe(2") verses the O.D.of the oblong pipe(2.5"X 1.25"). Actually because of the limitation of "Paint" i could not draw the oblong one correctly. The long sides of the oblong shape are flatter more like a rectangle with rounded corners. So the area of the flattened pipe will be more than my drawing depicts. So now someone smarter than me figure out the area of the two shapes for comparison please.
 
Attached Thumbnails STOP!!  Read This Before You Remove Your Center Muffler.-exhaust-diameter.png  
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Old 07-03-2014, 02:43 PM
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Just went through 4 different configurations. I never had a backfire with center muffler removed which was the first thing I did. Then I removed the rear mufflers, too loud, so added glass packs in middle. Still too loud. Then he added two glass packs in place of rear mufflers, made popping noises so finally I had all the glass packs removed, put an H pipe in center, lost the little axle mufflers and replaced the rear factory.
Perfect!! Sounds like the F type but a bit lower.
Everyone loves it so for now I'm done!!
 
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Old 07-03-2014, 03:25 PM
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Originally Posted by bigk9863 View Post
Here is the O.D. of the round exhaust pipe(2") verses the O.D.of the oblong pipe(2.5"X 1.25"). Actually because of the limitation of "Paint" i could not draw the oblong one correctly. The long sides of the oblong shape are flatter more like a rectangle with rounded corners. So the area of the flattened pipe will be more than my drawing depicts. So now someone smarter than me figure out the area of the two shapes for comparison please.
Area of the circle is 3.14 square inches and area of the ellipse is 2.45 square inches. The question is the significance of the difference under driving conditions.

Doug
 
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Old 07-03-2014, 04:06 PM
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Originally Posted by philhef View Post
Just went through 4 different configurations. I never had a backfire with center muffler removed which was the first thing I did. Then I removed the rear mufflers, too loud, so added glass packs in middle. Still too loud. Then he added two glass packs in place of rear mufflers, made popping noises so finally I had all the glass packs removed, put an H pipe in center, lost the little axle mufflers and replaced the rear factory.
Perfect!! Sounds like the F type but a bit lower.
Everyone loves it so for now I'm done!!

Phil, sounds like you have finally got there, how long have you now had that config? can you also post a pic of the position of the H pipe in case that has an influence.


Kim wants her car to sound better but I'm reluctant to start unless I can find someone that is happy.
 
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Old 07-03-2014, 04:07 PM
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Thanks for figuring it out. thats alot more area on the elipse than I thought it would have. and not a big enough difference to worry about. So I am saving my money. Now we know that the big over the axle restriction is not that significant after all.
 
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Old 07-03-2014, 04:13 PM
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So Phil, getting rid of the little factory mufflers and putting back the factory rears was the ticket. My muffler guy said that is what he would have done also and ofcourse kept the center muffler. Would love to hear it.
 
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Old 07-03-2014, 04:45 PM
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Originally Posted by bigk9863 View Post
Thanks for figuring it out. thats alot more area on the elipse than I thought it would have. and not a big enough difference to worry about. So I am saving my money. Now we know that the big over the axle restriction is not that significant after all.
Thinking more about it, and even though I am not an expert in fluid dynamics, I would suspect that the bending of the pipe over and around the axle is more significant in restricting the flow than the flattening of the pipe. Still someone smarter than me would have to run the analysis to see the impact of these multiple restrictions on actual operating conditions given the flow characteristics of the engine itself and the demands.

Doug
 
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Old 07-03-2014, 05:00 PM
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Originally Posted by philhef View Post
Just went through 4 different configurations. I never had a backfire with center muffler removed which was the first thing I did. Then I removed the rear mufflers, too loud, so added glass packs in middle. Still too loud. Then he added two glass packs in place of rear mufflers, made popping noises so finally I had all the glass packs removed, put an H pipe in center, lost the little axle mufflers and replaced the rear factory.
Perfect!! Sounds like the F type but a bit lower.
Everyone loves it so for now I'm done!!
So, philhef your car should sound about like K. westra's does in this thread only possibly a little quieter as he is running FlowMasters 40's instead of the stock rear muffler.

Is this correct?

https://www.jaguarforums.com/forum/x...ter-40s-37811/
 

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