Just had an exhaust pipe break off from the back of the front cat and before I could get it pulled to safety, it caught on a seam in the pavement, broke off part of the front of the pipe and put a nice kink in the pipe, to the extent that it can't be repaired.

So I'm thinking about taking the opportunity to replace the entire exhaust system, which has had a couple of leaks anyway on my car. I'm thinking of going with a 2.25-inch system and some kind of spiral flow muffler. Moroso makes one with 2.5 inlets but I've found others that offer 2.25 applications. Just wondering if anyone had tried that setup on a V12 XJS.

Jess

 

I really doubt it, not too many people change the exhaust on their XJS, and I don't blame them considering the 3-speed. The moroso spirals seems to be a generic muscle car with a JEGS sticker on the back kind of thing, so I have my doubts about them.

It is also really difficult to decide because their aren't many videos/sound clips to compare to (not including the delicious targa tazmania videos). Still, try to find vids of "normal" sounding v12s, like the older mercedes and bmws, or even videos of exhaust setups on inline sixes to get an idea of how different setups affect the sound.

Simply listening to a lopey camaro won't do, the sound is just entirely too different. The v12 inherently has a higher pitch that can make it sound very ricey and lame if not setup properly.

I would say if you are re-doing the whole system, that large diameter and an H pipe/X pipe are a must. I was recently looking into systems, and realize it will take some experimentation to get the right sound. E-types very commonly have simple glasspacks, so it is possible for the spiral-type to sound decent, and I suppose it could be worth a try for how cheap they are. Just try to setup an easy slip-on, so you can return them if you don't like them.

I think the XJS needs resonators to finely tune the sound and remove some of the tinny sounds. I was also looking into putting a helmholtz resonator on to help with the drone. I was planning on going through videos of various mufflers and finding ones that tend to deepen sound, because I think the XJS needs that the most if you are going to make it loud. Again, just make everything very modular so you can swap resonators and mufflers to fine tune your sound. Check out Jagzilla's sound clips, I think he has flowmasters on it, which you wouldn't first assume for an XJS but they work well. I immediately think monza, stebro, and borla, but I think the sound many of those accomplish on V8s would be too ricey on a v12.

 

I almost wish I could keep the sound I have now. Having one side off behind the cat gives it a throaty baritone sound that is neither too lopey nor too tinny.

I'm a little skittish of glasspacks, as I had a set once on a work truck and they made it over-the-top redneck under acceleration. The other thing I'm wary of is turning the cabin into a big resonance chamber.

Given that I don't have the ability to make a lot of test swaps by myself, I kind of have to get it right the first time. Scary.

Jess

 

Yeah, you have to keep in mind that, design wise, a glasspack is basically a resonator, and not a muffler. So using a glasspack only can be loud. I've had my driver's side pipe come loose before the muffler while driving, it was really drone-y at speed. Sounded decent at idle, but kind of lame since it was the single side.

I think with all the cats the XJS isn't too loud with just a glasspack, the store resonators/silencers are pretty big, which is why I think removing the mufflers is a common mod.

I'd like to get some tubing and make a substitute pipe for the mufflers since it is easy to change if I don't like it. AJ6 makes them but they are really overpriced.

Anyone with a ton of time and a megasquirt setup could probably design a sweet exhaust, the extra fuel is what makes the F-type crackle and pop like it does.

Really the open pipes from that targa tazmania car are hard to argue with.

After hearing the car with the pipe disconnected like you mentioned and knowing the drone issues with the 3-speed, I have tossed around the idea of electric cutouts several times, loud on demand

 

So if I'm reading your post right, you'd suggest leaving both factory cats in, the factory resonators/silencers in, but either deleting the aft mufflers and/or replacing them with glasspacks?

Shouldn't be too hard to try that option. I'd considered going to high-flow cats when I did this because I believe I can feel better performance with this one side running open right now. My mechanic put me in touch with an exhaust shop today who's not scared of the car and doesn't seem to know the meaning of the word "no" in regards to suggestions.

Jess

 

My 86 has both down pipes emptied, all four cars gutted, both mid mufflers removed, open "growler" air cleaners and an "H" pipe at the trans tail shaft. Not much difference in sound at all from the stock set-up. Be careful how much $ you throw at it in terms of seeking greater gains in "sound". No exhaust shop should be "afraid" of any car, it's just pipes. The two biggest restrictors to sound on the XJS in my experience is the rear resonators and the exhaust pipes small size. (All that's left on mine is the stock rear resonators).

 

Exhaust pipes, the lack thereof, gutted mufflers and glass and steel
packs and I go back a long way.


One of the best sounds I ever got was a pair of long glass packs and turn outs in front of the rear wheels. 283 SBC in 56 ****** Jeep 4x4 pickup. Mellow, no drone or back rap, just a nice purr.


Next is the arrangement in my 83 XJ wuzza six. 350 CI SBC as used in the 94 Cadillac Fleetwood Brougham. twin cats, H pipe, stock Jaguar mufflers and small glass packs as resonators at the tail. No rasp or back rap, just a nice purr. Definitely, not a six.


The X or H balance pipes can effect performance, but location is tantamount. They can eliminate the "red neck" truck sound nicely.
Oh, one side of my family descends from "red necks"!!! Good folks.


Cabin drone can be eliminated or reduced by proper pipe hangers.


Pipe diameter has a lot to do with the type of noise or lack thereof.


Use a shop that does the mandrel bends. Wrinkled bends lose a lot.


If the final plumbing is too noisy, glass packed tips can tone it down a lot.


Carl

 

.

used two 3" Spiral Flow mufflers on a BBC 454 Camaro,side pipes, YUP they could hear me coming and going!

Hey i likes it!!!

pic of my 12 cylinder Jag side pipe!

 

Is that picture "flipped", or is it really a EHD car?


Burnt or singed ankles???


Son has a Low T roadster. headers and side pipes. Very hot Ford
460. Like ripping thunder!!!


Decades ago, he took it to the local CHP office to get a VIN. On a trailer,as no registration yet for the scratch built car. Younger CHP'sd admired it. an older CHP commented, "can't wait to stop it on the road, tons of tickets". Young cop response, "if you can catch it!"


Carl

 

.

YEP, jagcad my 1978 XJS is a factory RHD (right hand drive ), last registered in Kent England UK, was custom modified from coupe to cabreolet Aston Martin Tickford, England, around 1980-81, also has a mott sticker in glove box saying it is a two(2) seater car only! not 4 seater.

it is fun to drive, and be aware of your side to side judgements,LOL.

 

Fun to be different!!!


Nice car, extra special interest!!!


Way back when, I spliced an extra pipe into the exhaust manifold
of my T Ford. Twin straight pipes. Teens like noise!!!


Pal Billy just swapped the manifold, back to front. No pipes, just straight into the radiator?? It worked???


The project before the Jaguar was a Warmed up Flat head Ford V8.
Headers and twin pipes, sans mufflers. Blocked heat risers added a neat crackle.


Jaguar now, just a nice dignified V8 purr!!




Carl

 

Do you mean to say you cut the ends off of your intake? I've seen that as a common mod as much as removing the mufflers and I've done it. Where I live the average speeds are 35-45mph, so it just sounds good around town.

However after about 55-60mph it starts droning really bad. How do you deal with that? I'm lucky I have my old set because I would have to put them back on to drive on the highway.

 

I'm running the K&N "growler" intakes from V-12 performance. There was a drone at highway speeds then I had the shop put the "H" pipe in. Drone gone.

 

Here's a picture of them