My 4.2L Coupe just doesn't have a proper voice. It's very sedate sounding; not befitting its looks. I have the stock Jaguar exhaust manifolds (which I'm not changing) and the stock twin "silencers". So there's a Y pipe off to front silencers with a rear silencers behind that. So four silencers all together. Forward of that Y pipe there is a Cat converter that a PO added for some reason (as there are no other emission controls on the car). I am eliminating the cat converter, replacing it with a straight pipe, so I know that will make some difference in sound. Maybe even in a little more HP. Has anyone experimented with any other systems that give the car more audible attitude? I'm not looking for a hot rod, or really bad *** sound. Just something a bit more raspy and tone-al... a little more growl and a little less meow. I've had the two rear silencers off when painting the rear valance but that didn't seem to do much (the Cat converter was on at the time). Thoughts?

 

WOW! Just read in another post labeled "Stakedown Kit" that the Cat converter, with its back pressure presumably, creates more heat on the exhaust side of the head. Another side benefit for removing it! Maybe the engine will run cooler?

 

In essence, you have what became to be known as a cat back dual exhaust system. Faux, when related to a true dual system.

The exhaust manifold on these cars is not bad at all. Note the two outlets !!!
Were I to consider an all out redesign, I'd start there. One from each outlet back to the silencers aka muflers. Include an X or H pipe to eliminate raspy harmonic. Eliminate the rear silencers, aka resonators. Whoah, that is pretty close to the system used by jaguar for the famed E type.

Dependant on the design of the Cat, removing it will alter the tone. Older units more restrictive and thusly quieter.

My "different" car has a true dual exhaust system with twin cats. An H pipe, stock jaguar front mufflers and small glass packs in the resonator position. It has a nice burble. Clear that it is V8 powered, but not obnoxious.

Carl

 

I installed the European front pipes without the cats and also deleted the front mufflers, car is still far from loud but it does have a bit more base in the exhaust note.

 

How do the European front pipes differ from the single pipe going back to the twin mufflers?

 

Cats are good for creating heat. Nothing else.
I liked the sound of my old 4.2, mostly due to the ample leaks in the pipes.
Did find that the muffler under the rear seat has a heat shield over it, then a layer of fiberglass(?) insulation. Did a fine job of rotting out the bottom of the seat pan.
No worries, had it cut out, cleaned up and patched shut in a matter of a couple short nights work.
Moral of the story, remove the mufflers under the seat (forever), the heat shields & any other insulation, and inspect for rust. The rear silencers replaced with adequate glass packs will give a nice, slightly aggressive growly sound.



It's much worse than it looks.

 

mines a series 3, us spec has the cats up in that area, it deletes everything,

 

When, quite recently, in colder weather, my "pipes" seemed to emit a generous amount of a white vapor, son and I suspected water in the front mufflers. The angular mount does suggest that. Son got under and with my sharpest Cobalt small drill bit put two holed in the lowest part. Odd, no water dripped out !!

A flaw that did not exist!! Seems so. 30+ year old mufflers still sound.

Carl

 

yachtmanbuttson,

I have a new European exhaust system for my 77XJ6C that I have not yet installed. when I get back into town next week I'll post some photos. got it years ago in a surplus sale at XK'S Unlimited.

geneo

 

in my '84, I deleted both cats but not the mufflers. The sound did not change much at all, slightly more growly but nothing to write a book about it. Horsepower-wise, not any noticeable change.

Heat wise? yes, a very noticeable decrease. The driver's side floor does not get hot anymore. Dammed cats!

I think the main issue is the engine: the 4.2 is a quiet engine.

the US Federal Y pipe has a secondary cat right at the Y intersection in the Series 3, the Euro pipe does not.

also the Euro down pipe (the one that connects to the two manifolds and to the Y pipe), does not have a cat.

you can get both Euro pipes in the US. I got mine from Motorcars Ltd. in Texas.

Now if you hear my '65 S type with a 3.8 liter engine and a stainless steel Bell Exhausts Ltd. system, then you will hear a Jaguar. It sounds like the old XK-120 Jags.

Why the difference if both exhaust systems are nearly identical? I have no clue.

 

Geneo - ME-OUW!!! That should take it from a kitty to a Tom Cat! Looking forward to seeing pics. Thanks.

 

I am looking for a Y-pipe part no. C38137. Other wise I have to fabricate a secondary market Y-pipe and do some welding which I don't have the tools for.

 

that is the one I installed in my '84 years ago. Had it shipped to Jet Hot Coatings where they coated it with their Sterling ceramic + silver coating to reduce the exhaust temperature. Works great. Also had the two over-the-cage pipes done. I had the front cat opened, striped, and rewelded so it looks like the cat is there, but mainly because of the O2 sensor, since the Euro down pipe shown in the image does not come with the O2 sensor mount.

 

That's it. Almost causes me to want to light up my torch, cut some pipe, and weld some in.

Two outlets from the manifold go into one and then split in to two. Connect the second outlet direct and have two true dual pipes all the way astern. Caveat, it mitht rap and an X or H pipe would help.

Or, way back, I added a 6 into one header and a longish glass pack to my 69 Toyota Land cruiser. It's similar sized six sounded nice.

Jose:

Why is the XK engine quiet as to exhaust tone. I've noted in past critters, that raising compression creates a sharper bite. And, of course displacement. Big inches bark loudly...

Carl, .

 

Jose - that is my other option regarding the CAT and that is to open it up, gut it and reweld it. It's rattling when I shake it anyway, so I think it's toast. I don't have an O2 sensor so that's not an issue. That would be my most inexpensive option moving forward. However you say that it won't make much difference gutting it and still leaving the other four stock silencers in place? Will it still heat up with it gutted?

My other option as I mentioned previously was to remove the CAT altogether and install a Y-pipe like the Cherry Bomb 429825 below.

 

1. Old tech lives on. Gutting the cat is similar to what we used to do with mufflers. Cut them open remove the guts and weld them back. As for the gutted cat, it might make a smidgeon of difference as to sound. It will no longer get "cat hot". It is no longer a cat, merely an open chamber, ala gutted muffler!!!

2. If the cat rattles, it is done for. Dump it for the Y pipe or gut it. It isn't cleansing the exhaust any more.

Carl

 

That's what I thought - I'll gut it - cheapest way out. It's no good anyway. To keep things on the cheap, the next thing I'll probably try is to eliminate the front most silencers with a straight pipe and see what that does. I'm about to spend $5,000 on a paint job so the bills are racking up.

 

Carl I don't know why the 4.2 engine is so quiet. Compared to the 3.8 engine which likes to growl even with the 5 muffler factory-spec system that I installed.

Yes, 5 mufflers, identical to the XJ factory system but with an additional silencer at the front of the Y. Loud like an old Jaguar from 1952.

when the car reaches 82-83 mph, the engine and exhaust become almost silent. The "sweet spot" I guess.

but the XJ is always quiet if not silent.

Note that the stuff inside the front catalityc is very toxic. I had my mechanic open it up then he gave it back saying "You clean it then bring it back, I'll seal it". So I did it underwater with gloves. There is a honeycomb mesh bag inside with platinum and I don't know what else, but it is toxic. The bag is spot welded to the inside of the canister.

Since removal of the cats, the engine exhausts better and runs cooler. Less obstruction.

 

I've arranged to bring the CAT and Y-pipe system (as pictured above) to my muffler guy tonight and he's going to perform the lobotomy on the CAT. So I hope he knows what he is doing, but I'll bring up the warning anyway. Thanks for the insight. I'll only do one thing at a time.

 

tell him to pressure test it after rewelding it to eliminate any leak.