Jose most of what you wrote is opinion and you are entitled to yours but the MK2 at least in 3.4 and 3.8 models had a twin exhaust system. Just routed differently than the 'S'. As far as the styling cues on the 'S' I suggest you look at the 3.8L Mk 10 for that.

 

Hi George, long time no argue with you!!

so the S type's twin tanks, more dash wood, roomier interior, Independent Rear Suspension, larger auxiliary lamp buckets, is opinion? or is it fact?

The Fog Lamp buckets and the Fog Ranger lamps themselves in the MK-2 are 4½" inches in diameter, ;
opinion or fact?

The Fog Lamp buckets and the Fog Ranger lamps themselves in the S type are 5½" inches in diameter;
opinion or fact?

I will agree that both cars have a twin exhaust system, but the exhaust system in the MK-2 exits on one side, while the S type's exhaust exits on both sides, as a normal twin exhaust system normally does. That is my point on that.

 

No argument on my part. Most of the differences you state are superior and the market then and now does not agree but I understand your loyalty. The differences are fact but whether they are superior or not is not. Don't forget that Hella lamps could be ordered on the 'S'. Only when you posted the pictures of both exhaust did I remember that in fact the MK2 does have a dual exhaust and the 'S' has a shared silencer which also acts as a balance device. Had the 'S' not had an IRS it is possible that the exhaust would have exited on the same side as had been the standard for Jaguar until the IRS. So what do you think about the styling cues being taken from the 3.8L MK10 rather than the VW bug?

 

here's what I think happened George:

Jaguar went with the rear wheel openings design of the E type and incoporated it into the MK10, S type, 420G, 420, and the Series 1, 2, and 3 XJ.

was it a form-follows-function decision because of the IRS? or simply a standardized styling decision? I think it was the latter.

or was it that the MK-1 and MK-2 full rear wheel opening style had gone out of style?

I don't know why, but if you look at all the Jaguar models above, they all have the same rear wheel openings with the only exception being the XJS of 1975 which has strange upside down "U" shaped wheel openings on all 4 wheels.

Most Small Saloon buyers prefer the looks of the MK-1 and MK-2 styling, I think because of the rear wheel openings with the removable full or half Spats.

in my case I drove both cars before buying one, and I felt cramped in a MK-2, especially at the rear seat. I also felt the ride was "jumpier" or "harsh" in the MK-2. Then I drove the S type and I was sold, it reminded me of the XJ ride and comfort which I already had experience with.

Being one of the few, I was also sold on the look of the rear Third of the S type, because otherwise the front and center sections of the S type are almost identical to a MK-2.

 

George,

I intrigued how the balancing of the S Type exhaust is achieved in the shared silencer ?

I would have thought that the design was more basic and it was simply space saving rather than performance related.

 

So the S type really isn't a dual exhaust like the MK2?

 

I am pretty sure it is, it is not uncommon for a dual exhaust to share a silencer "Shell", they are normally straight through with baffle material, so there is no balancing between the 2 pipes in any way, but George seems to know something I don't, so I await his reply with interest.

"Balancing" is usually referred to when an H or Y setup is used, and the exhaust pulses from one bank to another actually help each other by sort of a venturi effect, and also the total cross sectional area of exhaust pipe is greater after the balancing point, so the breathing is aided by less back pressure.

This is a whole discussion on it's own, the exhaust note is actually changed and there is an increase in BHP, this setup is often used in 8 cylinder engines, but has a great effect on the straight 6 engine due to the pulse pattern being at 90deg to the opposing exhaust pulse.

I will wait for George to respond to see what he thinks is going on in that silencer box.

 

John I have no idea what modern replacements look like inside but original ones on the MK10 and the 'S' were normal muffler design with packing material. They were pipes with a thousand holes (why they rot out so quick) and the normal material. They were not a true H or Y pipe but they did share pressure (gas) and the purpose was to blend and soften the note. Otherwise they had no purpose and a long straight pipe was not unknown to Jaguar--as in the MK2. You are on to the real reason with harmonics but that could have been handled in the rear silencers but not balance the exhausts to the degree a shared silencer could.

 

George, that's not how a normal muffler works, they do not share any gas as you say, the packing material and holes are to absorb sound waves, the size, position and number of holes determines the frequency range of absorption.

Straight through absorption mufflers create little back pressure as there is virtually no impedance to the gas flow, this is different to noise cancelling reactive mufflers which resonate sound internally to cancel noise within the internal chambers.

Yes they do soften the note by reducing noise, this type has a wider spectrum of frequencies for noise reduction than a reactive muffler, but is most effective at the higher frequencies, so that is where the note is softened as you say, but they do not in anyway "blend" the note between the 2 pipes.

The type of muffler you say is fitted to the S type and which is what I would have expected simply allows a space saving above having two separate silencers other than that there is absolutely no balancing that happens, the purpose is noise attenuation just as the rear muffler does the same.

The reason these type rot out so easily is that condensation gets absorbed by the packing material through the holes, so moisture is held in the muffler and rots the box out, this is worse when short journeys are the norm as the condensation is not evaporated by long term heat in the muffler. Some mufflers have holes in them to allow this water to drip out, if there was gas pressure within the absorption material then the muffler would be leaking gas from those holes.

Header design, muffler design and basically the whole exhaust system is a whole huge subject, but the bottom line is that there are always compromises because of the restrictions in the size, shape and road clearance of the vehicle, it's a fascinating subject that covers engine performance to actually tuning the sound itself.

 

John thanks for explaining that to me>what is on those cars is more accurately described as a mixing box. The MK 10 for example has 4 mufflers down stream and none are small and there is no reason to save space yet they have a "dual" inlet silencer. It is to balance the signal and reduce the effect that a true dual system would have. No more on this from me. Drive on as you wish.

 

Of course there will be a reason to save space, the manifolds are on one side of the car, it would be quite difficult to get 2 separate boxes at the front end of the car.

Jose, can you see on your S type if there is a simple way to route the exhaust and get a separate box in where the dual box is fitted ?

As there will be no more from George, I will not know what "It is to balance the signal and reduce the effect that a true dual system would have" means ! What effect is being reduced ????

 

Jon,

I am very familiar with the exhaust system in my S type. I installed it myself with the car high on blocks and the three of us, ( Me, Myself, and I ), under the car on a trolley. Everything new from the manifolds down to the end tips, piece-by-piece. A Bell Exhausts Ltd. polished stainless steel system purchased from SNG Barrat USA.

I found the below picture from 2005 when I laid the parts to become "learned". If that is not a twin exhaust system, I don't know what is.

what is not shown in the drawing that I posted previously, are the two rear resonators that fit behind the IRS before the end tips. So to me, the S type system has (count them) 5 mufflers. Trust me I would not want a 6th muffler. It was enough work with just the 5.

What surprised me most is that the S type system is identical to the XJ-6 system in my 1984 XJ, which I also did myself. Same amount of pipes and muffllers.

So, to answer your question: No more room under the car for more mufflers!!

 

Thanks Jose, that's what I would have thought, I would imagine that the S type is quite a but quieter than the MK2 ?

 

the old original system was shot when I got the car, it sounded "blown". When I finished installing the new system I started the car to check for leaks and was surprised that it sounded like a XK-120, a low rumble sound on idling, gets more agressive as the engine is accelerated, but it quiets down at the sweet spot of 81 mph.

The XJ6 is another story, it is mostly quiet, no rumble.

 

Interesting, you called the rear boxes resonators, which may well be possible, Jag or Bell Exhausts may well have used the rear box to give the engine a rumble sound, manufacturers often "Tune" the exhaust to provide a characteristic sound, Ferrari, Maserati etc. most definitely do to achieve a sound synonymous with the marque.

 

in the XJ, the two rearmost mufflers are called resonators, so I assume it's the same thing in the S type, they are identical systems in the sense of mufflers and pipes and how they are routed under the cars.

None of the parts are welded, I used Band clamps and exhaust paste adhesive on all joins. A factory-trained mechanic who worked for Motorcars Ltd. in Texas told me "do not weld anything, Jaguar exhaust parts are never welded" so I didn't.

 

A resonator has a bigger chamber inside which resonates the sound, hence the name, these are usually designed to remove certain frequencies which is how the tuning on the exhaust sound is modified. This is over simplified, but that the general gist.

Generally no system is welded when it is fitted, although you could, but if you had to change anything then it's a PITA ! Band clamps are def the best way to go.

 

here's an updated "schematic" of the 3.4 / 3.8 'S' exhaust system from the Factory Service Manual;

I still don't know what a "Balancer" is, because if you have two pipes going into, and two pipes going out of, the first, small "muffler" after the down pipes, what exactly is being "balanced" ??

I'm starting to think that first, small "Balancer" muffler is more of an "obstruction" than anything.

 

Jose, I think it's a made up name ! I will try and find a diagram of a standard 2 pipe muffler.

They are simply 2 straight through perforated pipes, so no obstruction, no back pressure, just sound absorbing, they a simply more compact than 2 separate mufflers plain and simple.

If you had the old one, you can look straight through both pipes, the gases don't fly out the perforations, it is the sound waves that expand into the sound absorbing packing around the pipes.