A couple weeks ago, I dragged out the exhaust system I had stashed behind the pool house, and shot a photograph of it for the "Tuning Exhaust" thread, and ever since then I've had to look at it standing against my fence every time I go into the back yard. Seeing it there made me think what a shame it is that such an expensive exhaust system is just being wasted out there like that. So, I decided to change that.

I decided to put it on SpeedDemon, my 88 coupe, and my son's daily driver. A few years ago, I deleted the forward mufflers, and replaced everything behind them with new stock pieces. The sound was a bit better, in as much as I could at least hear the car now. But, I wasn't satisfied with it, and the exhaust system leaning up against my fence seemed to beg me to put it on the car.



The exhaust system in question is a custom setup, which was originally on the 89 convertible parts car I bought back in 2008. It is comprised of 2-1/2" pipe with an H-pipe acting as a balancer between the two banks, and a couple Dynomax 17733 Super Turbo Mufflers in front of the rear axle. The pipes run under the center of the differential and through a couple 18" glasspacks, and exit through some very large chrome oval tips. The previous owner of the convertible said it was the system sold by Shafi Keisler before he sold his Jaguar performance parts business to the guy who now has The Driven Man website. The system does not have any catalytic converters, nor do the downpipes. They are not the Euro downpipes, but, have been modified to eliminate the first set of cats, and bolt up to the rest of the system. The left downpipe had been badly damaged when the convertible was wrecked, and I wasn't quite sure what to do with it.

Anyway, I dodged rain showers all day, as I removed SpeedDemon's exhaust, and began fabricating a new left side downpipe. I shot a YouTube video to document the sound of the nearly stock system I started with, and will make another of the car running through the new downpipes only (no mufflers), and then another when the installation is complete.


I also shot a few photos today, and will shoot more as the project progresses. One photo shows just how tightly the oil filter is nestled between the cat and the engine. another shows the modified downpipes, including the damage to the left one. Yet another shows the new downpipe pieces ready to be welded. A couple others show how restrictive the honeycomb inside the cats, and at the top of the downpipes is.




This is what's inside your have catalytic converters, restricting your exhaust flow.



It's been a very long day. Goodnight.

 

Busy day today. It's off to the hardware store for some stainless nuts & bolts, then mock everything up so I can correctly position the cat eliminator pipe on the left downpipe, tack that up, take everything off again, weld the new downpipe together, take a wire brush to everything, and spray it all with a couple coats of high temp ceramic paint, before installing it for the final time.

 

Looking good. I am interested in how your videos turn out. Good luck!!

 

I ran into a couple major snags, which are causing delays in the process.

1. While test fitting the new exhaust system, I discovered that when the system was originally configured on my convertible, it was built around the Richmond 6-speed manual transmission that was in the car. SpeedDemon still has a Turbo 400 automatic, and the 2'1/2" exhaust pipes wont clear the sides of the transmission pan. I'll have to take it to a muffler shop to have them bend up a couple new sections of pipe to correct this.

2. The O2 sensor is fused to the original right-side downpipe, and is impossible to remove. None of the local parts stores carry the proper sensor, so I had to order one from rockauto.com, and it should be here Thursday. Once it arrives, I'll install it in the new downpipe, and shoot a video of the car running. I'll try to do this around dusk, so that I can get it on video, if the car shoots flames out those 2-1/2" collectors at the end of the downpipes, as I suspect it might.

After that, it's a simple bolt-up operation that should take less than 20 minutes, including getting it down off the jack stands.

 

A good post, thanks. I'm reading every word! I'd like to put cutouts on my 89 xjs, like we used to do back in the 50s & 60s, get out on the open road and open them up, bet it's a sweet sound!!
Dick C.

 

Dick,

Although the setup on SpeedDemon won't include them, here is a neat kit to put electric cutouts on your exhaust. Simply push a button, and in about 3 seconds, you're running 12 cylinders straight out of your downpipes. That'll put the fear of God into the guy in the Mustang, who's romping on his accelerator, next to you at a traffic light.
Maybe I'll get one, and put it on JagZilla when and if I build a new exhaust for her.

 

I wish I could do anything in less than 20 minutes on the jags. Good luck!!

 

I know what you mean. Those downpipes had never been off the car, and they fought me every step of the way -- and because they were being modified, I had to remove and re-install them twice to make sure of fit, and alignment.

Mike90 mentioned, on another post, that doing a rear brake job on the inboard brakes is a "rite of passage" for the XJS owner. I'll say that anything which includes removing the downpipes on the V12 would qualify for that list, as would changing the spark plugs, and replacing the half moon seals at the rear of the cam towers on the V12. I think I'll start a thread on the "Rites Of Passage" for the XJS owner.

 

Great, thanks! I'll check into them.
Dick C.

 

Man...that exhaust cutout thing seems to be the thing to have, just to confuse the neighbors from one drive to the next if nothing else.

When you start your list, don't forget "removing and re-installing the exhaust manifolds". I've done it twice (well, 1-1/4 times I guess since on the second go-around I only had to remove one of the four).

I'm not sure why, but when I removed both my down-pipes, the platinum inserts on the front of both banks were beaten into the pipe (see photo). I've no clue as to why that might have been...any thoughts?

Thanks,

John
1987 XJ-S V12
64,000 miles

 

Forgot to attach pics...

John
1987 XJ-S V12
64,000 miles

 

Are you saying that you actually found them like that when you removed the pipes? Considering how tough it is to remove the stuff on purpose, I can't imagine what could have had enough force/pressure to do that with the pipes in place. That is an incredible blockage. I bet the car ran 100% better after you rectified this condition. Is there any honeycomb in place now, or has it all mysteriously disappeared, as it did in mine this weekend?

 

I just finished removing the even more complicated xj12 xj40 downpipes 2 weeks ago, took me nearly 6 hours to do it. The bolts fought me the whole way even with rust release spray. I ended up removing nearly everything on the top end to get to 2 bolts, and then I removed a bunch from the bottom including the steering rack and steering wheel linkage to get to the back bolts. The xj40 xj12 is much much worse than the xjs with cats. I can't wait to install my euro downpipes when I finish up swapping all the xjs engine parts to my 6.0, it will be so much easier.

 

86jag,
I would have thought there to be more room for that in the XJ12, given that it's a larger and wider car than the XJS. Is the motor positioned differently in relation to things like the steering rack, crossmember, etc. or are there other accessories that make the nuts so much harder to access?

 

I just posted a video to YouTube of The car running through just the downpipes. I don't think the microphone on my phone does it justice. Although it has a bit of a ragged sound, typical of uncapped exhaust, it also has that great V12 sound of the heavens being ripped asunder. once I put the car on the ground, it was even louder than when it was up on jackstands.

However, this is a Jaguar, and as such, you can never simply complete a task, without either creating or finding a problem with something else. If you watch closely at the end of the video, you'll see the problem that I must address before I can even finish the exhaust project... a serious coolant leak coming from the firewall/heater valve area. This is a real bear of an area to get at.

 

We got the coolant leak fixed much quicker and easier than I expected, and I had hoped to get the exhaust fitted, but, all the local muffler shops were too busy to work on it today. Since tomorrow is a holiday, it will be sometime next week before I can finish this project.

However, my son wanted to drive the car without the exhaust, and since he has helped out so much with this project, I thought that would be a nice treat. He came back smiling from ear to ear, and begged me to let him drive it to work just one day like that. Between the exhaust smell on our clothes, and the headache I have from the fumes, he knows that won't be happening, but, he enjoyed the experience just the same.

Here is the video of part that test drive:

 

Yes, the cat material in the down pipes was beaten down like that w/o any intervention by me...and I can't imagine why any PO would have done such a thing. I suspect it it one (of the many) mysteries of the XJ-S that may never be solved.

In any case, the blockage in both the down pips has "gone away", and it gives the engine a much richer sound.

Cheers,

John
1987 XJ-S V12
64,000 miles

 

Speed Demon with no mufflers.. I love it

3 months ago I went for a passenger ride in a P51 Mustang, and it sounds surpirisngly similar. I know they are both V12 but one is 5.3 and the other 27 litres...

https://www.youtube.com/watch?v=JbKN...ature=youtu.be

I am tempted to buy an X300 6 litre and fit cut outs.

 

AL NZ,

That was a cool video, althoguh a short one. I would love to have seen a bit more from higher altitudes. I got to go up in a lot of different aircraft back in my Air Force days, but, never anything quite as old or as cool as a P51.

 

I believe the main issue is that the engine bay was originally designed to not except a V style engine and it seems to me that they widened the engine bay only enough to fit the motor in. There is no way to get your hands between the motor and the walls of the chassis, between the front wheels. The front suspension subframe is also larger, and located slightly rearward compared to xjs.

See pic of empty engine bay https://www.flickr.com/photos/962632...7645102436510/