cataclysmic convertors

what would the downfall be to eliminating my catalytic convertors completely. would it mess up the environmental control system? I just think my jag would breathe easier without them and also reduce the risk of the fire if one of the coils go bad. plus I want cut down the air intakes and plumb them out to the front of the car for cold air as per "the book" any problems other than relocating the sensor on the left hand air cleaner? thanx again for all your help. you guys gave me the confidence to work on my car instead of shopping it out because I know if I run into problems I have a whole group of guys that have "been there done that" to help me through. thanx again,
Jarrod

What model of Jag do you have?

The main problem with removing the converters is if you have to have your car tested. While some cars will pass without the converter, many won't. IN addition, some states have a visual inspection.

Jarrod, depending on what year your car is, you may be exempt from emissions testing. If it's older than 1980 in the counties that have E-check, then you can get away with removing the converter. If it's newer, they usually look underneath with a mirror to see if everything's there. Or, if you get collector's or historic plates then I'm pretty sure you are automatically exempt, as long as it isn't your daily driver. I took it off my Midget since it was directly below the carburetor and made things wickedly hot under the hood.
-Dave

The testing problem(s) have been adequately addressed. The result of removing them is the car will run more efficiently and get better mileage due to reduced back pressure. I have had the converters off of my XJ6 for years and it has been a great performing car. Alabama does not have inspection (yet). If your are serious about this conversion, the best method is to obtain European exhaust system componenets to replace the catalytic piping. I got my parts from Coventry West years ago. A lesser method is to remove the converters and gut out the materials that form the conversion screen. That way you cannot tell that the modification has been done. The car will flunk the EPA testing however if checked.

sorry all it is a 1990xjs v12 I don't have e inspections in my area yet, I was just wondering if it would mess with my emissions computer and throw off the motor.basically are there sensors that are going to notice that the convertors are gone?

Jarrod, In the XJS V12, the Oxygen sensor (lambda) is up stream in the exhaust from the catalytics. A malfunctioning converter or lack thereof cannot effect the oxygen sensor or any other emisssion sensors in your car. You could use European exhaust pipes without catalytics with no check engine problems. As a matter of fact, I dont think that a bad oxygen sensor keys the ECU fault sensor! Best regards,

thank you sir for the info, those converters are gone, next stop Coventry West!!

If Coventry West cannot supply the European down pipes, you can do surgery on the existing down pipes and still keep the oxygen sensor or, as I said prior, you can "gut" the existing catalytics (in the case of XJS, four of them).

Pauls Jaguar in florida sells the european down pipes. This makes it a bolt on change, and you can keep a good set of cats around in case of future need.

Good information Jesse. Thats is the way to go!!

thanx Jesse and John, I'm going for the bolt on route

hello folks; in my 1984 XJ-6 I pryed open and "cleaned" the guts out of the front cataclysm, then had it re-welded and pressure-tested. I also eliminated the "Y" pipe and its secondary cataclysm (the one located under the driver's floor) by replacing it with the European-version of the "Y" pipe, since I was told the car will pass inspection without any cataclysms. It has passed the last three years. They do a visual as well, but since the front is still "there" technically speaking, it also passes the visual. The only complaint I got was about the fuel-filler Seals in each filler door, which I replaced. There has been no damage to the emissions system, in any case the engine breathes better and it responds better and faster, fuel economy has increased. I get about 540-550 miles on interstate long distance driving, at an average 70mph, out of the two tanks. I would say that is very decent mileage. Since I had dismantled the exhaust system, I ended up rebuilding the entire system front to back, sending the new "Y" pipe and the two old, over-the-axle pipes to Jet Hot Coatings, where they coated them with their Sterling (silver and ceramic) coating. They claim reduced exhaust temperatures and rust protection. The parts don't have to be new to get coated. I also used stainless steel Band clamps and bolts/washers throughout. "U" clamps crimp and deform the pipes where they join, so I refuse to use those. No parts were welded together, I used Permatex Exhaust Adhesive in every union, (the equivalent of Firegum, which is not available in the US), quickly clamping as I went. No leaks! The mufflers I found in stainless like the originals, n.o.s., beautiful parts. Now I don't want to use the car so it doesn't get dirty underneath!

here's a picture of the European "Y" pipe and the transmission-to-Y-pipe Clamp which most XJ are missing by now. The clamp is important for exhaust system stability.
I have seen many XJ without it.