Will this improve performance and sound? How many hours estimated to remove them?

1986 xjs 5.3 12

Thanks in advance!

 

If your converters are clogged then removing them should result in more power for sure. Otherwise....not so much. I gutted the cats on mine and the improvement was so slight I had to wonder if I was simply imagining it.

Removing them isn't hard, really....a bit of grunt labor in an unpleasant area f the car..... but you'll need the services of a muffler shop to make up new pipes. Or you'll need to find a set of non-converter pipes to bolt on


Cheers
DD

 

I had the cats removed for $60. I sold them for scrap for $90.
Improved exh flow and sound.
BTW my car has SBC stroker

 

I have to agree with Doug, emptied mine and I have to say any performance or sound increase was more imagined then anything, removing the mid mufflers didn't do much in that dept either.

 

The catfree models without lambdasonds have 295 bhp. With cat and lambdasond they are around 268 bhp. A simple cat removal won't result in more power as the lambdasons are still regulating the air fuel mixture...

 

Does anyone know if removing the cats resulted in improved cooling?

 

I noticed absolutely no difference. If you have cooling problems the first places to look are to remove the radiator, and more than likely the space between the radiator and condenser will be plugged with debris. Every one I have looked at has something there, some were blocking more than half the radiator.

The other place to look is proper thermostats, There is lots about that here. Just FYI, the dealer supplied thermostats are not correct!

 

no, mine cools pretty well, but i will be doing a major overhaul of the system, I just know the cats create a lot of restriction and heat and it stands to reason that removing them would improve that.

 

I don't think they do create that much restriction actually. Certainly when I removed mine I could tell no difference before and after. The only real difference was the exhaust smelled and it didn't before.

 

As far as heat, having what looks like a barrel of steel (downpipe CAT - which was 1 of 4 OE CATs that came in my 1990 v12) in proximity to (LH drive car) steering components, especially with the steering, was something I could not leave as is/was. Early on in ownership I needed to replace the steering rack,,, then do the job again, and the way that that catalytic converter was packed in there,,, well, I didn't like it.

I removed them all. Thing is, they were removed before I had my car running "right" (and I still don't) so it would be hard to report on B4 and after differences. Removing them MUST contribute to (especially in city driving) under hood temperatures and, due to the honeycomb I found in mine, removing them MUST have an impact on exhaust flow. I can't see how it couldn't.

I am DYING to go for a drive in a right running XJS just so I might have a reference point for so so many things.

I found CAT-less down pipes on eBay in the European Market with Greg's help. Cheap.

 

how bad is the exhaust smell? If it's bad, i may just leave them in, I'm only looking for a better exhaust note and maybe a few extra hp and some potential cooling improvements, but the exhaust smell might be a problem I'm not going to want.

 

I guess it smells like exhaust did before all the rules and regs...

Sorry, I don't have a link to "new" downpipes unfortunately. One leaf was provided by a great member here,,, the second required digging (which for me is half the fun of the ol girl) in EU eBay sites... It takes a little while to find stuff but it materializes eventually...

 

It was like a old car with a carb. Get too close and your eyes sting. Lets just say that I'd not do it again, as it made no difference to performance and fuel economy and made the car stink.

 

I replaced the two Cat's on each side with one several years ago. No noticeable difference in performance. However, years before that I removed the resonators and did notice an increase in performance. Nothing 'head snapping' but definitely stronger acceleration in the lower speed range.
PS...I like the throatier sound from the engine as well. With 2x Cat's on each bank, a muffler and a resonator the cars were built to be whisper quiet. I like the sound of a 'refined' V-12.

 

I gutted my cats for less heat and less chance of the car going up in flames, if you do this and delete the horrible center mufflers youll see some performance gain and better flow, better sound in my opinion.

The cars do not benefit from straight pipes at city driving speed in my experience. If you want nice proper downpipes check out https://simplyperformance.com