I'm looking for some advice on fitting a cat inside my exhaust can.

I've taken my can apart, and the pieces are shown in the photo alongside the cat, shown standing upright. Its a standard re-packable can.
My original plan was to chop a length from the perforated tube and weld the cat in its place, slide the assembly back into the body, repack it and rivet on the end cap.

There may be a flaw in my plan however. The perforated tube simply slides into a flared 'inlet tube' inside the exhaust can. Its a tight fit, but I'm worried that exhaust gasses may escape around my cat rather than go thorough it!

I hope my extremely rubbish sketch does a better job of explaining than the words above, but keen to hear people's thoughts on the arrangement. Think its unwise to rely on a push-in connection to channel gas through the cat? One alternative is to disassemble the can a little more by grinding out welds the welds and welding the cat directly to the inlet tube.

Jek






[Edited on 30/4/12 by JekRankin]

Can you not turn the can round 180 degrees and weld the cat inbetween the perf tube and the rivet on end part, so you can push the whole lot in one go with the cat at the front end of the can (assuming the tail pipe will go into either end of the can)

I did consider this, but I couldn't get a torch in to weld the cat onto the rivetted end. I'd need to grind out the welds between the cone end and the the inlet/outlet tube, weld on the cat, then weld the tube back into the cone end. Might be the best way to do it however.

[Edited on 30/4/12 by JekRankin]

Can the flange not be heated and adjusted with a pair of mole grips to lose the flare ?


I would be looking to cut the end out of the can, staying with the pipe diameter, weld on the cat then slide it back in and weld it up.

I would take out the inlet tube and weld the cat to the cap and use the cat inlet as the inlet for the silencer.

or mount it externally like me........

Designer, I think you've figured out the best way to do it - using the cat as the silencer inlet simplifies things and maximises the length of perforated tube for silencing.

I did look at having an external cat, but unfortunately I don't quite have enough room.

Jek

Haha! Might just be enough to distract the IVA man!

Cat now welded in place. I could have opened up the hole in the silencer inlet end some more and moved the cat forward a bit, but I was worried about welding so close to the cat filament. Turns out they need to get to about 500degC in operation. D'oh!

Still, hopefully this will be enough to get me through IVA, after which I'll replace it with something cat free.

On that note, what's a good solution for a post IVA silencer? Looking for something light and free flowing. Current one is fairly bulky at over 7kg.

I'm thinking of doing this job as well.

Be interested to know how it all went.

Did you lose any/much silencing?
Did it get through IVA ok?
Heard there could be problems with the cat maybe getting too hot for the
insides of the can. Did this happen?

Any info appreciated

I used exactly the same cat, works very well, got the ZX9R well under limits

Where did the exhaust and cat come from?

Both came off ebay.

Exhaust was said to be from a Westfield.

Can't remember who made the cat, but it's one of those 200 cfm ones you can pick
up for £100.

Everything I have is virtually identical to what's shown in Jek's first pic - hence the interest!