Retro fitting a CAT?

[Kevp]

MSA regs are asking for CATs to be fitted on cars newer than '99 if I understand the talk proparly. Has anyone done this yet? If so feedback & pointers please.
Iv a Stylus/Fury/Pheonix car.

Thanks

[Avocet]

I've only ever seen it done on a Ford V6 with a relatively standard engine management system back in the early 90s before they were fitted with cats. It worked quite well for a few years just having a cat stuck in it's exhaust but smelled of rotten eggs periodically! To do a "proper" cat installation, I think you really need closed-loop lambda control of the mixture as well. Keeping it as close as possible to the manifolds helps but if the mixture isn't pretty tightly controlled, I believe it's possible to start a "cat fire" under certain circumstances by chucking too much fuel in.

[BobM]

Yeah, all of us racing in RGB are having to fit cats. Have a look at some of the threads over in the RGB Forum

Most of us are just buying the cheapest, smallest cat we can find and getting it welded onto the front of the silencer can. Mine cost me £90 delivered via eBay, haven't fitted it yet though.

There's no requirement that it serve any actual function - no emissions testing etc, so no need for closed loop, lambda etc. How long a cat matrix lasts when the cars are used in anger is anybody's guess but since my Busa has 2 foot flames on overrun we all suspect not very long!

We're a bit concerned about the amount of heat generated, especially where the exhaust is within a sidepod like on a Fury/Phoenix etc.

[rdodger]

Are they going to check it has any internals?

[Comadis]

thats easy...buy a micro-cat, weld or clamp it between downpipe and silencer...and thats it.

be glad that you dont have to fit a controled cat-system!!!

[BobM]

rdodger said:

Are they going to check it has any internals?

There was some talk of the scrutes trying to stick some kind of probe up the exhaust to check it wasn't straight through to the headers but most of us have a curved exit pipe from the silencer so that will be tricky.

I do get the feeling that everyone actually involved at grass roots level appreciates that these cats are completely pointless and will do absolutely nothing so I can't see anyone getting terribly excited about checking we haven't just stuck a straight through cherry bomb on there. Unless there was a performance advantage, but the only back to back dyno test I know of failed to show a significant drop in power (well 1bhp!) with a cat and some additional 90 degree bends.

[BobM]

Comadis said:

thats easy...buy a micro-cat, weld or clamp it between downpipe and silencer...and thats it.

It isn't actually as simple as that as the cars being discussed have pretty limited space - I certainly don't have the room to just stick one in line between header and silencer. Most of us will require some form of fabrication to graft the cat into the front end of the silencer.

[Kevp]

Thanks for replies.

My Silencer is the full length of the side pod. It starts at the end of the downpipe collector, runs the length of the side pod (which is cut away) and ends with the tail bend just in front of the rear wheel.

To fit a CAT means running a smaller silencer to fit it all in. As the side pod is open I am hoping heat won’t be a problem. I guess the CAT offers the same silencing ability for its length, so the overall noise will be the same.

[BobM]

Kevp said:

My Silencer is the full length of the side pod. It starts at the end of the downpipe collector, runs the length of the side pod (which is cut away) and ends with the tail bend just in front of the rear wheel.

To fit a CAT means running a smaller silencer to fit it all in. As the side pod is open I am hoping heat won’t be a problem. I guess the CAT offers the same silencing ability for its length, so the overall noise will be the same.

Here are a couple of pics of RGB cat installations:





I think the only way Al got away with this one is because he seems to have a very small silencer:

[Kevp]

Thanks Bob for your input.

I understand the regulation applies to cars newer than 2000. Mine is a '98 but not registered until after the '00 date. So I am unsure if I will need one, but dont want to turn up at my 1st event to get sent home.

Thanks again

[BobM]

Kevp said:

I understand the regulation applies to cars newer than 2000. Mine is a '98 but not registered until after the '00 date.

Hmm, I would suggest that so far as racing is concerned when it was road registered is irrelevant. Can you prove it was first created in '98?

What club/series you planning on racing in? Maybe worth speaking to someone from the club?