need to put cats on my focus,, tonight i replaced the 3" straight throu tail boxes with cats but think its going to be too noisy (thought the cats would of muffled it more than the straight throu boxes),, so was going to build the cats onto the boxes,,


would it be quieter with the cats before or after the boxes????


wrc focus has the cat on the tail pipe....

 

A kit car I know of uses a cat inside a silencer.. Doesn't seem to be mega loud.

 

you getting it put on the road then Andy?

 

normal cars run the cats first,

and as you say WRC cars run the cats at the rear,

maybe ask M-Sport why they do it?

 

nope,,, they want it for racin!!

 

msa want all race cars cat equipped now.

A lot of the bec guys are putting them on the tailpipes and using bike ones.

They dont work like that of course, but theyre fitted and scruntineered

 

more rules

 

m-sport put the cat in the tailpipe so it dont slow the gases down in the turbo like

 

I totally misread the topic sentence of this post. i thought you meant something like this

 

they would need to be right next to each other if the cat was first would the extra heat not burn out the matting??

 

i would have thought that the silencers after the cat would bequiteter, as the cat will slow the gasses down before the silencer so the silencer would work more efficiently, however with the silencer before the cat, it would have to do more work as the gasses will be faster, however the cat might not work at the temperature needed, although being a turbo car yours might be hot enough...

 

i dont think it would matter,, the amount of air flow through the exhaust is huge so no matter where the cat is, the airspeed wil be the same
buy the biggest cat you can i guess

 

I'd hazard a guess at the CAT been on the back in a WRC car because of heat. Obviously on a normal car the EGT's are a LOT lower. On a WRC they will probably be at the right temp right at the back of the car.

Noise wise i'd imagine cat before the back box to be honest, your going to need some big cat's on there though.

I have a friend who has a lot more experience in CAT's in performance cars, something most of us quickly remove

 

Quite possibly, but if its getting really hot then its causing a restriction so it'll need to be bigger IMO

What cat's/bricks are you using?

 

i would rather the cat before the box but i think being joined to the box it will burn out the wool??

 

Above 2000ccm 90950044 Up to 76mm WRC 1279-10

 

Do you have a certain emissions target to reach? Closer the cat to the engine in normal applications= more temp=better conversion

Howver on a big power high temp race car, and may just put too much temp through it which would in effect age it and it wouldn't be as effective

 

no emission rules just needs to have one

 

Easy fix, cut open an old cat, gut it, weld it back up around your existing exhaust.

 

they check for heat thou with temp gauge

 

Gutted! Can you not try getting it ceramic coated then blag it?? It will get proper hot with exhaust pumping through it, obviously not as hot as normal but it would give you a fighting chance of talking your way out of it

 

this is what i ended up doing!!

 

 

looks good!!!

Nice integrated solution!!

You could probably sell those to loads of people

 

went for cat after as i'm sure the heat from them would of destroyed the silencers,, only worry doing that was going to be noise but is quieter now than ever,,

and the cats only were very noisy


so almost ready to head to croft tom night

 

nice one we will be there atleast put a show on and dont just rush to the front like normal

 

are you trying to say that you were expecting the exhaust gas to somehow get hotter inside the cat?

 

Andy, how do you get on with noise having just those single small boxes? Or is there another box in the system before the split?

Does having 2 make a difference even though they exit separate? I dont really understand it!!!

 

no problems with noise at race days , just some track days, its 4" system spliting into 2 x 3" side exits

 

Is there a silencer in the 4 inch section too?

 

nope