Sorry but I have a CAT question

[RobC]

I have a 100 cell universal one to go inside my silencer... but can someone please share with the class, best placement or any tips...

I am obv. aware that some people may not want to give anything away to others at to how they have fitted there's... but I need to bounce a few ideas/problems...

I have fitted it as far back as poss. however I am getting back pressure.. so it's forcing gasses out of the end cap (repackable exhaust) any thoughts...?

Don't want to end up with only 4k revs to play with...

Also how is this tested at events..?

[peterg]

QUOTE

Also how is this tested at events..?

popcorn anyone...  

maybe it should be worded "is it tested at events..."  

[CedricTheBrave]

I would have thought closest to the fanimould would have been better

[RobC]

I did do a search from 2007 and there was no real outcome as to what was the better option front or back..?

obv.. I could have it in the middle with perf. tube at the end.. but before I go down that route I thought I would ask the question...

I am ready popcorn to hand... bucket size option of coke, hot dog and beer...

Bring it on...

[stephenh]

I'm no expert on cats, but as I understand it it needs to be as close to the manifold as poss, because they only work when they get hot, so the hotter the better.

Of course, I appreciate your concern isn't so much how to make it work, but rather how to satisfy the scrute. I took part in 5 rounds of the Speed Series last year, and mine wasn't checked once, nor was I asked about it. Not sure how they would check it actually, short of insisting on taking the silencer box apart. The outlet is quite a sharp elbow, so a stiff wire or stick wouldn't reach up to where my CAT is, right at the front of my Simpson repackable. That said, I think I can see a slight heat stain (blueing) in the stainless steel in the region of the CAT, so perhaps they can see from that by looking closely.

[stewart pickles]

i had a chat with beardy (you will get to know him    )and he said the way it was worded by the msa he didn't care if it was taped to the roll bar and that it didn't say anywhere in the blue book that it had to be in the exhaust system      

blue book may have been re written since

[Paul Morcom]

Hi there,

I may be stating the obvious and you already know this but....

"Exhaust systems must include a working catalytic converter on all cars manufactured after 31st December 1999".

So if your car is Pre-2000 then you don't need a cat.

Paul

[MIKE.WILLIAMS1]

I fitted a100 cell cat inside my silencer box at the front end.Only lost 2bhp performance on a before and after test.The only problem I noticed is the stainless is getting discoulord from the higher temperature inside the silencer from the cat

[sport 2000 Dan]

Hi Rob,

I have no idea on what happens at events as i do not attend any, but from a technical point of view a ceramic monolith 3 way type cat usually operates around 600-900 degrees C and due to emmissions regulations that have stated different times over the years but basicaly state that the light off time (the temp that the cat starts operating) should be as short as possble from a cold start up which is why manufacturers fit them as close to the manifold as possible.

However.... this type of cat will melt at around 1000 degrees C which means that you have quite a small window of operation in terms of temp, espesialy when pushing it in a race car that is dumping fuel and O2 down the exhaust at allarming rates.

You need to be very careful of this because if it does melt then you will end up with a lack of power and possibly even a non-start.

Also if your universal one does not have enough flow as is possible from your description then this will also produce excessive heat.

You need to fit the correct size of cat. there are metal/stainless ect cats on the market that will reduce the temp issue but thats no good without the flow as you will still be down on power and cause excessive heat upstream of the unit.

The only way they can test for a working cat is to do an exhaust gas analysis test, i dont konw if they do this as i said but it is very cheap and easy to do.

I hope this has been of some help,

Regards,

Dan.

[RobC]

Cheers Matt...

I'm going to get the car MOT'd this weekend hopefully, so will give it a test then...

Cheers chaps

[Terry Everall]

ceramic cats appear to disintegrate. My CAT is fitted at front of silencer and reduces area for packing to silencer. At all my events last year I was never asked or had it checked. One idiot "scrut" pointed out to another apprentice "scrut" that it was in my manifold where the wire comes out!!!!!!!!!!!!!!!!!!!

That was the lamda sensor.

Waste of time effort and money  IMHO

[grahame]

I have the big standard WF stainless can on the hairdrier, it includes a catalyst. It's ahead of the perforated centre tube, a few inches behind where the downpipes enter. If the factory have decided that's where it's got to be to work, I suggest that's a good guide?

Again, it was on the car all last year, no one actually commented on it. Worryingly, the can gets very seriously cherry-red hot around it and has rippled badly. I suspect that the engine (having never been designed for a catalyst, no lambda, no feedback loop), isn't producing catalyst-friendly exhaust gas conditions. I've already left a smouldering gorse bush behind on one 'adventure'.

[Mid life crisis]

Why would the scrut's be interested? If the car is safe to compete.  I think this year getting enough entries will be most clubs main concern.

[RobC]

Sorted... Mucho's chaps