[duncanbanana]

Quote: Originally Posted by TallAndy

A heavy right foot?

Being driven hard from cold?

I did all that before i got the Manifold and my Standard one is fine

[Damo]

Glad all is sorted Problem with posts (and text messages and emails and...) is things can so be easily taken the wrong way as their is no body language to back up the way its meant to come across.

Talking from experience there

[Rickys'S]

I feel as if i should pipe in on this one guys.....i have one of the most highly tuned mcs,s out there and have destroyed 3 cats now, which is caused by the backfires, I have destroyed 1 GTT suplied one and 2 aftermarket 100 cell items that i have made to fit, what tends to happen is that the middle core gets hot and bends then the back pressure builds and restriction gets worse.

I must say i think we are lucky having the GTT one because we can remove the cat for inspection, milltek and even the new JCW items are all fixed so you will never be able to see the manifold side of the cat to inspect it.

Food for thought hey.....i bet there are loads of cars out there running around with a 30% bloked cat, i even might cut the standard one up now and see, all our cars backfire on the over run even from new so will have a look next week and then re-weld it back up!

I too got excellent servive from John at GTT at the time and we reached a good deal to get my car sorted....I now run a de-cat pipe between re-placing the cat but soon will be running de-cat for ever...*** it MOT time is another 18mnths away!

On the milltek front...i ask you this,whats the point in having an exhaust that has more back pressure than standard, uses stainless but is mig welded and burns your areo kit away also rattles and leaks on the joints....when running 230bhp plus blows your ear drums at WOT all for £400+ great hey!

I know all this because i have spent the money and tried it, i have better results with standard cat back and the GTT header/de-cat combo...the dyno plot is in my gallery!

The only thing is im quite gutted that Roland has no producd another bigger/better header/cat combo and i will have to spend £££ to get it!

Hope this does'nt upset people but this is how i see it and urge people to check their cats if you can, opened a can of worms i think

[Mike Edwards]

Interesting.

I asked JCW about the possiblility of flashing my ECU with one of their higher output maps when they were fitting the Works kit.

They said it would melt the standard Cat - but if I was interested in the JCM manifold and Cat (which has the Cat where the standard centre box goes) then it might be possible.

More boost and a remap to suit is likely to fry the standard cat it seems, so maybe damage to a cat that sits in roughly the standard position isn't all that surprising if you've done anything more.

[duncanbanana]

Quote: Originally Posted by Rickys'S

On the milltek front...i ask you this,whats the point in having an exhaust that has more back pressure than standard, uses stainless but is mig welded and burns your areo kit away also rattles and leaks on the joints....when running 230bhp plus blows your ear drums at WOT all for £400+ great hey!

I suppose its each to their own , the only problem ive had with my Milltek was the cat failing and its been on my Mini for 2 years
The Milltek i have on my car is the original one ie the cat back comes in several parts instead of the 2 parts it comes in now , it was a bit of a bugger to put all together but its stayed solid for 2 years , the beauty of it is that the tips can be moved in and out and up and down , so if it does catch the skirt it can be moved down easly without adjusting the exhaust mounts
Anyway maybe so called sports cats arnt up to the job after all and like someone said have the cat where the centre box is ? Could this solve the problem?

[duncanbanana]

I must appologise for going on but im just curious why all these cats have failed and is there a solution to it without loss of performance

[Rickys'S]

Quote: Originally Posted by duncanbanana

I suppose its each to their own , the only problem ive had with my Milltek was the cat failing and its been on my Mini for 2 years
The Milltek i have on my car is the original one ie the cat back comes in several parts instead of the 2 parts it comes in now , it was a bit of a bugger to put all together but its stayed solid for 2 years , the beauty of it is that the tips can be moved in and out and up and down , so if it does catch the skirt it can be moved down easly without adjusting the exhaust mounts
Anyway maybe so called sports cats arnt up to the job after all and like someone said have the cat where the centre box is ? Could this solve the problem?

Does yours leak at all, Rattle, or overly loud?

Hope im wrong...also check your cat after 1 track day!

I have'nt had a cat that has lasted on my car longer than 2 months, maybe they are up to the job but not with back fires!!

I think that everyone has the same probs, its interesting that jcw has moved it to the middle now and also has admitted there is a prob!

[Rickys'S]

Quote: Originally Posted by duncanbanana

I must appologise for going on but im just curious why all these cats have failed and is there a solution to it without loss of performance

Yes run a de-cat pipe, its illegal but re-fit the cat for mot....wrong i know but no worries and no lights on dash for 300 miles or so!

Then clear the light with the peake scan tool!

[duncanbanana]

Quote: Originally Posted by Rickys'S

Does yours leak at all, Rattle, or overly loud?

Hope im wrong...also check your cat after 1 track day!

I have'nt had a cat that has lasted on my car longer than 2 months, maybe they are up to the job but not with back fires!!

I think that everyone has the same probs, its interesting that jcw has moved it to the middle now and also has admitted there is a prob!

No it doesnt leak rattle or too loud , im actually removing the centre box to see if this will make it a bit more louder
I dont do trackdays
My car has run with emmision lights on for 3 months now due to failed cat and my MOT is due at the end of March so cant run with a de cat pipe (my car is 3 at the end of March)
Ill speak to my mate about maybe moving the cat further back to where the centre box is to see if that could cure the problem,
This just cant be a Mini problem surely , there are plenty modded cars about which pop and blow flames , maybe they are all de catted lol

[TallAndy]

I bet they all are de-cat Think you've just found the key to the global warming problem

[roland2003]

Duncan The Janspeed/GTT lifetime warranty is not just for corrosion (a worthless warranty on something made of stainless steel IMO) but covers the all important manufacturing & material defects too. NB I am taking the Miltek details purely,from the quote Andy put up from Miltek.

SPORTS CATS EXPLAINED (any brand)
Two problems firstly due to the reduced number of pores (ppsi) neccesary to reduce back pressure and gain power ,the 'cleaning' efficiency of the cat is often down on stock to start with ,therefore it has less headroom before wearing out from contamination. TBH you could get a fault code that tells you your cat is operating below STOCK expected efficiency ,yet is still well within mot legal limits ,so is actually still ok! Also dont confuse emmision light with cat failure ,emmision light comes on due to excess emmisions before the cat .(another topic but in short it can stay on all day every day and effect nothing)
Secondly the backfires you get on fast gearchange at 5000rpm ,can cause physical damage to the cat. With stock cat back system it is muted but still there. One big back fire has immense force and can 'wreck it in one'.
This is a good reason alone for having seperate cat. Another thing that will help is using a larger diameter cat. This will be much less inclined to fail than the 4.5" diameter cats others use as theres more core (surface area) to clean the gasses. Also backfire damage should be reduced due to increased area for the pressure wave to pass through. As a final bonus less back pressure gives potential for more power.
The new GTT Mk2 cat/manifold has a surface area almost 70% bigger than any other, (pi R squared) thats a lot more! Finally even the stock upstream metal cat melts on some highly tuned Minis.
Ricky -
the 'fat cat' part of the new system should be available as an upgrade for people with Mk 1 GTT manifold
Regards Roland GTT

[duncanbanana]

If remember isn't there a narrowing of the pipe before the cat on the standard manifold?Flame retardant?
I thought id read somewhere this is to stop any damage to the cat, but narrowing the manifold isn't good i guess
the Milltek cat isn't 4", well mine isn't , its alot fatter

[roland2003]

That flame retardant is another cat (metal and very restrictive 500-600ppsi?). And yes these melt or bend over too!). Actually stock cats and most aftermakets (inc miltek) are approx 4.5" dia. (not 4") .They look bigger so you need to get the calipers outto measure . The new GTT item is approx 28mm up on that .
Regards Roland GTT

[KLF]

Quote: Originally Posted by duncanbanana

No it doesnt leak rattle or too loud , im actually removing the centre box to see if this will make it a bit more louder
I dont do trackdays
My car has run with emmision lights on for 3 months now due to failed cat and my MOT is due at the end of March so cant run with a de cat pipe (my car is 3 at the end of March)
Ill speak to my mate about maybe moving the cat further back to where the centre box is to see if that could cure the problem,
This just cant be a Mini problem surely , there are plenty modded cars about which pop and blow flames , maybe they are all de catted lol

Hey i have'nt been on here for a while, how you doing dunc's ?

Yeah soo i have the milltek manifold + cat back, and the emission light is on all the time now! had it checked at dealer (£60 !! ) they reset and just said it could be to do with the map ... but came back on within a week.
Had my MOT at the end of January with light still on and it passed the MOT Emission limits no problem at all so have no idea whether there is a problem with it or not ?? it does rattle a bit and is loud when you put your foot down but seems to go ok.

Chris

[duncanbanana]

Quote: Originally Posted by KLF

Hey i have'nt been on here for a while, how you doing dunc's ?

Yeah soo i have the milltek manifold + cat back, and the emission light is on all the time now! had it checked at dealer (£60 !! ) they reset and just said it could be to do with the map ... but came back on within a week.
Had my MOT at the end of January with light still on and it passed the MOT Emission limits no problem at all so have no idea whether there is a problem with it or not ?? it does rattle a bit and is loud when you put your foot down but seems to go ok.

Chris

Hi Chris long time no see, hows your Mini ?
sounds like your cat has gone too mate .

[KLF]

Quote: Originally Posted by duncanbanana

Hi Chris long time no see, hows your Mini ?
sounds like your cat has gone too mate .

Ok yeah, its been fine since last summer no problems... well at least until you guys started talking about broken cats !! hehe It goes well so i may just leave it for now

Chris

[RedUn]

just read through this thread now, personally I don't think there are any sports cats out there that will stand the abuse a highly tuned mini engine gives them when they are sat so close to the engine!

if i was going for a manifold again i'd go for the works one with the cat mounted in centre section or go decat like I have now!

just for info the cat on my car was completly knackered after 5k or so hardish miles on my car, this was a metallic racing cat rated to over 450bhp!

don't get yer hopes up of cats lasting people they will only get blown to bits after a while.

[TallAndy]

This is true mine was nowhere near as damaged as yours, however no-one still has any real ideas on how the flexi joint was damaged on my manifold...

The flexi is practically right next to the side of the cat that was damaged facing towards the header.

[RedUn]

Quote: Originally Posted by TallAndy

This is true mine was nowhere near as damaged as yours, however no-one still has any real ideas on how the flexi joint was damaged on my manifold...

The flexi is practically right next to the side of the cat that was damaged facing towards the header.

my guess is the flexi isn't good enough quality to cope with the amount of back pressure that would of resulted from your damaged cat.

[TallAndy]

It does my make me extremely tempted to get the Janspeed de-cat pipe, and then stick the CAT back on at MOT time