Just installed a mongoose would like to gut the cats, UK SPECS tt 105K, providing this adds to performance? turbos seem to be ok, though you never know....! just passed the M.O.T. I've been told the cats have collasped can they be gutted and still pass the M.O.T? passed emmissions with flying colours , if the cats can be gutted whats the best way to do this? Is this worth it? I don't really see a significant difference in performance with the mongoose, however this is the only mod.

any help appreciated

rob b

How much was the mongoose? i want one too, also where stocks them?

got it through my mechanic payed £450+vat 5 something. Check out cybercraft same kind of prices, anyway I'm happy with my choice good luck.

rob b

hey m8,i wouldnt of expected you would notice any improvement in performance.you could probably do with an after market air filter/induction first,and then i expect you would really notice the difference ,especially if ya gut the cats!

you have just put an exhaust on to help release more air pressure,but you aint got more going in to start with,i'd nuy a new filter.

also if ya car has done that many miles,ya turbos wont be in the best condition and would probably blow.some people have been ok tho ,ask mac1,his are fine and i no his turbos have done a few miles,its up to you??

hope this helps jay

GUESS I need to know if gutting the cats leads to turbo problems? or does collapsed cats aid this anyway? if not could I gut the cats, if so how and what is the best way,

thanks rob b

ps

anyone else who replies so soon needs to get some sleep

Originally posted by rob29:

GUESS I need to know if gutting the cats leads to turbo problems? or does collapsed cats aid this anyway? if not could I gut the cats, if so how and what is the best way,

thanks rob b

ps

anyone else who replies so soon needs to get some sleep

It can cause your turbo seals to leak I paid £200 for SS decat pipes and £430 inc vat for a Mongoose from

http://www.grasshopperprosport.co.uk/Pages/Home%20and%20About.html 2 years ago.

now I am going to sleep .

 

 

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You will notice a definate difference in performance, as the car will spool up alot faster than normal.

You can gut them but you might aswell get replacment pipes fitted.

A turbocharged car wants the least backpressure it can find regarding the turbo.

std pipes have an egr connection point whereas decatt pipes dont. butb the egr system is crap anyway so who cares.

Actually, that depends on the age/model of the car. Mine didn't have them.

Collapsed cats are not good, infact *i have read* (so dont quote me ) that collapsed cats are worse than just having fully working cats. Probably.

hehe

 

But seriously, Id have it looked at collapsed are certainly doin you no favours.

 

[This message has been edited by Ay3388 (edited 02-07-2002).]

Don't know much about this. why are collapsed cats worse than,lets say no cats at all or working cats? couldn't I just open the orignal ones take eveything out and weld back? or just replace with new cats car has 105k stock turbo's

thanks

rob

OK, well im not *too* sure, but i think its something along the lines of the air can only flow through the *cat stucture* (if you get me) in one direction (exhaust exit direction obviously hehe), but if the material has collapsed...then it wont allow airflow though as *easy* as cats would (theres a contradiction) hehe. So would increase backpressure more so.

But yes you could open it up take the shit out and put it back together, there will be turbulence caused as the air 'mass' expands to fill the cat box, and the mass if forced back into the pipe again at the other side, how noticable this is i dont know.

 

Maybe best to get new (or second hand, good condition) cats, its a gamble that if you take the cats out on older turbos, then the backpressure will decrease too much and cause the seals to fail, but it may not, is it a risk you are willing to take? Its up to you...you may find that the collapsed cats may have degraded performance *so* much, that you just thought you were getting used to the power of the car, so cats could put performance back to normal.

In any case, collapsed cats are doing no good, cos they are broken, and i dont know of many broken things that work just the same as when they are 'new', heheh.

regards

 

[This message has been edited by Ay3388 (edited 02-07-2002).]

cheers mate any idea how much a new pair of cats will cost? if thats what it takes to try and preserve the turbos then thats what it will be, don't need me turbos goin

rob

Unfortunately Im not the best person to ask about 2nd hand (or new for that matter) zx parts, but Im sure someone will come to your help soon!

Its not like the performance of the car really requires de cats, I mean, it is nice to have probably that little bit more power and earlier spooling turbos etc. but I mean, its fast enough as it is!

If you want to add performance to the car, save the money you would have spent on decats and get a pukka driver training course, that'll make you faster than any decat pipes ever will

Assuming you havent already done driver training courses ehehhe

 

Just post up about the cats, or maybe someone will see this and post in here.

regards

when the cat collpases it constricts the flow of the turbo and causes waaayyy to much backpressure.

I would personally decat it as the performance gains are well worth it, and so long as you look after your turbos they wont cause to many hassles.

cheers I seem to be getting a lot of different views? should I just de-cat the original ones I have on right now? would be cheaper

rob

in my opinion decat them.

but then if you want a spare exhaust so can put them back on ect.

it makes the car very loud though.which can be a good thing or a bad thing depending on how you look at it.

Sorry, hope I havent confused you, 300z confirmed what I thought re. increased backpressure.

I just meant its up to you if you decat / remove the cats, or put on replacement cats.

I have seen stories of smoke caused by seal failure after decatting. but then people do post these stories up, but not the ones where they de cat and the is still no smoke! hehhe.

If you are happy to buy decat pipes then go with 300z's views, he has more experience of zxs than me! (read, actually has experience of 300zxs hehehe)

Might be wise to have a 2nd set of cats pipes in case MOT time.

As far as you are concerned with decatting, you may as well see how you like it by gutting the ones you have on now, cos they are knackered anyways. Then if you like it (sound, quicker spool up etc) then buy decat pipes, which are better if you want to remove cats.

A mate of mine removed his and was told "if your car smokes the cats can clean out the smoke, as it were, so when you take out the cats all of a sudden your car smokes, as in visibly, and people assume it was the removeing of the cats which causes the smoke..

A mate of mine removed his and was told "if your car smokes the cats can clean out the smoke, as it were, so when you take out the cats all of a sudden your car smokes, as in visibly, and people assume it was the removeing of the cats which causes the smoke..

 

nope, cats wont clean any smoke. in fact if your engine is smoking, from burning oil or overfuelling for example, then this will actually destroy your cats. they are quite delicate things really and only convert Nox, HC & CO (harmful)into O2 H20 CO2 & N2(not so harmful)

 

heres a basic explanation:

 

The Reduction Catalyst:

The reduction catalyst is the first stage of the catalytic converter. It uses platinum and rhodium to help reduce the nitrogen oxide emissions. When such molecules come in contact with the catalyst, the catalyst rips the nitrogen atom out of the molecule and holds on to it, freeing the oxygen in the form of O2. The nitrogen atoms bond with other nitrogen atoms that are also stuck to the catalyst, forming N2.

 

 

The Oxidization Catalyst:

The oxidation catalyst is the second stage of the catalytic converter. It reduces the unburned hydrocarbons and carbon monoxide by burning (oxidizing) them over a platinum and palladium catalyst. This catalyst aids the reaction of the CO and hydrocarbons with the remaining oxygen in the exhaust gas.

 

 

 

 

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I feel the need, the need for speed!

 

yep gutted my cats and no noticable noise increase in the exhaust, but performance deffinetly better i had new turbos fitted first though and they were double ringed 2 seals because of back pressue, have u ever seen inside a cat??? its a really long matrix that lets air pass through JUST!!! but if yours has collapsed then its deffinetly restricting air flow not good. if u dont like the idea of gutting them then u better get some other ones to replace your damaged ones!!!!

thanks for all your advice mmmmmmmm....! now I don't no what to do, first thing is I don't want to start replacing turbos£££££ so I might try gutting then see how that goes then if to loud replace them. The car just passed emisions with collasped cats, thus could it pass with no cats at all? guess its worth a try sometimes the car does feel bit heavy,i.e. slugish in the low gears.

cheers rob

ups forgot, whats a tail tail sign of turbo seal failure, is it smoke?. I use optimax and don't have any smoke with the engine cold or hot, the reason I ask this I don't want to start gutting the cats and then find the seals have gone, or does gutting the cats facilitate turbo seal failure

cheers rob b

im not convinced of this seal story. I think there are many guys who run around without cats and have no problems.

 

All the cats are doing is concealing the smoke, then when they come of its all of a sudden because you took the cats of and the seals went bad?

Is there any documented proof that this causes these seals to go bad, and if so are there any links to it?

cheers mate me think I'll just gut the cats see how it go's

rob b

ok so I've decided to try and get some pipes to replace the cats, I've just passed M.O.T so I thought I'd replace with new cats nearer next years MOT, so does anyone know anywhere for cheap staight through pipes to relace the two main cats?

Thanks rob b