Shoestring Budget Exhaust advice/ideas please

[MikeT]

I currently have two leaks at both ends - manifold to downpipe (gasket kit ordered) and rear box seam split.

The centre section is mint but it's got a restrictive cat in the middle

What (cheap as possible) options are available to me? I'd like to improve gas flow immensely.

[XantiaMan]

In my opinion, the actual exhaust diameter is not bad at all, looks to be 2.25 inch, obviously on earlier models no cat, mine has not cat just the single back box and i think apart from removing your cat, you would be wasting money in this area if looking for power. Far better to modify the induction side of things, although again, for a O.E set up its not bad at all, i would just give it a better cold air feed and free flowing element (not a cheap one that flows the dirt through)

[MikeT]

Far better to modify the induction side of things, although again, for a O.E set up its not bad at all, i would just give it a better cold air feed and free flowing element (not a cheap one that flows the dirt through)

I'm mildly confident induction won't be a problem.

[KP]

The OE induction route seems quite long and the IC is quite large so maybe a water misting spray on the IC would help a bit to bring charge temps down for you?

The exhaust is best to just get welded up and get the cat section cut into, knock its guts out and weld it back up

[MikeT]

Sorry, what is IC? Intercooler? As I said, induction is not a problem, it's the gas flow out the exhaust I want to improve (if possible). Yes, was thinking of either removing cat internals or cutting it out and slipping on a piece of pipe but with the latter, would I be accelerating corrosion?

[davek-uk]

I have similar problems to you. At the moment I'm running with a cat but no rear silencer.

The history for this odd arrangement is:

• rust hole in rear of cat pipe - cut out and replaced by mid-section pipe
  3 months later I decided I wanted to decat so I ordered non-cat full front pipe
  The day I ordered it the front pipe rusted off the silencer!

Temporarily, I threw away the silencer and fitted the old cut off mid section in to replace it.

Now my observations aren't scientific, but low rev running is slightly better and high rev running has freed up a lot. The noise is bubbly but no where near as loud as one of those silly exhaust boxes.

Over the weekend I'm going to fit the decat pipe and see if I can still run without a silencer. I'd much rather have a free flowing exhaust made up of two pipes (£16 and £7 - ex VAT, ex delivery) than having to buy a £50-60 silencer!

[KP]

Since fitting my new backbox as the old rusted off at the joint and i know why know , i can feel the engine being more larthargic and slower to pick up where as it used to spin quite well. when i get the free cash ill be buying one of the de-catted front sections possibly just from a scrappy and leave it be as the back box is restrictive but i wont spend much money on it other than maybe buying a cheap universal one to replace it in a years time if i haven't killed the car off by then

IC is intercooler yes

You could junk the lot and use the front pipe with some other bits and weld up a side exit exhaust?? very flee flowing

[handyman]

Intrigued by the comments about cutting out the innards of the cat. Does this affect the emissions on your MOT test?

I have always thought that cats were restrictive to engine efficiency, hence using more fuel to produce the same power. Engine manufacturers fail to tackle the problem where is exists - in the combustion chamber.

Handyman. IKBA

[MikeT]

I'd much rather have a free flowing exhaust made up of two pipes (£16 and £7 - ex VAT, ex delivery) than having to buy a £50-60 silencer!

You can get a proper silencer for about £27+VAT from Euro Car Parts but can you tell me more about the two pipes you've quoted? Is it legal to not have a silencer? I'd prefer a quieter exhaust but I'm used to the excessive noise of mine blowing anyway, just don't want to sound like a chav with those rediculously huge bore silencers.

You could junk the lot and use the front pipe with some other bits and weld up a side exit exhaust?? very flee flowing

I do like the idea of "different" and that surely is, but without the tools to fabricate my own, I'm after the simplest solution - premade bits that just fit. But again, how legal is it and will it pass the MOT?

[MikeT]

Intrigued by the comments about cutting out the innards of the cat. Does this affect the emissions on your MOT test?Handyman. IKBA

I've read on here that diesels don't need a Cat for the MOT and as I'm using veg oil, the tested-for emissions are greatly reduced as well. Interestingly, my petrol Ford has a Cat and the internals disintegrated prior to the MOT yet I still got a pass (though I noticed I didn't receive the emissions printout with the MOT )

[XantiaMan]

Water spray to the outside of an intercooler doesnt really work, i know, i've tried it on other cars and measured no difference in inlet temperatures. On the Xantia we are lucky, having a front mount as standard, where as other cars with the XUD9TE have a top mount which suffers from bad heat soak.

Removing the guts of the cat will work, MOT is done on visual smoke and if the engine is in good shape will pass regardless. Petrols you would have more of an issue with.

[handyman]

My query was regarding the cats fitted onto petrol engines primarily, as I know the emissions test looks for unburnt hydrocarbons. Maybe something worth trying on my old estate.

One of our Activas is fitted with water injection, a spray unit made in my workshop working automatically on manifold depression. All it ever requires is water. So far, I can see no deleterious effects on the induction side of the engine, but the lump does run alot smoother and there is a definite power increase with no loss of fuel consumption. If anything it is improved by about 5mpg.

I have been using this technology since the 1970s with a Norton Commando motorcycle as my first test bed. It has been used on a number of cars and bikes I have owned since then.

I do not know if it works on diesel engines, whether boosted or normally aspirated, but I am looking for another Xantia estate which may well be a diesel, so I may have the oppertunity to try it.

Handyman, IKBA

[KP]

Spraying water onto an IC isn't going to cool it that much. it needs to be a very very fine mist, ie the kind of nozzle that an aquamist system uses to inject water into the inlet tract. something like a .5mm nozzle, one either side of the IC would do it and it will bring down inlet temps. ive seen the stats before but on a Fiat Coupe 20vt. the engine bay is more cramped so they suffer from heat soak more but if you want to keep you inlet temps down its either that or a chargecooler setup, which again reduces airflow.

Another way to do it is to remove the IC and the pipework and use an aquamist system instead and keep it full of water and maybe mix in some meths to help thus more

[citronut]

GSF do the front pipe with no cat just staight through, this section goes from the manifold to the rear box and fit saloons and estates properly, as its the pipe listed for non cat cars, i have fitted one to my R reg 1.9TD estate and it gose much beter now GSFs pat No. N21052 £36.50 +vat
regards malcolm

[KP]

Do 2.1tds use the same pipe at all or is it different for the different turbo thats fitted to the cars?