The Rig

iTrader: (13)

1st off, does the classic saloon 1995 have 1 cat or 2 ?

if 1, an up pipe will remove it ?

will i need to alter fuelling for the up pipe ?

whats the odds of it passing an MOT with an up pipe ?

having looked on good old ebay, i see a few different designs of up pipe for the same models,











The 1st one looks kinda standard type,but cant see a thread for the 02 Sensor on it like the other 2 pipes

joz8968

iTrader: (13)

I think the 93-96 cars have two cats as std - one in the downpipe, the other in the centre section. Up pipe is cat free.

The ones in the pics with lamda sensor ports would be for New Ages - but if used on Classics, can be blanked off with threaded metal bungs.

The most cost effective thing to do, is to get a cheap, good condition OEM one ported by harvey - will help spool the turbo earlier by about 200-500rpm, I think. Then when you get it back from him, simply swap it over (he may even sell them pre-ported ,off the shelf!).

Seeing as it affedts spool i.e. speeding up the turbo sooner, I think it would be advisable to get it remapped, yes.

rossibeater

i got 1 of those up-pipes, my standard pipe dont have the fittings for the sensors, was just going to weld them up on the stainless 1 and it dont have a bracket that the standard 1 has, dont know if its needed but gonna weld 1 on ! was told the standard 1 dont have a cat in anyway , just a smaller diameter pipe than the up-rated 1

The Rig

iTrader: (13)

cheers guys.

so the top one is an original for a classic

ive got a knock link fitted so if i do fit an up-pipe i can always leave it unmapped and see if i get any knocking etc then re-map if i do,worth a try i suppose.

if i have 2 Cats in the system removing one isnt as bad as removing both i guess for the emiisons come MOT time

cheers

joz8968

iTrader: (13)

To the OP, importnat point - don't be tempted to fit a larger diameter one as for any given volume of exhaust gases, the speed of them will be slower through the larger pipe compared to the smaller diameter OEM one. It's the fast speed of the gases that's responsible for the turbine to turn faster.

joz8968

iTrader: (13)

Yes, top pic is OEM up pipe (with std heatshielding still attached).

You should still get through the MOT emissions with just the decat downpipe (can get rid of the centre section for for a straight through pipe).

The Rig

iTrader: (13)

cheers, having a quick look at the car, it only has the 1 Cat,the downpipe Cat.

Think its UK classics that have 2 Cats, Imports have 1 ???

At the end of the downpipe on my car it has a sensor in it,closest end to the centre section

The Rig

iTrader: (13)

Now im getting confused,if those pics above are up pipes,whats this ?



its hard to get a picture of the whole exhaust system on the car without doing the work 1st but then i dont want to remove parts and have the wrong ones to replace what ive took off like !!

is the up pipe like in a 2 part section and this pic in this post is the wholesection into one ?????

rossibeater

is that true for the whole system, thought larger diameter pipes help gases escape quicker, or is it just the cats that slow gases/noise down ?

joz8968

iTrader: (13)

Yes up to a point. You want the gas speed to be as fast as possible i.e. getting it in out the engine/turbo as fast as possible. I think the standard various OEM turbo fitments are good for the OEM 2.5" downpipe/system to work upto 350bhp (maybe more?). Only after then does it become resrictive, and stall gas flow - this is when a 3" system becomes necessary.

Obviously any resriction - e.g. a cat - will slow down exhaust gas speed too. They also help silence the system. One of tha main silencers of a turbo car is the actual turbo itself! - acts a kind of silencing resonator.

The Rig

iTrader: (13)

If this is the part im replacing, the up-pipe with CAT,(standard)




How can this Up-pipe be any good ?? too short isnt it ???




Or am i missing something, getting the 2 parts confused ???

weeebell

iTrader: (1)

Yes you are getting the two parts confused. Your top pic is the downpipe, from the turbo back.

Bottom pic is the uppipe from the headers to the turbo.

Uppipe- gasses going in to turbo to help spool up

Downpipe- gasses going out of turbo via rest of the exhaust system

joz8968

iTrader: (13)

Yes, top pic is a standard catted downpipe for a Classic.

Bottom pic is std up pipe - so it's length is correct. Any longer and the turbo would sit to high and nothing else attached to the turbo would be able to fit properly, etc.

The Rig

iTrader: (13)

i get it now guys, theres 2 attachements on the turbo, all becomin clear now ha ha !!

this pic helped




so to get the best benefit, i need to fit an up-pipe AND a Decat pipe ?

Whats the best size, i see some up-pipes are 2" or 2.5" Bore

i see some decat pipes are 3" bore

would a 2" up-pipe with a 3" decat/downpipe be a good combi ?



cheers guys

joz8968

iTrader: (13)

Just noticed that the pic of the new shiny downpipe in post # 8 is for a New Age - it is slightly longer than the Classic's - notice how the last bend (centre section end) is longer than the OEM one! If you're saying that you bought that and a matching up pipe, than the up pipe might be longer than a Classic's too (not sure?), hence your question about the OEM appearing too short!

To recap, I think that up pipe and downpipe that you've bought are New Age ones, mate!

joz8968

iTrader: (13)

I think a 2" up pipe is supposed to be great for turbo spool, as its small diameter promotes fast gas speed - without stalling the gases/turbo!

A 3" downpipe is fine, but I think a 2.5" one i.e. same size as OEM helps tha gas escape faster, up to a certain point i.e. probably only becomes restrictive at about 350bhp - at which point a 3" one and system is required.

weeebell

iTrader: (1)

Classics dont have a cat in the uppipe so no need to change it.

As for the downpipe, ideally, you should be looking for a 3" openmouthed one going down to 2.5" to match your existing system.

The Rig

iTrader: (13)

cheers guys.

i havent bought any parts yet,hence all the questions to stop me buying the wrong parts, too many sellers advertise parts as classic etc but they end up being for newage,as Joz has pointed out, all the pics i have posted are advertised as CLASSIC parts, tsk tsk !!!

so i can keep the original up-pipe i just need to ideally change my downpipe (which has the CAT in it) ?


cheers again for the help

joz8968

iTrader: (13)

Yes, swapping the OEM cat d/p for a decat - and mapping for it it! - will gain you serious bhp/lb ft increases, and a responsive car.

You should get about 280-300bhp and similar torque!

The Rig

iTrader: (13)

cheers.

do the de-cat pipes have the thread hole for the sensor that goes in it ?

just lookin under the car,i see near where the downpipe joins to the centre section there is a sensor

weeebell

iTrader: (1)

Yes, a stainless decat downpipe will have the threaded hole for the sensor.

The Rig

iTrader: (13)

Guys

joz8968

iTrader: (13)

Your 1995 lambda sensor should be in the driver side header - I think? (look under the car - it should be sticking out the side). If not, then the sensor in the d/p near the centre section end will be the Lambda sensor, as per your observation. If so, then you'll need to remove it and reuse it in the same port on the new decat d/p.

Also, if the new decat d/p has aport at the top, then that'd be for the EGT 'cat on fire' sensor, which is redundant on a decat d/p - so you wouldn't have to swap that over, anyhow.

The Rig

iTrader: (13)

Hmm,theres definately a sensor at the very bottom of my current downpipe,hmm,wonder what that is then, the wire as such coming off from it is a metal spiralled coated type.

joz8968

iTrader: (13)

Sorry Rig - reedited my post above toi answer your last post post about that sensor! lol ^

The Rig

iTrader: (13)

Ah,cool,all makes sense !

cheers again

The Rig

iTrader: (13)

So this bad boy is ideal then ?

Subaru Impreza (Classic) GC8 Decat Downpipe on eBay, also Engine Tuning Parts, Performance Tuning Parts, Car Tuning Styling, Cars, Parts Vehicles (end time 16-Mar-09 15:06:40 GMT)


its just a bummer every MOT time i will have to put the CAT back on !

cheers

joz8968

iTrader: (13)

Yeah any stainless steel bellmouth for a Classic is okay. Why not save dosh, and get a 2nd hand one on her in the Classifieds or on eBay - it's only a tube of metal after all. Nothing to go 'wrong' with it, is there? Prob pick one up for £60!

Taking the cat in/out once a year... Is it really hassle for the gains to be had for other 364days?! To put it in perspective that'd br for a paltry 0.27%!!! of a year!

The Rig

iTrader: (13)

yeah,True !

thing is wih 2nd hand,how do you know its 3" going intoo 2.5"? as the bellmout part isnt circular etc,or is that the 3" bit then the end of the bore the other end 2.5" ? As 2nd hand sellers try n sell you the stars ha ha ! A retailer it says it on the box ha ha

cheers

joz8968

iTrader: (13)

The bellmouth is the turbo gas collector part of the d/p and is all one size (as it has to fit the turbo flange, etc).

The actual pipework diameter is either OEM sized 2.5" with standard 2.5" centre section flange (to mate up to std sized centres)...

...Or it's 3" diameter pipework with either a 2.5" flange (see above), or a true 3" flange for larger 3" centres/back boxes - for a TRUE 3" system.