Hi everyone, my names John im new, have just bought a 300zx and am realy loving it, im just so scared it will go wrong cos the engine looks very difficult and expensive. i have a 92 2+2 twin turbo and it has a cat back stainless exhaust system, however my problem is the front half is holey and welded up by my mate at the weekend just to keep the noise down, i want to keep the car up together but without spending too much, basically i want to replace the front half but cheap as poss, i eventually want to de-cat it but think the cats all part of the downpipe too from looking, what is the best way to go about this please, i dont want to buy too exhausts both de cat and cat, sorry for long post,

 

drive safe (ish) john (notken)

Just buy a set of down pipes and keep the rear half of the system.

a de-cat system will give you more power but the lack of back presser will shorten the lifespan of the turbo. however, i hear that a screemer pipe gets round this problem and lets the turbo kick in sooner

a de-cat system will give you more power but the lack of back presser will shorten the lifespan of the turbo. however, i hear that a screemer pipe gets round this problem and lets the turbo kick in sooner

 

for a screamer pipe you need external wastegates, which you wouldn't use with standard tubs anyway!

confused, if i buy down pipes what do i do about the cats? the bits before the cats are the bad bits

cant help ya prob, but welcome

You are on about the manifold pipes down to the cats i take it?

 

Also, unless your turbos are newish or have been refubed, do not decat, it will change the pressure in the back of the exhaust blowing the turbo seals = very expensive to fix!

Just get a secondhand set of cats. Look in the 'for sale' section or put an ad in the 'wanted' section, there must be loads out there from all these breakers that are now appearing. Speak to Paul as SWZ, he is a spares trader on here.

for a screamer pipe you need external wastegates, which you wouldn't use with standard tubs anyway!

 

Think you can get some australian made screamers for standard tubs, bout £400

its not difficult to replace the downpipes (the downpipes are the ones that come from the turbo elbow to the midle section of the exhuat.

 

these contain the cats.

 

 

you can get stainless steel downpipes, with no cats for about £100 from ebay (brand new)

 

or i pickt up some normal steel ones for £50.

 

i paid mechanic to fit them, as lookt a bit difficult underneath lol

cost me £50 to fit.

 

you can weigh the cats in at a scrappys then for £30 each!

 

so this mod pays for itself more or less.

 

pay atention to Merts post tho regarding the turbo seals. if cars healthy shud be fine, but if turbos shagd itl smoke on boost

There is a cat in my Turbo elbow !

a de-cat system will give you more power but the lack of back presser will shorten the lifespan of the turbo. however, i hear that a screemer pipe gets round this problem and lets the turbo kick in sooner

 

do the screemer pipes keep the back pressure up? and by how much will the turbo's life be shortened?

Sometimes the oil seals on the back of the urbo's go instantly, sometimes they are fine. DO a search, theres loads of posts about de-cats and turbo seals

yea i forgot the UK versions have 4 cats all together,

 

2 in the downpipes (precats) then 2 normal.

 

the jap versions dont.

 

so i was told! :)

for a screamer pipe you need external wastegates, which you wouldn't use with standard tubs anyway!

 

You can get screamer pipes for the stock turbos too!

 

They're a bit like the Megan Racing divorced downpipes, except the one tube that comes from the wastegate vents to atmosphere not back into the exhaust.

 

 

You can get screamer pipes for the stock turbos too!

 

They're a bit like the Megan Racing divorced downpipes, except the one tube that comes from the wastegate vents to atmosphere not back into the exhaust.

 

 

yea their not "real" screamer pipes, as they come from external wastegates as someone said.

 

those screamer downpipes are similar, hear the air 'screaming' out the pipe on boost. sounds like a boost leak.

 

love it tho! really hear the air being thrown out!

if i want it really fast could i upgrade the turbos and get a stainless front half and do away with the cats, would it be a big difference, ive only had the car a week and it felt really fast acceleration to start with but the buzz has worn off :( thanks for all the help so far

yea their not "real" screamer pipes, as they come from external wastegates as someone said.

 

those screamer downpipes are similar, hear the air 'screaming' out the pipe on boost. sounds like a boost leak.

 

love it tho! really hear the air being thrown out!

 

What's the difference with an internal wastegate and an internal one?

 

They are both a valve that opens up to divert exhaust gasses away from the turbine are they not?

 

Or have I missed something on the external devices?

Internal/external.

 

Bugger, can't edit my posts :p

if i want it really fast could i upgrade the turbos and get a stainless front half and do away with the cats, would it be a big difference, ive only had the car a week and it felt really fast acceleration to start with but the buzz has worn off :( thanks for all the help so far

 

didnt you just say in your previous post yout scated at the engine bay, and looks like its expensive to do work on?

 

replacing the turbos itself is costly!! let alone the costs of the turbos!

 

 

not too sure the differences on internal/external wastegates,

 

sure theres some turbo gurus on here to advise