Recommended Downpipes For J-spec Mkiv

[Chillipower]

Anyone care to recommend the best (overall, considering cost as well) make of downpipe to replace only the 2nd cat on a j-spec mkiv supra, and a supplier for it?

If a 2nd cat only replacement pipe is unavailable then is the Rod Millen pipe with a restrictor ring the best bet, if so who is a good supplier of that? Are there better alternatives?

thanks,

Louis

[Karma Supra]

I'm not sure about second cat only, but the megane downpipe is a nice cheap, decat pipe, it does the job and doesn;t cost a fortune! -it does however remove both cats..

[Leeky]

I have a Megan Downpipe, over 3" from the turbo to the exhaust. Very well made and only cost me £60 brand new off eBay :D

[Chillipower]

Nice one, that sounds like good value for money,

is that a stainless pipe? does it have the holes for the exhaust gas sensor(s)?

Maybe that pipe plus the restrictor will do the trick nicely then,

cheers, Louis

[Leeky]

Yep stainless, tig welded. Straight as you'd ever need. Yep it has the sensor bung.

[Chillipower]

Ahhh excellent, you've got to love eBay :)

I'll see if I can locate one, don't suppose you know if it came from an eBay shop, if so remember its name?

cheers,

Louis

[Karma Supra]

You don;t need the restrictor ;)

[Leeky]

You don;t need the restrictor  ;)

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He will on a J-Spec as the wastegates are poop and you'll endup hitting the fuelcut or even worse detting

[Chillipower]

From what I've read, on a j-spec the problem is nothing to do with wastegates, fuel cut or detonation any more than it would be on a uk spec or a us spec car,

the only problem is the j-specs ceramic turbos, they spin up faster to provide less lag but don't handle extra boost well,

not sure the official safe limit, seems that 1.1 bar might be reasonable on totally stock set up,

if it needs a greddy bcc or whatever then thats the same regardless of j-spec/uk spec,

so until I'm ready with that big turbo upgrade, I want to manage the boost carefully to retain a reliable set up, and if a restrictor provides that reliabilit then it would be silly not to fit it,

cheers,

Louis

[Leeky]

The Ceramic turbos do spin quicker but its the wastegates that are too small for higher than stock boost levels and because of that they cant vent the excess boost so the boost level just continues to rise until you hit fuel cut.

The UK Spec cars have much bigger wastegates on them so they have no problem getting rid of the extra boost.

up to 1.2bar on ceramics is what most people run their supras at. Uk's up to 1.5bar, but thats only because of them being metal.

[Chillipower]

ok, now I understand what you are saying,

out of interest are the wastgates a changable part?

So, I've got an idea for the downpipe, just need to locate a source for the restrictor ring, any ideas?

cheers,

L

[Leeky]

ok, now I understand what you are saying,

out of interest are the wastgates a changable part?

So, I've got an idea for the downpipe, just need to locate a source for the restrictor ring, any ideas?

cheers,

L

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I think when i got my decat off eBay the guy offered me a restrictor ring for free. If not Envy can do you one ;)

[Chillipower]

I'll get ebaying then! cheers for the advice,

envy? they a good suplier of supra bits and pieces then?

cheers,

L

[Karma Supra]

I missed the J spec bit!!!

[Chillipower]

I missed the J spec bit!!! 

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hey no worries, I took a look and as Leeky says, Envy do the 1.2 bar restrictor ring :)

just need to locate the downpipe, none on eBay currently but I'll keep looking,

cheers for the help,

L

[Martin F]

out of interest are the wastgates a changable part?

Nope its part of the actual turbo

[Chillipower]

Ok no worries, thought that was probably the case,

I'm happy getting the most out of what I've got and keeping it reliable at the moment, 1.2 bar will be just fine until I put a big turbo kit on it:) There are other things to do to make the car quicker anyway, such as the racelogic traction control that I now have my eye on ;)

I'm currently at 1bar, which is just below fuel cut, so the increase to 1.2 will take me past the limit, its the Greddy BCC that's the recommended way to go isn't it, regarding fuel cut eliminators?

cheers for all the help,

L

[Leeky]

I bought the TRL VFCC fuel cut defender as Envy told me its the best on the market ;) Bloomin hope so at £80

[Chillipower]

Ahhh, just when I thought I had it all sussed, I emailed a company and they recommended to fit a single de-cat and a boost controller!

I wonder if this because the single de-cat might not produce high enough boost, and so the ebc can be used to tweak it higher as required?

Maybe this is safer than a double de-cat + restrictor and then realising the boost is still too high to be safe,

as far as I know, an ebc can never reduce boost below the minimum that you would get without it? unless I am much mistaken. They listed devices like the Blitz Dual-SBC Spec R & S Boost Controllers.

I see greddy make external wastegates, expect these are a nightmare to fit though, although would be a neat answer to j-spec boost creep,

cheers,

Louis

[Leeky]

Yeah some j-spec owners only remove one cat so they dont need the restrictor

[Chillipower]

ok sounds like I've got a plan at last then:

stage 1: 2nd cat only de-cat pipe

stage 2: see how it runs, will probably need a trl vfcc i expect at this point

stage 3: add an ebc to allow some boost tweakage, although if its close to 1.2 then this wont be worth it (not cost effective)

stage 4: add a big turbo :) (for the future...)

Leeky, did the trl vfcc need much setting up, was it hard to install?

cheers,

L

[Martin F]

Stage 0: Buy a half decent boost gauge if you don't have one already.

[Leeky]

Leeky, did the trl vfcc need much setting up, was it hard to install?

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Nah, only need to cut 3 wires. Long as you get it right first time it shouldnt take longer than 30mins

They come already set to run over 1.2bar (fuel cut lifted to 1.3bar)

[Chillipower]

lol :)

luckily stage 0 is complete already! at least thats one less thing to do,

btw, I am assuming I have the 2nd cat, I've looked under the car and the nice round cat-back pipe goes into what looks like a cat (I think), it looks like its made in two halves and then joined together, i.e. it has a seam or lip running along the length of it, sound like a cat?

Worth checking before I order my parts!!

cheers, L

[Leeky]

Sounds like you have cats Unusual to buy a car without a cat/cats without the dude who sold it to you telling you ;)