7 replies to this topic

[likwid_dzign]

Does anyone know the legalities behind opening up the cats on the LS? motors with the EURO3 cats mounted closer to the engine?

I see there are now a handful of 'shortie' 4-into-1 extractors w/ hiflowcats, but nowhere do I see people screaming praise for them. If anything it is the opposite. Introducing drone, not promoting scavenging as efficiently as others; infact the only benefit is a higher flow that retains the conventional cat position. It essential becomes a set of HSV extractors only bigger.

See I would like to go in the direction of some tri-ys or 4-into-1 'long tubes' but this makes me wonder it is legal to move the cats down to where they originally were mounted on VY and earlier models. Would this matter if god forbid, the EPA came snapping at the heels?

Personally I want 4-into-1 long tubes even if they aren't the best daily driven extractors... I just love the sound!

[sinister]

As far as I know it doesn't matter where they are mounted, as long as they are there. You quite obviously can't remove them, but moving should not be an issue.

[likwid_dzign]

As far as I know it doesn't matter where they are mounted, as long as they are there. You quite obviously can't remove them, but moving should not be an issue.

This is what I imagined but you hear everything about EURO3 and now EURO4 compliance with the cats being brought closer to the engine that there must have been some reason for it. I realise it would allow the cat to heat up to its optimum operating temp faster (and also reducing lifespan!) but it is from that point on that I get stumped as to the reason for them.

Something to do with the cats themselves, Maybe?

[sinister]

Just read the ADR regarding pollution gear.

Chances are if you do get pulled over no one will know where it is SUPPOSED to be anyway. Too many makes and models on the road to know where each is exactly located. Moving it 50cm down the exhaust, or whatever, is probably not going to do you any harm.

[aquabat]

I have a friend in Melbourne who I have been speaking to from LS1.com.au pretty much since I first got my car. He has a cammed/ headed VX SS and found that moving his cats right up behind the headers brought his torue curve forward around 500rpm as opposed to his old dyno runs!

I'm thinking od foing this myself when I have my Pacemaker 1 7/8 4 into 1's put on as from speaking to a couple of people, my car wouldn't be expected to make peak torque until 4500rpm - 5000rpm once my gear is finally in! That's without the addition of the 100shot of gas ofcourse.

Jason.

[likwid_dzign]

I have a friend in Melbourne who I have been speaking to from LS1.com.au pretty much since I first got my car. He has a cammed/ headed VX SS and found that moving his cats right up behind the headers brought his torue curve forward around 500rpm as opposed to his old dyno runs!

I'm thinking od foing this myself when I have my Pacemaker 1 7/8 4 into 1's put on as from speaking to a couple of people, my car wouldn't be expected to make peak torque until 4500rpm - 5000rpm once my gear is finally in! That's without the addition of the 100shot of gas ofcourse.

Jason.

There are a couple of companys that make big bore shorties!!! 1 7/8" primaries with 3" secondaries... Hi-flow cats... Big bore exhaust... You know you want to.

Picked up these bad boys yesturday for just under $500... They're genie short 4-into-1s AND they are HPC coated! They bolt straight up, have 1 5/8" primaries, have 2 1/2" secondaries, and are s/steel (I know they are prone to cracking but for mildly tuned street use).
I choose these cause:
1) They were cheap and unused!
2) They bolt straight up and have ready made hi-flow cats which mate to these
3) They're still 4-into-1... unfortunately they're just not 'long' tubes
4) Still retains low down torque - classified as interference design so the same as tri-y

I ended up choosing these cause there is a fair amount of hassel with shifting the cats until you get the car tuned (shifting the O2 sensors is a pain). Given the fact I'm forcedly stopping myself at just a tune I really didn't see the need of getting to anal about everything. Yes it will have an aftermaket exhaust, however this means the only trouble that should come of the authorities is "noise". Plus they're arguably the best 'shorties' I'm going to get.

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Edited by likwid_dzign, 27 July 2008 - 07:38 PM.

[aquabat]

You could have brought a brand new set of Pacemaker 1 7/8 4 into 1's (long tubes, obviously) for $700ish including freight. Aren't the short tubes just Tri-Y's? Like my current Pacemakers go from 4 into 2 into 1? Thought that was Tri Y's.

Not HPC coated but I don't really even know anything about that or what it is, don't think I'll be bothering with that.

Jason.

[likwid_dzign]

You could have brought a brand new set of Pacemaker 1 7/8 4 into 1's (long tubes, obviously) for $700ish including freight. Aren't the short tubes just Tri-Y's? Like my current Pacemakers go from 4 into 2 into 1? Thought that was Tri Y's.

Not HPC coated but I don't really even know anything about that or what it is, don't think I'll be bothering with that.

Jason.

Tri-y aren't really long or short since they are their own category. However "shorties" have 4 pipes going into 1 at the same point where 4 pipes go into 2 for the tri-y. Still the interference design just more compact.

HPC means they are ceramic coated. The coating gives lower under hood temps, rust resistance, and faster exhaust gas travel. However the HPC coating comes at a premium! This is why I said the headers were cheap.