VS V6 Exhaust - Honest Answers Please!

[lordtyranus]

Hello all

I'm looking at doing a complete 2 1/2" exhaust on my ecotec, including extractors...all in stainless...so this is my question: living in Adelaide, we don't have roadworthy inspections. So, honestly, has anyone or does anyone have the shell of a catalyctic converter with just a 2 1/2 inch pipe running straight through it (no mesh, just a fake shell)? Highly illegal I know, but just wondering...does it do any harm to the engine management side of things, and does it drop back pressure too much?

Some serious input please guys...I know this is cheeky but I have this on a VN once and it went much harder. Ecotec though...I have no idea.

The car has a cold air intake only at the moment, and no forced induction...just curious do I really need the cat????

Any thoughts? Cheers guys

[tr3nt]

I have a similar setup, however I don't have a rear muffler or resinator. If you don't have roadworthy inspections, how does the state ensure your car is RW?

[lordtyranus]

We just go in and re-register...no mechanics cert. or anything! You'd be amazed at some of the old heaps driving around here

[Reaper]

Hello all

I'm looking at doing a complete 2 1/2" exhaust on my ecotec, including extractors...all in stainless...so this is my question: living in Adelaide, we don't have roadworthy inspections. So, honestly, has anyone or does anyone have the shell of a catalyctic converter with just a 2 1/2 inch pipe running straight through it (no mesh, just a fake shell)? Highly illegal I know, but just wondering...does it do any harm to the engine management side of things, and does it drop back pressure too much?

Some serious input please guys...I know this is cheeky but I have this on a VN once and it went much harder. Ecotec though...I have no idea.

The car has a cold air intake only at the moment, and no forced induction...just curious do I really need the cat????

Any thoughts? Cheers guys

The answer is no but why would you want to risk a massive fine so that you can point out to your mates that you have a faker cat??? You aren't making your car go any faster. I am assuming you are in Aus - in which case yes you need a cat. Where do you blokes get these ideas?

Reaper

[lordtyranus]

Why would I want to show it off to my mates? It runs a pipe through the guts of the cat so it still looks legal if it is ever checked visually. The idea is to remove the constriction from the centre of the c/c...ever seen a cross section of a standard one? Quite constrictive yes? Or do you think they sell expensive high flow cats for fun...oh hang on...is it to increase AIR FLOW?!?!?

Yep, you tell it like it is...and i'll keep laughing mate

[savage1987]

You are an idiot. I cannot believe anyone still feels the need to run an exhaust without a catalytic converter. Your car does NOT 'go much harder' without one, you'd be lucky if there's 1/2 hp difference. If the dyno queens can run almost 2000rwhp through a pair of catalytic converters, no reason why you can't. If you're concerned about flow, waste some money on a highflow one which will make no difference anyway, or backdate to a VN/VP one because they flow extremely well iirc.

Anyone who bashes out a catalytic converter is a ****head in my books, you're making your car stink and spew out noxious ****ing chemicals, doing 1000 cars' worth of environmental damage in the proces. Grow up, leave your cat(s) in tact.

[savage1987]

The idea is to remove the constriction from the centre of the c/c...ever seen a cross section of a standard one? Quite constrictive yes? Or do you think they sell expensive high flow cats for fun...oh hang on...is it to increase AIR FLOW?!?!?

You obviously haven't seen the testing results that prove the Commodore (particularly VN/P and LS1 models) catalytic converters flow extremely well, as well as many 'high-flow' variants. Not every product out there is worth the money for every car. Don't assume that just because it exists it's an upgrade; think of the electric superchargers on ebay. Your air flow will increase two fifths of **** all with no catalytic converter.

[Reaper]

Why would I want to show it off to my mates? It runs a pipe through the guts of the cat so it still looks legal if it is ever checked visually. The idea is to remove the constriction from the centre of the c/c...ever seen a cross section of a standard one? Quite constrictive yes? Or do you think they sell expensive high flow cats for fun...oh hang on...is it to increase AIR FLOW?!?!?

Yep, you tell it like it is...and i'll keep laughing mate

If you think your stock boat anchor pumps enough air to trouble a stock cat then you are kidding yourself.

Reaper

[DannyboyDS]

Reaper and Savage are right mate, even on light boost that cat isn't a restriction yet.

I'm also wondering about.

"complete 2 1/2" exhaust on my ecotec, including extractors"

Good luck getting 3 X 2 1/2 pipes past the steering system on the drivers, stick with some pacies, unless your pretty good with tube bending and welding custom extractors can get real messy.

Otherwise.

CAI, full exhaust (With a functional cat or even two, one per bank) and a cam or something and you migt be onto a fun car there, sounds like the starting point for some light boost though tbh.

In a few weeks i'll be putting a twin 2 1/4 system into my car, one straight through muffler and one hot dog resi on each pipe, twin cats as well, oh and I allready have pacies, if that goes well, maybe you should consider that path :P

[lordtyranus]

Cheers Danny, good to get some 'Intelligent' feedback at last...being called an idiot by some typing hero with an attitude doesn't go down well with me on a monday morning . Good luck with your exhaust, be keen to know how it goes

[lordtyranus]

Hey Savage...You, sir, are a '****'. Shouldn't go calling people you don't know idiots. Not nice...

[_R_J_K_]

Hey Savage...You, sir, are a '****'. Shouldn't go calling people you don't know idiots. Not nice...

Um, that sentance is a bit hypocritical, isn't it? Do you know Savage?

[savage1987]

haha RJK, nice, I didn't even pick up on that

being called an idiot by some typing hero with an attitude doesn't go down well with me on a monday morning

And waking up on a Monday morning to yet another thread about the stupid idea of an open cat converter doesn't go down well with me. It's just about the most idiotic thing anyone can do to a car in my opinion.

Hey Savage...You, sir, are a '****'. Shouldn't go calling people you don't know idiots. Not nice...

You're right, I don't know you and whilst you seem to come across as an idiot from what I've read on here, you are probably a very nice person. I apologize for calling you an idiot, if that makes you feel better. Your idea is still stupid.

Sam

[kingrat502]

cat converters are a must but what about rear resonators..

[mulligan-can]

Hey Savage...You, sir, are a '****'. Shouldn't go calling people you don't know idiots. Not nice...

Hey lordtyranus... You sir, are a fool.

The search button is there for a reason. The number of people who come on here asking the exact same question you just did is astounding.

Each and every time they are flamed and quite deservedly so.

Bashing the insides of your cat out will no more than make it smell funny. The difference in flow is negligible (next to non-existant if you must, a dyno wouldn't pick up the difference between an engine with a cat and one without). Even on a turbo vehicle the difference is not enough to notice on a dyno.

In future, if you are going to ask a question that involves "we don't have annual roadies so...." search first, someone else has probably asked and been flamed for it. Save us the effort of flaming you and save your dignity/pride from being insulted.

[savage1987]

cat converters are a must but what about rear resonators..

not necessary for any reason really except in some states to keep police happy, and in most cases to reduce drone from a non turbo motor

Hey lordtyranus... You sir, are a fool.

The search button is there for a reason. The number of people who come on here asking the exact same question you just did is astounding.
+1
Each and every time they are flamed and quite deservedly so.

Bashing the insides of your cat out will no more than make it smell funny. The difference in flow is negligible (next to non-existant if you must, a dyno wouldn't pick up the difference between an engine with a cat and one without). Even on a turbo vehicle the difference is not enough to notice on a dyno.
+1
In future, if you are going to ask a question that involves "we don't have annual roadies so...." search first, someone else has probably asked and been flamed for it. Save us the effort of flaming you and save your dignity/pride from being insulted.
+1