4.5" Body Venom Cat

[Hanaldo]

It'll still smell even with a huge CAT in it

Not as bad, but ye - cruise behind a car with a hi-flow CAT and you can certainly still smell as if it was not running one.

Yeh my car has a little bit of a smell to it, but only if I'm giving it some; it doesn't smell when I'm just cruising. Certainly no where near as bad as when it was run without a cat

I just picked up a JJR 3" dump/front last week, are u saying it will make stuff-all difference to my set-up with stock turbo?? (see signature below for my set-up).. Just realized I have a 4" body 3" inlet and outlet 100 cell metal cat (Lobokka brand off ebay), instead of a 5" body which people recommend, is this going to restrict my exhaust when I get 280-300rwkw down the track later???

I didn't notice any difference in power when I got my bellmouth. It does make a bit of difference in terms of response though, I was coming onto boost about 500rpm sooner and making full boost about 300rpm sooner. Sounds good too

*EDIT* Also keep in mind that Zebra already had a 3" front pipe. So it's not surprising that changing to a 3" dump/front pipe didn't make much difference. Changing your exhaust isn't going to make a difference if the one you have isn't a restriction. But the stock setup becomes a restriction relatively soon, so if you tried to get that 300rwkw and then changed the exhaust, THEN you would notice a huge difference

Edited November 17, 2011 by Hanaldo

[luvpsi]

It'll still smell even with a huge CAT in it

Not as bad, but ye - cruise behind a car with a hi-flow CAT and you can certainly still smell as if it was not running one.

Yeah I know but it won't be as bad and it's legal mr plod can tap it and it won't sound hollowed out

[luvpsi]

Yeah hanaldo it reaks at idle at a set of lights when the breeze blows it towards you so I'm hoping a cat will help won't stop it but it will make it a bit better

[rondofj]

Thanks Hanaldo, good advice - coming onto boost 500 rpms sooner is YEEE HAAA...but not yet - still got just over 4 months of suspension left!

[Room42]

N/A & turbo are not the same by any means. Comparing the two is misleading.

And 2mph from removing a CAT is actually quite a big gain realistically for a stock turbo.

You quote me but you don't read what I write. We have had this conversation before. I said it was not a turbo engine. Can't get any clearer than that. What is misleading about that? 2mph could just be a harder launch or better shifting.

[zebra]

was 4 or 5 runs at 104mph then removed cat and did another 3 or so runs at 106mph

[luvpsi]

Looks like proof to me

[luvpsi]

Looks like proof to me

[R31Nismoid]

I read it, but why bring it up?

It has zero relevance to this thread, same as it did the last thread you brought it up in.

If this was a N/A thread, bring up 600hp on a 3" exhaust - in a FI thread, dont bring up pointless statements that would otherwise confuse people.

[luvpsi]

Agreed as this would have confused many people like it confused me at first until ash corrected it

[Room42]

I read it, but why bring it up?

It has zero relevance to this thread, same as it did the last thread you brought it up in.

If this was a N/A thread, bring up 600hp on a 3" exhaust - in a FI thread, dont bring up pointless statements that would otherwise confuse people.

Ash

"Why bring it up?". The fact you ask that means you should listen more. Trolling me is like kicking yourself in the nuts. It is pointless. I will humour your question however.

We are talking about flow here. Specifically exhaust gas flow through an exhaust pipe and even more specifically a catalytic converter. 600hp will be near enough to the same gas flow from either a NA engine or a turbo engine. If it works through a 3 inch then leave it there.

We are also talking about a street car here. There is more to consider than just having the biggest or highest flowing system. What is the point of having a 4 inch exhaust or a 5 inch cat when you can't leave the driveway cos you got defected? Police don't need a reason the send you over the pits. What about the guy that just spent a stack of cash to get his exhaust made up with a huge cat that now has to take his car over the pits? There go all his mods and his cash.

"Please, while reading this, keep in mind that we are all here to have fun, kill time, learn or whatever and that at all times the sites best interests are in mind with any actions taken towards individuals or groups".

Have you read that lately? The OP got confused, on his own admission, about exhaust flow. It is not in his best interest to get the biggest cat out there. I comment to help the bloke, not to have petty arguments about relevance that only you bring up.

If you want to be pedantic about the thread listing then move it to general maintenance as both NA and turbo cars have catalytic converters.

zebra

Fair enough. A few runs is proof enough.

luvpsi

He didn't correct anything. If you think from his comments that there is no comparison between NA and turbo cars then you have been misled. They are different but there are plenty of areas to compare them. Use your own judgement mate if you cant get a straight answer on this forum. Ring some performance shops and exhaust shops before you commit to anything. I'm happy to let you come for a drive and see how much the cat will actually affect the power you are chasing. It will make you think twice about using a possibly illegal and defectable setup.

Blokes I love cars and mechanics more than most and I would hate to see someone off the road due to an unnecessary or illegal mod. For a track car yes. For luvpsi's car, no. But each to their own.

[Hanaldo]

Well a 5" cat is going to be no more illegal than a 4.5" cat. So either way, his setup is illegal.

[zebra]

Exhaust tuning is apples and oranges with turbo and na engines.

[R31Nismoid]

Exactly. Cannot be compared, said that on page 1.

Which brings once again, my point from page 1...

Just because you "make" power, or "turns tyres" with obvious restrictions means sweet fa.

[Room42]

I disagree that it means sweet fa. Once again you are trying to influence younger and inexperienced readers by your comments which can lead them to huge amounts of grief.

I make "enough" power to make most blokes happy. I will never get defected with my exhaust setup. Not from the cat and not from the noise. Big deal if I lose 3 psi at the manifold by running a full legal exhaust. If I want to I just turn it up more no worries.

Lemme show you blokes some (not all) areas of comparison between na and turbo exhausts.

For both engines the more free flowing a system is, the more high rpm power you can develop.

A big system on a turbo or na car will lose low end/off boost power.

Both engines will benefit from the scavenging effect of a smaller exhaust at low rpm.

The only time a turbo engine benefits from a huge exhaust is when it is coming on or on boost. Less difference coming on and more when on.

Here is the "best" one...A big system on either engine is likely to get your car put off the road for several reasons.

Excessive noise will put you in the hoon category. This is identical for a turbo or an na car. Check out your local hoon laws. Its only 3 times that you get caught before you lose your car for good. This is more of a consideration for me than having the "highest flowing" cat out.

Everyone is different and some blokes are happy to risk huge fines for an illegal cat and/or losing their car for "hooning" from excessive noise.

The OP is choosing a cat. That is why he started this thread. He should consider every aspect to car modification, not just the biggest is best view.

On a side note, since when is being noisy "hooning"? In my eyes hooning is driving fast. Apparently our law makers have decided having a loud car is hooning too. Sounds like a bunch of crap to me.

Hey fellas its only advice. You can do whatever you want to do

[75coupe]

wow now your telling Nismoid how important it is stay legal when he is pretty much the spokesperson for having a legal or under the radar car...

you know Ive have many, what could be called illegal mods but Ive never had any problems, even when pulled over for rbt...

and Im not a grandpa driver so I dunno, dont hang with hoons I guess.

I'll go with the biggest cat, is half an inch really going to make that much diff in a negative way..

[wolverine]

A big system on a turbo or na car will lose low end/off boost power.

Both engines will benefit from the scavenging effect of a smaller exhaust at low rpm.

What effect does the turbine housing and wheel have on scavenging?

I am not sure your comparison is applicable at all.

[zebra]

Exactly! ^

its why I get pissed off every time I hear "tuned length turbo manifold"

It just cannot happen

[Hanaldo]

I make "enough" power to make most blokes happy. I will never get defected with my exhaust setup. Not from the cat and not from the noise.

What about for your 'gate setup?

[luvpsi]

As long as a external gate is plumbed back and not vent g it's legal I'm currently going through engineering process here in WA and as mentioned by my engineer as long as it's plumbed back your safe