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What Cat For Emissions Test

luvpsi

By luvpsi,
in Engines & Forced Induction

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luvpsi Mentor

luvpsi

Posted
Posted

hey guys i need to get a emissions test however i have a gutted cat. so im looking for a highflow cat that will help me with my emissions test but i can keep and will flow the best. i dont want to have to handle twice for one job.

currently im running stock turbo at 10psi with a microtech computer and my exhaust is as follows. 3inch from stock dump back with 1 resignator. however in the near future( couple of months) i will be upgrading my turbo to a atr43 and will be looking at the 300rwkw mark max.

so my question is what would be the best cat for me to get that will flow the best and help me with emissions. ( i dont want to keep chaning cats)

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R31Nismoid Grand Master

R31Nismoid

Posted
Posted

Any cat with a 4-4.5" Body will be what you want.

The exhaust shop will weld 3" flanges on and "taper" out to meet the body.

Always good to have a CAT larger than the exhaust as they are a restriction. So going bigger helps alleviate this whilst being legal.

There are various brands. Long as its a metal CAT, anything should be fine.

R31Nismoid Grand Master

R31Nismoid

Posted
Posted

4-4.5" body will be fine dude.

Remember you only have a 3" exhaust so that is a limiting factor in itself. So no bigger than a 4.5" body would be needed I reckon.

Going 5" probably just cost you more. But ye it'll need to have 3" flanges put on

luvpsi Mentor

luvpsi

Posted
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Posted

on the venom website it states that the 450 series would be best for my application. im only looking at running 300rwkw max so would the 400 serie(4" body) or the 450 series (4.5" body) be my best option im goign to go the venom cat but just which one

Harey Veteran

Harey

Posted
Posted

I would not run a hiflow metal cat for an emissions test. What is the penalty for failing? If its not much then yeah fine. In VIC an emissions test is ~$2k and you loose the $$ if you fail. In that scenario I would be bolting up a factory cat in the best condition possible. When I was getting a turbo commodore legal I ran a standard cat in the standard location and an extra one hidden in the dump pipe haha.

Most hiflow metal cats do not have to meet any emission standards especially not 100 cell cats. There primary focus is to flow well and reduce the emissions (mostly just to satisfy the legality of having a cat when inspected). To be honest its a bit of a loophole, I wouldnt be surprised if one day they force us to use the standard catalytic converter that came with the car.

Whereas factory cats have to meet all the emission standards.

Harey Veteran

Harey

Posted
Posted

on the venom website it states that the 450 series would be best for my application. im only looking at running 300rwkw max so would the 400 serie(4" body) or the 450 series (4.5" body) be my best option im goign to go the venom cat but just which one

I personally bought the 5" body one, fits fine on my R34. Why not have more flow it was only an extra $20 or so. Just as long as there is room.

SargeRX8 Grand Master

SargeRX8

Posted
Posted

Bigger is better. I didn't buy this cat to pass emissions, I bought it to get high flow without running no cat. Some cat is better than none. There are a couple out there which are approved but I don't think they are 100cell. Think about it. If nissan could have made a 100 cell metal cat which is legal, don't you think they would have? I've still got my stock cat with me just incase. With that said my old skyline has a gutted cat(i had no idea) for about a year. I didn't draw attention to my self so never got into shit for it.

wolverine Grand Master

wolverine

Posted
Posted

on the venom website it states that the 450 series would be best for my application. im only looking at running 300rwkw max so would the 400 serie(4" body) or the 450 series (4.5" body) be my best option im goign to go the venom cat but just which one

Email/contact George directly. He has 5" bodied cats with factory oriented flanges on the shelf but they may not be on the ebay site.

Ask him what might or might not pass emissions.

GTScotT Grand Master

GTScotT

Posted
Posted

I think all this talk about 5" cats gets a bit tiresome...

300rwkw, this will do it with no drama:

http://www.justjap.com/store/product.php?productid=18066&cat=275&page=1

If your worries about power:

http://www.justjap.com/store/product.php?productid=16441&cat=275&page=1

The second one is what you would call a '5" body' cat. The body is about 2 inches bigger in diameter than the flanges. Not sure if it will pass EPA..

Im just over how confusing the cat talk is.............. No offence Ash.

rob82 Mentor

rob82

Posted
Posted

From what I've seen personally:

A 4" 100cpi cat will be fine for 350rwkw. (less than 2psi back pressure between turbo and cat)

A 5" 100cpi cat will be fine for 450rwkw. (less than 2psi back pressure between turbo and cat)

Knock off about 12% of that for 200cpi cats.

Please note that this was on systems that have a very shallow merge from the rest of the exhuast. Thats very important.

Does anydoby know the emmssions compliance level they will be measuruing to for a VL?

Harey Veteran

Harey

Posted
Posted

I think all this talk about 5" cats gets a bit tiresome...

300rwkw, this will do it with no drama:

http://www.justjap.com/store/product.php?productid=18066&cat=275&page=1

If your worries about power:

http://www.justjap.com/store/product.php?productid=16441&cat=275&page=1

The second one is what you would call a '5" body' cat. The body is about 2 inches bigger in diameter than the flanges. Not sure if it will pass EPA..

Im just over how confusing the cat talk is.............. No offence Ash.

The second link is not a 5" body, I had one. It is either 4 or 4.5". Plus it is a 200 cell cat. I lost 8-10rwkw on the dyno when dropping it. That sounds a bit high to me, yes I know you will loose some power with a cat.

I had my cat stolen so bought a 5" body 100 cell venom cat for $230ish (without flanges as he didnt have them ready for an R34 yet). Why the hell would you pay $400 for a 200 cell 4.5" body cat??

Sure comparing the 4.5" to the 5" 100 cell venom cats you will prob be fine with the 4.5" but if there is room for it and its only $20 difference why not?? Especially if you up the power later on.

Harey Veteran

Harey

Posted
Posted

From what I've seen personally:

A 4" 100cpi cat will be fine for 350rwkw. (less than 2psi back pressure between turbo and cat)

A 5" 100cpi cat will be fine for 450rwkw. (less than 2psi back pressure between turbo and cat)

Knock off about 12% of that for 200cpi cats.

Please note that this was on systems that have a very shallow merge from the rest of the exhuast. Thats very important.

Does anydoby know the emmssions compliance level they will be measuruing to for a VL?

I believe it would be the ADR37/00 emissions test. Might be different in WA though. Shouldnt be too hard when your using a later model engine (more strict emissions limits).

SargeRX8 Grand Master

SargeRX8

Posted
Posted

The second link is not a 5" body, I had one. It is either 4 or 4.5". Plus it is a 200 cell cat. I lost 8-10rwkw on the dyno when dropping it. That sounds a bit high to me, yes I know you will loose some power with a cat.

I had my cat stolen so bought a 5" body 100 cell venom cat for $230ish (without flanges as he didnt have them ready for an R34 yet). Why the hell would you pay $400 for a 200 cell 4.5" body cat??

Sure comparing the 4.5" to the 5" 100 cell venom cats you will prob be fine with the 4.5" but if there is room for it and its only $20 difference why not?? Especially if you up the power later on.

Exactly this. That Catco cermaic cat is a piece of arse, My old skyline which when tuned was making close to 250rwkw had one.... and it was gutted. Doesn't that tell you something? They bought the cat to get a high flow cat, realised its a restriction, then bashed it because they wasted money on one cat and deemed it a shit idea to buy another one. Its flow rate isn't too great, I recall about 450 - 550cfm. These 100cell metal cats flow close to 700 - 800cfm. You are paying close to $200 for it delivered. Why not pitch in an extra $30, and save an extra $130, get a 5" full venom cat. Having a bigger cat is not going to harm the system at all. If anything you are allowing for future modifications. Spend once, rather than burn money on a cat you will change when it starts glowing red and the ceramic insides come shooting out the ass.

I don't care what anyone says but the better your exhaust flows, the better your car will perform and the longer your turbo may last because of the better exhaust heat removal.

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