LZY13B build thread

[LZY13B]

It would just be a cheap hiflow cat nothing special he said around $500 with cat and he is just a local mechanic in silverwater just up from my work he does all our work cars I told my boss I'll send him the bill haha

[seangti]

You see a lot of cats placed right up the front quite close to the downpipe section. My guy explained that to get a front section only to work well you need to build maximum volume into it by going no less then 3 inch and also by positioning the cat as far back as practical. That way you extend the 'filling time' of the front section before back pressure starts to ramp up. If you place the cat right up at the start of the system you are just taking the component that is singularly most responsible for causing restriction and moving it into a position that cuts unrestricted 'volume' out of your system and causes backpressure rise to occur sooner. That was the theory anyway. Tradeoff would be that it'll take longer for your cat to heat from an emissions perspective. anyway food for thought.

My car has a 4" expansion chamber as part of the dump pipe on it, done by the previous owner, Anthony. There's quite some detail in his thread on the theory behind it, which supports what you're saying. As I understand it, it's essentially a high pressure system behind the turbo which allows it to spin freely, leading into a lower pressure (exhaust) to suck/accelerate the exhaust gas out. You want as much capacity in the exhaust before introducing a restriction.

In talking with a race shop when getting other work done, he did say for the power produced by these cars, it's pretty useless, if making double the power, say 300kw, yeah absolutely go for it. That's in reference to the 4 inch expansion chamber. 3" is more than adequate on these cars IMO. Even the stage 3 cars, in reality we're not making big numbers anyway.

[Paazuzu]

I've been running a custom 2.5 inch downpipe with a xforce cat on stage 2 tune and it performs very well.

I don't think I'd bother going to 3 inch unless I was going stage 3.


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[h100vw]

I've been running a custom 2.5 inch downpipe with a xforce cat on stage 2 tune and it performs very well.

I don't think I'd bother going to 3 inch unless I was going stage 3.


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Probably nothing much to be gained with the 3 inch on a std turbo. Scene points maybe. I got mine knowing that I'd be doing the turbo soon enough.

PS Wasted no time getting the MCAs in the signature Dan

[Paazuzu]

Lol yes. Technically they are fitted to the car just waiting to drive it


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[sambb]

Would agree that if you are comparing full free flowing systems that 2.5 versus 3 has probably nothing in it with the amount of gas that a K03 will push. If you intend on doing a half system though then going to 3'' over 2.5'' is a about the only way to build maximum volume into a relatively short run of pipe. ie you are operating on a different premise to a full system - you know that after a point that back pressure will steadily ramp up as the back section will struggle to evacuate gasses. eg flow restrictors don't really become restrictors until they are flowing hard.
Building volume into the front section buys you time before that back pressure becomes an issue - hopefully enough time that given our 5000 rpm shift point it won't even be one. I can only pass on what my exhaust guy crunched in his brain but he was adamant that a 2.5'' half system wouldn't cut it in this respect. Remember volume is cubed, area is squared. The cross sectional area of a 2.5in versus 3'' is still significantly different but when you multiply that c.s.a by 2 meters of pipe length, the volume change is enormous.

[Blue9N3]

Going to test that theory. Getting a 3" dump installed but with the standard cat. Am curious to see if it makes a difference....


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[h100vw]

Std cat is pretty dense. 800 cpi I think. That's a fair amount of cell wall.

[Blue9N3]

You're probably right, but I'm curious (and a cheapskate)


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[LZY13B]

I spoke to my mechanic again and asked him about a hiflow cat and he just installed one in a 180sx and not sure what brand or who his supplier is but he gets stuff cheap he said it was only $120 for the 3" hiflow cat lol. I told him what I wanted 3" off the turbo with the hiflow cat and the two sensors and he will get back to me with a final price

[sambb]

I can't remember what you are intending on doing. Are you going to phase 2/stage 2 to account for the exhaust or are you going to try to run it on a base tune?

[LZY13B]

I'll be going stage 2 tune already running stage 1 revo and it's only $100 for the upgrade to stage 2

[HAR80N]

your gonna love it once you get the dump pipe on becomes a whole new beast head up your gonna need good tyres

[seangti]

Can people please stop raving about stage 2, it's making me want to do that to my daily I just can't seem to part with that car. It makes no sense to mod it, over even really keep it, lol, but, but, we all know how it goes.

Keep us posted on cat and dump prices

[rgvlee]

I don't think it's worth owning a pog unless you have stage 2 at a minimum