Quick Exhaust Question

[rocksteady_racer]

I know this is going to be a stupid question but thanks in advance for the help guys. I just bought a 3 inch cat back for my 1991 240sx. Right now I am running the KA and I need to install this so I can pass emissions. After I pass emissions and inspection and finish building my sr I'm going to drop it in. Well anyway here is the question, I'll be running this 3 inch on the stock KA for now, is there anything I need to run in between the exhaust manifold and the stock catalytic converter for this to fit or will it fit just fine? Is there a catalytic converter with a stock exhaust manifold opening on one side and a 3 inch on the other side or something? I'll be running a 3 inch greddy down pipe and 3 inch catalytic converter when I get my sr but what do I need to get now for this to fit? Thanks in advance again.

[fliprayzin240sx]

The exhaust flange should bolt up to the stock cat for now. Once you go SR, you get the DP, ditch the cat for a testpipe and rebolt the exhaust back to the testpipe.

As for right now, you dont need anything other than some fresh gasket which your exhaust should have came with.

[punxva]

i've got a ka, s13, with an s14 exhaust manifold running a 3in downpipe, test pipe, and hks hi-power 80mm exhaust, for the time being

[g6civcx]

just bought a 3 inch cat back for my 1991 240sx.


is there anything I need to run in between the exhaust manifold and the stock catalytic converter for this to fit or will it fit just fine?

Catback means the exhaust replaces everything behind the cat, excluding the cat. Therefore the cat will meet up to your stock downpipe. It goes engine-exhaust manifold-downpipe-cat-catback.

Is there a catalytic converter with a stock exhaust manifold opening on one side and a 3 inch on the other side or something?

Any cat meant for the car will fit the stock downpipe and any exhaust meant for the car.
what do I need to get now for this to fit?

Nothing. Just bolt it to the cat, provided the catback comes with all installation hardware and new gasket.

[rocksteady_racer]

Thanks for all your help guys. I'll post up pics after the install. And pics of my custom back seat stereo setup.

[PoorMans180SX]

Don't ditch your cat.

It's pointless and throws about 3000X more hydrocarbons into the air.

[g6civcx]

Don't ditch your cat.

It's pointless and throws about 3000X more hydrocarbons into the air.

Not to mention that's illegal and you can be fined/jailed. Chances are stock S13 cats are blown by now. You should invest in an cat with EPA stampings on it if you want to be legal.

[PoorMans180SX]

^^yup

ihatemssglength

[rocksteady_racer]

What do you guys recommend for aftermarket cats? I remember my 90 240sx barely passing emissions by the skins of it's teeth. I know because I'm friends with the emission guy and he thought it failed because the machine doesn't usually freeze right before passing or failing but it did which usually means it failed. I also have a leaky cylinder in that car so eh. What cats do you guys run? I'm hoping for a 3 inch that bolts instead of having to be welded. Thanks in advance.

[punxva]

Catco, magnaflow, or a jdm company if your really feeling saucy

[rocksteady_racer]

Ok if I swap in a Catco catalytic converter on the stock KA downpipe will it still pass emissions? It is the stock KA24DE exhaust manifold. I live in PA so it should be a little easier to pass than california. A 3" Catco will fit onto the stock ka exhaust manifold right? or will I need an adapter of some sort? Thanks in advance.

[driftxing]

Also, I have noticed that on a turbo engine, the test pipe does breath a little easier, but it spooled a little easier with the cat on it.. fyi.