Catalytic convertors affect emissions test?

[Lanc3r]

My 84 318 is currently getting an engine overhaul. I am debating about exhaust options. And since I rarely drive the car, Im wondering if I can get away without a CAT. I know the legal ramifications, so please save me the flames for that.

My question is: Does the CAT affect the actual emissions test. I have a friend with an Audi Inline 5 cyl Turbo, with 3" from the turbo straight to a muffler. And he has had no probs with emissions. On the other hand, Ive heard of people not passing in American V8s without the CATS.

Whats the scoop?

[Kaz]

Depends. In CA, you're going to have a REALLY hard time passing a car without a converter. I have heard of euro E24s passing in CA without a cat, but it required VERY careful tweaking of sender outputs and a bunch of other stuff in order to make it do this.

In CA, at least, if the car originally came with a catalytic, it needs to have one to pass, regardless of whether or not it'll pass sniffer without one. The euro E24 didn't need a cat to pass since it never came with one, on top of passing sniffer.

[The Roadstergal]

I know the legal ramifications, so please save me the flames for that.

How about the we-all-have-to-breathe-the-same-air ramifications?

You're not going to suddenly have a fire-breathing E30 monster without the cat. Keep it on, spend some money on suspension mods. You'll have plenty of fun and your kids will thank you.

[chopper]

Really depends on the state. Also, turbo exhaust is a ton hotter than NA engine exhaust most of the time.

You can get universal high-flow SS cats for relatively little there days. Might help the car sound a bit more manageable too.

[Lanc3r]

Really depends on the state. Also, turbo exhaust is a ton hotter than NA engine exhaust most of the time.

You can get universal high-flow SS cats for relatively little there days. Might help the car sound a bit more manageable too.


I think thats the direction I will go. High flow cats run about 250, BMW cats run about $500. I am going to be running headers and a high flow muffler. Also while the motor is out for machining, Im gonna bore the block to about 2.0 liters. I know the M10 is not a screamer, but since Im there, might as well free up as much HP as possible, but still be able to pass emission. Here in WA, there is no visual or under the hood inspection, they just do the sniff test. My understanding is that CATS just burn off Methane gas, which is not tested in WA state emissions.

Rgal: I agree air quality is a worthy reason to use the CAT. Thanks for pulling me back to reality.

Another thing, I have heard port/polish of the head is a waste of time on the M10, in fact it might decrease flow.

What do ya'll think?

[Mark in TX]

well, since you're asking, I think you should forget about putting a dime into the M10 and instead do an M50 or M52 (e36 2.5 or 2.8L) conversion. See terrysaytherauto.com .

Then, see the best bang for the buck e30 upgrade article in last May's Roundel magazine, p. 76. If any of you want to see the article, PM me and I'll email a scanned version. Include your email address.

Mark

[LmtdSlip]

How about the we-all-have-to-breathe-the-same-air ramifications?

You're not going to suddenly have a fire-breathing E30 monster without the cat. Keep it on, spend some money on suspension mods. You'll have plenty of fun and your kids will thank you.

:thumbup: