Calif emissions and aftermarket cats
05-18-2008, 08:15 PM
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Calif emissions and aftermarket cats
So the motor is out, and operation bore-and-stroke is underway for my 88 S4.
While that's going on, I'm debating the eventual exhaust setup details.
My goals are to sail past California emissions inspectors, whilst not strangling the bigger motor.
I'm considering either running a 2.5 inch low restriction dual system aft of the stock cats (and thus be 100% visually compliant, including factory cats, airpump, etc).
Alternatively, I'm looking at an X-pipe, followed by dual 3 inch aftermarket cats, and then more 3 inch plumbing to some appropriate sized mids and a final.
Clearly the second setup might flow a bit better, but I'm wondering if the non-oem cat setup will trip me up at your average inspection station. Yes, they've probably not seen a 928 and have no idea what it should look like. But they will have a checklist asking for cats, airpump, etc.
What's the experience of my fellow Californians on inspections and after-market cats in an X-pipe?
While that's going on, I'm debating the eventual exhaust setup details.
My goals are to sail past California emissions inspectors, whilst not strangling the bigger motor.
I'm considering either running a 2.5 inch low restriction dual system aft of the stock cats (and thus be 100% visually compliant, including factory cats, airpump, etc).
Alternatively, I'm looking at an X-pipe, followed by dual 3 inch aftermarket cats, and then more 3 inch plumbing to some appropriate sized mids and a final.
Clearly the second setup might flow a bit better, but I'm wondering if the non-oem cat setup will trip me up at your average inspection station. Yes, they've probably not seen a 928 and have no idea what it should look like. But they will have a checklist asking for cats, airpump, etc.
What's the experience of my fellow Californians on inspections and after-market cats in an X-pipe?
05-19-2008, 02:53 PM
#4
Race Director
In "theory" aftermarket cats are not legal...but most all of the high flow cats are CARB certified.... If I remember correctly (always a challenge) you can change the cats to a newer design as long as the sniffer test still passes..... The stock cats will seriously hurt your HP of the stroker.....a dual 3" system with high flow cats is the way to go!
05-20-2008, 02:24 AM
#5
Three Wheelin'
In "theory" aftermarket cats are not legal...but most all of the high flow cats are CARB certified.... If I remember correctly (always a challenge) you can change the cats to a newer design as long as the sniffer test still passes..... The stock cats will seriously hurt your HP of the stroker.....a dual 3" system with high flow cats is the way to go!
05-20-2008, 10:35 AM
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Hi Shawn,
After I failed smog last year, Devek installed an after market cat in my 90 S4. After the cat was installed I had the car re-tested and yes, it passed.
I've been to a few inspection stations and I have not seen one that has a lift. During the inspection, they look pretty carefully under the hood but I've never been to a shop that puts the car up on the lift and inspects underneath.
Good Luck,
Jim
After I failed smog last year, Devek installed an after market cat in my 90 S4. After the cat was installed I had the car re-tested and yes, it passed.
I've been to a few inspection stations and I have not seen one that has a lift. During the inspection, they look pretty carefully under the hood but I've never been to a shop that puts the car up on the lift and inspects underneath.
Good Luck,
Jim
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08-12-2008, 02:55 AM
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Engine is still out, heads are being matched to the new valves this week.
After much debate, I've decided to run the exhaust in a cat-back manner - keeping the factory cats (gasp!) and then running a large 2 inch set of plumbing aft of those cats to some well ventilated resonators and finals.
With luck, we'll have the whole thing up and running in a month or so - always longer than you'd have expected.
Hey - at least I'm not like the rest of the folks on this board selling their big v8 beast to ease the monthly fuel bills
After much debate, I've decided to run the exhaust in a cat-back manner - keeping the factory cats (gasp!) and then running a large 2 inch set of plumbing aft of those cats to some well ventilated resonators and finals.
With luck, we'll have the whole thing up and running in a month or so - always longer than you'd have expected.
Hey - at least I'm not like the rest of the folks on this board selling their big v8 beast to ease the monthly fuel bills
