catalytic converters
Thread Starter
Pro
Joined: Dec 2015
Posts: 578
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From: colo
catalytic converters
I am getting ready to drop a 2017 LT1 in my 1978 Corvette. The car currently has the original catalytic converter in it. It doesn't have any place for O2 sensors, and I am thinking about buying new ones to attach near the manifolds like the camaro it came out of.
My question is since I will be using 2 'cats' on a 6.2 engine , would smaller ones designed for maybe a 3.8 liter work.
I live in californicated Colorado and emissions are required where I live .
Hopefully there are knowledgeable people that can guide me through this.
Ed
My question is since I will be using 2 'cats' on a 6.2 engine , would smaller ones designed for maybe a 3.8 liter work.
I live in californicated Colorado and emissions are required where I live .
Hopefully there are knowledgeable people that can guide me through this.
Ed
Thread Starter
Pro
Joined: Dec 2015
Posts: 578
Likes: 107
From: colo
Thanks for replying. The LT1 cats are $350 - $400 ea , and they have fittings for 4 O2 sensors.. The wiring harness I have only has the before fittings. Since I have to make the entire exhaust system I figured it would be cheaper to get aftermarket cats.
Race Director
Joined: Jul 2015
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From: SW Florida.
ok, you are using some kind of aftermarket efi controller? cuz any oem setup will give you P0420 codes for the after-cat oxy sensors not reading. OTOH i don't think the CO emissions guys are gonna plug their OBD2 connector into your 78. best to try to find 2 matching used OEM cats. i don't think junkyards can sell them, which is stupid. the aftermarket cats are junk. it may be cheaper to buy 2 junk vehicles with cats and re-junk the cars with exhaust removed. and i think cats from a 3.3 caravan or similar may do the trick. or maybe try to find a chevy express van 96-02. last of the vortec 350 engines. they all blew intake manifold gaskets and got sold off cheap. cars these days emissions had to be guaranteed a long time. they run pretty clean and the exhausts are stainless and cats last a long time.
Drifting
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Team Owner
Joined: Oct 2004
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From: altered state
St. Jude Donor '05
Thats the best plan. Let us know what they say. Good chance you may need less emissions stuff than you think
Wont have a problem burning clean, for sure. I would not use 6 cyl cats...noone likes spending more but do it once/right.
Wont have a problem burning clean, for sure. I would not use 6 cyl cats...noone likes spending more but do it once/right.
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From: North Georgia, USA
I am getting ready to drop a 2017 LT1 in my 1978 Corvette. The car currently has the original catalytic converter in it. It doesn't have any place for O2 sensors, and I am thinking about buying new ones to attach near the manifolds like the camaro it came out of.
My question is since I will be using 2 'cats' on a 6.2 engine , would smaller ones designed for maybe a 3.8 liter work.
I live in californicated Colorado and emissions are required where I live .
Hopefully there are knowledgeable people that can guide me through this.
Ed
My question is since I will be using 2 'cats' on a 6.2 engine , would smaller ones designed for maybe a 3.8 liter work.
I live in californicated Colorado and emissions are required where I live .
Hopefully there are knowledgeable people that can guide me through this.
Ed
If they require full OBD-II suport including "catalyst efficiency monitor" functionality, you will need downstream o2 sensors.
If you run full dual system, use 2 cats. If you run single exhaust from a Y pipe, you can use one.
For mixture monitoring, you need 2 upstream O2 sensors that match your PCM requirements.
For dual exhaust /dual cats, if catalyst efficiency monitoring is required, you'll need 2 downstream O2 sensors for that.
For single exhaust with single cat, you'll need a third upstream O2 just before the cat and a downstream O2 after the cat for catalyst efficiency monitoring if that is required.
The upstream ones for mixture control can be in the header collectors. It's trivial to weld them in if the header doesn't have them already.
Thread Starter
Pro
Joined: Dec 2015
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From: colo
Colorado isn't that bad on older vehicles as long as all the parts are there. On the older vehicles they test through the exhaust pipes at idle- 2500 rpm - and back to idle. there may be a couple of cycles or something similar. It has always passed with flying colors, except when my gas gap didn't pass. One time I took it in and only one person had the knowledge of what they were looking for . If I didn't live in the Denver metro area , I wouldn't even need an inspection. My concern is when I change engines, will I need to meet the new standards .
The wiring harness I bought only has upstream O2 connectors. I made sure that they knew I lived in Colorado where there are emission inspections.
As soon as I stop by the emissions place and get more info I will let everyone know.
Ed
The wiring harness I bought only has upstream O2 connectors. I made sure that they knew I lived in Colorado where there are emission inspections.
As soon as I stop by the emissions place and get more info I will let everyone know.
Ed