351w, smog system question.
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Joined: Apr 2004
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351w, smog system question.
Ok here's the deal. I want to remove all of the non functioning smog CRAP from my engine. I would like to basically redesign the smog system. If I rework the exhaust to have a NON-air injected high flow cat, will the cat still do it's job if the engine is in good running order?
The current cats are clogged/dead/something, and must be replaced anyway, and since I haven't yet found a place to get a new y-pipe for an '87, I have time to think about it, and do a redesign using current technology. It has to have gotten better since 1987.
Thanks for any and all info in advance!
The current cats are clogged/dead/something, and must be replaced anyway, and since I haven't yet found a place to get a new y-pipe for an '87, I have time to think about it, and do a redesign using current technology. It has to have gotten better since 1987.
Thanks for any and all info in advance!
Fleet Mechanic
Joined: Mar 2004
Posts: 1,529
Likes: 35
From: Kansas
If you remove your smog equipment and drive it on the street, that is illegal. If you have smog checks on your car, they will visually catch it when they do their inspection. Even if your modifications make the exhaust burn cleaner than the original factory system, it is still illegal. However, in some states, older vehicles are now exempt from inspections. As far as the air tubes, your cats may work, it's just that the air tubes are designed to inject oxygen in the system right before the cats so there is a more complete catalyst and a cleaner exhaust.
I hope I've answered any of your questions.
BTW, I live in a state that has no yearly vehicle or exhaust inspections......
I hope I've answered any of your questions.
BTW, I live in a state that has no yearly vehicle or exhaust inspections......
Post Fiend
Joined: Nov 2001
Posts: 14,947
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From: Topsfield, MA
I have to back up my buddy there. I'm putting all my emissions stuff back on my brand new 393, i just washed all the parts and made them look as good as they can be, it's a fairly neatly run system and it's sorta hard for the average guy to notice. The goal with my project is to have a clean looking engine compartment, with a few nice touches and still uphold the everyday driver lifestyle. Something I don't wash every day but don't mind showing off. Mine's a 95, I wonder if the system on the 87 is run differently, and you could switch to the newer style stuff and keep its functionality but adopt it's simplicity. Is that what you were trying to get at in your post? I was a little confused.
I also got a y-pipe/cat combo from bassani (through proficient performance), I can still see through the cat in it, it's tiny and doesn't look to obscure airflow much at all.
I also got a y-pipe/cat combo from bassani (through proficient performance), I can still see through the cat in it, it's tiny and doesn't look to obscure airflow much at all.
Post Fiend
Joined: Nov 2001
Posts: 14,947
Likes: 6
From: Topsfield, MA
Thermactor tube....you mean the tube that goes from the exhaust pipe up to the back of the engine to a small cluster of hose/valves, and bolts to the back of the heads....ya thats the termactor system.
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Post Fiend
Joined: Nov 2001
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From: Topsfield, MA
My understanding is that the system is used to take exhaust gas and re-circulate it into the combustion chamber, because some of it can be burned again to lower emissions. Thats what those black valves are with the vacuum lines, they open and close based on vacuum (think of engine load there), so when the engine is jsut crusing along without a heavy load on it, those valves are open and some exhaust gas is being recirculated. When you stomp on the gas, those valves close, and you get nothing but fresh oxygen for power. It's tied into the air pump that is run on the accessory belt. I believe part of the system is to add oxygen to the exhaust downstream for the cat.
Lead Driver
Joined: Nov 2002
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From: Concord, NC
The thermactor system is entirely separate from the EGR system. The thermactor system pumps fresh air into the exhaust under certain conditions programmed in the computer to help the 3-way catalytic converter function properly. Long story short, it helps reduce harmful emissions. The EGR valve vents exhaust gases to the intake manifold mainly during part-throttle cruise.
Lead Driver
Joined: Nov 2002
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From: Concord, NC
Under some conditions (mostly cold start up I believe) the computer decides to send the air to the heads, possibly to light off the first cat a little quicker. The ports on the back of the head connect with all the exhaust runners in the heads, not the intake (maybe that's what you were thinking?). There is a check valve in place to keep the exhaust from blowing back into the air lines. When the vehicle warms up, the computer sends the air to the second cat, or could choose to bypass the air from the smog pump straight to the atmosphere.