Installing dual exaust
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Installing dual exaust
I want to put duals on my 86 F150 4X4. I am not putting on a split off the muffler setup. I want a true dual setup, but I am going to need 2 cats, probably the smaller the better. I am looking through the dynomax catalog and they list a bunch of direct fit converters, not really what I want, and they list some others with thier sizes. It talks about 2-way, 3-way, qualified engine displacement, qualified vehicle weight. I don't really know what they are talking about here. I assume you can't use them with engines bigger, or vehicles heavier, then listed. What about 2- and 3- way?
Also, my truck currently has the two cats and then the muffler off the back. Do I have to worry about this? Why does it currently have two cats? I shouldn't need two on each pipe after duals are installed right?
I want to do this once and do it right so I can pass NJ inspection with it.
Also, my truck currently has the two cats and then the muffler off the back. Do I have to worry about this? Why does it currently have two cats? I shouldn't need two on each pipe after duals are installed right?
I want to do this once and do it right so I can pass NJ inspection with it.
New User
Joined: Jul 2003
Posts: 11
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From: Mid-Missouri
The way your emissions system is setup from the factory, there is an air pump that injects air in between the two cats. To stay legal you would have to buy two cats and figure out how to get air to both of them. The stock pump may not be able to supply the volume of air needed for two cats. If you have emissions check in NJ, you may not be able to pass.
You are better off with a catback system. Use one air injected cat.
You are better off with a catback system. Use one air injected cat.
Senior User
Joined: Mar 2003
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From: NE TX
If you are not supercharging, then you won't be producing much more exhaust than before. It just has bigger pipes to go through and less pressure. I wouldn't think the volume of air needed from the AIR pump would be much more. Just Y off the pipe and plumb them the same. The stages of cats is because most chemical reactions are due to variables, like barometric pressure, ambient temp., and humidity. If 1 cat reduces emissions 50%, then 2 alike could reduce emissions 75%. Some trucks use several HEGO sensors to work the EGR and other emission correcting systems. Some have oxygen sensors after cats to let PCM know what is going on. Yours would not be that complicated though for a '86. 1 aftermarket cat could do as well as a stock 2 cat system. I'm no exhaust expert though. I'd talk to a shop in NJ and get their input. You should have friends/neighbors have have put on dual exhausts.
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