The stupid exhaust question thread

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jdyates

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I've got the stock headers and y-pipe going to 3" piping to the stock cat, then cut. If i replaced the cat with a flowmaster or a thrush, would the engine have enough backpressure or would that be too little? The cat is clogged and sounds like ****, but i dont want to put the piping back on, i like it cut.
 

Tempted

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Could I make a y-pipe from a k2500 4.3 fit my k1500 4.3??

I have never seen a 2500 4x4 with a 4.3.



I've got the stock headers and y-pipe going to 3" piping to the stock cat, then cut. If i replaced the cat with a flowmaster or a thrush, would the engine have enough backpressure or would that be too little? The cat is clogged and sounds like ****, but i dont want to put the piping back on, i like it cut.

Back pressure is a myth, an engine does not need it. Where that has been confused is with scavenging. My suggestion to you is to look up "engine scavenging effect" for yourself rather than rely on someone else's information in this thread.
 

94K1500KBAR

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I have never seen a 2500 4x4 with a 4.3.QUOTE]

http://www.summitracing.com/parts/wlk-40295/overview/make/chevrolet

look at the application. It will fit a k2500 with a 4.3. and the Catco direct fit for the k1500 is exactly the same one as the catco part number for the k2500 with the 4.3 too. So if thats the case then shouldnt this walker one fit both as well? I believe the only diffrence is that my y-pipe and cat come welded together. So I would have to cut the pipe and use a reducer coupler from a 3in to a 2.5in. between the y-pipe and the cat.

EDIT: Just so we dont waste the post asking why I just dont buy the catco... its $130 with my discout bc it has the cat when I only need the y-pipe which is $30
 

Horns

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The only situation you would ever need more back pressure then what the engine puts out right from the heads is maybe if you had just built the engine and wanted more back pressure to make sure the valve train is set right.

One thing to keep in mind though, is that the whole point of having better flowing exhaust, is to allow air to flow through your engine better. If you don't have a stream of air coming into your engine that matches the flow of air you have leaving it, you're just wasting your money going huge with your exhaust.
 

jdyates

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The only situation you would ever need more back pressure then what the engine puts out right from the heads is maybe if you had just built the engine and wanted more back pressure to make sure the valve train is set right.

One thing to keep in mind though, is that the whole point of having better flowing exhaust, is to allow air to flow through your engine better. If you don't have a stream of air coming into your engine that matches the flow of air you have leaving it, you're just wasting your money going huge with your exhaust.

That's probably why it runs like crap then. I've got decent airflow, but the cat is seemingly clogged. I'm going to be opening up the airflow a little as a little project, and i want the exhaust to be free-flowing too, but not anything crazy like 3" straight pipe.
 

Horns

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You could even just cut the shell off of the cat and weld it onto a new pipe. So there wouldn't really be a cat there at all, just looks like it. I'm pretty sure you guys only do visual inspections in Texas.
 

Tempted

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look at the application. It will fit a k2500 with a 4.3. and the Catco direct fit for the k1500 is exactly the same one as the catco part number for the k2500 with the 4.3 too. So if thats the case then shouldnt this walker one fit both as well? I believe the only diffrence is that my y-pipe and cat come welded together. So I would have to cut the pipe and use a reducer coupler from a 3in to a 2.5in. between the y-pipe and the cat.

EDIT: Just so we dont waste the post asking why I just dont buy the catco... its $130 with my discout bc it has the cat when I only need the y-pipe which is $30

It could, I was just confessing that I've never seen one so I can't verify any of it. But, that said, a 4.3 and 5.0/5.7 all use the same parts. A 4.3 is nothing but a 350 with two cylinders lopped off. You might be able to go with a 4.3, 5.0 or 5.7 part number and be fine.
 

Tempted

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You could even just cut the shell off of the cat and weld it onto a new pipe. So there wouldn't really be a cat there at all, just looks like it. I'm pretty sure you guys only do visual inspections in Texas.

No I lived in Houston for 4 years, it has to pass a sniffer.
 
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