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Gutting Catalitic Converters..??


cormy

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I'm thinking NOT..found this...

 

The major one being that the current generation of catalyst elements are not very restrictive at all. In fact, they actually work like a tuned collector on normally aspirated engine. As the exhaust gases pass through them, they act like a check valve for exhaust flow. As the exhaust valve closes, momentum causes the gases to continue to travel through the exhaust system. This is plenty of energy to pass through the cats. This causes a vacuum to build up between the exhaust valves and the catalytic converter. The energy required to pull the gases back through the element can't build fast enough to work before the next exhaust valve opens. When that next exhaust valve opens, it is opening to a vacuum environment which helps to PULL the gases out of the cylinder due to what is called "scavenging effect". This translates into more power as the piston now does not have to do all the work to evacuate the cylinder of spent combustion gases.

Second, if you were to remove them, you would definitely want to use a cat removal pipe. The chamber left after you would "gut" the cat is actually worse at losing energy than a catalytic element (understand I mean element designs after around 1990). This is because as the gases enter the empty chamber, exhaust velocity slows down. As it then regroups to enter back into the exhaust piping, it does not have the energy it did before, therefore it "stacks", causing backpressure. This backpressure now works against the flow of spent gases out of the cylinder when the exhaust valve opens, causing the piston to do all the work. Now, energy is being wasted for gas removal that could otherwise be used to turn the crankshaft

 

 

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Good points. Cats were power robbers when mandated forty years ago. That was before a lot of design adjustment to them and the advance of engine computer tech. It seems that unless the car is being run at high redline rpms, there is little or no advantage to removing them.

 

Any numbers from independent tests at all various rpm ranges?

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The only reason one needs, or should gut cats is if you're making over 700 RWHP. The reason is to protect your engine from cats failing/ collapsing. Even green high performance cats at 700-750 RWHP your playing with fire. Over 750 RWHP only a matter of time before they collapse/ fail. If your not making that much power it's best to keep them, then get rid or gut them.

Mark

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The only reason one needs, or should gut cats is if you're making over 700 RWHP. The reason is to protect your engine from cats failing/ collapsing. Even green high performance cats at 700-750 RWHP your playing with fire. Over 750 RWHP only a matter of time before they collapse/ fail. If your not making that much power it's best to keep them, then get rid or gut them.

Mark

Very true - I was making 715 and cats went south quickly. I have kooks set-up and went with off-road pipes. I caught the collapsing cats just in time.

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