Thorley headers questions -
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Unread 06-21-2006, 01:29 PM   #1
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1997 ZJ 
Join Date: Jun 2004
Location: Ohio
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Thorley headers questions

I'm excited I just got the last piece of my complete exhaust system and new intake from Kolak today. One question though. All the piping is 2.5". I noticed though the pipe from the headers is only like a 2" pipe at the flange. Why is this, isn't that a choke point?

eagleknight is offline   Reply With Quote
Unread 06-21-2006, 08:57 PM   #2
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I think it has to do with scavenging the combustion chamber to create better flow. The smaller pipe acts like a carburetor venturi where the pressure drops, but the velocity thru the venturi actually increases. The faster you get the exhaust out of the engine, the more air can go in, the more power the engine makes.
zjhitman is offline   Reply With Quote
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