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Discussion Starter · #1 ·
A mechanic friend of mine gave me a little idea today. Apparently he bought a catalytic converter from a junk yard and guttted it out. He then installed some exhaust tubing straight through the converter and out to the muffler. I guess the idea was to gain some HP while still fooling the visual inspection. Also his truck has continued to pass the emission test with room to spare. He has lost some low end HP but gained a great deal of top end. WHat do you think?

How does it feel to be beaten by a sewing machine?
HUSQVARNA WXC610
 

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Why not just hollow out the cat and run it like that? Beats doing the work to put the pipe in it.

1992 Blazer Sport, 350 TBI, 4L60, 3" Flowmaster, K&N, MSD coil & wires, Rancho 2.5" lift, 285/75R16 AT's/wwwthreads_images/icons/laugh.gif
 
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Discussion Starter · #3 ·
yup, ive done this to several friends trucks. just get a big screwdriver and hammer and hollow it out

Mike ~
* Earnhardt Forever *

89 Chevy K1500 - 350TBI/700R4/NP241 - 3" lift - 33's
 

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Actually if you just hollow out the cat, you still have other issues to deal with, such as the dynamics of the air flow. When the exhaust gasses are in the manifold, and the tubing before the cat, they're moving fast. This gives them low pressure. They slow way down when they hit a hollowed out cat (most of them at least, since they have a bigger diameter (by quite a bit) than the surrounding exhaust. Then the gasses hit higher speeds again when they get out of the cat. Bernouli's principle tells us that. (the same principle that makes airplanes fly)... This will affect the backpressure and exhaust scavenging as well I think. At least it would make sense for it to. /wwwthreads_images/icons/crazy.gif

A friend tried just hollowing out the cat, but it didn't help as much or change as much as it likely would have to have the tube through it. Just a thought.

Tim "Sandman"

ORC Land Use columnist:
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