NO CAT VS CAT

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JetBlackNali

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Did seeing first hand time slips or dyno pulls help you to arrive at this conclusion?





Have been many articles on this. Here's a vid for ya. Every car is different in the way they react to removing or adding parts. If LOUDER means faster than I guess it's a no brainer.
 

iamdub

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I think saying cats rob power is far too broad of a statement. As Stu mentioned, every car is different. On an otherwise stock vehicle, I'd say that removing them can free up some power because engineers are gonna design an exhaust to be as small as possible while remaining sufficient. So, removing even a relatively minimal amount of restriction such as a modern cat should show improvement. It won't be anything as drastic as something like switching from manifolds to long tubes, but an improvement nonetheless. On a hot rod that's likely to have a somewhat large exhaust, maybe even oversized for the setup, there's not much gain to be had. If anything, removing them may slightly shift the powerband up a little.

That Flowmaster video doesn't say much other than exemplifying what I just said. For a 318 inch, 250-300 HP motor, that exhaust looked plenty oversized (dual 2.5"?). So adding a couple of equally-oversized "plugs" wasn't gonna change much of anything.

The catalytic converter may not flow as well as a straight pipe. But, if it's big enough, it can be flow plenty well enough to not adversely affect it. It's just like an air filter. A square inch of a standard paper element doesn't flow as much air as a square inch of a cotton gauze "performance" filter. But, stock air filters are generally larger and have so much area due to the pleats and the overall dimensions of the element that they aren't a restriction to what the engine can ingest. Yet, they usually do a better job at filtering than the "performance" filters due to the media itself.
 
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SmileB44Death

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I would have preferred to leave them on but when I went to long tubes, I also got a y pipe and the shop said there wasn't room to weld on cats. I had already bought 2 aftermarket high flow cats--which are for sale. I live in NJ, which is a smog state. They also do a visual here, so i don't know how im gonna do at inspection time. My 2 O2 sensors down stream are deleted. Tuned out at the pcm.
How much did it cost?
 

swathdiver

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Wow, and I'm being sarcastic here, didn't know Belvedere's needed cats! Never trust a man who spends that much time and effort on his hair to look like a rooster.

Anyhow, those are short cats on an oversized exhaust system, that little motor doesn't need pipes that big. A long time ago this old man used to hollow out the broken cats and then run the cars at Moroso, it was usually good for about... well, I cannot remember anymore but somewhere in the garage are the time slips! Nothing drastic but it did make a difference.

In a week or so I'm going to baseline the truck and maybe, just maybe, I'll fix my cats and make another trip to Moroso, uhh, Palm Beach International Raceway.

It is sad when the left's religion of environmentalism invades every facet of society, I never could have dreamed that the nonsense I see today is so embedded within this hobby of going fast.

Even with gutted cats my cars still passed the emissions testing. Stu, none of my comments are directed you personally. Just funnin' on the video and what the rooster guy was saying.
 

JetBlackNali

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No problem man.

Regardless of the car in the video or what the guy with the bad hair says - what I'm saying is on a street car or truck the gains would be very little. If gutting a cat produces a small gain I would think that it was plugged or clogged. Would benefit more from a better flowing exhaust.

Good argument both ways. Cheers
 
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Tonyrodz

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How much did it cost?
Somewhere around $800, but the front prop shaft had to be removed because the 2 inner tubes on the ds header were in the way, so the Hoe is no longer 4wd:mad:. If you want to hear it, look at the bottom of this and you'll see a youtube link to my cold start.
 

SmileB44Death

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Somewhere around $800, but the front prop shaft had to be removed because the 2 inner tubes on the ds header were in the way, so the Hoe is no longer 4wd:mad:. If you want to hear it, look at the bottom of this and you'll see a youtube link to my cold start.
I don’t see a video link?
 

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