High Flow Catalytic Converter

[SykVSyx]

Just wondering if some of the swapped/boosted guys are able to confirm/deny whether there is benefit to running one?

I will be running it with the APEXi WSII full exhaust and XS Power headers.

 

[2002CG3coupe]

Just the tone of the exhaust is deeper, and I have stock piping. I can imagine with your world sport it would be even deper and possibly louder too.

 

[RedRyder]

I keep thinking about getting one. But I keep wondering since I opened up the exhaust manifold and y-pipe with aftermarket headers, and opened up the catback with a Magnaflow…should I keep the OEM cat to keep some back pressure? Or is a high flow cat not open enough to lose any backpressure and would it help the engine breathe better?

On Derek’s behalf…lol

 

[SykVSyx]

Thanks Chris, good questions.

I am waiting to hear back from Paul on V6P about it as well, so I will post his response once I have heard back.

My hope is it won't be too loud. The WSII is only loud on acceleraton, and not all that much.

 

[98ExAccordwv]

Here's my understanding of catalytic converters and high flow catalytic converters:

So with the increase in modern technology the more recent converters already flow at decent rate and do not drastically inhibit power. If you purchase a high flow catalytic converter from a reputable EPA compliant company, the difference in flow between a stock and high flow is minimal. That being said, it will provide a small increase in horsepower at the top of the RPM range and a small bit of torque at the bottom of the RPM range but these are going to be hardly noticeable on a stock motor. Now the reason for the difference is the amount of material used in the substrate, stock typically uses around 700 cells per square inch, and an EPA compliant high-flow will use around 400.

If you do decided to go with a high-flow, ask the sales people what the cells per square inch are. Obviously the higher the number the more restricted the flow, but if you get too low, you start getting into the problems with CEI's and also the ECU not being able to adjust the A/F mixture properly without being tuned, since it will have no idea whats being emitted.

As far as sound goes, obviously the less restrictive, the louder it will be, I personally have no idea how much difference a high flow-cat will make since I've never purchased one.

And again, this is all based on reading I've done in the past, so it may not be 100% accurate anymore. But hopefully it will help.

 

[SykVSyx]

Alex, appreciate the info, thanks.

Heard back from Paul as well, it he also mentioned it would open up the flow. As for as the performance gains, he said it wouldn't be alot, but there would be a gain of a few hp.

I was wondering about the bottom line(performance gains), as I am trying to squeeze as much as I can out of this engine.

I am sure a test pipe would have even more benefit, but I don't want to have to deal with any smells, and of course the emissions issues as well.

 

[99CcordMTF23]

I am running catless right now, and i personally wish i still had the stock cat. (Mine went bad, so i smashed the guts out) and I think it sounds terrible... For my h22 swap, i really wanted to keep everything legit, and I see no reason not to have them. (Almost EVERY new vehicle has them, and there are plenty of lingenfelter vettes running cats and still making power) I mean, sure you have a giant turbo and you're making 600hp on the street, a stock cat might be a little bit of a choke point, but as far as anything for street duty, A catalytic converter really isnt holding you back. Obviously a High flow cat, will flow more. Less back pressure, more sounds, blah blah blah. The Catalyst is just going to be a cleaner exhaust, less emissions, and it can usually cut most of the rasp and horrible straight piped civic sound out of your system. I need another one... I'm also a firm believer in "If you can do it without ruining the environment, why not" I mean... My powerstroke diesel has a Gigantic Catalytic converter on it. I plan on leaving it too.

 

[SykVSyx]

Thanks for the feedback/information, all.

I think I will go with the high flow for now, when I comes to emissions, I have an aftermarket one(stock replacement), I can throw on there.

Don't see myself bothering with the test pipe, it's not a track car, and I rather not have to deal with the potential headache of being stoppd on the street.

 

[Jefe02]

I have a high flow cat with my magnaflow cat back and its not loud at all unless im accelerating hard. Why would you not be able to pass emmisions with a high flow cat?

 

[SykVSyx]

Some of the machines here(from what I have been told) are picky.

Even with aftermarket Cats, those don't always pass inspection, so I imagine the same might be true with a high flow setup as well.

I would be more concerned about the noise with a test pipe than a high flow unit.