High Flow Catalytic Convertor?

[Jack93prj]

So I guess its about time to either get rid of my factory cat with a new one or go with a high flow.

I don't have to pass inspection(cause I live in Mississippi and my tint is too dark anyways) but are they loud and annoying or do they just give me a little more usable power? I can't find any reviews on our cars so I was wondering if anyone had used one and if it was worth like the 40-60 bucks?

[Jarrett]

The universal catalytic converters are in that price range but will not be direct fit. You'll have to account for the cost of having a muffler shop weld flanges on it and installing it.

An OEM direct fit you can install yourself but will run you a little more money. They're usually in the low $100 range.

After so many miles even an OEM replacement catalytic converter can restore a few hp. Going to to a universal high flow will be even better. But keep in mind we're talking about 3-4 hp tops on a factory or lightly modified engine.

[Jack93prj]

I am not after lots of hp increase I don't expect much, but I am after the power i have lost through a clogged cat. and this is what I was looking at.

http://www.amazon.com/90-93-Honda-Ac.../dp/B003XG2KQ0

also welding isn't a big thing I can weld my own part togeather, I rarely go to a shop to do anything. But do you have any idea what it might sound like?

[wed3k]

have you fixed the issue that clogged your cat in the first place?

[pupildel]

i was wondering this too about the high flow cat

[Djmoua]

I am not after lots of hp increase I don't expect much, but I am after the power i have lost through a clogged cat. and this is what I was looking at.

http://www.amazon.com/90-93-Honda-Ac.../dp/B003XG2KQ0

also welding isn't a big thing I can weld my own part togeather, I rarely go to a shop to do anything. But do you have any idea what it might sound like?

That sir...is not a legit catalytic converter (CC)...that's a test pipe with false advertisement. I got mine for about 80 and it sounded nice for less than half a year (within 6months or less) with no noticeable gain of power. The best part, it led my whole exhaust to become raspy and farty = annoying. Luckily I still had my stock CC and slapped it back on. Sounds quieter and better!

[Jack93prj]

That sir...is not a legit catalytic converter (CC)...that's a test pipe with false advertisement. I got mine for about 80 and it sounded nice for less than half a year (within 6months or less) with no noticeable gain of power. The best part, it led my whole exhaust to become raspy and farty = annoying. Luckily I still had my stock CC and slapped it back on. Sounds quieter and better!

I don't care if its not a catalytic convertor I don't need to pass emissions so i am all good with that. What supporting exhaust modification did you have? I know my cat is clogged cause there is a noticeable drop in power and i have already taken the cat off and inspected it.

[Jack93prj]

Also I am so damn low I am scraping a hole in my cat so its gonna be time to change pretty soon anyways

[904dr]

Here's some links that answer your questions.

http://www.cb7tuner.com/vbb/showthread.php?t=165056


http://www.cb7tuner.com/vbb/showthread.php?t=186764

[Jack93prj]

Thank you for the links..with that I am just gonna stay with my cat till it dies and then replace it with one from honda...

[accordztech]

I don't care if its not a catalytic convertor I don't need to pass emissions so i am all good with that. What supporting exhaust modification did you have? I know my cat is clogged cause there is a noticeable drop in power and i have already taken the cat off and inspected it.

A good way to test for a clogged cat, or clogged exhaust system is to get a vacuum tester. Run the engine at idle, Then hold the rpms around 2500 rpm. The vacuum should stay consistant near (i think) 18-20 hg. If it starts falling then if you have a exhaust restriction. It can be from bent manifold, or the CAT.

If you think its the CAT, then disconnect it and run the same test.

Personally, if your state doesnt care about emmisions, get a long flat head and murder the inside of your cat. There you go, high flow, low cost lol.

[Jack93prj]

I will just run a full cat...I mean 2 hp isn't enough to care

[deevergote]

A good way to test for a clogged cat, or clogged exhaust system is to get a vacuum tester. Run the engine at idle, Then hold the rpms around 2500 rpm. The vacuum should stay consistant near (i think) 18-20 hg. If it starts falling then if you have a exhaust restriction. It can be from bent manifold, or the CAT.

If you think its the CAT, then disconnect it and run the same test.

Personally, if your state doesnt care about emmisions, get a long flat head and murder the inside of your cat. There you go, high flow, low cost lol.

High flow? Hardly. Hollowing a cat will cause a hell of a lot of turbulence in that hollow chamber. It will end up being much more of a restriction than a properly functioning cat, while sounding and smelling awful. That is one of the dumbest things anyone can possibly do.



Anyway, the OEM cat is very free flowing, so getting a performance cat isn't really much benefit in any way. Many of the performance cats on the market are considerably cheaper than the OEM units... because they have less material in them. They don't function as well, or last as long. The additional flow provided is minimal.
You'd be best getting a quality OEM replacement. As Jarrett said, a good weld-in will potentially be cheaper than a bolt-in, especially since the stock bolts around your old cat are very likely so stuck on there they might as well be welded!
If you have it set so you can remove it, and you actually WANT to gain that couple extra HP later on, you can always have it set up so you can slap a test pipe in there for racing. My friend used to do that when he went to the track, and then replace the cat the following morning.

[accordztech]

High flow? Hardly. Hollowing a cat will cause a hell of a lot of turbulence in that hollow chamber. It will end up being much more of a restriction than a properly functioning cat, while sounding and smelling awful. That is one of the dumbest things anyone can possibly do.



Anyway, the OEM cat is very free flowing, so getting a performance cat isn't really much benefit in any way. Many of the performance cats on the market are considerably cheaper than the OEM units... because they have less material in them. They don't function as well, or last as long. The additional flow provided is minimal.
You'd be best getting a quality OEM replacement. As Jarrett said, a good weld-in will potentially be cheaper than a bolt-in, especially since the stock bolts around your old cat are very likely so stuck on there they might as well be welded!
If you have it set so you can remove it, and you actually WANT to gain that couple extra HP later on, you can always have it set up so you can slap a test pipe in there for racing. My friend used to do that when he went to the track, and then replace the cat the following morning.

I share the same thoughts as you. But I personally think that a free flow (no cat) cat is a loss in power (except in turbo applications). I ran one for a while and it felt way better with a CAT in place. And it will sound like shit lol. Thats why I said "if you don care..."

But ill tell you, those aftermarket ones suck in longevity compared to oem. They dont filter that great either.

[deevergote]

Yeah, the aftermarket ones really aren't very good. I've seen a number of cars that sounded and smelled terrible, even with a brand new aftermarket cat... even those from a known manufacturer!

OEM replacement is ideal. Larger sizes can be had, especially when using the weld-in variety. Figure, cars like the S2000, RX8, STi, Evo... they all make WAY more power than our cars in stock form (I used a variety of small-displacement engines for valid illustration), and they all HAVE to come with cats by federal law. Even a 300hp turbo CB7 could probably use a factory replacement cat for an Evo.