PDA

View Full Version : Gutted Cat vs TP



Nor_Cal_Driver
01-17-2008, 06:20 PM
Just passed my SMOG inspection today, $140 for two cars plus DMV fees . . . Anyhow is there any major disadvantage to using a gutted cat on a k03s/k04 setup versus using a test pipe? Seems like a safer bet for me in California where a test pipe can easily send me to a state referee where as a gutted cat gives me a much better chance. So does the gutted cat have any major draw backs?

Maybe disrupted exhaust flow from the large chamber when going back to piping??[confused]

D's Avant
01-17-2008, 06:41 PM
I gutted my cat on our old '84 VW quantum sedan many, many years ago when cat's were very expensive and it had failed. (the insides/cells of it were rattling around) It sure made a difference with the power on that old five cylinder, but the exhaust was real tinny and had an odd resonance at full throttle. Just something to think about if you punch out the insides of the cat and put it back on the car.

grip_racer
01-17-2008, 06:48 PM
onemoremile's car gained power when he switched from a gutted cat to a TP

he'll come in here and tell you that it did, and then he'll tell you to get a HFC

::grandpa voice:: "99% of the power, none of the drawbacks!"[:D]

Nor_Cal_Driver
01-17-2008, 07:47 PM
I have an extra gutted cat so it's no loss to me other then my labor, I do have two small children so my free time is next to nil so I would like to do this once and was hoping to hear that the gutted kitty would work but maybe I will search for onemoremile's posts, I DO NOT want a HFC though as I think it's a bit of a waste.

onemoremile
01-17-2008, 07:49 PM
You've got little kids. Kids breathe. Get a HFC.

Nor_Cal_Driver
01-17-2008, 07:54 PM
You've got little kids. Kids breathe. Get a HFC.

My little 1.8 ULEV car isn't going to make a difference in the air my children breathe, cat or no cat, the car just runs way to clean to start with. Like I said before, I had my car smogged today and noticed that it averages half the emissions that the rest of passenger cars average, it's those H2's EVERYWHERE on the other hand do.

onemoremile
01-17-2008, 08:00 PM
Then do whatever the hell you want. Without a cat to convert the carbon monoxide to carbon dioxide your car is not a ULEV or LEV. An H2 may make more exhaust but I'd bet their CO levels are lower than yours.

Under it's previous owner, my car passed New Jersey tailpipe emissions testing with a non-chipped K04 and gutted cat. Clean as it was, it is much cleaner now with proper tuning and a HFC.

Nor_Cal_Driver
01-17-2008, 08:02 PM
Then do whatever the hell you want.

Aw come on, just looking for the facts sir. [;)] I'm going to search out the posts you made about this now.

supamannn99
01-26-2008, 11:09 PM
is a gutted cat the same as a high flow cat? what's the worst trouble you could get into when getting caught with a test pipe? i'm considering getting one because its alot cheaper than a high flow cat

Kyle H
01-26-2008, 11:15 PM
is a gutted cat the same as a high flow cat? what's the worst trouble you could get into when getting caught with a test pipe? i'm considering getting one because its alot cheaper than a high flow cat
In california it's a major no no to run without a cat. A highflow cat still converts the crap in the exhaust to not-so-bad crap, but a gutted cat doesn't (because theres nothing in it to do that).

Get a HFC, it's not that much more.

VTAudiA4
01-27-2008, 08:15 AM
I would just get a Labree HFC. Its on sale now for $250 until the end of this month but its usually $269 so no big difference. This way you can conform with the emissions and get the same results as a TP. Plus the price isnt that bad. A TP is like $200 anyways (sometimes lowers and sometimes higher depending on the company).

onemoremile
01-27-2008, 10:14 AM
is a gutted cat the same as a high flow cat? what's the worst trouble you could get into when getting caught with a test pipe? i'm considering getting one because its alot cheaper than a high flow cat

Not even remotely the same. The cat converts highly toxic carbon monoxide to carbon dioxide. Just install a high flow cat and stop deliberating about cheap shortcuts that hurt the planet and don't provide performance benefit. HFC vs. test pipe or gutted cat = all the good with none of the bad.

This is what a gutted cat looks like.
http://audizine.com/forum/showthread.php?t=89276&highlight=gutted+cat

http://i23.photobucket.com/albums/b397/onemoremile/IMG_2601.jpg

VTAudiA4
01-27-2008, 10:31 AM
Here is another bonus for a HFC. Don't quote me on this but when you install a TP you get a CEL or 2. You would have to do the anti-fouler mod. HFC on the other hand works fine without it. But you would know more about this then I would probably.

Kyle H
01-27-2008, 10:37 AM
HFC's with a lower cell count can sometimes give you a CEL, but for the most part you're right. [:)]

Nor_Cal_Driver
01-27-2008, 01:20 PM
. . . $269 so no big difference. This way you can conform with the emissions and get the same results as a TP. . . .

Not quite, I'm sure a TP would net more gains the a HFC, maybe only a few ponies, but it's simple flow, the HFC is more restrictive then a TP and more expensive too, but a HFC is an easier mod as you don't have to be skilled enough to deal with the o2 sensor reading which you can use the mentioned anti-fouler or do a diode mod.

I have to say again, the amount of carbon monoxide the clean burning 1.8l motor puts out with out a cat will not change the world we live in.

onemoremile
01-27-2008, 04:27 PM
Not quite, I'm sure a TP would net more gains the a HFC, maybe only a few ponies, but it's simple flow, the HFC is more restrictive then a TP and more expensive too, but a HFC is an easier mod as you don't have to be skilled enough to deal with the o2 sensor reading which you can use the mentioned anti-fouler or do a diode mod.

I have to say again, the amount of carbon monoxide the clean burning 1.8l motor puts out with out a cat will not change the world we live in.

Our engine is not clean burning. No internal combustion engine is. That is why we have two catalytic converters (in one case) on our tiny little engines. Turbo cars are dirtier than naturally aspirated cars since they are more rich at full throttle.

I've run them both and there really isn't much of a difference, if any. This would be different with a large turbo but with a K04 the real flow restrictions are the manifold outlet and small turbine section. I can send you a gutted cat if you really want to find out how wrong you are.

A4Rollin
01-27-2008, 05:16 PM
+1 on the HFC, its not worth the trouble going TP in cali

Nor_Cal_Driver
01-27-2008, 05:25 PM
Our engine is not clean burning. No internal combustion engine is. That is why we have two catalytic converters (in one case) on our tiny little engines. Turbo cars are dirtier than naturally aspirated cars since they are more rich at full throttle.

I've run them both and there really isn't much of a difference, if any. This would be different with a large turbo but with a K04 the real flow restrictions are the manifold outlet and small turbine section. I can send you a gutted cat if you really want to find out how wrong you are.

I have a gutted cat sitting in the garage, but thanks for offering to save me the money.

I do have an idea, is CAPS a way of measuring the improvement over stock?
I'm guessing test conditions must be pretty close. . .

Militant-Grunt
01-27-2008, 09:26 PM
http://a134.ac-images.myspacecdn.com/images01/8/l_75fc07ac16cc162796932be6f021bd3d.jpg
http://a250.ac-images.myspacecdn.com/images01/4/l_d880ef8da0f0f7a847a4d53cb07fd3a1.jpg

Can't go wrong with custom made for cheapie cheapie. No CEL with foulers.

Nor_Cal_Driver
01-28-2008, 07:47 AM
Wow, 3" on the ole k03! Works well though ha?

How stiff are those 034 mounts?

onemoremile
01-28-2008, 08:08 AM
That is one hell of a bend in that test pipe. Probably drops to 2.5" or less right there.

Nor_Cal_Driver
01-28-2008, 10:06 AM
. . .

I do have an idea, is CAPS a way of measuring the improvement over stock?
I'm guessing test conditions must be pretty close. . .

ANYONE????

ILoveT
01-28-2008, 11:55 AM
CAPS is just a way for Audi owners with similar mods to compare their cars.

Nor_Cal_Driver
01-28-2008, 12:01 PM
CAPS is just a way for Audi owners with similar mods to compare their cars.

But would this not help settle the issue if I ran my car with the cat in place vs a gutted cat, the CAPS time would show an improvement or not right?

ILoveT
01-28-2008, 12:05 PM
What Onemoremile was saying was that there is really no noticeable difference in a HFC and a test pipe/gutted cat - Performance wise

I think we all agree a test pipe will outperform our stock converter. Or am I just misunderstanding?

onemoremile
01-28-2008, 12:15 PM
Both the test pipe and HFC outperformed the gutted cat but it was a small difference. I'm sure all of them outperform the stock cat.

CAPS times are one of the best ways to look at before/after performance. Do runs in both directions and average the times to minimize grade errors. Do several runs and use the best times and average times for comparison.

Nor_Cal_Driver
01-28-2008, 12:56 PM
I will try and make this a project this weekend possibly, but I have kids so it may be a month before I have time to do the experiment.

A4Rollin
01-28-2008, 01:06 PM
http://a134.ac-images.myspacecdn.com/images01/8/l_75fc07ac16cc162796932be6f021bd3d.jpg
http://a250.ac-images.myspacecdn.com/images01/4/l_d880ef8da0f0f7a847a4d53cb07fd3a1.jpg

Can't go wrong with custom made for cheapie cheapie. No CEL with foulers.

No way its 3" at that hella bend