Removing a Catalytic Converter (Cat Con) - Do you guys think its worth it?

ananthkamath · 5th July 2007, 01:28

A recent post by some guy on another board made me think - Are we doing the right thing by advocating removal of the cat on our cars in exchange for the supposed HP gain?

Some things we need to think about before removing the cat -

1) Do we need to remove it in the first place? What gains are APPARENT & MEASURABLE from this?

2) Is there any published data on the gains from removing a cat either on our Indian engines, or from similar engines abroad?

3) What is the impact on the environment?

Why not do some research and form a conclusion before senselessly contributing to slaughtering the environment more than necessary?

Mpower · 5th July 2007, 17:49

I think every car will respond differently to this. Some will show a lot of gain and others negligible..but generally it will improve top end power.

Late model cars which are designed for LEV and ULEV emissions have a catalyst that is stuck into the manifold that prevents any kind of header installation. Thats another problem.

Another thing to worry about is what is the ECU going to do when it detects a missing cat. Might need a remap for that.

n_aditya · 5th July 2007, 18:27

Quote:

Originally Posted by Mpower

Another thing to worry about is what is the ECU going to do when it detects a missing cat. Might need a remap for that.

Wouldnt the ECU "remap" itself as it is a self learning thingy? If the battery is disconnected and reconnected after few mins the ECU gets reset and would "learn" the new inputs. Wouldnt this work at least to some extent?

mail4ajo · 5th July 2007, 21:07

Quote:

Originally Posted by n_aditya

Wouldnt the ECU "remap" itself

ECU cannot remap itself. But it will learn the new values and work based on the map loaded.
But we are not fiddling with any sensor, right? So will there be any difference in the values at all??

AUTO_CRAZY · 5th July 2007, 21:14

I think considering the damage to the environment........it is strongly recommended not to remove the CAT CON.

veyron1 · 5th July 2007, 22:29

1) Removal of cat-con is unnecessary unless the car is being tuned for serious performance gains (Upwards of 30%). Even more unnecessary if CC of engine is below 2000.

2) For anything below, cat-backs should suffice; the muffler & expansion chamber (pre-exhaust) reduces the EG velocity by a greater margin than the cat-con itself.

Quote:

Originally Posted by Mpower

Another thing to worry about is what is the ECU going to do when it detects a missing cat.

Most ECM's won't detect the cat-con; lambda sensor's at the exhaust manifold, na...there aren't separate sensors for cat-cons in most cars...at least not the non-expensive ones...

theMAG · 5th July 2007, 22:42

Quote:

Originally Posted by ananthkamath

..
3) What is the impact on the environment?

Why not do some research and form a conclusion before senselessly contributing to slaughtering the environment more than necessary?

I hear you man. I'm all for healing the environment while still making our lives exciting. Thats a very difficult choice curently.

mail4ajo · 5th July 2007, 23:34

I was just wondering if removing the CAT will give more pickup while driving on LPG. I wont be damaging the environment a lot since LPG creates minimal pollution.....

veyron1 · 6th July 2007, 00:25

LPG, hm...now there's a thought...why not have a dedicated high-compression engine for LPG? We could do away with cat-con altogether...

We have Diesels. We have petrols. Why not consider LPG as an alternate fuel..? Could make for some really interesting powertrain designs...and even more interesting specs...

devilvtec · 6th July 2007, 00:55

Quote:

Originally Posted by veyron1

LPG, hm...now there's a thought...why not have a dedicated high-compression engine for LPG? We could do away with cat-con altogether...

We have Diesels. We have petrols. Why not consider LPG as an alternate fuel..? Could make for some really interesting powertrain designs...and even more interesting specs...

thats an interesting topic

but do you think that india has the resources and technical saport for designing and developing a new engine for only LPG ..?? LPG is also a kind of non renuable energy source .. which in turn cannot make it a alternate fuel .. if we actualy care for mother earth we should try and develope a solar or hydrogen car that can be as easy to use and run as a internal combustion engine ..

ananthkamath · 6th July 2007, 03:43

LPG and other alternate fuels aside, the point I'm trying to make is that there are lot of guys out there who think "Hey, that cat con is robbing me of 15 hp, so lets remove that, I dont care about the environment anyway".

I dont think that's the right approach. But we dont have any figures to prove that. Has anyone come across data which shows the flow losses across the cat? At any rate I doubt its above 2 psi of loss which means a miniscule amount of power on a "street tune" engine.

Now if you're planning to improve the torque of your engine significantly through a turbo or NOS, the answer is clear. Get a high-flow cat. Or ditch it if you're racing. Stock engines are already flow-challenged on the exhaust side so when you do these mods its imperative you improve on that end.

But what about stock and street-modified engines? Post away, guys......

PS: My access to the SAE paper database is down for some reason but I'll try and come up with something when its up.

ananthkamath · 6th July 2007, 04:04

I found this through google:

http://www.fluent.us/direct/dieselnet-listing/ex185.pdf

You can see in Fig. 3 that the velocity loss through the cat is negligible, and the contours prove that the velocity in the headers is the same as that in the cat. But the pressure loss is considerable as in Fig. 4. Is this enough to hurt flow and thus power? We dont know yet.

anandpadhye · 6th July 2007, 06:14

Ananth,
I second you.
We should not harm the environment.
In fact we should help our RTOs to gear up and nail down such modded vehicles on Indian roads. Pune and Bangalore have had enogh of air pollution already.
And automakes are spending so much on Euro 4 and 5 requirements and the consumers are being passed on some part of that cost...the so called car enthusiasts that moodify the exhaust for "audible power" should be heavily penalised.

Hellcat · 6th July 2007, 13:17

I have one question for all you guys who have removed you Catalytic Converter. What about emissions standards? How do you manage to get you emission certificate?

Hellcat

tsk1979 · 6th July 2007, 13:20

Unleaded Petrol when burnt without a CAT gives out Benzene apart from N oxides and other undesired stuff.
Benzene is highly carcinogenic.

5th July 2007, 01:28	#1
ananthkamath Senior - BHPian Join Date: Jul 2005 Location: Mangalore Posts: 1,209 Thanked: 80 Times View My Garage	Removing a Catalytic Converter (Cat Con) - Do you guys think its worth it? A recent post by some guy on another board made me think - Are we doing the right thing by advocating removal of the cat on our cars in exchange for the supposed HP gain? Some things we need to think about before removing the cat - 1) Do we need to remove it in the first place? What gains are APPARENT & MEASURABLE from this? 2) Is there any published data on the gains from removing a cat either on our Indian engines, or from similar engines abroad? 3) What is the impact on the environment? Why not do some research and form a conclusion before senselessly contributing to slaughtering the environment more than necessary?
	() Thanks

5th July 2007, 17:49	#2
Mpower Senior - BHPian Join Date: Mar 2005 Location: Bangalore Posts: 10,409 Thanked: 1,730 Times View My Garage	I think every car will respond differently to this. Some will show a lot of gain and others negligible..but generally it will improve top end power. Late model cars which are designed for LEV and ULEV emissions have a catalyst that is stuck into the manifold that prevents any kind of header installation. Thats another problem. Another thing to worry about is what is the ECU going to do when it detects a missing cat. Might need a remap for that.
	() Thanks

5th July 2007, 21:14	#5
AUTO_CRAZY BHPian Join Date: Feb 2005 Location: Bangalore Posts: 86 Thanked: 6 Times	I think considering the damage to the environment........it is strongly recommended not to remove the CAT CON.
	() Thanks

5th July 2007, 23:34	#8
mail4ajo Senior - BHPian Join Date: Mar 2006 Location: San Antonio, TX Posts: 1,957 Thanked: 331 Times View My Garage	I was just wondering if removing the CAT will give more pickup while driving on LPG. I wont be damaging the environment a lot since LPG creates minimal pollution.....
	() Thanks

6th July 2007, 00:25	#9
veyron1 Senior - BHPian Join Date: Mar 2005 Location: Mumbai Posts: 1,424 Thanked: 52 Times View My Garage	LPG, hm...now there's a thought...why not have a dedicated high-compression engine for LPG? We could do away with cat-con altogether... We have Diesels. We have petrols. Why not consider LPG as an alternate fuel..? Could make for some really interesting powertrain designs...and even more interesting specs...
	() Thanks

6th July 2007, 03:43	#11
ananthkamath Senior - BHPian Join Date: Jul 2005 Location: Mangalore Posts: 1,209 Thanked: 80 Times View My Garage	LPG and other alternate fuels aside, the point I'm trying to make is that there are lot of guys out there who think "Hey, that cat con is robbing me of 15 hp, so lets remove that, I dont care about the environment anyway". I dont think that's the right approach. But we dont have any figures to prove that. Has anyone come across data which shows the flow losses across the cat? At any rate I doubt its above 2 psi of loss which means a miniscule amount of power on a "street tune" engine. Now if you're planning to improve the torque of your engine significantly through a turbo or NOS, the answer is clear. Get a high-flow cat. Or ditch it if you're racing. Stock engines are already flow-challenged on the exhaust side so when you do these mods its imperative you improve on that end. But what about stock and street-modified engines? Post away, guys...... PS: My access to the SAE paper database is down for some reason but I'll try and come up with something when its up. Last edited by ananthkamath : 6th July 2007 at 03:46.
	() Thanks

6th July 2007, 04:04	#12
ananthkamath Senior - BHPian Join Date: Jul 2005 Location: Mangalore Posts: 1,209 Thanked: 80 Times View My Garage	I found this through google: http://www.fluent.us/direct/dieselnet-listing/ex185.pdf You can see in Fig. 3 that the velocity loss through the cat is negligible, and the contours prove that the velocity in the headers is the same as that in the cat. But the pressure loss is considerable as in Fig. 4. Is this enough to hurt flow and thus power? We dont know yet.
	() Thanks

6th July 2007, 06:14	#13
anandpadhye Distinguished - BHPian Join Date: Apr 2007 Location: Pune Posts: 3,054 Thanked: 3,313 Times	Ananth, I second you. We should not harm the environment. In fact we should help our RTOs to gear up and nail down such modded vehicles on Indian roads. Pune and Bangalore have had enogh of air pollution already. And automakes are spending so much on Euro 4 and 5 requirements and the consumers are being passed on some part of that cost...the so called car enthusiasts that moodify the exhaust for "audible power" should be heavily penalised.
	() Thanks

6th July 2007, 13:17	#14
Hellcat BHPian Join Date: Jul 2005 Location: Bangalore Posts: 222 Thanked: 5 Times View My Garage	I have one question for all you guys who have removed you Catalytic Converter. What about emissions standards? How do you manage to get you emission certificate? Hellcat
	() Thanks

6th July 2007, 13:20	#15
tsk1979 Team-BHP Support Join Date: Feb 2005 Location: San Jose, CA Posts: 23,717 Thanked: 22,825 Times View My Garage	Unleaded Petrol when burnt without a CAT gives out Benzene apart from N oxides and other undesired stuff. Benzene is highly carcinogenic.
	() Thanks