Bama gives a reason to not use them

[StrayBullitt]

It will hurt top end power.

Again, I want to SEE proof. Something concrete.

Surface area increases at the cat, and I believe enough that it compensates for any restriction.. which is why I would like to see dyno evidence. Location in the exhaust plays a part as well.

I can see the potential for hurting top end power.. but does it really? and if so I want to see by how much and at what power level? At what point do you maybe need to go to 3" system (V8)

 

[gimmie11s]

Do you have any proof of really high back pressure and reduced performance?

I want proof.

Really? This topic is pretty well covered all over the world. Cats hurt performance. Period.


https://www.svtperformance.com/foru...hal-performance-offroad-h-x-pipe-test.801975/


http://www.fordgt500.com/forums/177-exhaust/5967-truth-about-off-road-x-pipes-3.html

 

[StrayBullitt]

Cats hurt performance. Period.

OK, by how much ??

at quick glance, I am not seeing any before / after dyno of Cat/no Cat ONLY . They are changing systems and pipe size ect.

 

[DHG1078]

Again, I want to SEE proof. Something concrete.

Surface area increases at the cat, and I believe enough that it compensates for any restriction.. which is why I would like to see dyno evidence. Location in the exhaust plays a part as well.

I can see the potential for hurting top end power.. but does it really? and if so I want to see by how much and at what power level? At what point do you maybe need to go to 3" system (V8)

I'm not sure why you think increasing the surface area of a cat increases airflow. Increasing the surface area of a cat increases the amount of air a cat can treat at any given moment, but its also providing restriction to that much more air at the same time.

Its like going from a coarse mesh to a fine mesh filter or strainer.

If you don't think a cat restricts anything, try breathing through a cork.

 

[gimmie11s]

The amount gained will increase with the amount of air you want to pump through the motor.

On a N/A coyote application, its a 10whp or so gain by itself.

On a 600+ whp GT500 those gains will be over 20hp... ive seen as high as 30.

I dont think its a question of whether or not they hurt performance, but whether or not you are willing to deal with the trade offs that come with offroad pipes... i.e. the smell and louder noise.

 

[DHG1078]

OK, by how much ??

at quick glance, I am not seeing any before / after dyno of Cat/no Cat ONLY . They are changing systems and pipe size ect.

The amount will change based on the engine. The more air an engine moves, the more it will gain.

 

[DSG2003Mach1]

Can't you go in and disable them yourself? Like I said, I can understand them no longer being able to do it, however it's still a function on your hand held right? just curious . .

I believe they have to have left those options unlocked, its a bit foggy but I think under the same "guidance" that led them not to make the changes themselves they arent leaving it for the end user anymore either. I believe you'd have to have the actual tuning software license.

BTW, I do believe it was all these idiots rolling coal that really got the feds attention on the tuning stuff

 

[StrayBullitt]

I just want to see a dyno pull.. that's all. I've never seen a legit cat vs no cat pull.. and I want to, It's something I have wondered about. Thinking I might just spend the $ and do it.

Prefer to run cats on my car, and tbh they don't seem to affect it at all. But being N/A, if it makes a few more hp.. I'll take all I can get

 

[StrayBullitt]

I'm not sure why you think increasing the surface area of a cat increases airflow. .

Specifically I was referring to the inlet/outlet of the Cat. The increase in Diameter I probably should have said.

If you don't think a cat restricts anything, try breathing through a cork.

I Lol'd...

More like breathing through a respirator imo, but ok.

 

[DHG1078]

I just want to see a dyno pull.. that's all. I've never seen a legit cat vs no cat pull.. and I want to, It's something I have wondered about. Thinking I might just spend the $ and do it.

Prefer to run cats on my car, and tbh they don't seem to affect it at all. But being N/A, if it makes a few more hp.. I'll take all I can get

There aren't tons of apples to apples comparisons of exactly what you are looking for. Stock tunes won't like rear 02 readings without cats. Aftermarket tunes go more aggressive than factory tunes.

Not many people just cut the cats off the mid pipe and put in a new section. They buy the whole pipe, and that is what lethal did which you didn't like because sizing could be different.

 

[DHG1078]

Specifically I was referring to the inlet/outlet of the Cat. The increase in Diameter I probably should have said.

Increasing the diameter of a pipe in a small section will actually decrease velocity across that section.

 

[StrayBullitt]

There aren't tons of apples to apples comparisons of exactly what you are looking for. Stock tunes won't like rear 02 readings without cats. Aftermarket tunes go more aggressive than factory tunes.

Not many people just cut the cats off the mid pipe and put in a new section. They buy the whole pipe, and that is what lethal did which you didn't like because sizing could be different.

Agreed would be tough to do on some setups I am sure and maybe not even worth the trouble and $.. however my SLP mid the cats aren't welded, that full slp system is just a ton of pieces slip fit, I could probably do this pretty easily.

The tune is dialed in, rear O2's aren't going to have any impact in wot open loop. anyway, This would just be testing how much restriction the cats are causing.

 

[StrayBullitt]

Increasing the diameter of a pipe in a small section will actually decrease velocity across that section.

My opinion is that will be negligible, but slice it however you want. Be it overall restriction, or a loss in velocity from the diameter increase, I still want to see what kind of affect they have.

 

[Coosawjack]

Modern Cats are designed to flow for BIG HP......some actually make MORE POWER........plus NO STENCH!!

 

[DHG1078]

Modern Cats are designed to flow for BIG HP......some actually make MORE POWER........plus NO STENCH!!

Nobody makes more power with cats.

 

[StrayBullitt]

Nobody makes more power with cats.

Lol @DHG1078 I picture you saying this with a big ****ing hammer in hand ready to go pound out the cats on your 77 Camaro.

 

[DHG1078]

on your 77 Camaro.

No personal insults outside of SD please.

 

[StrayBullitt]

No personal insults outside of SD please.

LOL !


..Pictured this one wielding the BAN HAMMER

 

[P49Y-CY]

Here is a great video discussing this exact topic from another popular tuner

What did he mean at 1:55 when he said, "think 03/04 cobra..."?

 

[03Sssnake]

What did he mean at 1:55 when he said, "think 03/04 cobra..."?

I am not a 100%, but think he was referring to Mil eliminators...