I have seen posts about folks asking about cat delete for the better sound but not much on other benefits.
A catalitic converter by it's nature severally restricts exhaust flow so with it out does anybody have any stats onower; mpg; lower egt?
Our is it better to leave in the cat and take out the masive stock muffler?
2005 6.0 fully stock (so far).

 

I'm not going to sit here and tell you all kinds of lies about how much your mileage will improve. This is what I did to my '04....

https://www.ford-trucks.com/forums/9...ml#post8281083

I've noticed right about 1 to 2 mpg improvement over what I've done in the past. Did loosing the kitty make that much of a difference? Maybe. But I've been vigial about my tire pressures & rotation on the Michlins and running fuel additives to each tank as well. So, maybe all three have helped, maybe not. I'm still running factory "tunes" on the truck. Maybe Santa will bring me a SCT tuner this year and I can really see what kind of mileage I can get out of the Pavement Princess.

 

The amount of restriction from a properly working CAT is there, but not really that large - much more restriction comes from the muffler, which you cannot remove.

Remember that the diesel flows the same amount of air regardless of throttle, (though the amount of exhaust increases with larger throttle because of thermal expansion and combustion creating more gases), so there is less to be gained from upgrading the exhaust vs. the gas.

If the Cat is constricted (clogged by particles), there is the problem.

The best "mod" is to put a large hole (about tube diameter) down the middle without taking out the cat and without damaging the ceramic enough to cause the cat to rattle.

That way, it technically still passes the smog test requirement (there is a functioning cat), but the restriction is nearly all gone.

 

I don't want to hijack and take this thread in another direction, but this is simply false. As with any other internal combustion engine, airflow in a diesel increases as rpm's increase.

 

Yes as the "RPM's/Load on the engine increase" you need need to introduce more air and fuel to produce more power. If the amount of air was consistent you would be running way to lean at idle...

 

He said with throttle, not with rpm. Implying there is nothing restricting the intake when the throttle is let off like the throttle body in a gas engine.

 

For diesels, Lean= Mean..

 

so far as putting a hole in the cat. it is not leagal to do so and as a result you would fail for tampering. sorry but thats just the way it is. So if you are gonna go that far just knock it all out.

why cant the muffler be removed. I see it done all the time.

what kind of gains from removing the cat. I saw 0 change in mpg, egt may be lower but I dont have a pyro installed as of yet.
the exhaust note did not even change all that much.

 

Steve: Agree!

What I should have said is given x rpm...

 

100-maybe 200 degree drop in egts on a stock exhaust and gutted cat. You can faintly hear the turbo at idle. Overall noise is not really much difference. No big gains in mpg. Might have gotten 1mpg but that is not great enough to proclaim a gain in my book. Loosing the muffler is next on the list st some point. Knocking a hole in the ceramic is pointless. Unless your truck is running terrible is should pass a sniffer. Also unless they either run a camera or pull the cat there is no way they will be able to prove it was gutted. Worst case they fail you for opacy or something else. Visually though it is there. Proving it is not functioning or altered will be extremely difficult.

 

sorry but not so again.
You can tap on a cat with a hammer and tell if its there are not. big big differance in tone.
also you need to do a little reading on delta testing. for less then $100 tool I can tell you what cat is working and what cat is not.

 

As far as inspections go in my town I have had a cat on my truck twice during inspections. Two different trucks because they got inspected at purchase. I've been driving since 1996. Gas and diesel. No issues with being cited or failing a inspection. A tech might be abe to tell. A inspection place? I doubt they would do that. Law enforcement? Again very doubtful unless they had some sting. I could run a camera down my tail pipe if I really wanted to just like we do for problem drains and prove it was gone as well.

 

I have an 05 catless with a bored out silencer ring, my truck screams, sounds really really good, heads turn when i go by, especially in the school parking lot i get alot of complements on the sound

 

Well just went out and took a video for the sound of my exhaust, sounds good other than the static from wind/exhaust, ill take a better one tomorrow.

YouTube - 2005 6.0 turbo whistle

 

Man I'm old...lol