No check engine light - no issues whatsoever except your mileage jumping up a few points.

 

my mph would go up?

 

The cat represents a substantial restriction to flow. Removing that restriction allows for better breathing and can improve efficiency and therefore mileage.

 

The cat represents a substantial restriction to flow. Removing that restriction allows for better breathing and can improve efficiency ...

This is relevant only when the engine is operating at a high power setting -- at or near redline rpm and at or near pedal-to-the-metal.

When cruising at a moderate power setting, which is where 99% of your fuel economy is determined, the exhaust temperature & velocity aren't terribly high. The muffler and catalytic converter (provided it's in good condition, not damaged or clogged) impose a negligible amount of back pressure. Removing them would only be "solving" a problem that you do not have.

Removing them will increase the amount of power the engine develops, but power and fuel economy are two completely different things.

im from fl so emissions really isnt a problem ...

Emission law is federal. It's illegal to remove a catalytic converter everywhere in the United States. Perhaps it isn't enforced in Florida today, but it's likely that it will be enforced tomorrow, and you may wish to drive through other states that aren't so lax. Plan ahead, don't plan ahead -- your choice.

Hollowing out a catalytic converter, reinstalling the empty shell and avoiding detection is a thing of the past. When a catalytic converter is functional, the temperature of the exhaust increases as it passes through. This temperature rise (or lack of temperature rise) can now be observed with a $99 infrared thermometer as part of a "visual" inspection. (Courts have ruled that observations in the IR spectrum fall within the definition of "visual" and "in plain sight") So any DUI checkpoint, roadside stop, weigh-station visit, impromptu safety check or plate-renewal visual inspection could turn into a fine for "Tampering: to modify, remove, render inoperative, cause to be removed, or make less operative any air pollution emission control device or element of design installed on a motor vehicle or motor vehicle engine which results in an increase in emissions beyond established federal motor vehicle standards." And fines for deliberately tampering and attempting to conceal it can be steep.

 

How about removing the cat and leaving the muffler? Same MPG increase or is the muffler restrictive? I don't want the cab too loud as my hearing is getting worse and it is getting harder to hear conversation over noise.

 

The muffler is minimally restrictive. You could always put a Walker BTM if you wanted a straight through that muffled some of the roar. I can't tell its any louder than stock.

 

Rt., I think you may have missed he lives in the dreaded salt zone. That muffler has a life expectancy of 3-4 years up here.
Oops my mistake, Ford06 is in VA. Not Corbin98

 

The simplest way to delete the cat is to do a turbo back exhaust. If you had the tools you could make up some pipe and replace the cat, but an exhaust shop won't do it because you're removing emissions equipment.

 

You can also remove the cat by installing a Ford OEM test pipe. Install is only about an hour and you can reinstall your cat later if for some reason you need it.

I bought one a few years back and just finally got around to the install. Truck sounds better, I don't know about any mileage improvement yet.

I have the ford part# on my garage wall at home if anybody wants it. Was about $150 and bolts right in with no modification to the factory exhaust.

 

im from fl so emissions really isnt a problem, my previous post about mph was actually supposed to say mpg my bad so i have gotten mix reviews on removing the cat, my buddy dad said it would perform worse because the lack of black pressure, also my abs light keeps popping on and off and ideas?

 

Don't believe your buddies dad. You want the least amount of pressure downstream of the turbo as possible. All the magic has already happened by that point. The only thing left to do is get rid of the exhaust gases and minimize the pressure to do it.

 

Yes, backpressure is force against which the turbo has to work. Reducing it makes the turbo's job easier. That means more efficiency, which is never a bad thing.

 

I did a turbo back, cat removal exhaust system and couldn't tell the difference. I had to put the cat back on due to Califunny law and I can't
tell any difference after that either.

 

And what is the Ford part number??

 

Ford factory test pipe is part# F81Z-5246-DA. It can be found on google from various suppliers for less than $100.

I don't know if it helps performance but it makes removing/reinstalling the cat in the factory exhaust system really easy.

 

if you don't want to spend money and leave pipe the same and look legal remove the exhaust, remove the guts of the cat, turn the muffler around backwards as the flow fins will not catch air/noise that way on a straight thru muffler and then put it back together SHAZAM..........more airflow and not costs other than your time.

 

Power and fuel economy are not entirely different. When tuning for max power on a dyno a savy operator looks very closely at the BSFC (Brake Specific Fuel Consumption) numbers. Its a measure of the engine's efficiency, because when efficiency is maxed, power is usually close behind.

I also find that in operation an engine with more power in the same vehicle tends to get either the same or slightly better fuel economy. My conclusion is that people do not change their driving style. They still travel the same speed, but the more powerful engine spends less time getting there. Transition throttle is where most fuel is consumed in daily driving. So even though the more powerful engine may use a bit more fuel in transition it does it for a shorter period of time. The easiest way to think of it is that you don't have to press as hard on the go pedal to get the vehicle to do what you want. Initially I would have to floor my truck a lot. Now I drive at 1/4-1/2 throttle, almost never putting it on the floor. My fuel economy now is the same as its always been since the truck was new.

 

I did a turbo-back exhaust (MBRP S6212PLM 4" - $280 on amazon, free shipping with Prime) and egr delete at the same time. I saw a 25% increase in mpg (16 to 20). I can't say for sure what the split between exhaust and egr delete is, but it's probably ~20% to exhaust and ~5% to egr delete. There is a temp rise at the cat (DOC really) because it is a restriction, even at cruising.

The turbo-back also gets rid of the resonator in the stock exhaust. The sound is amazing. I love the sound of the turbo. Bat Mobile when on <1/2 throttle, dragster when really getting into it. Plus, no drone when cruising.

 

There is a temp rise at the cat (DOC really) because it is a restriction, even at cruising.

The temp rise isn't because it's a restriction, it's the function of a converter. Technically, the farther the exhaust gas flows down the pipe, the cooler it should get... there's nothing there to add heat... until you hit a device which performs a chemical reaction to remove emission particulate. In that phase, heat is generated.

That said, I would say that at cruising throttle I'd agree that it's not a substantial enough restriction to cause a tremendous drop in efficiency, but when people typically put an 'exhaust system' on, you're curing an efficiency loss from the point of exit from the turbo, all the way to the end behind the rear tire. A big increase in efficiency is had there, but it's not just at the cat.

 

theiba, drcampbell: I stand corrected on the temp rise.

I was trying to explain the fact that by eliminating the resonator, DOC, and muffler (and egr), my fuel economy went from ~16mpg to ~20mpg, so to me it's worth while. The turbo also spools more quickly resulting in a 4 second reduction in 0-60 time (14 down 10).

 

This topic (and the like) is a good conversation piece.

Here's my two cents on the catalytic converter and the 6.0L, which is tragically becoming more and more sparse. Some may disagree.

This boy is running stock exhaust (oh, NO!) with 210,000 mi., and to my knowledge, it has never been replaced. How, you ask? A desert truck can do amazing things, but I digress.

I recently talked to my muffler guy and he suggested drilling a hole and testing the backflow, as I only achieve about 8.5 mpg on a good day in the city. Some have advised me to remove it all, others say do not. I was only considering a high-flow cat in place of the factory unit if the backflow was in a negative state, which I'm sure it is.

The previous owner had the EGR system completely replaced, and I had diesel pumps and a new set of injectors installed shortly after I acquired the vehicle, in addition to a new, updated FICM at the recommendation of the service center.

What could possibly go wrong with a simple cat upgrade and new muffler, possibly?

In short, the engine itself is dynamically louder than the exhaust system, so a few more db's out the back couldn't hurt anything. I refuse to replace the air intake to an open element system. If the stock air filter is good enough in military applications, it's good enough for me. The sheer amount of dirt they trap is beyond amazing. Yes, especially in the desert.

Thoughts? :smile2:

 

The only reason to retain the cat would be if you live in an area where it must be retained for emissions compliance.

 

I, as like all others, have traveled all over the U.S. pulling several different camping trailers with several different Ford Diesels. I have been stopped in several DUI check points, but i never had been stopped so someone could conduct a safety check. I lived in California where the most C.S. CHP hangs out. Not that it doesnt happen, But I think the chances of even a commercial enforcement Officer stopping you, even in California, for a safety check is very remote.