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Posted: 5/5/2011 6:37:46 AM EDT
I have a 2000 Chevy Silverado 1500 z71, 3.73 gear ratio, with 285/75R16 tires. 150,000 miles.
I had been getting about 12 mpg around town, and right about 14mpg on the highway this winter. I have since added a Spectre cold air intake, and a Flowmaster catback dual exhaust. I also put on a soft tonneau cover.

The exhaust and cold air intake didn't seem to make much difference, maybe .5 to 1 mpg, MAYBE; I have yet to make a long highway trip with the truck to find out for sure.

Yesterday, I changed out all 4 Oxygen sensors. The 2 O2 sensors upstream from the catalytic convertors came out just fine, and the new one went in just fine. The 2 Downstream sensors were a bitch to get out, and I actually had to run a Thread Tap through the holes to allow me to put in the new sensors. I am guessing that the new sensors SHOULD make a difference, considering how siezed up the 2 downstream sensors were.

I have been told that removing the catalytic convertors, and welding in straight pipe, will improve my mileage. Is this true?

Also, I have been told that on the 2 downstream O2 sensors, I will need to add an extra spacer/washer to set them back far enough to not throw a trouble code. Is this true? And, if so, how much thickness do I need? Will the spacer that comes with it, PLUS one of the spacers from the old O2 sensor (essentially doubling up) be sufficient?

And, how does adding thickness prevent a trouble code?

The one advantage I see, is that even if I don't get better mileage, I can scrap both of the convertors, and get enough for a tank of gas.

I have also seen independent reviews, not advertising the Fitch Fuel Catalyst, to show it to actually add 1 to 2 mpg. I am still dubious.
Link Posted: 5/5/2011 6:38:27 AM EDT
[#1]
Probably wouldn't pass inspection if they look for it...
Link Posted: 5/5/2011 6:40:16 AM EDT
[#2]
Yes it will work.  No, it's not legal.
Link Posted: 5/5/2011 6:42:00 AM EDT
[#3]
Quoted:
Probably wouldn't pass inspection if they look for it...


We don't have inspections, or emissions testing here, so that is a moot point. Plus, if it pisses off the greenies, all the better.
Link Posted: 5/5/2011 6:43:39 AM EDT
[#4]
Quoted:
Yes it will work.  No, it's not legal.


Not legal? Damnit. Niether are silencers.... I HAVE to have a silencer on my truck, and yet am not allowed to own one for my guns. Gay.
Link Posted: 5/5/2011 6:44:55 AM EDT
[#5]
Quoted:
Quoted:
Probably wouldn't pass inspection if they look for it...


We don't have inspections, or emissions testing here, so that is a moot point. Plus, if it pisses off the greenies, all the better.


Instead of welding a new piece of pipe in, just drop the back half, take something metal I used a golf club shaft, and a rubber mallet, and knock the shit out.  Fire it up, rev it to blow the shit out, repeat till it's all gone.  Only took an hour.  Another 20 min to clean up the mess.
Link Posted: 5/5/2011 6:45:08 AM EDT
[#6]
you can purchase replacement O2 "fakes" for cat-less purposes from Amazon
Link Posted: 5/5/2011 6:45:33 AM EDT
[#7]
Quoted:
Quoted:
Probably wouldn't pass inspection if they look for it...


We don't have inspections, or emissions testing here, so that is a moot point. Plus, if it pisses off the greenies, all the better.


The irony, removing the cats to increase mileage, thus using less carbon based fuel, pisses off the green weenies.

Posted Via AR15.Com Mobile
Link Posted: 5/5/2011 6:46:16 AM EDT
[#8]
Quoted:
Yes it will work.  No, it's not legal.


In all 50 states?  Starting with what year of manufacture?  This is why I like my route, it's still there, just not functional.
Link Posted: 5/5/2011 6:47:32 AM EDT
[#9]
But it still smells like poop
Link Posted: 5/5/2011 6:48:31 AM EDT
[#10]
short answer....probably not.

I had 4 cats in my lightning...I cut out two and noticed not one damned thing other than lovely sound
Link Posted: 5/5/2011 6:49:29 AM EDT
[#11]



Quoted:


But it still smells like poop




 
To me it smells like unburned fuel without a cat. Not really too bad.

Leaking or busted catalytic converters smell like bunghole though.
Link Posted: 5/5/2011 6:50:07 AM EDT
[#12]
Quoted:
I have a 2000 Chevy Silverado 1500 z71, 3.73 gear ratio, with 285/75R16 tires. 150,000 miles.  


The part highlighted in red...  That's the reason for your poor fuel mileage. Not the Cat converter.
Link Posted: 5/5/2011 6:51:35 AM EDT
[#13]
Quoted:
But it still smells like poop


Not mine.
Link Posted: 5/5/2011 6:52:50 AM EDT
[#14]
Quoted:
Instead of welding a new piece of pipe in, just drop the back half, take something metal I used a golf club shaft, and a rubber mallet, and knock the shit out.  Fire it up, rev it to blow the shit out, repeat till it's all gone.  Only took an hour.  Another 20 min to clean up the mess.


Correct answer here. ^^^

Removing the cat entirely...  your truck won't pass the "visual equipment inspection". Removing Cats is illegal... but nobody will know if the guts are knocked out of them. You will see better performance, mileage and sound.
Link Posted: 5/5/2011 6:59:46 AM EDT
[#15]
I think that when you see 4 of them 2 are pre-heaters and then you have 2 cats.



I sold a 2006 Tacoma to a friend 2 years ago. He works at Miami International Airport and parks the truck in the garage. Last year after he got off of work he went to his truck to go home. Started it up and it was loud as hell. Looked under it and noticed somebody stole the cats from under the truck while he was at work. He went to buy one it was $1,500 at the dealer. Maybe sell yours?
Link Posted: 5/5/2011 7:02:56 AM EDT
[#16]
Look closely at this image. See the skinny pedal on the right? Don't push that one there very hard.



I once took the cat off my Ford Festiva. The mileage dropped from 48 mpg to 42 mpg because I revved it harder. If I remember right, it was worth about three tenths in the quarter.
Link Posted: 5/5/2011 7:04:18 AM EDT
[#17]
Before I started gutting cats or toying with the legality of the vehicle, I'd be sure I was doing all of the obvious things first like ensuring that maintenance is up-to-date, carefully selecting fluids, maintaining proper tire pressures, using highway tires, sticking to a moderate driving style, making good route choices (highway vs back roads, combining trips, and so on), preventing excessive idling and engine "warm-up", removing excess weight from the vehicle, etc.  Assuming you have all of these bases covered, I'd look at getting a good tune that is maximized for efficiency, which might well get you a MPG or so if done right.  

FWIW, Casper's used to build O2 simms, which would allow you to disconnect your rear O2 sensors (and still pass OBD-II inspection) without having to actually remove the sensors, but production got shut down by EPA a few years back. Might be that you could find some on eBay still.  If not, anyone with EFI LIve or HPTuners can simply shut off the DTCs associated with the rear O2's and you'll be good to go with straight pipe or gutted cats.  Again, if it were me, I'd look elsewhere besides the cats for improvement, but then again I don't have a problem with catalytic converters since the modern ones really don't cost you much in the way of hp anyway.
Link Posted: 5/5/2011 7:05:52 AM EDT
[#18]
they usually will pick up 10% fuel economy with removing or adding high flow ones. also the flow master is a chambered muffler you could change to a straight through design and cat less. i would also go with getting fuel injectors cleaned and tune up!
Link Posted: 5/5/2011 7:15:16 AM EDT
[#19]
The guys that run the exhaust shop in my town will give you "lifetime" cats for a small fee because they sell your old ones.  I'd look into making sure your truck (I have pretty much the same truck, a 99 Sierra) will run correctly without them before you cut them off.

Edit:  I put a SLP Shotgun resonator on instead of the muffler.  It saved the exhaust going through the garbage can shaped and sized old muffler to basically a straight pipe that expands for a few inches then contracts.  I'm sure it helped my mileage a little bit, though I didn't measure it before and after.
Link Posted: 5/5/2011 7:19:11 AM EDT
[#20]
Quoted:
Quoted:
Quoted:
Probably wouldn't pass inspection if they look for it...


We don't have inspections, or emissions testing here, so that is a moot point. Plus, if it pisses off the greenies, all the better.


Instead of welding a new piece of pipe in, just drop the back half, take something metal I used a golf club shaft, and a rubber mallet, and knock the shit out.  Fire it up, rev it to blow the shit out, repeat till it's all gone.  Only took an hour.  Another 20 min to clean up the mess.


Does the scrapyard pay for the material, or just the entire convertor? Punching them out seems somewhat easier/cheaper.
Link Posted: 5/5/2011 7:22:08 AM EDT
[#21]
Quoted:
Quoted:
I have a 2000 Chevy Silverado 1500 z71, 3.73 gear ratio, with 285/75R16 tires. 150,000 miles.  


The part highlighted in red...  That's the reason for your poor fuel mileage. Not the Cat converter.


Well no kidding. Having the most efficient 4x4 truck is kind of like being the smartest kid with Down's Syndrome. You can spell your name, but you're still fucking retarded.

I'd just like to save gas where I can. I have a 2000 Ninja 600 I ride when weather permits; fun, AND saves gas.
Link Posted: 5/5/2011 7:23:40 AM EDT
[#22]
Quoted:
Look closely at this image. See the skinny pedal on the right? Don't push that one there very hard.

http://t0.gstatic.com/images?q=tbn:ANd9GcSIb-kb9bd4UI0qeYggCQ9VfEgV7e6ppnRNfNjyRDbxkrhgxOFA

I once took the cat off my Ford Festiva. The mileage dropped from 48 mpg to 42 mpg because I revved it harder. If I remember right, it was worth about three tenths in the quarter.


You drag raced a Ford Festiva? 3 tenths in the quarter, and zero to 60 in 15 minutes, lmao!
Link Posted: 5/5/2011 7:26:36 AM EDT
[#23]
The first 2 sensors are the only ones that affect how your car/truck runs.  Their job is to adjust the fuel mixture as needed.  The downstream sensors only job, is to tell if the cats are working.  They have no affect on fuel economy.  They can and will throw a code if the cats stop working or have been taken out.  You can get MIL  eliminators, that plug in where the sensors were to get rid of the trouble light.  Like others have said this won;t pass a visual inspection. You can also replace your old cats with new high flow cats.  This will improve the exhaust flow, sound and may improve you fuel economy a bit, but with 3.73 gears and 32 inch tires, you can only improve so much.  
Link Posted: 5/5/2011 7:35:06 AM EDT
[#24]
Quoted:
Quoted:
Quoted:
Quoted:
Probably wouldn't pass inspection if they look for it...


We don't have inspections, or emissions testing here, so that is a moot point. Plus, if it pisses off the greenies, all the better.


Instead of welding a new piece of pipe in, just drop the back half, take something metal I used a golf club shaft, and a rubber mallet, and knock the shit out.  Fire it up, rev it to blow the shit out, repeat till it's all gone.  Only took an hour.  Another 20 min to clean up the mess.


Does the scrapyard pay for the material, or just the entire convertor? Punching them out seems somewhat easier/cheaper.


I think you'd get more for the whole thing.  If it's complete they'll at least have an idea of what's in the converter without having to take you for your word on it.  Not saying you're untrustworthy, but it's a business.
Link Posted: 5/5/2011 7:38:39 AM EDT
[#25]
Link Posted: 5/5/2011 7:40:38 AM EDT
[#26]
Took mine off my duramax diesel. I averaged 19.3 mpg doing 80mph from Phoenix to Orange county yesterday. That's up from 16 mpg when I had the cat on.
Link Posted: 5/5/2011 7:47:00 AM EDT
[#27]
Quoted:
Quoted:
Look closely at this image. See the skinny pedal on the right? Don't push that one there very hard.

http://t0.gstatic.com/images?q=tbn:ANd9GcSIb-kb9bd4UI0qeYggCQ9VfEgV7e6ppnRNfNjyRDbxkrhgxOFA

I once took the cat off my Ford Festiva. The mileage dropped from 48 mpg to 42 mpg because I revved it harder. If I remember right, it was worth about three tenths in the quarter.


You drag raced a Ford Festiva? 3 tenths in the quarter, and zero to 60 in 15 minutes, lmao!


We drag raced anything that would roll down the road.

Went from 18.70 or so to 18.000 in the quarter by removing air filter, shifting at the rev limiter, removing the cat, removing the passenger and back seats. I don't recommend any of those be performed on a daily driven rig.
Link Posted: 5/5/2011 8:52:13 AM EDT
[#28]
Quoted:
Took mine off my duramax diesel. I averaged 19.3 mpg doing 80mph from Phoenix to Orange county yesterday. That's up from 16 mpg when I had the cat on.


I hate you Duramax guys, lol. How many HP you running?
Link Posted: 5/5/2011 8:53:06 AM EDT
[#29]
Quoted:
Quoted:
Quoted:
Look closely at this image. See the skinny pedal on the right? Don't push that one there very hard.

http://t0.gstatic.com/images?q=tbn:ANd9GcSIb-kb9bd4UI0qeYggCQ9VfEgV7e6ppnRNfNjyRDbxkrhgxOFA

I once took the cat off my Ford Festiva. The mileage dropped from 48 mpg to 42 mpg because I revved it harder. If I remember right, it was worth about three tenths in the quarter.


You drag raced a Ford Festiva? 3 tenths in the quarter, and zero to 60 in 15 minutes, lmao!


We drag raced anything that would roll down the road.

Went from 18.70 or so to 18.000 in the quarter by removing air filter, shifting at the rev limiter, removing the cat, removing the passenger and back seats. I don't recommend any of those be performed on a daily driven rig.


LOL, Sir, you are awesome! Although, I think I have a gokart that would beat it, lol!
Link Posted: 5/5/2011 8:56:09 AM EDT
[#30]





I have also seen independent reviews, not advertising the Fitch Fuel
Catalyst, to show it to actually add 1 to 2 mpg. I am still dubious.



I ran one in my first motorcycle and it had absolutely no measurable effects on MPG, or how the bike ran.



 
Link Posted: 5/5/2011 9:04:54 AM EDT
[#31]
Quoted:
The first 2 sensors are the only ones that affect how your car/truck runs.  Their job is to adjust the fuel mixture as needed.  The downstream sensors only job, is to tell if the cats are working.  They have no affect on fuel economy.  They can and will throw a code if the cats stop working or have been taken out.  You can get MIL  eliminators, that plug in where the sensors were to get rid of the trouble light.  Like others have said this won;t pass a visual inspection. You can also replace your old cats with new high flow cats.  This will improve the exhaust flow, sound and may improve you fuel economy a bit, but with 3.73 gears and 32 inch tires, you can only improve so much.  


My wife's Expidition was throwing a rear O2 sensor code so I made a MIL eliminator for it for $3 worth of parts from Radio Shack. Somewhere on the interwebz is a site that explains how to do it.  A lot cheap than $75 for a new O2 sensor.
Link Posted: 5/5/2011 9:09:25 AM EDT
[#32]
Quoted:
Quoted:
The first 2 sensors are the only ones that affect how your car/truck runs.  Their job is to adjust the fuel mixture as needed.  The downstream sensors only job, is to tell if the cats are working.  They have no affect on fuel economy.  They can and will throw a code if the cats stop working or have been taken out.  You can get MIL  eliminators, that plug in where the sensors were to get rid of the trouble light.  Like others have said this won;t pass a visual inspection. You can also replace your old cats with new high flow cats.  This will improve the exhaust flow, sound and may improve you fuel economy a bit, but with 3.73 gears and 32 inch tires, you can only improve so much.  


My wife's Expidition was throwing a rear O2 sensor code so I made a MIL eliminator for it for $3 worth of parts from Radio Shack. Somewhere on the interwebz is a site that explains how to do it.  A lot cheap than $75 for a new O2 sensor.


True, but I already bought AND installed the O2 sensors, lol. I doub't I could get a refund, no matter HOW buddy buddy I am with the folks at Autozone, lmao!
Link Posted: 5/5/2011 9:25:42 AM EDT
[#33]
If you cut them out and replace them with straight pipe, just have a couple O2 sensor bungs welded into the pipe. Then go to the auto parts store and get a couple spark plug non-foulers that fit your downstream O2 sensors. Improved mileage and no check engine lights will result, not that I've ever done this.
Link Posted: 5/5/2011 9:27:19 AM EDT
[#34]
Quoted:
Quoted:
The first 2 sensors are the only ones that affect how your car/truck runs.  Their job is to adjust the fuel mixture as needed.  The downstream sensors only job, is to tell if the cats are working.  They have no affect on fuel economy.  They can and will throw a code if the cats stop working or have been taken out.  You can get MIL  eliminators, that plug in where the sensors were to get rid of the trouble light.  Like others have said this won;t pass a visual inspection. You can also replace your old cats with new high flow cats.  This will improve the exhaust flow, sound and may improve you fuel economy a bit, but with 3.73 gears and 32 inch tires, you can only improve so much.  


My wife's Expidition was throwing a rear O2 sensor code so I made a MIL eliminator for it for $3 worth of parts from Radio Shack. Somewhere on the interwebz is a site that explains how to do it.  A lot cheap than $75 for a new O2 sensor.


That part in red, the mother in law eliminator. How do I get one of those?

Link Posted: 5/5/2011 9:28:50 AM EDT
[#35]
Quoted:
Probably wouldn't pass inspection if they look for it...



Some us don't have emission tests.

Link Posted: 5/5/2011 9:35:26 AM EDT
[#36]
Quoted:
Quoted:
Quoted:
The first 2 sensors are the only ones that affect how your car/truck runs.  Their job is to adjust the fuel mixture as needed.  The downstream sensors only job, is to tell if the cats are working.  They have no affect on fuel economy.  They can and will throw a code if the cats stop working or have been taken out.  You can get MIL  eliminators, that plug in where the sensors were to get rid of the trouble light.  Like others have said this won;t pass a visual inspection. You can also replace your old cats with new high flow cats.  This will improve the exhaust flow, sound and may improve you fuel economy a bit, but with 3.73 gears and 32 inch tires, you can only improve so much.  


My wife's Expidition was throwing a rear O2 sensor code so I made a MIL eliminator for it for $3 worth of parts from Radio Shack. Somewhere on the interwebz is a site that explains how to do it.  A lot cheap than $75 for a new O2 sensor.


That part in red, the mother in law eliminator. How do I get one of those?



Several ways, but the important thing to know is it will cost you half of what you currently own.
Link Posted: 5/5/2011 9:40:41 AM EDT
[#37]
Test Pipes
Link Posted: 5/5/2011 9:43:26 AM EDT
[#38]
Quoted:

I have also seen independent reviews, not advertising the Fitch Fuel Catalyst, to show it to actually add 1 to 2 mpg. I am still dubious.

I ran one in my first motorcycle and it had absolutely no measurable effects on MPG, or how the bike ran.
 


I was an engineer at a company involved with the Fitch Fuel catalyst people.

Simply put: It is a fucking scam.  
Link Posted: 5/5/2011 9:53:33 AM EDT
[#39]
Modern catalysts present no flow restriction unless at wide open throttle.  How much of your driving is a wide open throttle?



Back in the early days, catalysts were a bed of small spheres, these had high flow restrictions at moderate throttle.  But today, all catalysts are monolithic blocks with thousands of hexagonal channels.  Flow area is higher than the inlet flow area.  It is only skin friction.



Now what happens when you pull the converters?  You will get a check engine light because the back oxygen sensors see zero change.  



Fitch is worthless.
Link Posted: 5/5/2011 9:55:39 AM EDT
[#40]



Quoted:



Quoted:

Probably wouldn't pass inspection if they look for it...






Some us don't have emission tests.





Removing a catalyst in a post 1995 vehicle will cause the check engine lamp to illuminate which is failure to pass annual inspection.  No testing, just a fail.
 
Link Posted: 5/5/2011 10:02:56 AM EDT
[#41]



Quoted:





Quoted:


Quoted:

Probably wouldn't pass inspection if they look for it...
Some us don't have emission tests.

Removing a catalyst in a post 1995 vehicle will cause the check engine lamp to illuminate which is failure to pass annual inspection.  No testing, just a fail.



You can get dummy sensors or signal modifiers for most OBDII cars with multiple O2 sensors.

The signal modifiers let you keep the same sensors, they just alter the signal to the ECU to make it read within the acceptable range as if the cat was still there...



 
Link Posted: 5/5/2011 10:05:30 AM EDT
[#42]
Quoted:

Quoted:

Quoted:
Quoted:
Probably wouldn't pass inspection if they look for it...
Some us don't have emission tests.
Removing a catalyst in a post 1995 vehicle will cause the check engine lamp to illuminate which is failure to pass annual inspection.  No testing, just a fail.

You can get dummy sensors or signal modifiers for most OBDII cars with multiple O2 sensors.
The signal modifiers let you keep the same sensors, they just alter the signal to the ECU to make it read within the acceptable range as if the cat was still there...
 


O2 simulators and the like are illegal to run "on road", they are solely an "off road" application.
Link Posted: 5/5/2011 10:06:24 AM EDT
[#43]



Quoted:


Took mine off my duramax diesel. I averaged 19.3 mpg doing 80mph from Phoenix to Orange county yesterday. That's up from 16 mpg when I had the cat on.


Impossible, no diesel owner on the internet gets less than 24 mpg.



 
Link Posted: 5/5/2011 10:08:04 AM EDT
[#44]



Quoted:



Quoted:




I have also seen independent reviews, not advertising the Fitch Fuel Catalyst, to show it to actually add 1 to 2 mpg. I am still dubious.


I ran one in my first motorcycle and it had absolutely no measurable effects on MPG, or how the bike ran.

 




I was an engineer at a company involved with the Fitch Fuel catalyst people.



Simply put: It is a fucking scam.  


I rubbed Fitch Fuel Catalyst on my missing finger, and it grew back.



 
Link Posted: 5/5/2011 10:11:52 AM EDT
[#45]



Quoted:





Quoted:




Quoted:


Quoted:

Probably wouldn't pass inspection if they look for it...
Some us don't have emission tests.

Removing a catalyst in a post 1995 vehicle will cause the check engine lamp to illuminate which is failure to pass annual inspection.  No testing, just a fail.



You can get dummy sensors or signal modifiers for most OBDII cars with multiple O2 sensors.

The signal modifiers let you keep the same sensors, they just alter the signal to the ECU to make it read within the acceptable range as if the cat was still there...

 


And still, no improvement in mileage.  The problem is pushing 5500 pounds around town with a projected area of 30 square feet with a coefficient of drag in the 0.35 range.



My 2k C1500 Suburban with the 5.3 will get 20 MPG at 60 MPH.  But being 2WD, it has less projected area and a better CD.  



Drag is based on the square of speed multiplied by one half the area*drag coefficient*air density.  Since area and density are fixed, the most you can do is improve the drag coefficient or just slow down on the highway.  In the city, most of that fuel is wasted in brake wear.  Keep it light and again, slower.





 
Link Posted: 5/5/2011 10:13:46 AM EDT
[#46]
If you went to all the trouble to improve the intake and exhaust, I doubt removing the cc would make enough difference to risk breaking the law.
Link Posted: 5/5/2011 10:28:11 AM EDT
[#47]
Quoted:

Quoted:
Quoted:
Probably wouldn't pass inspection if they look for it...



Some us don't have emission tests.


Removing a catalyst in a post 1995 vehicle will cause the check engine lamp to illuminate which is failure to pass annual inspection.  No testing, just a fail.


 


Uh, some of us don't have ANY annual inspection........emission or safety.......NOTHING. You register and insure your vehicle and you drive.
Link Posted: 5/5/2011 10:35:21 AM EDT
[#48]



Quoted:



Quoted:




Quoted:


Quoted:

Probably wouldn't pass inspection if they look for it...






Some us don't have emission tests.





Removing a catalyst in a post 1995 vehicle will cause the check engine lamp to illuminate which is failure to pass annual inspection.  No testing, just a fail.





 




Uh, some of us don't have ANY annual inspection........emission or safety.......NOTHING. You register and insure your vehicle and you drive.


Yet.  But soon.  http://thehill.com/blogs/floor-action/house/159397-obama-floats-plan-to-tax-cars-by-the-mile
 
Link Posted: 5/5/2011 10:36:47 AM EDT
[#49]
Damn Kieth J is smart.
Link Posted: 5/5/2011 10:40:28 AM EDT
[#50]
Quoted:

Quoted:

Quoted:

Quoted:
Quoted:
Probably wouldn't pass inspection if they look for it...
Some us don't have emission tests.
Removing a catalyst in a post 1995 vehicle will cause the check engine lamp to illuminate which is failure to pass annual inspection.  No testing, just a fail.

You can get dummy sensors or signal modifiers for most OBDII cars with multiple O2 sensors.
The signal modifiers let you keep the same sensors, they just alter the signal to the ECU to make it read within the acceptable range as if the cat was still there...
 

And still, no improvement in mileage.  The problem is pushing 5500 pounds around town with a projected area of 30 square feet with a coefficient of drag in the 0.35 range.

My 2k C1500 Suburban with the 5.3 will get 20 MPG at 60 MPH.  But being 2WD, it has less projected area and a better CD.  

Drag is based on the square of speed multiplied by one half the area*drag coefficient*air density.  Since area and density are fixed, the most you can do is improve the drag coefficient or just slow down on the highway.  In the city, most of that fuel is wasted in brake wear.  Keep it light and again, slower.

 


No way!  There is a silver bullet somewhere out there that will allow F350s weighed down carrying ammo hoards on 37 inch mud tires to get 30 mpg at 85 mph.  


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