cat removal to have better fuel mileage?
#1
05-26-2012, 09:50 PM
cat removal to have better fuel mileage?
Trying to find out if I were to replace my 4 cats with hollowed out one`s, would it gain me better fuel usage?
on average 250 miles a day. 16 miles per gallon
I have a 2006 E150 with the 4.8 it has 4 cats with 4 o2 sensors. I have an exact exhaust system off a donor e150. I was wanting to hollow or straight pipe the cats out the donor exhaust to install on e150 to see if it would be of any benefit.
Would it trow engine codes?
Any input would greatly appreciated.
PS I do understand that it not legal to do such a thing just trying to get some info on doing this type of modification
on average 250 miles a day. 16 miles per gallon
I have a 2006 E150 with the 4.8 it has 4 cats with 4 o2 sensors. I have an exact exhaust system off a donor e150. I was wanting to hollow or straight pipe the cats out the donor exhaust to install on e150 to see if it would be of any benefit.
Would it trow engine codes?
Any input would greatly appreciated.
PS I do understand that it not legal to do such a thing just trying to get some info on doing this type of modification
#2
05-27-2012, 11:37 AM
Yes, you will have CEL issues. The obvious and immediate effect will be catalyst efficiency codes. Some will argue you can use simulators to trick the computer. The problem is simulators unless they pull in external power, only simulate a stable waveform, but they still have a lower voltage, lower voltage means more oxygen, more oxygen tell the computer that even if the waveform is stable, the cats are not functioning. On an older vehicle, the simulators would likely work, on a 2006, I doubt they would.
The stock cam in your engine is set up for use with cats, in such a way that it can use the cats to flow the right amount of fuel and air. Without the cats, the engine will likely over scavenge during the overlap period, wasting fuel and potential power, and also messing with the O2 sensor readings. These readings would detect excess oxygen and interpret that you need more fuel, so it would richen the mixture to compensate.
Hollow cat shells produce turbulence. Turbulence is not conducive to flow, and will likely create backpressure, which will rob potential power. The type of backpressure produced would negate any benefits.
So at the end of the day, while it is possible you could see an increase, it is not likely. The idea that catalytic converter is restrictive is based upon old information dating to the early days of smog controls. Lets do a little history lesson.
Many early designs used a pellet type catalyst system. These basically consistent of a bunch or round ceramic or metal beads sandwiched between screens. This design was used because it was cheap to manufacture, it was highly efficient at reducing emissions, and when it was developed, the ceramic honeycomb substrate had not been invented yet. The result was a severe penalty to performance and economy. Fords did not use this type of design, it was more common amount the GM and various imports. However, the reputation of these designs took hold.
The early designs were focused on CO and HC emissions. The manufacturers would lean out the mixtures to keep the emissions clean. This was good for economy and emissions, but bad for performance. Many of these designs, depending on manufacturer, also used high compression, also good for economy and emissions. Or was it. Pretty soon a new emission gas was identified as a threat, NOX, which tends to for visible smog, it burns the eyes, nose, and throat, contributes to acidic rain, etc. These gases form most readily at lean conditions, the same conditions that minimize HC and CO. There is no true middle ground, any typical compromise produces lots of CO, HC, and NOX. And early solution was air injection, AKA smog pump. This works by tuning the engine rich (bad for economy) to keep NOX from forming, then using an external pump to deliver air into the catalyst bed to clean up the HC and CO that are produced by the rich combustion. The EGR valve also came onto the scene and started to catch on.
A little more on EGR, a lot of people misunderstand the relationship an EGR has, and misunderstand rich and lean mixtures, and what that means. EGR stand for Exhaust Gas Recirculation. Its primary function is to reduce combustion temperatures, and effectively, dynamically reduce displacement. Some would argue that the introduction of exhaust gas would lean out the mixture. This is not true. Rich or lean is not the ratio of fuel to air, it is the ratio of fuel to a specific gas. That specific gas is oxygen. Exhaust gas is a byproduct of combustion, and has already had most of the oxygen in in depleted from the combustion. As a result it is considered an inert gas. All it is doing is occupying space in the cylinders, effectively making the engine behave more like a smaller engine when the engine is not under heavy load. This helps conserve fuel, and also reduces NOX emissions by lowering the combustion temperatures, since the inert gas also slows down the combustion, a similar effect to raising the octane as well. I am pointing out how this function because I have heard many people incorrectly describe how it works, and encourage disabling or bypassing these systems, based on an incorrect understanding of its function.
As fuel injection began to really take hold and the systems because fast and more powerful, the fuel management became more tightly controlled, which introduces a new method that became the new standard. By using rare each metals in the catalyst, it became possible to store oxygen in the catalyst substrate, eliminating the need for smog pumps. Basically by monitoring an O2 sensor, you could switch between slightly rich to slightly lean, creating optimal conditions within the catalyst to efficiently clean up HC, CO, and NOX at the same time. The rare earth metals in the substrate store the oxygen from the lean cycle, and from the breakdown of NOX so that the oxygen is available to break down HC and CO more efficiently especially during the rich phase. Once this method came into use, the fuel economy and performance penalties associated with emissions controls previously. This type of technology started coming into use in the mid eighties!!! It did not get used industry wide till the early nineties, but Ford was among the first to use it. It works very well when combined with EGR.
In the early nineties, some of the manufacturers started coming up with new cam profiles that worked best when used with converters. The new profiles took advantage of the overlap period in particular to maximize economy, and performance in the typical part of the power band that most driving is done in. These profiles provide good performance and economy with a catalyst in place, unlike earlier or race cams, which get penalized by the presence of catalytic converters. But these profiles cause poor use of fuel if the catalyst is not presence, for the reasons I described earlier, basically some of the intake charge can get pulled straight though the cylinder and into the exhaust when it is not only wasted, but it messes with the engine management, causing additional waste. This is especially true of newer engines with variable valve timing, dual overhead cams, etc.
You can in some cases use higher flow catalysts, but the benefits are magical on most vehicles, and can introduce the same over scavenging problems of running without cats. True high flow cats are best for vehicles with performance cams, or for forced induction setups.
While it is still of questionable legality, you can run just two cats. You will get more exhaust noise, but it probably won't have any performance or economy benefits, and it might cause CEL issues.
The stock cam in your engine is set up for use with cats, in such a way that it can use the cats to flow the right amount of fuel and air. Without the cats, the engine will likely over scavenge during the overlap period, wasting fuel and potential power, and also messing with the O2 sensor readings. These readings would detect excess oxygen and interpret that you need more fuel, so it would richen the mixture to compensate.
Hollow cat shells produce turbulence. Turbulence is not conducive to flow, and will likely create backpressure, which will rob potential power. The type of backpressure produced would negate any benefits.
So at the end of the day, while it is possible you could see an increase, it is not likely. The idea that catalytic converter is restrictive is based upon old information dating to the early days of smog controls. Lets do a little history lesson.
Many early designs used a pellet type catalyst system. These basically consistent of a bunch or round ceramic or metal beads sandwiched between screens. This design was used because it was cheap to manufacture, it was highly efficient at reducing emissions, and when it was developed, the ceramic honeycomb substrate had not been invented yet. The result was a severe penalty to performance and economy. Fords did not use this type of design, it was more common amount the GM and various imports. However, the reputation of these designs took hold.
The early designs were focused on CO and HC emissions. The manufacturers would lean out the mixtures to keep the emissions clean. This was good for economy and emissions, but bad for performance. Many of these designs, depending on manufacturer, also used high compression, also good for economy and emissions. Or was it. Pretty soon a new emission gas was identified as a threat, NOX, which tends to for visible smog, it burns the eyes, nose, and throat, contributes to acidic rain, etc. These gases form most readily at lean conditions, the same conditions that minimize HC and CO. There is no true middle ground, any typical compromise produces lots of CO, HC, and NOX. And early solution was air injection, AKA smog pump. This works by tuning the engine rich (bad for economy) to keep NOX from forming, then using an external pump to deliver air into the catalyst bed to clean up the HC and CO that are produced by the rich combustion. The EGR valve also came onto the scene and started to catch on.
A little more on EGR, a lot of people misunderstand the relationship an EGR has, and misunderstand rich and lean mixtures, and what that means. EGR stand for Exhaust Gas Recirculation. Its primary function is to reduce combustion temperatures, and effectively, dynamically reduce displacement. Some would argue that the introduction of exhaust gas would lean out the mixture. This is not true. Rich or lean is not the ratio of fuel to air, it is the ratio of fuel to a specific gas. That specific gas is oxygen. Exhaust gas is a byproduct of combustion, and has already had most of the oxygen in in depleted from the combustion. As a result it is considered an inert gas. All it is doing is occupying space in the cylinders, effectively making the engine behave more like a smaller engine when the engine is not under heavy load. This helps conserve fuel, and also reduces NOX emissions by lowering the combustion temperatures, since the inert gas also slows down the combustion, a similar effect to raising the octane as well. I am pointing out how this function because I have heard many people incorrectly describe how it works, and encourage disabling or bypassing these systems, based on an incorrect understanding of its function.
As fuel injection began to really take hold and the systems because fast and more powerful, the fuel management became more tightly controlled, which introduces a new method that became the new standard. By using rare each metals in the catalyst, it became possible to store oxygen in the catalyst substrate, eliminating the need for smog pumps. Basically by monitoring an O2 sensor, you could switch between slightly rich to slightly lean, creating optimal conditions within the catalyst to efficiently clean up HC, CO, and NOX at the same time. The rare earth metals in the substrate store the oxygen from the lean cycle, and from the breakdown of NOX so that the oxygen is available to break down HC and CO more efficiently especially during the rich phase. Once this method came into use, the fuel economy and performance penalties associated with emissions controls previously. This type of technology started coming into use in the mid eighties!!! It did not get used industry wide till the early nineties, but Ford was among the first to use it. It works very well when combined with EGR.
In the early nineties, some of the manufacturers started coming up with new cam profiles that worked best when used with converters. The new profiles took advantage of the overlap period in particular to maximize economy, and performance in the typical part of the power band that most driving is done in. These profiles provide good performance and economy with a catalyst in place, unlike earlier or race cams, which get penalized by the presence of catalytic converters. But these profiles cause poor use of fuel if the catalyst is not presence, for the reasons I described earlier, basically some of the intake charge can get pulled straight though the cylinder and into the exhaust when it is not only wasted, but it messes with the engine management, causing additional waste. This is especially true of newer engines with variable valve timing, dual overhead cams, etc.
You can in some cases use higher flow catalysts, but the benefits are magical on most vehicles, and can introduce the same over scavenging problems of running without cats. True high flow cats are best for vehicles with performance cams, or for forced induction setups.
While it is still of questionable legality, you can run just two cats. You will get more exhaust noise, but it probably won't have any performance or economy benefits, and it might cause CEL issues.
#3
05-27-2012, 01:46 PM
Wow!! Great info!!
That`s why I first sign up to this forum. So I would`t waste my time and efforts into something that would have being a wasted effort.
Thank you for the great info that you have posted. What I`m going to do is just do a good tune up such as plugs,filters and also replace my o2 sensors in pairs as money aloud`s.
Just really trying hard to get as best fuel mileage as possible.
Thank you for the great info that you have posted. What I`m going to do is just do a good tune up such as plugs,filters and also replace my o2 sensors in pairs as money aloud`s.
Just really trying hard to get as best fuel mileage as possible.
#5
06-01-2012, 12:15 AM
Yes, you will have CEL issues. The obvious and immediate effect will be catalyst efficiency codes. Some will argue you can use simulators to trick the computer. The problem is simulators unless they pull in external power, only simulate a stable waveform, but they still have a lower voltage, lower voltage means more oxygen, more oxygen tell the computer that even if the waveform is stable, the cats are not functioning. On an older vehicle, the simulators would likely work, on a 2006, I doubt they would.
The stock cam in your engine is set up for use with cats, in such a way that it can use the cats to flow the right amount of fuel and air. Without the cats, the engine will likely over scavenge during the overlap period, wasting fuel and potential power, and also messing with the O2 sensor readings. These readings would detect excess oxygen and interpret that you need more fuel, so it would richen the mixture to compensate.
Hollow cat shells produce turbulence. Turbulence is not conducive to flow, and will likely create backpressure, which will rob potential power. The type of backpressure produced would negate any benefits.
So at the end of the day, while it is possible you could see an increase, it is not likely. The idea that catalytic converter is restrictive is based upon old information dating to the early days of smog controls. Lets do a little history lesson.
Many early designs used a pellet type catalyst system. These basically consistent of a bunch or round ceramic or metal beads sandwiched between screens. This design was used because it was cheap to manufacture, it was highly efficient at reducing emissions, and when it was developed, the ceramic honeycomb substrate had not been invented yet. The result was a severe penalty to performance and economy. Fords did not use this type of design, it was more common amount the GM and various imports. However, the reputation of these designs took hold.
The early designs were focused on CO and HC emissions. The manufacturers would lean out the mixtures to keep the emissions clean. This was good for economy and emissions, but bad for performance. Many of these designs, depending on manufacturer, also used high compression, also good for economy and emissions. Or was it. Pretty soon a new emission gas was identified as a threat, NOX, which tends to for visible smog, it burns the eyes, nose, and throat, contributes to acidic rain, etc. These gases form most readily at lean conditions, the same conditions that minimize HC and CO. There is no true middle ground, any typical compromise produces lots of CO, HC, and NOX. And early solution was air injection, AKA smog pump. This works by tuning the engine rich (bad for economy) to keep NOX from forming, then using an external pump to deliver air into the catalyst bed to clean up the HC and CO that are produced by the rich combustion. The EGR valve also came onto the scene and started to catch on.
A little more on EGR, a lot of people misunderstand the relationship an EGR has, and misunderstand rich and lean mixtures, and what that means. EGR stand for Exhaust Gas Recirculation. Its primary function is to reduce combustion temperatures, and effectively, dynamically reduce displacement. Some would argue that the introduction of exhaust gas would lean out the mixture. This is not true. Rich or lean is not the ratio of fuel to air, it is the ratio of fuel to a specific gas. That specific gas is oxygen. Exhaust gas is a byproduct of combustion, and has already had most of the oxygen in in depleted from the combustion. As a result it is considered an inert gas. All it is doing is occupying space in the cylinders, effectively making the engine behave more like a smaller engine when the engine is not under heavy load. This helps conserve fuel, and also reduces NOX emissions by lowering the combustion temperatures, since the inert gas also slows down the combustion, a similar effect to raising the octane as well. I am pointing out how this function because I have heard many people incorrectly describe how it works, and encourage disabling or bypassing these systems, based on an incorrect understanding of its function.
As fuel injection began to really take hold and the systems because fast and more powerful, the fuel management became more tightly controlled, which introduces a new method that became the new standard. By using rare each metals in the catalyst, it became possible to store oxygen in the catalyst substrate, eliminating the need for smog pumps. Basically by monitoring an O2 sensor, you could switch between slightly rich to slightly lean, creating optimal conditions within the catalyst to efficiently clean up HC, CO, and NOX at the same time. The rare earth metals in the substrate store the oxygen from the lean cycle, and from the breakdown of NOX so that the oxygen is available to break down HC and CO more efficiently especially during the rich phase. Once this method came into use, the fuel economy and performance penalties associated with emissions controls previously. This type of technology started coming into use in the mid eighties!!! It did not get used industry wide till the early nineties, but Ford was among the first to use it. It works very well when combined with EGR.
In the early nineties, some of the manufacturers started coming up with new cam profiles that worked best when used with converters. The new profiles took advantage of the overlap period in particular to maximize economy, and performance in the typical part of the power band that most driving is done in. These profiles provide good performance and economy with a catalyst in place, unlike earlier or race cams, which get penalized by the presence of catalytic converters. But these profiles cause poor use of fuel if the catalyst is not presence, for the reasons I described earlier, basically some of the intake charge can get pulled straight though the cylinder and into the exhaust when it is not only wasted, but it messes with the engine management, causing additional waste. This is especially true of newer engines with variable valve timing, dual overhead cams, etc.
You can in some cases use higher flow catalysts, but the benefits are magical on most vehicles, and can introduce the same over scavenging problems of running without cats. True high flow cats are best for vehicles with performance cams, or for forced induction setups.
While it is still of questionable legality, you can run just two cats. You will get more exhaust noise, but it probably won't have any performance or economy benefits, and it might cause CEL issues.
The stock cam in your engine is set up for use with cats, in such a way that it can use the cats to flow the right amount of fuel and air. Without the cats, the engine will likely over scavenge during the overlap period, wasting fuel and potential power, and also messing with the O2 sensor readings. These readings would detect excess oxygen and interpret that you need more fuel, so it would richen the mixture to compensate.
Hollow cat shells produce turbulence. Turbulence is not conducive to flow, and will likely create backpressure, which will rob potential power. The type of backpressure produced would negate any benefits.
So at the end of the day, while it is possible you could see an increase, it is not likely. The idea that catalytic converter is restrictive is based upon old information dating to the early days of smog controls. Lets do a little history lesson.
Many early designs used a pellet type catalyst system. These basically consistent of a bunch or round ceramic or metal beads sandwiched between screens. This design was used because it was cheap to manufacture, it was highly efficient at reducing emissions, and when it was developed, the ceramic honeycomb substrate had not been invented yet. The result was a severe penalty to performance and economy. Fords did not use this type of design, it was more common amount the GM and various imports. However, the reputation of these designs took hold.
The early designs were focused on CO and HC emissions. The manufacturers would lean out the mixtures to keep the emissions clean. This was good for economy and emissions, but bad for performance. Many of these designs, depending on manufacturer, also used high compression, also good for economy and emissions. Or was it. Pretty soon a new emission gas was identified as a threat, NOX, which tends to for visible smog, it burns the eyes, nose, and throat, contributes to acidic rain, etc. These gases form most readily at lean conditions, the same conditions that minimize HC and CO. There is no true middle ground, any typical compromise produces lots of CO, HC, and NOX. And early solution was air injection, AKA smog pump. This works by tuning the engine rich (bad for economy) to keep NOX from forming, then using an external pump to deliver air into the catalyst bed to clean up the HC and CO that are produced by the rich combustion. The EGR valve also came onto the scene and started to catch on.
A little more on EGR, a lot of people misunderstand the relationship an EGR has, and misunderstand rich and lean mixtures, and what that means. EGR stand for Exhaust Gas Recirculation. Its primary function is to reduce combustion temperatures, and effectively, dynamically reduce displacement. Some would argue that the introduction of exhaust gas would lean out the mixture. This is not true. Rich or lean is not the ratio of fuel to air, it is the ratio of fuel to a specific gas. That specific gas is oxygen. Exhaust gas is a byproduct of combustion, and has already had most of the oxygen in in depleted from the combustion. As a result it is considered an inert gas. All it is doing is occupying space in the cylinders, effectively making the engine behave more like a smaller engine when the engine is not under heavy load. This helps conserve fuel, and also reduces NOX emissions by lowering the combustion temperatures, since the inert gas also slows down the combustion, a similar effect to raising the octane as well. I am pointing out how this function because I have heard many people incorrectly describe how it works, and encourage disabling or bypassing these systems, based on an incorrect understanding of its function.
As fuel injection began to really take hold and the systems because fast and more powerful, the fuel management became more tightly controlled, which introduces a new method that became the new standard. By using rare each metals in the catalyst, it became possible to store oxygen in the catalyst substrate, eliminating the need for smog pumps. Basically by monitoring an O2 sensor, you could switch between slightly rich to slightly lean, creating optimal conditions within the catalyst to efficiently clean up HC, CO, and NOX at the same time. The rare earth metals in the substrate store the oxygen from the lean cycle, and from the breakdown of NOX so that the oxygen is available to break down HC and CO more efficiently especially during the rich phase. Once this method came into use, the fuel economy and performance penalties associated with emissions controls previously. This type of technology started coming into use in the mid eighties!!! It did not get used industry wide till the early nineties, but Ford was among the first to use it. It works very well when combined with EGR.
In the early nineties, some of the manufacturers started coming up with new cam profiles that worked best when used with converters. The new profiles took advantage of the overlap period in particular to maximize economy, and performance in the typical part of the power band that most driving is done in. These profiles provide good performance and economy with a catalyst in place, unlike earlier or race cams, which get penalized by the presence of catalytic converters. But these profiles cause poor use of fuel if the catalyst is not presence, for the reasons I described earlier, basically some of the intake charge can get pulled straight though the cylinder and into the exhaust when it is not only wasted, but it messes with the engine management, causing additional waste. This is especially true of newer engines with variable valve timing, dual overhead cams, etc.
You can in some cases use higher flow catalysts, but the benefits are magical on most vehicles, and can introduce the same over scavenging problems of running without cats. True high flow cats are best for vehicles with performance cams, or for forced induction setups.
While it is still of questionable legality, you can run just two cats. You will get more exhaust noise, but it probably won't have any performance or economy benefits, and it might cause CEL issues.
Keep your cats unless you can meet these two conditions:1. you have long tube headers
2. you have a way to turn off the check engine light.
Simply cutting out your stock muffler and welding in a Magnaflow, Borla, BAmuffler style muffler with inlet/outlet the same size as stock is your best bet. No guarantees that you'll gain mpg, but if the muffler case is properly sized you'll keep your low end scavenging and gain some top end hp.
Here are the restrictions in the stock system in the order of most restrictive to least restrictive:
1. muffler
2. manifolds
3. y pipe
4. cats
5. tubing size
With cats being second to last on the list, and if you don't replace everything before it, there is no point in getting rid of the cats.
Here's a great exhaust thread that I wrote on another forum, it should help, if you have the time to read it
:How a properly built exhaust system works
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