Mustang GT and K&N air charger

WindsorFox wrote:
> C. E. White wrote:
>> "Michael Johnson" > wrote in message
>>
>>> Are you saying a car gets the same mileage when a filter is new
>>> compared to when it is dirty? Gas mileage decreases gradually over
>>> time and not like dropping off a cliff. Here's another one to think
>>> about.... an engine with a more efficient intake in front of the
>>> throttle body makes more horsepower than with a stock setup. That
>>> power increase happens across the rpm range. The engine making more
>>> power will get better mileage because the engine is more efficient at
>>> making that power. What difference does it make whether it is a more
>>> efficient intake or a clean verses dirty filter that causes the
>>> increase in efficiency?
>>
>> You just don't get it. Unless you are at wide open throttle, the
>> restriction of a normal air filter is irrelevant for a modern fuel
>> injected engine.
>
> I don't believe that. The computer may know to adjust the amount of
> fuel based on the flow of air, but having to pull that air through a
> stiffer restriction is still going to make the engine work harder. I
> also think depending on how restricted the intake is it may cause some
> of the electronics to not perform as efficiently as well.

It is not irrelevant. Almost anytime you can use less throttle (i.e.
the engine is more efficient) to travel the same speed under the same
conditions the mileage will increase. It is the same reason going with
a less restrictive exhaust will also improve gas mileage. Why do under
drive pulleys increase mileage? Think about it. They increase
horsepower to the rear wheels across the ENTIRE rpm range which will
result in a mileage increase in normal driving.

"Michael Johnson" > wrote in message
...
> WindsorFox wrote:
>> C. E. White wrote:
>>> "Michael Johnson" > wrote in message
>>>
>>>> Are you saying a car gets the same mileage when a filter is new
>>>> compared to when it is dirty? Gas mileage decreases gradually
>>>> over time and not like dropping off a cliff. Here's another one
>>>> to think about.... an engine with a more efficient intake in
>>>> front of the throttle body makes more horsepower than with a
>>>> stock setup. That power increase happens across the rpm range.
>>>> The engine making more power will get better mileage because the
>>>> engine is more efficient at making that power. What difference
>>>> does it make whether it is a more efficient intake or a clean
>>>> verses dirty filter that causes the increase in efficiency?
>>>
>>> You just don't get it. Unless you are at wide open throttle, the
>>> restriction of a normal air filter is irrelevant for a modern fuel
>>> injected engine.
>>
>> I don't believe that. The computer may know to adjust the amount
>> of fuel based on the flow of air, but having to pull that air
>> through a stiffer restriction is still going to make the engine
>> work harder. I also think depending on how restricted the intake is
>> it may cause some of the electronics to not perform as efficiently
>> as well.
>
> It is not irrelevant. Almost anytime you can use less throttle
> (i.e. the engine is more efficient) to travel the same speed under
> the same conditions the mileage will increase. It is the same
> reason going with a less restrictive exhaust will also improve gas
> mileage. Why do under drive pulleys increase mileage? Think about
> it. They increase horsepower to the rear wheels across the ENTIRE
> rpm range which will result in a mileage increase in normal driving.

This is hopeless. Air flow is what mattes, not the exact position of
the throttle plate. You change the throttle position to adjust the air
flow to achieve a certain power level. The fact that the air flow is
restricted at the air filter instead of the throttle plate doesn't
affect the fuel economy to any measurable degree for a modern fuel
injected engine (at least as measurable by typical consumers). You
seem to have the idea that you'll get more power for the same amount
of air just because the restriction is at the throttle instead of
because of the total intake tract flow restriction. This is simply
wrong. If you remove the throttle from the equation, by completely
opening it (i.e., WIDE OPEN THROTTLE), then yes the maximum air flow
is controlled by the other parts of the intake tract and the air
filter will be one of the factors limiting maximum power output.
However this doesn't mean the engine is more efficient for a given
power output than if the restriction is caused by a partially closed
throttle. Unless you are at wide open throttle, there is no increase
in horsepower across the rpm range. You are setting a power level by
throttling the air flow. You are confusing measuring horsepower on a
dynometer with driving a car on the highway. On a dynometer, you are
at wide open throttle. To measure the power at different rpms, you
load the engine up to slow it down to the speed of interest - you
don't close the throttle to achieve the lower rpm. The power output
of a gasoline engine is primarily a result of the amount of air
flowing into the engine. I am not claiming that a less restrictive
air filter won't affect the power output at wide open throttle. A
restrictive air filter will reduce the maximum flow rate of air into
the engine and this will reduce the maximum power at wide open
throttle. But you cannot use this fact to claim that it will affect
the fuel economy. Throttling the amount of air because of a
restrictive air filter is no different that using a moving plate to
throttle the amount of air. Until I can get you to understand this, I
am not going to get you to understand the situation.

I'll try this analogy again - if I blindfold you and ask you to suck
on a straw, and then partially block the straw, will you be able to
tell where I am blocking the straw by how hard it is to suck in air?
Certainly you will know I am restricting the air flow through the
straw, but you won't be able to tell where, or even how I am
restricting it (without looking). This is the situation with the
engine when you are driving at anything but wide open throttle. As far
as the engine is concerned something is restricting air flow into the
engine and limiting the power to the level required to move the car.
As a practical matter the engine doesn't care whether the restriction
is due to the throttle position or a reasonable air filter
restriction. There may be a slight difference in the position of the
throttle plate because of a slight increase in the restriction in
front of the throttle plate at the air cleaner, but the difference
will be trivial as far as the TPS is concerned. We are talking
percentage point differences and the PCM can easily handle this sort
of drift based on feedback from the O2 sensor.

1) Do you believe that unless you are at wide open throttle that the
air flow into the engine is restricted by the complete intake tract
flow restriction (cumulative restriction of air intake, air filter,
piping, throttle, valves, etc)? If you don't believe this, why not?
Why is the restriction imposed by the air filter different than the
restriction imposed by the throttle plate (assuming you are not at
wide open throttle)?

2) Do you believe that to cruise at a given speed, or accelerate
moderately, that you are not operating at wide open throttle?

3) If you are not operating at wide open throttle, do you believe that
you can compensate for a "normally" restricted air filter with a
slight increase in the throttle opening to achieve a given steady
state speed or moderate rate of acceleration?

4) Do you believe that a modern fuel injection system can adjust for
changes in the input parameters by adjusting fuel delivery based on
feedback from the O2 sensor?

5) If you believe the answers to 3 and 4 are yes, why do you think the
fuel economy is affected by a "normally" restricted air filter. And if
you still think it is significantly affected, why wouldn't the PCM see
this as an error and turn on the check engine light?

Ed

C. E. White wrote:
> "Michael Johnson" > wrote in message
> ...
>> WindsorFox wrote:
>>> C. E. White wrote:
>>>> "Michael Johnson" > wrote in message
>>>>
>>>>> Are you saying a car gets the same mileage when a filter is new
>>>>> compared to when it is dirty? Gas mileage decreases gradually
>>>>> over time and not like dropping off a cliff. Here's another one
>>>>> to think about.... an engine with a more efficient intake in
>>>>> front of the throttle body makes more horsepower than with a
>>>>> stock setup. That power increase happens across the rpm range.
>>>>> The engine making more power will get better mileage because the
>>>>> engine is more efficient at making that power. What difference
>>>>> does it make whether it is a more efficient intake or a clean
>>>>> verses dirty filter that causes the increase in efficiency?
>>>> You just don't get it. Unless you are at wide open throttle, the
>>>> restriction of a normal air filter is irrelevant for a modern fuel
>>>> injected engine.
>>> I don't believe that. The computer may know to adjust the amount
>>> of fuel based on the flow of air, but having to pull that air
>>> through a stiffer restriction is still going to make the engine
>>> work harder. I also think depending on how restricted the intake is
>>> it may cause some of the electronics to not perform as efficiently
>>> as well.
>> It is not irrelevant. Almost anytime you can use less throttle
>> (i.e. the engine is more efficient) to travel the same speed under
>> the same conditions the mileage will increase. It is the same
>> reason going with a less restrictive exhaust will also improve gas
>> mileage. Why do under drive pulleys increase mileage? Think about
>> it. They increase horsepower to the rear wheels across the ENTIRE
>> rpm range which will result in a mileage increase in normal driving.
>
> This is hopeless. Air flow is what mattes, not the exact position of
> the throttle plate. You change the throttle position to adjust the air
> flow to achieve a certain power level. The fact that the air flow is
> restricted at the air filter instead of the throttle plate doesn't
> affect the fuel economy to any measurable degree for a modern fuel
> injected engine (at least as measurable by typical consumers). You
> seem to have the idea that you'll get more power for the same amount
> of air just because the restriction is at the throttle instead of
> because of the total intake tract flow restriction. This is simply
> wrong. If you remove the throttle from the equation, by completely
> opening it (i.e., WIDE OPEN THROTTLE), then yes the maximum air flow
> is controlled by the other parts of the intake tract and the air
> filter will be one of the factors limiting maximum power output.
> However this doesn't mean the engine is more efficient for a given
> power output than if the restriction is caused by a partially closed
> throttle. Unless you are at wide open throttle, there is no increase
> in horsepower across the rpm range. You are setting a power level by
> throttling the air flow. You are confusing measuring horsepower on a
> dynometer with driving a car on the highway. On a dynometer, you are
> at wide open throttle. To measure the power at different rpms, you
> load the engine up to slow it down to the speed of interest - you
> don't close the throttle to achieve the lower rpm. The power output
> of a gasoline engine is primarily a result of the amount of air
> flowing into the engine. I am not claiming that a less restrictive
> air filter won't affect the power output at wide open throttle. A
> restrictive air filter will reduce the maximum flow rate of air into
> the engine and this will reduce the maximum power at wide open
> throttle. But you cannot use this fact to claim that it will affect
> the fuel economy. Throttling the amount of air because of a
> restrictive air filter is no different that using a moving plate to
> throttle the amount of air. Until I can get you to understand this, I
> am not going to get you to understand the situation.
>
> I'll try this analogy again - if I blindfold you and ask you to suck
> on a straw, and then partially block the straw, will you be able to
> tell where I am blocking the straw by how hard it is to suck in air?
> Certainly you will know I am restricting the air flow through the
> straw, but you won't be able to tell where, or even how I am
> restricting it (without looking). This is the situation with the
> engine when you are driving at anything but wide open throttle. As far
> as the engine is concerned something is restricting air flow into the
> engine and limiting the power to the level required to move the car.
> As a practical matter the engine doesn't care whether the restriction
> is due to the throttle position or a reasonable air filter
> restriction. There may be a slight difference in the position of the
> throttle plate because of a slight increase in the restriction in
> front of the throttle plate at the air cleaner, but the difference
> will be trivial as far as the TPS is concerned. We are talking
> percentage point differences and the PCM can easily handle this sort
> of drift based on feedback from the O2 sensor.
>
> 1) Do you believe that unless you are at wide open throttle that the
> air flow into the engine is restricted by the complete intake tract
> flow restriction (cumulative restriction of air intake, air filter,
> piping, throttle, valves, etc)? If you don't believe this, why not?
> Why is the restriction imposed by the air filter different than the
> restriction imposed by the throttle plate (assuming you are not at
> wide open throttle)?
>
> 2) Do you believe that to cruise at a given speed, or accelerate
> moderately, that you are not operating at wide open throttle?
>
> 3) If you are not operating at wide open throttle, do you believe that
> you can compensate for a "normally" restricted air filter with a
> slight increase in the throttle opening to achieve a given steady
> state speed or moderate rate of acceleration?
>
> 4) Do you believe that a modern fuel injection system can adjust for
> changes in the input parameters by adjusting fuel delivery based on
> feedback from the O2 sensor?
>
> 5) If you believe the answers to 3 and 4 are yes, why do you think the
> fuel economy is affected by a "normally" restricted air filter. And if
> you still think it is significantly affected, why wouldn't the PCM see
> this as an error and turn on the check engine light?

Haven't we beat this to death between us? I was replying to WF because
you and I are never going to agree on this issue.

C. E. White wrote:
> "WindsorFox" > wrote in message
> ...
>> C. E. White wrote:
>>> "Michael Johnson" > wrote in message
>>>
>>>> Are you saying a car gets the same mileage when a filter is new
>>>> compared to when it is dirty? Gas mileage decreases gradually
>>>> over time and not like dropping off a cliff. Here's another one
>>>> to think about.... an engine with a more efficient intake in front
>>>> of the throttle body makes more horsepower than with a stock
>>>> setup. That power increase happens across the rpm range. The
>>>> engine making more power will get better mileage because the
>>>> engine is more efficient at making that power. What difference
>>>> does it make whether it is a more efficient intake or a clean
>>>> verses dirty filter that causes the increase in efficiency?
>>> You just don't get it. Unless you are at wide open throttle, the
>>> restriction of a normal air filter is irrelevant for a modern fuel
>>> injected engine.
>> I don't believe that. The computer may know to adjust the amount
>> of fuel based on the flow of air, but having to pull that air
>> through a stiffer restriction is still going to make the engine work
>> harder. I also think depending on how restricted the intake is it
>> may cause some of the electronics to not perform as efficiently as
>> well.
>
> Again, why do you believe this? Air flow into the engine is restricted
> by the throttle plate at anything less than wide open throttle.

By this thinking if the car is at an idle and not WOT then putting
your hand over the intake should do nothing. A clogged filter ads more
resistance to what it already there.

--
"Yah know I hate it when forces gather in ma' fringe..." - Sheogorath

"Daytime television sucked 20 years ago,
and it still sucks today!" - Marc Bissonette

"WindsorFox" > wrote in message
...
> C. E. White wrote:
>> "WindsorFox" > wrote in message
>> ...
>>> C. E. White wrote:
>>>> "Michael Johnson" > wrote in message
>>>>
>>>>> Are you saying a car gets the same mileage when a filter is new
>>>>> compared to when it is dirty? Gas mileage decreases gradually
>>>>> over time and not like dropping off a cliff. Here's another one
>>>>> to think about.... an engine with a more efficient intake in
>>>>> front of the throttle body makes more horsepower than with a
>>>>> stock setup. That power increase happens across the rpm range.
>>>>> The engine making more power will get better mileage because the
>>>>> engine is more efficient at making that power. What difference
>>>>> does it make whether it is a more efficient intake or a clean
>>>>> verses dirty filter that causes the increase in efficiency?
>>>> You just don't get it. Unless you are at wide open throttle, the
>>>> restriction of a normal air filter is irrelevant for a modern
>>>> fuel injected engine.
>>> I don't believe that. The computer may know to adjust the
>>> amount of fuel based on the flow of air, but having to pull that
>>> air through a stiffer restriction is still going to make the
>>> engine work harder. I also think depending on how restricted the
>>> intake is it may cause some of the electronics to not perform as
>>> efficiently as well.
>>
>> Again, why do you believe this? Air flow into the engine is
>> restricted by the throttle plate at anything less than wide open
>> throttle.
>
> By this thinking if the car is at an idle and not WOT then
> putting your hand over the intake should do nothing. A clogged
> filter ads more resistance to what it already there.

ARRRRGGGGGGGGGGGGGGGGGGG -you really don't get it do you. What is so
hard to understand here. The amount of air that flows into the engine
is what determines the amount of power the engine developed. For a
given speed, or moderate acceleration rate, you need a certain amount
of power that is most likely less than what can be developed at wide
open throttle (I know, some people claim to drive all the time at
WOT). The total restriction to air flow is the sum of all the little
restrictions that make up the inlet tract from the air intake to the
actual cylinders (including the piping, air filter, throttle plate,
etc). For a properly maintained engine, NOT at wide open throttle, the
biggest single source of flow restriction is the throttle plate. If
there is a minor increase in the restriction in another part of the
intake system, you can decrease the total restriction of the entire
intake system by opening the throttle a little more - as long as the
additional restriction is not something outlandish, LIKE PUTTING YOUR
HAND OVER THE INTAKE!!!!!!!!!!!!!!!!!!!!

If you guys want to argue that cramming a potato in the intake will
affect fuel economy, I'll agree with you, although the results might
not be what you expect. Assuming you don't block the intake so
completely that the PCM can't properly adjust the A/F Ratio, it might
even increase the fuel economy since you'll be reducing the available
power . I have never claimed that an idiot with an air filter so
clogged that the check engine light is on won't have fuel economy
problems. I am just talking about the range of restrictions associated
with a properly maintained air filter and an otherwise stock engine in
good condition. If you want to talk about what happens if you do
something stupid, all bets are off.

Ed

"Michael Johnson" > wrote in message
...

> Haven't we beat this to death between us? I was replying to WF
> because you and I are never going to agree on this issue.

We beat it to death long ago. I just can't turn away. You clearly
don't understand how modern feedback fuel injection systems work and
because of this you are drawing bad conclusions. Foolishly, I hope I
can make a subtle change in my arguments so that you can understand
that unless you are at wide open throttle, the restriction of the air
filter is largely irrelevant as far as the performance of the engine
is concerned. Except at WOT, the throttle plate is the final
adjustment to the air flow rate. If you increase the restriction in
another part of the intake tract, you can open the throttle a little
more to get the same overall flow restriction. This doesn't effect
fuel economy because the PCM has the ability to correct the A/F ratio
based on the output of the O2 sensors (as long as the restriction is
not so gross as to set the malfunction indicator). The system is
designed to be able to compensate for changes like increasing air
filter restriction, drift in the response of the various sensors,
altitude, etc. Compared to other changes over time, a minor increase
in the flow restriction related to the air filter is trivial. Until
you understand this, you'll continue to draw the wrong conclusion.

Ed

C. E. White wrote:
> "Michael Johnson" > wrote in message
> ...
>
>> Haven't we beat this to death between us? I was replying to WF
>> because you and I are never going to agree on this issue.
>
> We beat it to death long ago. I just can't turn away. You clearly
> don't understand how modern feedback fuel injection systems work and
> because of this you are drawing bad conclusions. Foolishly, I hope I
> can make a subtle change in my arguments so that you can understand
> that unless you are at wide open throttle, the restriction of the air
> filter is largely irrelevant as far as the performance of the engine
> is concerned. Except at WOT, the throttle plate is the final
> adjustment to the air flow rate. If you increase the restriction in
> another part of the intake tract, you can open the throttle a little
> more to get the same overall flow restriction. This doesn't effect
> fuel economy because the PCM has the ability to correct the A/F ratio
> based on the output of the O2 sensors (as long as the restriction is
> not so gross as to set the malfunction indicator). The system is
> designed to be able to compensate for changes like increasing air
> filter restriction, drift in the response of the various sensors,
> altitude, etc. Compared to other changes over time, a minor increase
> in the flow restriction related to the air filter is trivial. Until
> you understand this, you'll continue to draw the wrong conclusion.

Ed, let it go. Mileage doesn't drop from a dirty filter at some magical
point. It is a gradual reduction that gets progressively more
noticeable as the filter collects more dirt.

"C. E. White" > wrote in message
news:47a1d416$1@kcnews01...
>
> "Michael Johnson" > wrote in message
>
>> Are you saying a car gets the same mileage when a filter is new compared
>> to when it is dirty? Gas mileage decreases gradually over time and not
>> like dropping off a cliff. Here's another one to think about.... an
>> engine with a more efficient intake in front of the throttle body makes
>> more horsepower than with a stock setup. That power increase happens
>> across the rpm range. The engine making more power will get better
>> mileage because the engine is more efficient at making that power. What
>> difference does it make whether it is a more efficient intake or a clean
>> verses dirty filter that causes the increase in efficiency?
>
> You just don't get it. Unless you are at wide open throttle, the
> restriction of a normal air filter is irrelevant for a modern fuel
> injected engine. Yes, certainly the engine may develop more power with a
> clean air filter AT WIDE OPEN THROTTLE. This is not because the engine it
> is more efficient, it is because you can draw more air into the engine -
> more air equals more power. But unless the throttle is wide open, the air
> filter is not the limiting factor. So unless you are driving around with
> your foot on the floor most of the time, the air filter restriction is not
> a significant factor in fuel economy. And if you are driving around with
> your foot on the floor most of the time, fuel economy is not something you
> care about.

BULL****! Your theory is flawed, try some actual real world applications of
it. Get back to us with your corrections...

>
> You seem to think there is a huge difference in the pressure drop across
> air filters - this isn't true. At a normal cruise you only need less than
> 20 horsepower to go 65 mph. This is somewhere around 0.034 gallons of
> gasoline per minute (around 27 miles per gallon). This is around 0.21 lbs
> of gasoline per minute. This amount of gasoline requires around 2.9 lbs of
> air. This is about 26 cubic feet of air. So, when cruising you can assume
> that your engine only needs about 26 cfm of air. Go look at the K&N web
> page. They compare filter performance at 300 cfm - over ten times what is
> required to cruise. And even at 300 cfm the difference in pressure drop
> between a clean K&N and a clean paper filter is on the order of 0.03 PSI.
> At a 65 cruise the pressure drop across a normal filter is probably too
> low to be measured without very sensitive equipment. There is a reason K&N
> always rates the flow rate of there filters for a given pressure drop,
> instead of giving you a pressure drop for a given flow rate - it over
> hypes the difference in filters.
>
> Discussing this subject with you is like watching a train wreck. You know
> there is nothing you can do about it, but you just can't turn away. I know
> you don't get it, I even understand why you don't get it, but I can't seem
> to come up with the proper way of explaining things to make you understand
> where your thinking is going wrong. You just can't get your thoughts
> around the idea that for a modern feedback controlled fuel injected
> engine, the PCM can adjust the fuel flow to compensate for changes in the
> system. Does a dirty air filter flow less air than a clean air filter, yes
> of course. Is the difference significant as far as fuel economy is
> concerned - no, not for a properly serviced air filter. We are talking
> about hundredths of a psi difference in pressure drop at normal cruising
> speeds. This difference is well within the adjustment range of any modern
> fuel injected engine.

Bull**** again, "Also included in this package is a new high flow conical
filter assembly, custom filter shroud that separates it from the engine
compartment heat, MAF mounting bracket, mounting hardware, installation tool
and instructions. Dyno testing the 2005 GT has shown that the computer is so
sensitive to airflow changes that a computer modification is necessary in
order to control the air/fuel ratio at the proper level. Installing this air
intake assembly on a 2005 GT without any tuning will result in a
leaner-than-ideal 14:1 air/fuel ratio. While certainly not lean enough to
cause engine durablility concerns, it is leaner than what is desired for
optimum performance. Even when replacing the air filter ONLY to a higher
flow assembly, the air/fuel ratio leans out at an alarming rate. This means
that any 2005 Mustang owner who is interested in modifying their new car for
better performance will have to use some form of tuning"
http://www.allfordmustangs.com/revie...hp/product/394



Heck, changes in the air filter are not close to the most
> significant factor that changes with time. Drift in the measuring
> capabilities of the MAF and TPS are more significant than the change in
> the pressure drop across the air filter. Until you understand that unless
> you are at wide open throttle, the air pressure drop across the air filter
> is trivial, you'll never understand why the pressure drop across the air
> filter is not a significant factor in determining fuel economy. An air
> filter dirty enough to significantly affect fuel economy should also set a
> fault code in the PCM and turn on the check engine light.
>
> Ed

Until you actually move from the realm of theory into practical application,
you'll never understand how it actually works.

"C. E. White" > wrote in message
news:47a2312a$1@kcnews01...
>
> "Michael Johnson" > wrote in message
> ...
>
>> Haven't we beat this to death between us? I was replying to WF because
>> you and I are never going to agree on this issue.
>
> We beat it to death long ago. I just can't turn away. You clearly don't
> understand how modern feedback fuel injection systems work and because of
> this you are drawing bad conclusions.


Nice Fantasy Ed.

"Also included in this package is a new high flow conical filter assembly,
custom filter shroud that separates it from the engine compartment heat, MAF
mounting bracket, mounting hardware, installation tool and instructions.
Dyno testing the 2005 GT has shown that the computer is so sensitive to
airflow changes that a computer modification is necessary in order to
control the air/fuel ratio at the proper level. Installing this air intake
assembly on a 2005 GT without any tuning will result in a leaner-than-ideal
14:1 air/fuel ratio. While certainly not lean enough to cause engine
durablility concerns, it is leaner than what is desired for optimum
performance. Even when replacing the air filter ONLY to a higher flow
assembly, the air/fuel ratio leans out at an alarming rate. This means that
any 2005 Mustang owner who is interested in modifying their new car for
better performance will have to use some form of tuning"
http://www.allfordmustangs.com/revie...hp/product/394


Do you have any actual real world data to support your position? Any at
all?
I'm talking real world automotive air flow data, not paragraphs of hot air.


> Foolishly, I hope I can make a subtle change in my arguments so that you
> can understand that unless you are at wide open throttle, the restriction
> of the air filter is largely irrelevant as far as the performance of the
> engine is concerned. Except at WOT, the throttle plate is the final
> adjustment to the air flow rate. If you increase the restriction in
> another part of the intake tract, you can open the throttle a little more
> to get the same overall flow restriction. This doesn't effect fuel economy
> because the PCM has the ability to correct the A/F ratio based on the
> output of the O2 sensors (as long as the restriction is not so gross as to
> set the malfunction indicator). The system is designed to be able to
> compensate for changes like increasing air filter restriction, drift in
> the response of the various sensors, altitude, etc. Compared to other
> changes over time, a minor increase in the flow restriction related to the
> air filter is trivial. Until you understand this, you'll continue to draw
> the wrong conclusion.
>
> Ed
>

C. E. White wrote:
> "WindsorFox" > wrote in message
> ...
>> C. E. White wrote:
>>> "WindsorFox" > wrote in message
>>> ...
>>>> C. E. White wrote:
>>>>> "Michael Johnson" > wrote in message
>>>>>
>>>>>> Are you saying a car gets the same mileage when a filter is new
>>>>>> compared to when it is dirty? Gas mileage decreases gradually
>>>>>> over time and not like dropping off a cliff. Here's another one
>>>>>> to think about.... an engine with a more efficient intake in
>>>>>> front of the throttle body makes more horsepower than with a
>>>>>> stock setup. That power increase happens across the rpm range.
>>>>>> The engine making more power will get better mileage because the
>>>>>> engine is more efficient at making that power. What difference
>>>>>> does it make whether it is a more efficient intake or a clean
>>>>>> verses dirty filter that causes the increase in efficiency?
>>>>> You just don't get it. Unless you are at wide open throttle, the
>>>>> restriction of a normal air filter is irrelevant for a modern
>>>>> fuel injected engine.
>>>> I don't believe that. The computer may know to adjust the
>>>> amount of fuel based on the flow of air, but having to pull that
>>>> air through a stiffer restriction is still going to make the
>>>> engine work harder. I also think depending on how restricted the
>>>> intake is it may cause some of the electronics to not perform as
>>>> efficiently as well.
>>> Again, why do you believe this? Air flow into the engine is
>>> restricted by the throttle plate at anything less than wide open
>>> throttle.
>> By this thinking if the car is at an idle and not WOT then
>> putting your hand over the intake should do nothing. A clogged
>> filter ads more resistance to what it already there.
>
> ARRRRGGGGGGGGGGGGGGGGGGG -you really don't get it do you.

It seems more like you don't get it. If the filter is clogged enough
it can still restrict more than the throttle at part way.

--
"Yah know I hate it when forces gather in ma' fringe..." - Sheogorath

"Daytime television sucked 20 years ago,
and it still sucks today!" - Marc Bissonette