Mustang GT and K&N air charger

"My Name Is Nobody" > wrote in message
news:STGoj.4$f73.3@trndny08...

> IGNORING THE TRUTH WON'T MAKE IT GO AWAY ED!

What truth?

> Tuning, needed or not? YES! I made the dyno runs like this, on the first
> car
> I installed the stock air box and ran it three times and then installed
> the
> Bullitt airbox and did the same. With both intakes I had the stock tune
> installed in the car. Sure enough with the stock airbox and tune it went
> rich down to the high 11's and low 12's like normal. When I installed the
> Bullitt airbox it went lean, very very lean, in the mid to high 14's. Yes,
> this intake requires a tune. Any tuner can verify this as well by looking
> at
> the stock Bullitt tune, which SCT has in their database, and noting that
> the
> MAF adjustments are different for the new Bullitt air box.
> http://forums.bradbarnett.net/showthread.php?t=75262

I have never said a restricted air filter won't affect performance. I am
strictly talking about fuel economy. As long as we aren't talking about some
absurdly restricted filter, the filter throttles the maximum power of the
engine, just like the throttle plate. There is no reason to think in the
case of a modern fuel injected engine that a properly service air filter
will reduce fuel economy any more than driving around at anything less than
WOT. The air filter, intake piping, and throttle all work to limit maximum
air flow through the engine. The fuel economy is not going to be affected
just because the throttling occurs at the air filter instead of at the
throttle plate. And again, I am only talking about modern feedback
controlled fuel injected engines operating with an air filter that is not
absurdly contaminated.

When you swapped air boxes, how did you measure the A/F ratio? Were you
measuring it at wide open throttle? Did you complete a drive cycle so that
the PCM could adjust the long term fuel trim to compensate for the changes
in the system? The company who wrote the advertising you keep reposting
claims that at 450 cfm the pressure drop through the stock Mustang GT air
box is only 20 inches of water (see
http://www.cnlperformance.com/images...Racer_Flow.jpg ). This is 0.7
psi. And this is for a flow rate of 450 cfm - well beyond the flow necessary
to develop 250 hp. At a normal cruise the pressure drop is a fraction of
this. Probably less than 0.1 psi. Atmospheric pressure at sea level is 14.7
psi. Atmospheric pressure at 5000 feet (Denver more or less) is 12.2 psi.
You seem to think that the PCM can't adjust the A/F ratio if you reduce the
pressure at the throttle plate by less than 1 psi, yet modern cars can
easily handle the 2.5 psi drop associated with driving from sea level to
Denver Colorado. Think about what you are claiming.

> 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.
> http://www.allfordmustangs.com/revie...hp/product/394

Why do you keep posting this advertisement. It is not even related to what I
am talking about. Plus it contradicts itself. In one passage they are
claiming that just installing an aftermarket air filter leans out the A/F
ratio to an "alarming" degree, yet in another passage, they claim that
replacing the complete air intake in front of the throttle body (including
replacing the MAF with a large bore MAF) won't lean the engine enough to
cause engine durability concerns. If installing a completely different MAF
(one not calibrated for use with the PCM) and the complete induction tract
doesn't lean the mixture enough to cause durability concerns, what in the
world could be "alarming" about any change related to changing the air
filter to a low restriction air filter. If you left the air filter out you
wouldn't decrease the intact tract resistance my more than a few tenths of a
psi at wide open throttle. At anything less that wide open throttle the
difference will be close to nil. Just based on this one paragraph it is easy
to see that this advertisement is poorly researched crap.

There are plenty of sources for information on air filter flow restrictions.
Read a few and quit falling for this advertising crap.

From http://www.filtercouncil.org/techdata/tsbs/89-3R3.html :

"Most engine manufacturers suggest a maximum allowable restriction between
15 inches and 20 inches of water (3.75 - 5.00 Kpa) for gas and LP engines,
and from 20 inches to 30 inches of water (5.00 - 7.50 Kpa) for diesels.
Exceeding these maximums will affect engine performance. "

20 to 30 inches of water is 0.7 to 1 psi. This is the maximum you should
ever see under any condition if you follow the manufacturers recommended
replacement intervals (I doubt most people ever get close to this).

http://www.filterminder.com/bulletins/restriction2.pdf includes a chart
showing the increase in air filter restriction versus mileage. This chart is
"typical" for diesel trucks, but it demonstrates that we are not talking
about large difference in the pressure drop across filters (by the way,
filter restriction is a much bigger issue for diesel engines, since they
don't include throttle plates). The chart shows typical values for filter
restriction ranging from 5 inches of water to 20 inches of water (and since
this is a diesel engine chart, we are talking about pressure drops at much
higher air flow rates than is typical for a gas vehicles cruising down the
highway at part throttle). 5 inches of water is 0.03 psi. 20 inches of water
is 0.7 psi.

From http://www.bobistheoilguy.com/airfilter/airtest1.htm and
http://www.bobistheoilguy.com/airfilter/airtest2.htm :

"The differential pressure was measured between atmospheric and the pressure
drop after the air filter in the stock airbox. The max pressure drop in this
test was seen at only 7.0 inches of water or 0.25 psi. The factory airbox
and piping with no filter yielded a pressure drop of 5.0 inches of water or
0.18 psi. That means that the worst filter in this test only caused a
pressure drop of 0.07 psi."

Again, filters are not particularly restrictive....

See http://www.visteon.com/utils/whitepa...05_01_1139.pdf Figure 14.
This chart shows the increase in filter restriction versus contaminant
loading for a long life air filter prototype in a fleet test. The pressure
drop across the filter increases from 0.5 kPa (0.007 psi) to 2.5 kPa (0.362
psi) as the contamination increased by a factor of 5. Again, we are not
talking about large changes in the pressure drop across an air filter during
its normal service life.

See http://www.fuelinjection.net/kne/kne_test.htm. The chart on this
reference claims that a paper filter will flow 508 cfm with a pressure drop
across the filter of 1.5" of water. A pressure drop of 1.5" of water is
0.054 psi! 508 cfm is well in excess of the flow rate needed for a stock
Mustang to develop maximum power. What do you think the pressure drop will
be across the filter when cruising at 65 mph? I am sure it will be way less
than .05 psi. Do you honestly believe that removing an air filter with this
sort of restriction will have any affect on the PCM? It you quadruple the
restriction, do you think the PCM can't compensate to correct the A/F ratio?

See http://www.eurosporthighperformance....s/K&N_test.pdf . One of the
charts on this page tracks the air filter pressure drop versus
contamination. The chart ranges from 0 to around 1 psi for the test set-up
employed.

I don't believe any properly serviced air filter will exhibit a pressure
drop as great as 1 psi. Think about what this means....................

Explain to me how a change in the pressure drop across the air filter from a
few hundredths of a psi to a few tenths of a psi at the maximum air flow
rate (WOT). Then tell me how this is going to affect fuel economy when the
air flow rate is a fraction of the WOT air flow rate.

Ed

I knew this was hopeless when he made the absurd assertion that you get more
horsepower (which he incorrectly associates with fuel economy) just by
changing the exhaust.

"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. 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
>
>

"Michael Johnson" > wrote in message
...
> 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.

That's not true, there is a knee point in the curve. As long as the filter
is capable of delivering more air than the engine is capable of demanding
then the percentage of blockage is not a factor. Once the blockage exceeds
a certain amount then you will experience a power roll off as you approach
WOT. As far as mileage is concerned there should be little or no change,
(at cruising speeds) as the fuel mixture is relatively constant because of
the electronics.

Ironrod wrote:
> "Michael Johnson" > wrote in message
> ...
>> 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.
>
> That's not true, there is a knee point in the curve. As long as the filter
> is capable of delivering more air than the engine is capable of demanding
> then the percentage of blockage is not a factor. Once the blockage exceeds
> a certain amount then you will experience a power roll off as you approach
> WOT. As far as mileage is concerned there should be little or no change,
> (at cruising speeds) as the fuel mixture is relatively constant because of
> the electronics.

The air filter is a restriction to air flow under ALL CONDITIONS. This
is an undeniable fact. As it gets dirty is becomes a larger and larger
restriction. This restriction affects performance under all conditions.
How much varies with the conditions and the efficiency of the filter.
An engine is an air pump. Anytime the pump can move more air it makes
more power and becomes more efficient.

So you claim a dirty filter doesn't reduce mileage?

Ironrod wrote:
> I knew this was hopeless when he made the absurd assertion that you get more
> horsepower (which he incorrectly associates with fuel economy) just by
> changing the exhaust.
>
> "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. 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
>>
>>
>
>

Ironrod wrote:
> I knew this was hopeless when he made the absurd assertion that you get more
> horsepower (which he incorrectly associates with fuel economy) just by
> changing the exhaust.

My truck did and I can actually feel the difference in my Mustang
between 6" pipes off the mufflers and pipes that go all the way out the
back.

--
"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

"Michael Johnson" > wrote in message
...
> Ironrod wrote:
> > "Michael Johnson" > wrote in message
> > ...
> >> 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.
> >
> > That's not true, there is a knee point in the curve. As long as the
filter
> > is capable of delivering more air than the engine is capable of
demanding
> > then the percentage of blockage is not a factor. Once the blockage
exceeds
> > a certain amount then you will experience a power roll off as you
approach
> > WOT. As far as mileage is concerned there should be little or no
change,
> > (at cruising speeds) as the fuel mixture is relatively constant because
of
> > the electronics.
>
> The air filter is a restriction to air flow under ALL CONDITIONS. This
> is an undeniable fact. As it gets dirty is becomes a larger and larger
> restriction. This restriction affects performance under all conditions.
> How much varies with the conditions and the efficiency of the filter.
> An engine is an air pump. Anytime the pump can move more air it makes
> more power and becomes more efficient.

Approach it this way, imagine walking down a hallway 10 foot square with its
sides converging. As you move towards the end the corridor gets narrower
until you can no longer pass. Now as long as you remain in the portion of
the hallway that is as large or larger than you are, you can run back and
forth at whatever speed you feel like. It won't be until you reach the
point where your start rubbing up against the walls that your forward
progress will be slowed. So goes the Air Filter, as it becomes dirtier the
walls close in, so to speak, but still you can move about freely. It won't
be until after the walls have narrowed to the point that you can no longer
walk upright that your movement is significantly impeded.

"WindsorFox" > wrote in message
...
> Ironrod wrote:
>> I knew this was hopeless when he made the absurd assertion that you get
>> more
>> horsepower (which he incorrectly associates with fuel economy) just by
>> changing the exhaust.
>
> My truck did and I can actually feel the difference in my Mustang
> between 6" pipes off the mufflers and pipes that go all the way out the
> back.

Changing the exhaust can increase maximum power by lowering back pressure,
although it might shift the peak torque curve, or even reduce the peak
torque (even as it increases maximum horsepower). IC engines are air pumps.
Anything you do to reduce the total resistance to flow from the air intake
to the muffler exhaust can increase the maximum power. Air moves into the
engine because of the pressure differential between the outside air and the
gas in the cylinders. If you lower the pressure in the cylinders (by
decreasing the exhaust back pressure) you can draw more air into the
cylinder. More air in, equals more power out, assuming that the PCM can
adjust the A/F ratio - which in can unless you do something really strange.
However, adding duals does not always improve performance. Poorly designed
duals may actually be worse than the OEM exhaust. And even if they increase
the maximum horsepower, they may adversely affect performance and
drivability under normal driving conditions by screwing up the torque curve
(or even reducing horsepower). All too often people confuse increased noise
with increased power.

Ed

Not until it reaches the point where it can no longer flow enough air to
meet the engine's needs.


"Michael Johnson" > wrote in message
...
> So you claim a dirty filter doesn't reduce mileage?
>
> Ironrod wrote:
> > I knew this was hopeless when he made the absurd assertion that you get
more
> > horsepower (which he incorrectly associates with fuel economy) just by
> > changing the exhaust.
> >
> > "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. 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
> >>
> >>
> >
> >

"WindsorFox" > wrote in message
...
> Ironrod wrote:
> > I knew this was hopeless when he made the absurd assertion that you get
more
> > horsepower (which he incorrectly associates with fuel economy) just by
> > changing the exhaust.
>
> My truck did and I can actually feel the difference in my Mustang
> between 6" pipes off the mufflers and pipes that go all the way out the
> back.
>
> --
> "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

I made a similar mistake myself, I replaced the stock 2.25" pipes with 2.5".
In a flat out drag race they could be said to be an improvement. In real
world part throttle driving I discovered that I had lost a lot of low end
torque, this really became apparent when driving along I 80 going to Reno
NV. I found myself constantly downshifting on hills that previously the car
could climb with no effort. (This blows the hell out of your mileage by the
way.) It wasn't until I replaced the 2.5" mufflers with 2.25" that I
regained that lost bottom end.