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Car Forum / Ford / Ford Mustang / February 2008Mustang GT and K&N air charger
I would like to know if anyone has experience with the K&N 63 series aircharger system on a Mustang GT. Is the reported 15 hp boost there? More importantly, has anyone had challenges with their Ford warranty as a result of installing this item? Thanks! > I would like to know if anyone has experience with the K&N 63 series > aircharger system on a Mustang GT. Is the reported 15 hp boost > there? More importantly, has anyone had challenges with their Ford > warranty as a result of installing this item? Thanks! You shouldn't have any issues with the warranty unless the kit directly caused the problem. As for the horsepower boost, you will likely be lucky to get half of what the manufacturer claims. They typically get their numbers from a very specific set of parameters that most people never see. If you want to make a real difference in performance then get a dyno tuned chip. That will improve throttle response and get you around 30 rwhp and about the same amount of torque. Also, rear end gears is another good modification that you can really feel in the seat of your pants. Most of these other mods, on a stock engine, like air intake systems etc. are just fluff and mostly serve to let you point at something when you raise the hood. >> I would like to know if anyone has experience with the K&N 63 series >> aircharger system on a Mustang GT. Is the reported 15 hp boost [quoted text clipped - 13 lines] > fluff and mostly serve to let you point at something when you raise the > hood. 15 is way to high, perhaps 2 or 3 at 6,000 RPM, no low end grunt torque improvement at all. not worth it, but the chip is, especially to get rid of some of the throttle lag. >I would like to know if anyone has experience with the K&N 63 series > aircharger system on a Mustang GT. Is the reported 15 hp boost > there? More importantly, has anyone had challenges with their Ford > warranty as a result of installing this item? Thanks! See http://home.mindspring.com/~ed_white/id5.html for my opinion. Ed >>I would like to know if anyone has experience with the K&N 63 series >> aircharger system on a Mustang GT. Is the reported 15 hp boost [quoted text clipped - 4 lines] > > Ed While I agree K&N filters are a potentially dangerous and certainly a pain in the a.s, this statement "Claims of greatly improved fuel mileage for K&N Filters are bogus." Is absolutely FALSE! I still have the mileage records of every fill up for a 1994 Taurus SHO that I bought new with 7 miles on it, to over 70,000 miles. This car was a daily driver commuter car that went 70 mostly freeway miles each weekday. The first 25,000 miles it consistently recorded 24.5 MPG each fill up. A K&N air filter was installed into the stock air box, zero other changes. The fuel mileage took an immediate (and documented over 50,000 miles) jump up to 26.5 MPG, and stayed there. I personally would NEVER use a K&N oil bath air filter again. My preference is to filter my intake air as well as I possibly can and I don't think the K&N's do that as well as the stock paper filters.... But throwing out a blanket statement that fuel mileage gains from their use are bogus, is simply bogus. You may or may not like K&N filters, I don't, but for crying out loud, don't post bullshit about them. >>> I would like to know if anyone has experience with the K&N 63 series >>> aircharger system on a Mustang GT. Is the reported 15 hp boost [quoted text clipped - 22 lines] > simply bogus. You may or may not like K&N filters, I don't, but for crying > out loud, don't post bullshit about them. K&N air filters do flow better than most OEM filters. The problem with them is they can leave an oil film residue over time if the MAF is installed after the filter. Especially, if the user gets too much oil in the filter after cleaning it. The remedy for this is to clean the MAF element more often, which isn't a big hassle. Where they really pay off is on heavily modified engines (i.e. super/turbo charged) where the OEM filter becomes a bigger restriction due to the greatly increased air flow requirements. Additionally, I don't think K&N filters decrease the life of an engine due to poor filtering. I have had one on my '89 LX since it was new and it has 150k+ miles (the last 30k-40k miles with a blower) on it and it burns the same amount of oil as when it was new. I have also had the heads off numerous times and see no accelerated wear on the cylinder walls. The original cross hatching is still very visible. Anyone worried about engine wear from using a K&N is splitting hairs regarding their effectiveness verses an OEM/paper filter. > Additionally, I don't think K&N filters decrease the life of an engine > due to poor filtering. I have had one on my '89 LX since it was new and [quoted text clipped - 4 lines] > worried about engine wear from using a K&N is splitting hairs regarding > their effectiveness verses an OEM/paper filter. Yep, I now use the dry cleanable Donaldson filters from Amsoil.  Signature"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 would like to know if anyone has experience with the K&N 63 >>>series [quoted text clipped - 19 lines] > immediate (and documented over 50,000 miles) jump up to 26.5 MPG, > and stayed there. But why? Explain how the K&N could increase fuel economy on a fuel injected engine. Except at WOT, the air filter restriction is trivial compared to the throttle restriction. The MAF and other part of the FI control system are measuring the mass of flow through the induction tract, and they don't know whether the flow is restricted by the air filter or the throttle plate. With an older carbureted engine, I can see how a restricted air filter upsets the fuel air ratio and affects gas mileage. This is not the case for modern fuel injected engines. I don't know why your mileage jumped, but I suspect other factors are at play. > I personally would NEVER use a K&N oil bath air filter again. My > preference is to filter my intake air as well as I possibly can and [quoted text clipped - 3 lines] > like K&N filters, I don't, but for crying out loud, don't post > bullshit about them. I don't believe my opinion is BS. I don't see any reason to expect a K&N filter to increase the fuel economy of a modern fuel injected engine. Not even K&N makes the claim that their filters will increase fuel mileage Go read K&N's carefully worded FAQ on this subject (http://www.knfilters.com/faq.htm#1) - "we do not go so far as to make a general claim that our air filters and intake systems will provide an increase in mileage." K&N is willing to let you think their filters might increase fuel mileage, but they are not so foolish as to claim that they will. Ed >>>> I would like to know if anyone has experience with the K&N 63 >>>> series [quoted text clipped - 29 lines] > don't know why your mileage jumped, but I suspect other factors are at > play. Exactly, I don't believe an air filter will change mileage. The auto makers would be on it and so would the rest of this small world. I do however see a two mile per gallon decrease when using the now, "required by law in Oregon" E10. Pisses me off! >> I personally would NEVER use a K&N oil bath air filter again. My >> preference is to filter my intake air as well as I possibly can and [quoted text clipped - 15 lines] > > Ed SignatureTropic Green Y2K Mustang GT W/bits & pieces http://tinyurl.com/2uqoat > I do however see a two mile per gallon decrease when using the now, > "required by law in Oregon" E10. Pisses me off! Are you really seeing a 2 mpg decrease when using E10? Ethanol has about 85% as much energy as gasoline, so I would guess E10 has about 98.5% as much energy as plain old gas. Assuming the gas suppliers are keeping the octane the same (i.e., using the octane improvement related to ethanol to use lower octane gasoline for the other 90% of the blend), I would guess your mileage should only decrease by 4% at the most. A 2 mpg decrease on 25 mpg is an 8% decrease. This seems like an unreasonably high decrease for a modern fuel injected vehicle. Of course if you have an older carbureted vehicle, then the use of E10 screws up everything and a larger decrease is certainly possible (and even likely). Ed >> I do however see a two mile per gallon decrease when using the now, >> "required by law in Oregon" E10. Pisses me off! [quoted text clipped - 10 lines] > screws up everything and a larger decrease is certainly possible (and > even likely). It could be the engine control electronics and programming that causes a further reduction in mileage. Unless the engine is increasing the ignition timing to take advantage of the higher octane rating of ethanol it might reduce mileage even further. Also, I wonder if they use a lower octane gasoline to mix with the alcohol to end up with 87 octane. If that is the case then there is no benefit to be had from blending in the ethanol, only a loss of specific energy when compared to 100% gasoline. >> I do however see a two mile per gallon decrease when using the now, >> "required by law in Oregon" E10. Pisses me off! [quoted text clipped - 12 lines] > > Ed My 97 Ranger was getting between 17-18mpg and now is around 16, so maybe not quite 2mpg. Could be winter oxygenated fuel too, I don't know? SignatureTropic Green Y2K Mustang GT W/bits & pieces http://tinyurl.com/2uqoat >>>>> I would like to know if anyone has experience with the K&N 63 series >>>>> aircharger system on a Mustang GT. Is the reported 15 hp boost [quoted text clipped - 29 lines] > Exactly, I don't believe an air filter will change mileage. The auto > makers would be on it and so would the rest of this small world. Ever notice that an engine running with a dirty filter sees a drop in gas mileage? The same principle applies to an OEM filter verses a filter that flows better (i.e. a K&N etc.). There are two things that can happen when air flow through an engine is made more efficient. One is an increase in horsepower and the second is an increase in mileage. Sometimes both can happen simultaneously. If you don't believe me then take your air filter and clog it up and run your car for a tank of gas then put in a new one and see whats happens to your gas mileage and power output. I'll bet the farm that they both will see a substantial increase when a clean filter is installed. > I do however see a two mile per gallon decrease when using the now, > "required by law in Oregon" E10. Pisses me off! That's because the overall specific energy of E10 is less than pure gasoline. This is why going to biofuels is a horrible idea, IMO. We use up our top soil to fill our tanks and at the same time increase the cost of food substantially. I would rather eat for a reasonable cost than fill up my tank with something that gives me less mileage, for about the same cost, than evil old 100% gasoline. >>> I personally would NEVER use a K&N oil bath air filter again. My >>> preference is to filter my intake air as well as I possibly can and I [quoted text clipped - 15 lines] >> >> Ed >> Exactly, I don't believe an air filter will change mileage. The auto >> makers would be on it and so would the rest of this small world. [quoted text clipped - 9 lines] > farm that they both will see a substantial increase when a clean filter is > installed. While this was certainly true with carbureted engines, there is no reason to think this is the case for modern fuel injected engines. For carbureted engines, a clogged air filter acts like a choke and enriches the mixture because of the effect on air pressure in front of the throttle plates. This reduces the fuel economy. In a modern fuel injected engine, the mixture is not influenced in this way. The amount of fuel injected is determined based on the MAF sensor and other sensors. These sensors can't tell the difference between a restriction to the flow related to the air filter and a restriction to the flow related to the throttle plates. There is no difference as far as the computer is concerned between the restriction of the air filter and the restriction of the throttle plates. The engine speed / power output is determined by the total intake restriction (intake tract plus throttle opening). The only thing a slightly restricted air filter does on a modern engine is require you to open the throttle a slight amount more and reduce the maximum power output. The effect on fuel economy for a modern engine is minimal. I won't claim it is zero, but I doubt you would be able to tell the difference unless the filter was absurdly restrictive. Ed >>> Exactly, I don't believe an air filter will change mileage. The auto >>> makers would be on it and so would the rest of this small world. [quoted text clipped - 26 lines] > engine is minimal. I won't claim it is zero, but I doubt you would be able > to tell the difference unless the filter was absurdly restrictive. A dirty filter will lower gas mileage on EFI engines too. Instead of going into a long rebuttal I'll just provide a few links to some credible web sites. http://www.fueleconomy.gov/feg/maintain.shtml http://www.edmunds.com/reviews/list/top10/103164/article.html http://tinyurl.com/2a9v2 http://tinyurl.com/2hyeyx http://www.mass.gov/Eoca/docs/doer/pub_info/dt.pdf There are a huge number of sites stating that a dirty filter decreases mileage. There is more than just a MAF reading that the computer uses to determine the amount of fuel needed. Air density, throttle position, air temperature etc. also come into play. Excessive opening of the throttle plate on a fuel injected car also tells the computer the engine is under a greater load which effects how much fuel is delivered to the cylinders. I'm not saying a K&N filter will give a noticeable improvement in gas mileage over an OEM unit but with all things being equal the engine with a more efficient filter will perform better. Do you think an engine with a dirty air filter would pass an emissions test? If so then why not? >>>> Exactly, I don't believe an air filter will change mileage. The auto >>>> makers would be on it and so would the rest of this small world. [quoted text clipped - 33 lines] > going into a long rebuttal I'll just provide a few links to some > credible web sites. Yes but I'd bet that by "dirty filter" they mean clogged. I can see Ed's point here but there is probably a point at which the clog becomes so bad the electronics can not compensate. I once bought a 1977 Thunderbird for $50. It would not start, the guy and 4 friends tried to get it started to get it home. When I went to get it I had a battery, some gas and tools. It was full of gas, I cranked, smelled gas and popped the hood. Took off the air breather and put it in the trunk, started it and drove home to all their amazement. Three months and $500 later I sold it for $4500. It had 267K miles on it. The buyer was still driving it 4 years later. :oP Signature"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 >>>>> Exactly, I don't believe an air filter will change mileage. The >>>>> auto makers would be on it and so would the rest of this small world. [quoted text clipped - 44 lines] > later I sold it for $4500. It had 267K miles on it. The buyer was still > driving it 4 years later. :oP Clogged or mildly dirty, it is all variants of the same thing. That is a restriction to air flow. > >>>>> Exactly, I don't believe an air filter will change mileage. The > >>>>> auto makers would be on it and so would the rest of this small world. [quoted text clipped - 47 lines] > Clogged or mildly dirty, it is all variants of the same thing. That is > a restriction to air flow. You are being too simplistic, example a clean filter capable of delivering 1000 cfm new, but only 700 cfm dirty, is still quite adequate if the engine only requires 500 cfm at max rpm to start with. Air resistance is an exponential factor, it doesn't really come in to play until you get into the upper limits of your overall air flow capability. Honestly, how much time does your engine spend at 5000 rpm? >> >>>>> Exactly, I don't believe an air filter will change mileage. The >> >>>>> auto makers would be on it and so would the rest of this small [quoted text clipped - 57 lines] > upper limits of your overall air flow capability. Honestly, how much time > does your engine spend at 5000 rpm? Nice theory, but it does not explain my documented 2 MPG fuel mileage increase from a simple filter change, on a 1994 SHO commuter car that I CAN SAFELY SAY NEVER HIT 5000 RPM while my wife drove it, 99.9% of it's miles. >>>>>>> Exactly, I don't believe an air filter will change mileage. The >>>>>>> auto makers would be on it and so would the rest of this small [quoted text clipped - 51 lines] > upper limits of your overall air flow capability. Honestly, how much time > does your engine spend at 5000 rpm? 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? "Michael Johnson" <cds@erols.com> 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 [quoted text clipped - 6 lines] > 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. 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. 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 > "Michael Johnson" <cds@erols.com> wrote in message > [quoted text clipped - 12 lines] > 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. Signature"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" <cds@erols.com> wrote in message >> [quoted text clipped - 19 lines] > 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. To achieve a particular level of power, you need a given amount of air. The flow of air into the engine is restricted if you are trying to develop anything but maximum power. Where in the intake this restriction occurs is irrelevant. The pumping losses (this is what you are talking about) are the same whether the restriction occurs at the air filter or at the throttle plate. For any power level less than maximum, a slightly more restricted air filter will just require a slightly more open throttle to compensate. And the difference will be tiny. You guys seem to have it in your mind that a normal air filter is very restrictive. It isn't. We are talking about a difference in restriction in the noise range (0.01 to 0.03 psi). Which electronics do you thing will be affected? There are only two, possibly three, sensors in front of or concurrent with the throttle plate - the mass air flow sensor - MAF, throttle position sensor - TPS, and possibly the intake air temperature sensor (these are often combined with the MAF). The MAF is designed to measure the mass of air flowing through the intake tract. The trivial differences in pressure related to normal changes in air filter restriction are not going to affect the MAF operation beyond what would be considered a normal variation. The PCM can compensate for this based on feedback from the O2 sensors. The TPS is a gross throttle position measurement device. It is not highly accurate. Any minor changes in the position of the TPS for a given power output caused by a slightly more restricted air filter will be easily compensated for by the PCM based on feedback from the O2 sensors. Again, I am not talking about grossly contaminated air filters. I am talking about filters serviced in a reasonable manner per the manufacturer's recommendations. Any air filter so restrictive that the PCM cannot adjust the A/F to compensate, should turn on the check engine light. And to be clear, I am talking about differences measurable by normal consumers. I wouldn't claim that there is no difference at the level that could be measured under tightly controlled laboratory conditions with precision equipment. I doubt there is any significant difference even in that case, but given the uncertainty of almost any complex system, I can't be absolutely sure that there won't be minor differences down in what would be the noise range for normal vehicle operation. Also, I am not claiming that a restricted air filter will have no effect on performance. It certainly can reduce maximum power. With the throttle wide open, other restrictions in the intake tract are what limits the air flow. The more air you can get into the engine the more power you can develop. A K&N filter may provide more power, but in most cases the differences will be trivial. For most cars, it is not the air filter that is the most restrictive part of the system, it is the actual plumbing (intake opening and connecting tubing). Air filters are usually sized to provide minimal restrictions. K&N provides a means of calculating an air filter size to minimize power loss due to air filter restrictions. See http://www.knfilters.com/filter_facts.htm#SELECT. K&N used to provide a filter factor for their filters and for paper filters (they have dropped the paper filter number from the current web page, but I recorded it). They claimed that their filters would flow 6.02 cfm per square inch and that a paper filter would flow 4.38 cfm per square inch (they don't clue us in on as to the pressure drop needed to achieve these flow rates). You should use the K&N method to calculate the filter size needed for your engine. Then derate it by 73% (4.38/6.02). Compare the resulting filter size to the stock filter for your engine. I'll wager you that your stock filter is at least one and a half times the size this calculation suggest is required (assuming it is stock). And the calculation is very conservative. Working backwards through the K&N calculations for a 350 engine turning at 5500 it can be shown that they are assuming an air flow of 560 cfm. This much air flow should be sufficient for a 450 hp engine. So the K&N calculation is clearly for a very powerful engine - hardly a normal production engine. >>> "Michael Johnson" <cds@erols.com> wrote in message >>> [quoted text clipped - 20 lines] > 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. Signature"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" <cds@erols.com> wrote in message >>>> [quoted text clipped - 25 lines] > 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" <cds@erols.com> wrote in message >>>>> [quoted text clipped - 25 lines] > > 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. Signature"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-{SS}-" <windsorfox@NOSPAMcox.net> wrote in message news:UEroj.576 > 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. Again, I am not talking about some wildly contaminate filter. I am talking about a normally serviced filter. A filter that is so contaminated that it will significantly effect fuel economy will be outside the range the PCM can compensate for and in response, the PCM should turn on the check engine light. I keep repeating I am not talking about some hypothetical case where the filter is absurdly contaminated. I am talking about normal filters, in normal sorts of use, replaced at the proper intervals - NOT SOME HYPOTHETICAL FILTER SO PLUGGED THAT IT IS MORE RESTRICTIVE THAN THE THROTTLE PLATE UNDER NORMAL DRIVING CONDITIONS. And most especially I am talking about a comparison between a K&N filter and a standard paper filter in reasonable condition. Ed >> "Michael Johnson" <cds@erols.com> wrote in message >> [quoted text clipped - 18 lines] > 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" <cds@erols.com> wrote in message >>> [quoted text clipped - 27 lines] > 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 >>>> "Michael Johnson" <cds@erols.com> wrote in message >>>> [quoted text clipped - 100 lines] > 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. > 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 >> 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. [quoted text clipped - 17 lines] > 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. >>> 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. [quoted text clipped - 21 lines] > point. It is a gradual reduction that gets progressively more > noticeable as the filter collects more dirt. I can see each side of this, and each argument makes sense in its own right. That said, the only thing that will put this to bed is honest, real world test results, which seem to be in short supply these days. >>>> 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. [quoted text clipped - 24 lines] > right. That said, the only thing that will put this to bed is honest, > real world test results, which seem to be in short supply these days. Agreed. >>>>> 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. [quoted text clipped - 27 lines] > > Agreed. I think I said something similar to that several weeks ago.... Signature"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 think I said something similar to that several weeks ago.... And I pointed you guys to the Consumer Reports article where they said a dirty air filter doesn't significantly affect fuel economy (http://www.consumerreports.org/cro/cars/tires-auto-parts/car-maintenance/get-the -most-mileage-for-your-fuel-dollars-406/ or http://tinyurl.com/2datps. I even tracked down the source of the EPA claim that a dirty air filter could reduce fuel economy by up to 10% (it is based on data analysis by a company called Energy and Environmental Analysis, Inc.) I e-mailed the company and discovered they have no actual test data to back up this claim. They are basing it on studies of vehicles that failed the OBDII test because the check engine light was on. I've never claimed that a filter that was so restrictive that it turned on the check engine light would not affect fuel economy. I am only addressing reasonably contaminated air filters. And actually this thread got started because I disparaged the notion that K&N air filters can improve the fuel economy of a properly maintained modern fuel injected car. Ed >>>> 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. [quoted text clipped - 26 lines] > right. That said, the only thing that will put this to bed is honest, > real world test results, which seem to be in short supply these days. There is plenty real world proof that: 1. Filters alone change the airflow restrictions in modern EFI cars enough to dramatically effect their horsepower and fuel mileage. 2. Filters alone can and do alter the airflow beyond the stock engine management computers ability to correct. The real world results are overwhelming! None of them support Ed's misguided positions on this. 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 http://www.allfordmustangs.com/reviewpost/showproduct.php/product/394 >>> 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. [quoted text clipped - 22 lines] > magical point. It is a gradual reduction that gets progressively > more noticeable as the filter collects more dirt. Tell me why you believe this to be true. Why is the PCM unable to correct the A/F ratio. Exactly why is the restriction imposed by the air filter uniquely different than the restriction imposed by the throttle plate. AND AGAIN, I AM NOT TALKING ABOUT SOME HYPOTHETICAL FILTER THAT IS ABSURDLY CONTAMINATED. I have a hard time letting it go because you aren't getting it right. get it. Modern EFI feedback systems are designed to compensate for exactly the sort of gradual changes associated with things like changes in the restriction of an air filter, the drift of sensors like the MAF and TPS, etc. You seem to think that air filters become very restrictive over time. This is simply not true if they are serviced per the manufacturer's recommendations. We are talking about restrictions that range from less than 0.05 psi for a new filter to 0.5 psi for a heavily used filter (I'll bet you've never seen one this contaminated). This is a change on the order of tenths of a psi. At cruise the difference between atmospheric pressure and manifold pressure is in the rage of 5 to 8 psi. The air filter contributes less than 1% of this pressure drop, even for a restrictive filter. As I pointed out before, drift in the TPS sensor is on the order of +/-10%. If you doubled the pressure drop across the air filter, it will be an insignificant factor in the total pressure drop between the atmosphere and the cylinders. It is simply ridiculous to believe that the PCM can compensate for a 10% drift in the output of the TPS or the MAF sensors, but cannot handle a 1% drift in the restriction of the intake tract. Ed >>>> 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. [quoted text clipped - 27 lines] > AGAIN, I AM NOT TALKING ABOUT SOME HYPOTHETICAL FILTER THAT IS ABSURDLY > CONTAMINATED. IGNORING THE TRUTH WON'T MAKE IT GO AWAY ED! 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 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/reviewpost/showproduct.php/product/394 > I have a hard time letting it go because you aren't getting it right. get > it. Modern EFI feedback systems are designed to compensate for exactly the [quoted text clipped - 17 lines] > > Ed > 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 [quoted text clipped - 10 lines] > 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/STREET_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 [quoted text clipped - 6 lines] > assembly, the air/fuel ratio leans out at an alarming rate. > http://www.allfordmustangs.com/reviewpost/showproduct.php/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/whitepapers/2005_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.com/pdfs/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 > >> 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. [quoted text clipped - 21 lines] > 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. >>>> 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. [quoted text clipped - 27 lines] > (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. > >>>> 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. [quoted text clipped - 34 lines] > 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. >> >>>> 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. [quoted text clipped - 55 lines] > be until after the walls have narrowed to the point that you can no longer > walk upright that your movement is significantly impeded. Your example assumes that the clean filter provides ZERO restriction, that just isn't so. > >> >>>> 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. [quoted text clipped - 58 lines] > Your example assumes that the clean filter provides ZERO restriction, that > just isn't so. No, I am saying that the restriction remains constant throughout its service life, further that when the filter reaches the end of its service life you will only feel it at the engines top end, remember in this example I'm just talking about the air filter. Now when you take the entire intake tract as a whole then the walls of my hypothetical corridor are by necessity only as wide as the engine's air flow requirements need them to be. The variable, of course, is the throttle plate which can only reduce the intake restriction by a specific percentage determined by the engine load. Opened wider the engine goes faster, closed it goes slower. Change the filter or remove it entirely then the throttle plate must be adjusted (by means of your foot) to restrict the air flow down to only the required amount. No more no less. > 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 [quoted text clipped - 3 lines] > pump can move more air it makes more power and becomes more > efficient. You keep saying "more efficient." In what way is it more efficient. I agree that a restrictive air filter can limit maximum power (by limiting MAXIMUM air flow). I do not agree that it will affect fuel economy to a measurable degree as long as it is not grossly restrictive (i.e., it has been serviced properly per the manufacturers design intent). You just can't seen to get your arms around the idea that for a modern fuel injected engine the restriction imposed by the air filter is no different than the restriction imposed by the throttle plate. The entire intake tract restriction is what matters, not just the air filter. You also seem to have an exaggerated idea of how restrictive air filters may be when properly service. We are talking about differences of a few tenths of a PSI at the maximum flow rate. At cruise, the difference in restriction is trivial. Until you understand this, you will continue to draw bad conclusions. Modern feedback controlled EFI engines are easily able to adjust to compensate for all sorts of changes over time - changes in altitude and sensor drift being the most significant. When it comes to correcting the A/F ratio because of changes over time, the change in air filter restriction over time is so trivial it is below the noise range for other factors. Ed >> 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 [quoted text clipped - 12 lines] > fuel injected engine the restriction imposed by the air filter is no > different than the restriction imposed by the throttle plate. The You just don't get it Ed, certainly it's not different, but it is in addition to the throttle plate. It is an additional restriction! All filters cause a flow restriction, regardless of their flow capacities! > entire intake tract restriction is what matters, not just the air Exactly, and the entire intake system is an accumulative restriction, each individual restriction has it's own distinct effect. Simple airflow dynamics at work here. > filter. You also seem to have an exaggerated idea of how restrictive air > filters may be when properly service. We are talking about EVERY SINGLE brand new clean air filter ADDS restriction to the system regardless of it flow rate abilities. > differences of a few tenths of a PSI at the maximum flow rate. At Yet... > cruise, the difference in restriction is trivial. Until you understand > this, you will continue to draw bad conclusions. Modern feedback [quoted text clipped - 5 lines] > > Ed >> You just can't seen to get your arms around the idea that for a modern >> fuel injected engine the restriction imposed by the air filter is no [quoted text clipped - 3 lines] > addition to the throttle plate. It is an additional restriction! All > filters cause a flow restriction, regardless of their flow capacities! I absolutely get it. Tell me why you think the filter restriction affects fuel economy more than the throttle plate. >> entire intake tract restriction is what matters, not just the air > > Exactly, and the entire intake system is an accumulative restriction, each > individual restriction has it's own distinct effect. Simple airflow > dynamics at work here. And again, why do you seem to believe the restriction of a properly serviced air filter has a significant effect on fuel economy? >> filter. You also seem to have an exaggerated idea of how restrictive air >> filters may be when properly service. We are talking about > > EVERY SINGLE brand new clean air filter ADDS restriction to the system > regardless of it flow rate abilities. Absolutely true, but the restriction is trivial as far as it's effects the ability of the PCM to adjust the A/F Ratio. For a properly serviced air filter the pressure drop across the filter at WOT will be around 0.5 psi or less (for a stock engine). At part throttle operation, the pressure drop across the filter is likely to be in the hundredths of a psi range. The only time the small restriction of the air filter is going to be meaningful is when the throttle is wide open. Even then, the air filter restriction is likely to be less than a fraction of the total restriction from air intake to cylinder. Assuming the engine is in good condition and the PCM has completed a drive cycle so that it can learn the long term fuel trim, the A/F Ratio will not be out of the acceptable range even when running in open loop mode. PCMs incorporate long term fuel trim parameters to compensate for changes in engine parameters (sensor drift, air filter restriction, increased back pressure in the exhaust, increased flow from the PCV system, etc). The long term fuel trim is learned when the car is running in closed loop and is used to modify the original look-up table fuel delivery parameters. While in closed loop mode, the A/F ratio is continually adjusted based on the feedback from the O2 system. Closed loop mode is the primary operating mode of the vehicle, and the only one that really matters as far as average fuel economy is concerned. The time spent in open loop mode is trivial for most street vehicles. >> differences of a few tenths of a PSI at the maximum flow rate. At > [quoted text clipped - 9 lines] >> >> Ed One more time - I am not claiming that the filter restriction will not reduce maximum air flow and therefore possibly reduce maximum power. I agree that it may. I am only saying that a properly serviced air filter will not have a measurable effect on fuel economy. The change in the restriction of the air filter over time is an insignificant factor as far as the ability of the PCM to properly adjust the A/F Ratio is concerned. Ed >>> You just can't seen to get your arms around the idea that for a modern >>> fuel injected engine the restriction imposed by the air filter is no [quoted text clipped - 6 lines] > I absolutely get it. Tell me why you think the filter restriction affects > fuel economy more than the throttle plate. To start with I have 70,000 miles of detailed records that say it does. >>> entire intake tract restriction is what matters, not just the air >> [quoted text clipped - 4 lines] > And again, why do you seem to believe the restriction of a properly > serviced air filter has a significant effect on fuel economy? Again, I have 70,000 miles of detailed records that say it does. >>> filter. You also seem to have an exaggerated idea of how restrictive air >>> filters may be when properly service. We are talking about [quoted text clipped - 6 lines] > filter the pressure drop across the filter at WOT will be around 0.5 psi > or It has nothing to do with wide open throttle! My car gained 2 miles per gallon from a simple filter element change, and like saw WOT for a total of 5 or 10 of those 70,000 miles. > less (for a stock engine). At part throttle operation, the pressure drop It was a bone stock engine. > across the filter is likely to be in the hundredths of a psi range. The > only time the small restriction of the air filter is going to be > meaningful is when the throttle is wide open. Even then, the air filter > restriction is BULLSHIT! > likely to be less than a fraction of the total restriction from air intake > to cylinder. Assuming the engine is in good condition and the PCM has > completed a drive cycle so that it can learn the long term fuel trim, the > A/F Ratio will not be out of the acceptable range even when running in > open I'm sure it did by 20,000 - 70,000 miles at 70+ miles a day. > loop mode. PCMs incorporate long term fuel trim parameters to compensate > for changes in engine parameters (sensor drift, air filter restriction, [quoted text clipped - 26 lines] > will not have a measurable effect on fuel economy. The change in the > restriction of I am saying you are WRONG, My detailed records show the exact opposite to be true... > the air filter over time is an insignificant factor as far as the ability > of the PCM to properly adjust the A/F Ratio is concerned. > > Ed >> One more time - I am not claiming that the filter restriction will not >> reduce maximum air flow and therefore possibly reduce maximum power. I >> agree that it may. I am only saying that a properly serviced air filter >> will not have a measurable effect on fuel economy. The change in the >> restriction of the air filter over time is an insignificant factor as far >> as the ability of the PCM to properly adjust the A/F Ratio is concerned. > I am saying you are WRONG, My detailed records show the exact opposite to > be true... I am not wrong, at least in the general case. So why do you think there is a difference? What is your explantion? Do you think your PCM wasn't able to maintain the correct A/F ratio? Without seeing your data, and knowing what was changed, I can't say you are right or wrong for your specific situation. However, I keep records on all my vehicles, and I've never seen any indication in a change in fuel mileage related to changing air filters. Consumer Reports recently tested fuel economy "myths" and came to the same conclusion - dirty air filters (and I am talking about normally dirty filters, not some widly plugged filter) don't measurably effect fuel economy. The operating mode of modern fuel injection system is designed to handle changes in vehicle operating parameters and adjust the A/F ratio to the proper range (as determined by the vehicle manufacturer). If the system can't maintain the proper A/F ratio, then it should set the check engine light. If the A/F ratio is in the proper range, and assuming the vehicle is being operated in the same manner, the fuel economy should not change. If you are claiming that just changing the air filter significantly affected your fuel economy, then I would suspect that either something was wrong with your car, or that you changed your driving style. Ed In case you are intersted, you can see my fuel economy records at http://home.mindspring.com/~cewhite3/. Ed >> 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/reviewpost/showproduct.php/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 [quoted text clipped - 13 lines] > > Ed >>> 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. [quoted text clipped - 21 lines] > form of tuning" > http://www.allfordmustangs.com/reviewpost/showproduct.php/product/394 We coverred this before. Did you even bother to read what C&S is selling. This advertisement is talking about a "complete throttle-body forward package" that includes a large bore MAF. Clearly the stock PCM needs to be modified if you change the MAF to a completely different design. Please note that the company also sells an alternate system, that doesn't require modifying the PCM programing. I don't see any data to support the line that says "replacing the air filter ONLY to a higher flow assembly, the air/fuel ratio leans out at an alarming rate." I am not even sure what this means. Does this apply to an otherwise stock engine? How did they measure the A/F Ratio? Just what is "alarming" since in another line they claim making a major change including a new large bore MAF didn't lean the engine out enough to cause engine damage. Was the A/F ratio measured at wide open throttle? Did they drive the car long enough after changing the air filter to allow the PCM to adapt to the change (by altering the long term fuel trim parameter)? The engine runs open loop at WOT, and unless the PCM has had a chance to learn a new long term fuel trim values, the WOT A/F ratio might be less than ideal. However if you complete a drive cycle, the new long term trim value should compensate for any reasonable changes in the intake tract (and I don't consider a compeltely different large bore MAF to be a reasonable change). At any rate, I am not talking about WOT operation. If you are driving around at WOT a lot of the time, you aren't really interested in what happens to fuel economy. If their modifications changed parameters so much that the PCM can't correct the A/F ratio to the ideal range (as defined by Ford, not C&S), then the PCM will turn on the check engine light. If this is on, you are talking about conditions outside of what I am talking about. > 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. Where is your real world data? Quoting some advertisement for a complete intake system is hardly "data" to refute my claim. I've never claimed that you couldn't screw up an intake system enough to effect performance (including gas mileage). My only claim is that fuel mileage is not going to be significantly affected (measurable by a consumer) by the normal sorts of changes in a properly maintained air filter (including changing from a clean paper filter to a clean K&N filter). How much air do you think you need to flow to go 65 mph? If your car gets 25 mpg, you are using about 0.25 lbs of gasoline per mile, or .23 per minute. To burn this much gasoline, you need about 3.2 lbs of air. At standard conditions, this is about 40 cubic feet of air. So to cruise at 65, you only need to flow around 40 cfm per minute, not the hundreds of cfm that C&S is trying to sell you on. Like all good advertising, C&S try to emphasize the performance of their product. They have a chart comparing the restrcition of their intake to the stock intake at http://www.cnlperformance.com/images/Stock_Street_RACER_Flow2.jpg. The chart starts at 450 cfm and goes up 1100. Nobody is sucking in 1100 cfm with a streetable car. They are showing that it takes a pressure drop of around 20 inches of water to suck 450 cfm through a standard 2005 Ford GT intake. This is a pressure drop of 0.72 psi. What do you suppose the pressure drop would be at 40 cfm? If you tried to interpolate from their chart, it is going to look a lot like zero (but rally it is probably a lot like .05 psi). Try to keep within the bounds of what I am claiming. 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. > > 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. [quoted text clipped - 19 lines] > > Ed So you claim a dirty filter doesn't reduce mileage? > 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 [quoted text clipped - 22 lines] >> >> Ed Not until it reaches the point where it can no longer flow enough air to meet the engine's needs. > So you claim a dirty filter doesn't reduce mileage? > [quoted text clipped - 24 lines] > >> > >> Ed > Not until it reaches the point where it can no longer flow enough air to > meet the engine's needs. Ok who and what part of that kludge of text are you replying to??? Havn't you been here long enough to catch on?? >> So you claim a dirty filter doesn't reduce mileage? >> [quoted text clipped - 25 lines] >>>> >>>> Ed Signature"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 can't claim to be totally blameless but he top posted so I top posted. > > Not until it reaches the point where it can no longer flow enough air to > > meet the engine's needs. > > Ok who and what part of that kludge of text are you replying to??? > Havn't you been here long enough to catch on?? I can't claim to be totally blameless but he top posted so I top posted. > >> So you claim a dirty filter doesn't reduce mileage? > >> [quoted text clipped - 31 lines] > "Daytime television sucked 20 years ago, > and it still sucks today!" - Marc Bissonette I have given my views and opinions over and over again in this thread. All I am doing now is repeating myself. I went through it with Ed and I don't have the time or inclination to do it all over again with someone else. Let's just agree to disagree and leave it there. I'd still have a beer with you or Ed even though we strongly disagree on this topic. > Not until it reaches the point where it can no longer flow enough air to > meet the engine's needs. [quoted text clipped - 28 lines] >>>> >>>> Ed > I have given my views and opinions over and over again in this thread. > All I am doing now is repeating myself. I went through it with Ed and I > don't have the time or inclination to do it all over again with someone > else. Let's just agree to disagree and leave it there. I'd still have > a beer with you or Ed even though we strongly disagree on this topic. Hey LQQK!! PenisPill spammers are arrested.... http://www.theregister.co.uk/2008/02/05/sweden_pharmacy_bust/ Signature"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 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. Signature"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 |
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