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Car Forum / Nissan / Nissan Cars / July 2005Does K&N Air Filter Increase Gas Mileage on 2001 Pathfinder LE 4x4?
Has anyone installed the K&N factory replacement air filter on their Pathfinder and gotten better gas mileage, even just a couple of miles better? http://www.knfilters.com/search/product.aspx?Prod=33-2259 Has anyone installed the complete K&N mass air system and seen better results than just the K&N factory replacement filter? http://www.knfilters.com/search/product.aspx?Prod=57-6011 Most of my driving is highway and I'm getting about 18 mpg right now. Thanks, Paul The filters sometimes provide slight additional fuel economy. They also sometimes provide slight additional engine wear. You couldn't give me one. Butch > Has anyone installed the K&N factory replacement air filter on their > Pathfinder and gotten better gas mileage, even just a couple of miles [quoted text clipped - 11 lines] > Thanks, > Paul > Has anyone installed the K&N factory replacement air filter on their > Pathfinder and gotten better gas mileage, even just a couple of miles [quoted text clipped - 11 lines] > Thanks, > Paul No, not unless your stock one is dirty. I've heard they (they filter) can contaminate the mass air flow sensor (at least on other cars). I'd look into it first before using one... > Has anyone installed the K&N factory replacement air filter on their > Pathfinder and gotten better gas mileage, even just a couple of miles [quoted text clipped - 11 lines] > Thanks, > Paul > Has anyone installed the K&N factory replacement air filter on their > Pathfinder and gotten better gas mileage, even just a couple of miles > better? Yea they'll give you several MPG better. Nissan left them out because they wanted to save the money these cost and be able to advertise lower MPG figures (and lower HP figures) for better sales.. They install lots of expensive aluminum parts on the truck and expensive dual cam 4 valve heads on the engine trying to gain .5MPG when they know they could gain 2-3 and gain 10-20HP just changing the air filter.. Think about that for a moment....  SignatureSteve http://www.atlantaracing.com >>Has anyone installed the K&N factory replacement air filter on their >>Pathfinder and gotten better gas mileage, even just a couple of miles [quoted text clipped - 8 lines] > > Think about that for a moment.... For a moment there I was like "WHAT*&?" but then I realized, your sarcasm is sinister:) CD >For a moment there I was like "WHAT*&?" but then I realized, your >sarcasm is sinister:) K&N's have their application and advantages. They also have some disadvantages. They were not designed to increase mileage or to add any performance in normal driving conditions. >>For a moment there I was like "WHAT*&?" but then I realized, your >>sarcasm is sinister:) > > K&N's have their application and advantages. They also have some > disadvantages. They were not designed to increase mileage or to add > any performance in normal driving conditions. So what pray tell is their advantage? SignatureSteve http://www.atlantaracing.com >> K&N's have their application and advantages. They also have some >> disadvantages. They were not designed to increase mileage or to add >> any performance in normal driving conditions. > >So what pray tell is their advantage? Under wide open throttle (or close) conditions, a K&N will allow for increased air flow. This works particularly well with a redesigned intake on an engine that needs more air that stock due to modifications. Whether or not your engine needs more air than the stock system can deliver without any mods is highly debatable. It is true that manufacturers tend to design for "normal" driving, not WOT, so if you drive WOT a lot <BWG> it might matter to you. But, back to the original question: it will not do anything to affect performance at reasonable throttle. In addition, if a K&N clogs from dust, WOT will tend to clear the filter. The dirt ends up in the engine though. This is actually by design. K&N's were originally engineered for racing where the goal was "finish the race" and a clogged A/F could prevent that. Dirt in the engine is considered preferable to not finishing due to a clogged filter. A K&N has relatively large holes and when combined with sticky oil to hold the dirt, it quickly "clogs" the holes to create a very efficient filter. Put enough suction on it though and you will suck the particles out of the oil "adhesive" and into the engine. That doesn't happen wit paper. Of course, the expectation is that you will rebuild a race motor after the race - few of us do that after driving to the store. One other advantage: A K&N also has a long maintenance interval (50K miles maint/1 million miles estimated life). >>> K&N's have their application and advantages. They also have some >>> disadvantages. They were not designed to increase mileage or to add [quoted text clipped - 4 lines] > Under wide open throttle (or close) conditions, a K&N will allow for > increased air flow. You really believe nissan would give up HP because the engineers are too stupid to design an air filter correctly? Like they can design a 4 cam, 4 valve per cyl engine that turns 7,000 RPM and lasts 200,000 miles but can't figure out changing the air filter would give 10% more power? You do realize how important HP numbers are for sales don't you? > This works particularly well with a redesigned > intake on an engine that needs more air that stock due to > modifications. You're talking about those "hot air tubes" that put a cone filter in the engine bay? Yea those do a lot of good. They do make cool noises that make people believe the car is faster though! And the chrome ones really work the best. Ever dyno tested those things yourself or just believe the ads from people selling them? > In addition, if a K&N clogs from dust, WOT will tend to clear the > filter. > The dirt ends up in the engine though. That sounds good but I asked for advantages.. > One other advantage: A K&N also has a long maintenance interval (50K > miles maint/1 million miles estimated life). But if it "cleans itself" by passing dirt into the engine, why not just remove the filter altogether? SignatureSteve http://www.atlantaracing.com >>>> K&N's have their application and advantages. They also have some >>>> disadvantages. They were not designed to increase mileage or to add >>>> any performance in normal driving conditions. > >>>So what pray tell is their advantage? On a road car - not much. Better to look for ways to get more air in to the air box and keep the paper filter. >> Under wide open throttle (or close) conditions, a K&N will allow for >> increased air flow. [quoted text clipped - 4 lines] >figure out changing the air filter would give 10% more power? You do >realize how important HP numbers are for sales don't you? They and all car makers do lose power on the inlet. They have noise limits to reach. Putting a restrictive inlet on the air box and tuned small bore ducts in the air box inlet and exit is how they silence the inlet. But it's the inlet ducting that's restrictive not the paper filter. >> This works particularly well with a redesigned >> intake on an engine that needs more air that stock due to [quoted text clipped - 5 lines] >the best. Ever dyno tested those things yourself or just believe the ads >from people selling them? K&N's does a good job when fitted on things like motorbikes in place of the air box for production racing but not on current ram air ones. I used dry S&Bs on mine but car owners are suckers for a branded name. On a 250cc bike I gained 500rpm in top gear - 9,500rpm up to 10,000rpm, that's more speed which can only have come from more power. OK it wasn't the filters, losing the inlet trumpets and putting some big holesin the standard air box may have done the same. Useful on sports and competition cars with carbs that poke out of the side or top of the bonnet (hood). A K&N is very much better for engine life than open carbs or inlet ports. >> In addition, if a K&N clogs from dust, WOT will tend to clear the >> filter. [quoted text clipped - 4 lines] >> One other advantage: A K&N also has a long maintenance interval (50K >> miles maint/1 million miles estimated life). Have to keep and run the car at least 100,000 miles to get payback by saving money on paper filters. >But if it "cleans itself" by passing dirt into the engine, why not just >remove the filter altogether? That would allow larger grit, stones, insects and small birds to go into the engine which would prevent the engine finishing the race. It also allows mice to nest in the inlet during the winter season when the race car is laid up. A K&N has to be seen as a step up from a wire mesh stone guard. > A K&N has to be seen as a step up from a > wire mesh stone guard. I'll buy that one.. SignatureSteve http://www.atlantaracing.com >>>>K&N's have their application and advantages. They also have some >>>>disadvantages. They were not designed to increase mileage or to add [quoted text clipped - 10 lines] > figure out changing the air filter would give 10% more power? You do > realize how important HP numbers are for sales don't you? But making a K&N filter stock would increase production costs. Besides, Nissan's winning the HP wars handily with the stock paper filter. >>This works particularly well with a redesigned >>intake on an engine that needs more air that stock due to >>modifications. > You're talking about those "hot air tubes" that put a cone filter in the > engine bay? Yea those do a lot of good. They do make cool noises that make > people believe the car is faster though! And the chrome ones really work > the best. Ever dyno tested those things yourself or just believe the ads > from people selling them? If you enhance your intake AND exhaust, your Nissan actually does get quite a bit more powerful. The engine is a pump, and just as you increase the airflow going in, you have to increase the exhaust going out. Just the intake change does not yeild as much a boost in HP, admittedly. >>In addition, if a K&N clogs from dust, WOT will tend to clear the >>filter. >>The dirt ends up in the engine though. > That sounds good but I asked for advantages.. > [quoted text clipped - 3 lines] > But if it "cleans itself" by passing dirt into the engine, why not just > remove the filter altogether? CD >>>>>K&N's have their application and advantages. They also have some >>>>>disadvantages. They were not designed to increase mileage or to add [quoted text clipped - 12 lines] > > But making a K&N filter stock would increase production costs. Yea variable timing controls for a camshaft is so much cheaper than a K&N filter.. SignatureSteve http://www.atlantaracing.com >>>>>>K&N's have their application and advantages. They also have some >>>>>>disadvantages. They were not designed to increase mileage or to add [quoted text clipped - 15 lines] > Yea variable timing controls for a camshaft is so much cheaper than a K&N > filter.. The variable timing control is a given. Nissan *has to* employ that technology just to stay ahead of the rest. Same with 4 valve cylinder heads. Nissan does not have to use K&N and does not need to. CD > The variable timing control is a given. Nissan *has to* employ that > technology just to stay ahead of the rest. Same with 4 valve cylinder > heads. Nissan does not have to use K&N and does not need to. If HP was as easy as installing a K&N filter, don't you think SOMEONE would use them to be able to post the higher HP numbers? It's like those bosch platinum or splitfire plugs, ever wonder why -NO- OEM uses them? SignatureSteve http://www.atlantaracing.com K/N would be good for my lawn mower engine! K/N in the car? well, there is a lot more that stick that filter on the car. I had it on my cars and I remove it. Anyone want to buy a hardly used K/N? you can have it in exchange for stock filter. > > The variable timing control is a given. Nissan *has to* employ that > > technology just to stay ahead of the rest. Same with 4 valve cylinder [quoted text clipped - 8 lines] > > http://www.atlantaracing.com >>The variable timing control is a given. Nissan *has to* employ that >>technology just to stay ahead of the rest. Same with 4 valve cylinder [quoted text clipped - 3 lines] > use them to be able to post the higher HP numbers? It's like those bosch > platinum or splitfire plugs, ever wonder why -NO- OEM uses them? That's a valid point. Hmmmmm . . . . . . I could venture a guess at the car companies not wanting to deal with the complicated maintenance that's required of a K&N filter; over-oil them and there goes your MAF, or that K&N has a patent so it isn't worth it for Nissan etc. But maybe you're right. But then again . . . . . As for the split fires, yeah they're not OEM but you ever notice how the OEM manufacturers, like NGK, make a plug with a U groove now? Its sort of imitating the split fires. That's an interesting correlation. Then there's Bosch. Bosch plugs must be OEM on the german makes, no? What plug do Mercedes, BMW, Porsche, Audi, Volkswagen use? I bet they use Bosch. My point is that car makers try to keep thier domestic industry active. Chrysler, bad example, since Mercedes "merged" with them I bet they come with Bosch plugs now! Ford has autolite plugs, Nissan has NGK etc. But I digress. Interestingly, Bosch MAFs and O2 sensors are actually OEM on Nissans. So there!:) CD >>>The variable timing control is a given. Nissan *has to* employ that >>>technology just to stay ahead of the rest. Same with 4 valve cylinder [quoted text clipped - 6 lines] > car companies not wanting to deal with the complicated maintenance > that's required of a K&N filter; If they go 50,000 they could just sell you a new one? > But then again . . . . . > [quoted text clipped - 5 lines] > What plug do Mercedes, BMW, Porsche, Audi, Volkswagen use? I bet they > use Bosch. Sure but NONE use those "platinum" plugs autozone sells. They have specific plugs for specific application like NGK and they work great. My point is these "hyped" products are not used by ANY manufacturer and some times these hyped products are CHEAPER than what the OEM uses so that point doesn't work either... SignatureSteve http://www.atlantaracing.com > You really believe nissan would give up HP because the engineers are too >stupid to design an air filter correctly? Like they can design a 4 cam, 4 >valve per cyl engine that turns 7,000 RPM and lasts 200,000 miles but can't >figure out changing the air filter would give 10% more power? You do >realize how important HP numbers are for sales don't you? The increased airflow of a K&N comes at a cost - original, maintenance, convenience, familiarity, reliability, shop time, warranty issues, etc. Decisions about which components get selected are not entirely about HP - why doesn't Nissan use a radical grind cam in their street motors ? Why don't Nissan motors spin 10K RPM like a formula motor? There would be more HP, wouldn't there? Using your theory they'd do it simply because it gets more HP. >> This works particularly well with a redesigned >> intake on an engine that needs more air that stock due to [quoted text clipped - 5 lines] >the best. Ever dyno tested those things yourself or just believe the ads >from people selling them? I wrote "redesigned intake" not "any plug-n-play intake you can buy on the internet". There is a difference. A modified engine can make use of increased (and properly ducted cold) airflow to produce more HP. >> In addition, if a K&N clogs from dust, WOT will tend to clear the >> filter. The dirt ends up in the engine though. > >That sounds good but I asked for advantages.. It's an advantage on a track when you want to finish the race instead of stalling. You cut that part of my post out. It's not a durability advantage. K&N stared out on the dirt circuit. >> One other advantage: A K&N also has a long maintenance interval (50K >> miles maint/1 million miles estimated life). > >But if it "cleans itself" by passing dirt into the engine, why not just >remove the filter altogether? You've made a bad assumption. K&N filters have to be washed and re-oiled every 50K miles to remove the dirt. A K&N does not clean itself, it *un-clogs* itself under WOT and severe dirt conditions. As I posted, that's an advantage on the track - not with a street motor. FWIW - removing the filter would increase HP under WOT conditions. Just like a K&N, there's advantages and disadvantages to doing that. >> You really believe nissan would give up HP because the engineers are too >>stupid to design an air filter correctly? Like they can design a 4 cam, 4 [quoted text clipped - 5 lines] > maintenance, convenience, familiarity, reliability, shop time, > warranty issues, etc. Familiarity? And if they make HP and last 50,000 between cleaning etc what's the problem? > Decisions about which components get selected > are not entirely about HP - why doesn't Nissan use a radical grind cam > in their street motors ? Honda does, it's called VTEC. Nissan doesn't because of the emmisions problems with a high overlap camshaft. > Why don't Nissan motors spin 10K RPM like a > formula motor? Some go 8000 (JDM) and yes engine life is part of the reason they don't. K/N doesn't shorten the engines life does it? >>> This works particularly well with a redesigned >>> intake on an engine that needs more air that stock due to [quoted text clipped - 9 lines] > the internet". There is a difference. A modified engine can make use > of increased (and properly ducted cold) airflow to produce more HP. Oh so now we are talking "modified engine", so you've modified the engine in your maxima? >>> In addition, if a K&N clogs from dust, WOT will tend to clear the >>> filter. The dirt ends up in the engine though. [quoted text clipped - 3 lines] > It's an advantage on a track when you want to finish the race instead > of stalling. Who was talking about track racing here? > You cut that part of my post out. It's not a durability > advantage. K&N stared out on the dirt circuit. [quoted text clipped - 8 lines] > re-oiled every 50K miles to remove the dirt. A K&N does not clean > itself, it *un-clogs* itself under WOT and severe dirt conditions. Ah so where does this "clog" go? and it's dirt clogging it right? > FWIW - removing the filter would increase HP under WOT conditions. $20 says it doesn't. BTW I use a K&N on my modified Zcar, but not because I think it makes more power, it was just the easiest solution for my custom sheet aluminum intake manifold design. http://atlantaracing.tripod.com/280zmods/myzengine.html SignatureSteve http://www.atlantaracing.com > Honda does, it's called VTEC. Nissan doesn't because of the emmisions > problems with a high overlap camshaft. I was waiting for VTEC to be mentioned. VTEC comes at significant cost to Honda. You ever notice how the only DOHC VTEC V6 in Honda/Acura's *entire* lineup is/was the NSX? All their other VTEC V6s are SOHC. Why? Cost and probably emissions, too. Nissan doesn't bother because they can make a great DOHC V6 and it doesn't hurt their bottom line as much as Honda's VTEC. Sheesh, the NSX priced itself out of existence with its $80K price tag. And here we have the 350Z and G35 with 300 hp for less than half the cost decently more hp and much beefier torque than that NSX ever had. ANd the new RL with a 3.5 VTEC SOHC V6 makes the same HP, so how good is VTEC really? It's almost like you have to choose, DOHC or SOHC VTEC. Nissan's doing fine with DOHC:) CD >> Honda does, it's called VTEC. Nissan doesn't because of the emmisions >> problems with a high overlap camshaft. [quoted text clipped - 5 lines] > make a great DOHC V6 and it doesn't hurt their bottom line as much as > Honda's VTEC. Probably honda has a patent on the design as well. There is a reason those rice boys can make the HP they do from those vtec 4 cyl and still drive them on the street. It's a cool setup, wish my old Z car had it! :-) SignatureSteve http://www.atlantaracing.com >> The increased airflow of a K&N comes at a cost - original, >> maintenance, convenience, familiarity, reliability, shop time, >> warranty issues, etc. > >Familiarity? And if they make HP and last 50,000 between cleaning etc what's >the problem. The problems are what I cited. Initial cost, stocking cost, maintenance cost. Manufacturers use actuarials and other estimators to predict production costs, warranty costs, stocking costs, etc. The big picture is way bigger than "does this part give us more HP?". >> Decisions about which components get selected >> are not entirely about HP - why doesn't Nissan use a radical grind cam >> in their street motors ? > >Honda does, it's called VTEC. Nissan doesn't because of the emmisions >problems with a high overlap camshaft. The point is not camshafts. The point is that there are ways to make more HP but they all come at a cost. Manufacturers make choices about costs. >> I wrote "redesigned intake" not "any plug-n-play intake you can buy on >> the internet". There is a difference. A modified engine can make use >> of increased (and properly ducted cold) airflow to produce more HP. > >Oh so now we are talking "modified engine", so you've modified the engine in >your maxima? What has my motor got to do with the design value of a K&N ? See my previous post on the advantages of a K&N where I wrote "This works particularly well with a redesigned intake on an engine that needs more air that stock due to modifications. Whether or not your engine needs more air than the stock system can deliver without any mods is highly debatable." NOtice that I *was* talking about modified motors and notice that I don't think a K&N helps an unmodified motor. >> It's an advantage on a track when you want to finish the race instead >> of stalling. >Who was talking about track racing here? I was in my original post on the advantages of a K&N. I thought that was what you were arguing about: My suggestions about the advantages of a K&N. >> You've made a bad assumption. K&N filters have to be washed and >> re-oiled every 50K miles to remove the dirt. A K&N does not clean >> itself, it *un-clogs* itself under WOT and severe dirt conditions. >Ah so where does this "clog" go? and it's dirt clogging it right? It goes in your engine. I thought I made that clear. >> FWIW - removing the filter would increase HP under WOT conditions. > >$20 says it doesn't. Guess I took a different class on intake restriction than you did. >BTW I use a K&N on my modified Zcar, but not because I think it makes more >power, it was just the easiest solution for my custom sheet aluminum intake >manifold design. > >http://atlantaracing.tripod.com/280zmods/myzengine.html >>> The increased airflow of a K&N comes at a cost - original, >>> maintenance, convenience, familiarity, reliability, shop time, [quoted text clipped - 7 lines] > predict production costs, warranty costs, stocking costs, etc. The big > picture is way bigger than "does this part give us more HP?". Yea these variable camshaft timing engine designs (and having to produce and stock VTC's at $500 a pop) are so much cheaper than a K&N filter would cost. And you don't think saying "It has a K&N filter!" would be a selling point for people who believe this marketing hype? >>> Decisions about which components get selected >>> are not entirely about HP - why doesn't Nissan use a radical grind cam [quoted text clipped - 6 lines] > more HP but they all come at a cost. Manufacturers make choices about > costs. The POINT is a $15 AF (their cost) is WAY cheaper than these engine mods. They do these engine mods because they actually do something. >>> FWIW - removing the filter would increase HP under WOT conditions. >> >>$20 says it doesn't. > > Guess I took a different class on intake restriction than you did. You're making a big assumption that the air filter itself is a bottle neck. Again $20 says removing the filter element makes zero difference unless it's way beyond need of replacement. SignatureSteve http://www.atlantaracing.com >Yea these variable camshaft timing engine designs (and having to produce and >stock VTC's at $500 a pop) are so much cheaper than a K&N filter would >cost. And you don't think saying "It has a K&N filter!" would be a selling >point for people who believe this marketing hype? You are suggesting that a K&N can/should produce HP comparable to a VTEC design. That's ridiculous. Th discussion is whether or not a K&N can add HP at WOT conditions. In modified motors that require more air a K&N can help provide that air by providing less restriction as compared to a paper filter. >The POINT is a $15 AF (their cost) is WAY cheaper than these engine mods. >They do these engine mods because they actually do something. Compare that to a paper filter cost of $2. Consider the time cost of oiling the filters for installation in production or in the repair shop. Multiply that times cars produced and add filters replaced under warranty. Consider possible MAF issues from oil contamination. Then consider that a K&N would only help at under extreme air demand conditions (WOT) while other modifications add practical HP (torque) across the power bandwidth that the consumer will actually feel. >You're making a big assumption that the air filter itself is a bottle neck. >Again $20 says removing the filter element makes zero difference unless >it's way beyond need of replacement. The air intake and filter are designed for a certain CFM. If you modify your engine you will exceed those design requirements. Simple engineering. So, you need more air. There are several ways to get it. One is to use a filter with less restriction. >>You're making a big assumption that the air filter itself is a bottle >>neck. Again $20 says removing the filter element makes zero difference >>unless it's way beyond need of replacement. > > The air intake and filter are designed for a certain CFM. If you > modify your engine you will exceed those design requirements. This discussion was about "Does a K&N filter get better MPG/HP?" not "If I modify my engine, could the factory air filter and filter box be a restriction?". And again you really think the engineers are so stupid they are going to undersize the AF element to leave 10-15HP on the table? Yea right.. SignatureSteve http://www.atlantaracing.com >This discussion was about "Does a K&N filter get better MPG/HP?" not "If I >modify my engine, could the factory air filter and filter box be a >restriction?". And again you really think the engineers are so stupid they >are going to undersize the AF element to leave 10-15HP on the table? Yea >right.. Nope, they won't. The filter and box they design will provide adequate air to the stock engine. But, if you modify that engine, your intake air requirements increase as do your exhaust requirements. An engine is a pump - you can't pump more through an engine without increase the inlets and outlets.
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