I see the claims for improved HP and fuel economy with the K&N air filter, does anyone have experience with this? Is it all Marketing hype? I'd love to get a couple more MPG on the J30 as well as HP but would like some success stories for this relatively cheap enhancement.
Thanks
K&N Air Filter, Myth or Fact
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HeavyDuty
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Edit: (Sorry Jcorwin, I was typing while you already hit send)
Let's clarify which styly of K&N or the like you're asking about.
1) A drop in filter that installs in the factory air box, the same size as the stock.
2) An 'intake' or POP charger style open element system like the JWT.
1) Drop ins have a 1M mile warranty, they're made from gauze, like a bandage and are oiled to attract dirt. If they're not *over* oiled, like everyone does anyway, they, IMHO, are good. Some claim the tiny droplets of oil adhere themeselves to the MAF hot wire & alter engine management duties.
2) A POP charger intake does draw air from the engine compartment behind the driver's side headlight. It eliminates the stock airbox that has ducting from the front of the car that provides an area of cool(er) outside non-turbulent air. IMHO, the temps underhood vs outside ambient are higher when stopped, but I doubt much difference when in motion.
I have a JWT POP charger that came with my car, I like it.
Let's clarify which styly of K&N or the like you're asking about.
1) A drop in filter that installs in the factory air box, the same size as the stock.
2) An 'intake' or POP charger style open element system like the JWT.
1) Drop ins have a 1M mile warranty, they're made from gauze, like a bandage and are oiled to attract dirt. If they're not *over* oiled, like everyone does anyway, they, IMHO, are good. Some claim the tiny droplets of oil adhere themeselves to the MAF hot wire & alter engine management duties.
2) A POP charger intake does draw air from the engine compartment behind the driver's side headlight. It eliminates the stock airbox that has ducting from the front of the car that provides an area of cool(er) outside non-turbulent air. IMHO, the temps underhood vs outside ambient are higher when stopped, but I doubt much difference when in motion.
I have a JWT POP charger that came with my car, I like it.
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Q45tech
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- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
With modern engines [fuel injected] the fuel economy is fixed to match the catalytic convertors, anyway more air would require more fuel so if anything a better filter would use more gasoline to maintain the air fuel ratio.
Paper Filters have improved greatly in the last 15 years.
The paper filter itself is sized so that no more than 1.5" [water column]of vacuum is created thru it. 1.5/28=0.535714 x 6.6%=0.35%............that is the maximum gain for a paper filter vs absolutely no filter of any kind.
If you have a 300HP engine 0.35% is 1.05 HP with no filter of any kind.
The usual flow restriction is not the filter but the filter box and the piping convoluting out to the atmosphere. Infinti uses a design that varies up to 7" [water column restriction][including the oem air filter], so 7-1.5=5.5---------5.5/28= or another 1.3%=~~4 HP.
So perfection might be 5.05 HP gain but the usual amount is around 2-3 HP with a K&N cone filter and no air box.
The problem is the air density decreases with temperature increases [1% per 11F].
A K&N cone can gain 3HP and lose 3-20HP due to hot underhood air..........severe problems in Summer traffic and idle ......it eventually gets colder at highway speed......maybe?
What most don't under stand is an engine can only fill with so much air from the amospheric pressure...........0.9 psi is lost from the cylinder, valves, runners, plnum, throttle body, MAF, filter , and air box to the atmospheric pressure....~~6%
Paper Filters have improved greatly in the last 15 years.
The paper filter itself is sized so that no more than 1.5" [water column]of vacuum is created thru it. 1.5/28=0.535714 x 6.6%=0.35%............that is the maximum gain for a paper filter vs absolutely no filter of any kind.
If you have a 300HP engine 0.35% is 1.05 HP with no filter of any kind.
The usual flow restriction is not the filter but the filter box and the piping convoluting out to the atmosphere. Infinti uses a design that varies up to 7" [water column restriction][including the oem air filter], so 7-1.5=5.5---------5.5/28= or another 1.3%=~~4 HP.
So perfection might be 5.05 HP gain but the usual amount is around 2-3 HP with a K&N cone filter and no air box.
The problem is the air density decreases with temperature increases [1% per 11F].
A K&N cone can gain 3HP and lose 3-20HP due to hot underhood air..........severe problems in Summer traffic and idle ......it eventually gets colder at highway speed......maybe?
What most don't under stand is an engine can only fill with so much air from the amospheric pressure...........0.9 psi is lost from the cylinder, valves, runners, plnum, throttle body, MAF, filter , and air box to the atmospheric pressure....~~6%