what good are K&N air filters
what good are K&N air filters
I've seen a lot about these K&N air filters all over the internet. Are they any good and do they increase performance or gas mileage? Any info would be nice.Thanks
-
greg_atlanta
- Posts: 1111
- Joined: Tue Jul 23, 2002 4:37 pm
- Car: 2008 G35 Journey Sedan, silver/black (no sunroof), 1992 Q45 (in a past life)
well, they are good for a little intake growl. many say that they screw up the MAF sensor, or "fool" it into returning false resistances, allow extraneous dirt into the system, suck in warm engine compartment air...etc. all this is probably true to an extent. Of course, almost all modifications you do to your infiniti will make it wear faster. However, with proper reworking of the restictive intake and exhaust of the J30, maybe about 10-15 HP can be expected. I would like to think that as long as the MAF sensor doesnt break right away, and one does frequent quality oil changes and a good oil filter, the harm is minimal to none. I have had a K&N filter in for about 2 years with no associated problems. I must admit, though, the filter alone is just good for some growl, with no palpable power increase.
-
Q45tech
- Moderator
- Posts: 14296
- Joined: Tue Apr 30, 2002 3:19 am
- 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
The question is HOW bad is the stock filter [drop in] NOT VERY BAD at all only creating a 2" W.C. vacuum differential at max air flow [redline]...2/28=0.0714 x 0.066= 0.47% restriction on peak power.
Half a percent on a J30 is 1 HP MAX maybe 1.5-2HP at absolute best on a Q!!!!!!!!!!!!!!!!!!!!!!!!!
But until the air starts flowing above 4,000 rpm there is nothing nada nunca measurable difference .
My most accurate manometer goes zero to 3 " W.C. [1/10 of a psi full scale] and is precise in 0.05" W.C. graduations.
A straw is a type of manometer how high can you suck soda up how long a straw .......hopefully this illustrates the sensitivity of my measurements--------- 2" of soda rise is the number for the factory air filter vs 1.48" for the K&N drop in!I usually start out with no filter nothing in air box as a calibration then A/B B/A and back to nothing as a control and do every test twice with 15 minutes to correct for temperature , humidity and baro pressure variations.
By the way I have measured new vs used [15k} factory filters and this told me to change then every 15-20k [obviously depends on local conditions]---------- bugs per cubic meter, rat hair count, diesel trucks per mile.
Reminds me we had a Q customer whose 2 fuzzy dogs sleep in garage in front of car, he needed a new filter twice per year!
Half a percent on a J30 is 1 HP MAX maybe 1.5-2HP at absolute best on a Q!!!!!!!!!!!!!!!!!!!!!!!!!
But until the air starts flowing above 4,000 rpm there is nothing nada nunca measurable difference .
My most accurate manometer goes zero to 3 " W.C. [1/10 of a psi full scale] and is precise in 0.05" W.C. graduations.
A straw is a type of manometer how high can you suck soda up how long a straw .......hopefully this illustrates the sensitivity of my measurements--------- 2" of soda rise is the number for the factory air filter vs 1.48" for the K&N drop in!I usually start out with no filter nothing in air box as a calibration then A/B B/A and back to nothing as a control and do every test twice with 15 minutes to correct for temperature , humidity and baro pressure variations.
By the way I have measured new vs used [15k} factory filters and this told me to change then every 15-20k [obviously depends on local conditions]---------- bugs per cubic meter, rat hair count, diesel trucks per mile.
Reminds me we had a Q customer whose 2 fuzzy dogs sleep in garage in front of car, he needed a new filter twice per year!
-
Mayhem_J30
- Posts: 2643
- Joined: Tue Apr 30, 2002 2:00 am
- Car: Ummm...My Car
- Location: Louisville, KY
Eswift wrote:well, they are good for a little intake growl. many say that they screw up the MAF sensor, or "fool" it into returning false resistances, allow extraneous dirt into the system, suck in warm engine compartment air...etc. all this is probably true to an extent. Of course, almost all modifications you do to your infiniti will make it wear faster. However, with proper reworking of the restictive intake and exhaust of the J30, maybe about 10-15 HP can be expected. I would like to think that as long as the MAF sensor doesnt break right away, and one does frequent quality oil changes and a good oil filter, the harm is minimal to none. I have had a K&N filter in for about 2 years with no associated problems. I must admit, though, the filter alone is just good for some growl, with no palpable power increase.
agreed
-
Q45tech
- Moderator
- Posts: 14296
- Joined: Tue Apr 30, 2002 3:19 am
- 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
Sad that testing, mathematics and physics gets in the way of selling a product. Luckily few consumers understand what they are buying. Dreams.
I have never understood why owners don't install under hood speakers and play recordings [generate the sound] they want.....Blooopidy blooopidy blop........tape your favorite NASCAR and replay on the street.......mmmm a 454 cammed Chevy .....anybody want plans to shoot fire out your exhaust.....Hank Hill has the propane.
I have never understood why owners don't install under hood speakers and play recordings [generate the sound] they want.....Blooopidy blooopidy blop........tape your favorite NASCAR and replay on the street.......mmmm a 454 cammed Chevy .....anybody want plans to shoot fire out your exhaust.....Hank Hill has the propane.
-
AZhitman
- Administrator
- Posts: 54541
- Joined: Mon Apr 29, 2002 2:04 am
- Car: 58 L210, 63 Bluebird RHD, 64 NL320, 65 SPL310, 66 411 RHD, 67 WRL411, 68 510 SR20, 75 280Z RB25, 77 620 SR20, 79 B310, 90 Z32, 91 GTi-R, 92 Silvia Qs, 98 S14, 23 Z.
- Location: Surprise, Arizona
- Contact:
Hey Dennis - You obviously haven't seen the ad in SportCompactCar magazine for the $149 "Turbo Blow-off Valve Simulator". Consists of a speaker and some wiring, makes a "pssssssst" sound at a certain RPM to make people think you have a turbo...
Easily the stupidest thing I've seen - I have more respect for someone who buys a Tornado, a K&N and 3 bottles of ZMAX than I do for this crap.
Easily the stupidest thing I've seen - I have more respect for someone who buys a Tornado, a K&N and 3 bottles of ZMAX than I do for this crap.
I'll be the dissenting voice here about the evils of K & N filters. I had the head off an Eagle Talon I used to own that had a K & N on it for most of it's life at 125K miles. Most of the factory cross hatching was still visible on the cylinder walls, and the cylinders were still in spec for out-of-round and taper. If K & Ns weren't effective at filtering, that would not have been the case. I'd have no hesitation putting one on a car. A drop-in filter that goes in the stock box probably isn't worth much power over a clean stock filter, but it does save money over the long run.
-
Q45tech
- Moderator
- Posts: 14296
- Joined: Tue Apr 30, 2002 3:19 am
- 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
The pop charger works {?} by reducing the vacuum restriction from the stock filter forward thru the plumbing. This stock restriction is 7.5" water column at its absolute worst 6900 rpm === at 4,000 rpm the restriction is down to 3.9" .
The BIG popcharger has a restriction of 1.2" at the max flow rate of a Q at max rpm WOT! So a 6.3" improvement is possible at 6900 rpm and say 3.3" at 4,000 rpm.
6.3/28=0.225 x 6.6%=1.465%
Remember 360 CFM is all that is required for 300 HP.....on my flow bench testing I use 385 CFM to allow for 320 HP just in case a hot engine is found with JWt ecu, exhaust, intake mods....really clean and perfect injectors
Putting a cone in the stock air box defeats the purpose, a dropin will fit, a cone that would filt would be too small to flow the amount..........all the restriction is from the box forward to the air.
125,000 miles is nothing on a well designed engine how did they look at 500,000 miles? The cylinder bores are never a problem with the hardened liners......the rings and bearings are the places you look and measure.
Obviously good oil changes habits mitigate bad dust ingestion to a degree......if it were up to me I would always add extra filtration every where.
The problem with cones is more the heated air they suck, than the filtration efficiency [if maintained well]................a 1.5% power restriction advantage gets used up quickly when [even 11 x 1.5= 17F] hotter air is ingested.
Your MAF voltage tells the truth what ever air mods you do must increase this voltage to prove more air [density] is flowing......at rpms above 6,000 [the MAF reads above 4.0 volts [4.44 would be great] and every 0.01 volts increase counts big!
Do some accurate and precise testing!
If all you want is sound and a measly 125,000 miles of engine life, K&N cones are great.
When you get around 250,000 miles and are trying to get more those things you did early tend to come back to haunt you.
The BIG popcharger has a restriction of 1.2" at the max flow rate of a Q at max rpm WOT! So a 6.3" improvement is possible at 6900 rpm and say 3.3" at 4,000 rpm.
6.3/28=0.225 x 6.6%=1.465%
Remember 360 CFM is all that is required for 300 HP.....on my flow bench testing I use 385 CFM to allow for 320 HP just in case a hot engine is found with JWt ecu, exhaust, intake mods....really clean and perfect injectors
Putting a cone in the stock air box defeats the purpose, a dropin will fit, a cone that would filt would be too small to flow the amount..........all the restriction is from the box forward to the air.
125,000 miles is nothing on a well designed engine how did they look at 500,000 miles? The cylinder bores are never a problem with the hardened liners......the rings and bearings are the places you look and measure.
Obviously good oil changes habits mitigate bad dust ingestion to a degree......if it were up to me I would always add extra filtration every where.
The problem with cones is more the heated air they suck, than the filtration efficiency [if maintained well]................a 1.5% power restriction advantage gets used up quickly when [even 11 x 1.5= 17F] hotter air is ingested.
Your MAF voltage tells the truth what ever air mods you do must increase this voltage to prove more air [density] is flowing......at rpms above 6,000 [the MAF reads above 4.0 volts [4.44 would be great] and every 0.01 volts increase counts big!
Do some accurate and precise testing!
If all you want is sound and a measly 125,000 miles of engine life, K&N cones are great.
When you get around 250,000 miles and are trying to get more those things you did early tend to come back to haunt you.