Air Filters

I have no idea why you're getting gas vapors after shut down.

You need to take a look at your car. If it were a Carbureted car I'd say "sure I can understand this a carb still pumps/sucks/drips some gas after you shut it down." A fuel injected system though shouldn't be pumping any fuel when you shut off the key. If you're getting fuel vapors coming out of your intake after you shut it off you need to have a look at it. I knew of a Porsche 951 that came into a shop I was once at that had something similar to this that was running very poorly. We pulled the intake system only to find gas being blown into the intake. One of the injectors had broken and was just spewing gas. After the car was shut down it's just continue to leak the fuel until the fuel rail was empty.

You need to have a look at your car if you think you're getting a lot of fumes out of it. You may also just be sensing things now that were there before that you didn't really notice. But, because of the change you're being a bit more aware of your car.

Once again a thread filled with conjecture based on nothing other than false assumptions. K&N filters meet all DOT, EPA, and CARB standards.

Don’t believe me do a little research:
Aftermarket Parts Device Type Listing of Executive Orders
You can search the CARB database of which aftermarket modifications have an EO# and are therefore legal for street use.

http://www.arb.ca.gov/msprog/afterm...ces/amquery.php

Smogsite.com
If you want to learn about how smog related components on the car work and affect emissions, this site sells books about smog. I purchased one of these books for my smog class and I recommend it.

http://www.smogsite.com/

Smog Check.ca.gov
For all the latest information and regulations regarding smog in CA.

http://www.smogcheck.ca.gov/

SmogCentral.com
Some basic information on smog.

http://www.smogcentral.com/

California/BAR Regulations
Resource for official BAR Regulations -- Expand Title 16, Division 33.
ARB regulations -- Expand Title 13, Division 3

http://ccr.oal.ca.gov/cgi-bin/om_is...owse_Frame_Pg42

Smog Tips
Another site with useful info - good summary of visual inspection items, and basic FAQ's.

http://www.smogtips.com

CA BAR Site : Engine Replacement/Rebuilding Guidelines

http://www.smogcheck.ca.gov/StdPage...es-Jan_1994.htm

 

While you will get very little if any additional HP, you will get much better filtering as long as you keep the K&N clean and oiled.

 

In response to Senna 21.........

Nsx's only come fuel injected, not carb's. You can see the vehicle in question at the Acura website.
The gas fume odor stopped 100% when the K&N air filter was replaced by a stock Acura paper filter. There was nothing wrong the the vehicle and it easily passed all smog tests .
It should be noted that the gas fume odor started immediately upon installing the K&N filter and stopped upon removal.
The motorcycle in question is a cbr 929 , again with fuel injection....again fumes stopped upon removal of the K&N filter.

The Acura dealer I purchased the K&N filter from (for the NSX ) called K&N and they agreed to take back their. filter and issued a full refund.
No explanation was provided by K&N either for the fumes or the Whistling noise.

 

Interesting. The question seems to be: what would a less restricted air flow on intake do to cause fuel leakage? Off the top of my head, I have no idea!

Ken

 

From The Europa Boys (carbs only?):

You can alleviate the smell to some degree with two small pieces of an American car PCV filter. Go tp your favorite parts store and buy an air filter breather for some 70's or 80's V8 anything. It should be a couple of bucks at most. Take the filter pad out of it's plastic holder and throw the holder away. Take a pair of scissors and cut a couple of small pieces that are a little larger rectangle then the vent in the carb and about 1/2" long. Stuff them about 1/2 their legnth into the vents. They should go in without too much effort but not be packed it so tight you have to force them or be in so loose they will fall out on their own. They will serve as a vapor trap for the vent without restricting the vents. (actually. that's what they did in their original application) This should kill the smell of fuel in the float bowls evaporating and will keep inside of the carbs cleaner a lot longer. This also helps if you are using the original airbox as it keeps the oil fumes from the head vent from getting into the float bowl. Change the little filters once in a while as they get dirty and have at it. One breather pad should make 3 or 4 pair of filters. Hope this helps !

 

I think that using a K&N filter in an otherwise stock airbox will yield very little (if any) gain over a clean paper filter. Emphasis on clean. A dirty K&N readily outperforms a dirty paper filter.

Of course, the K&N will indeed pass more dirt than a paper filter.

In a well designed intake system, you will likely lose performance (as in the Lotus case) by messing with the airflow. But in cars where the intake is optimized for noise control or emissions, going to a less restrictive intake and filter will help.

Rule of thumb... if changing the air filter requires rejetting or redjustment of the carb mixture, then it indeed adds performance.

In an economy tuned engine (like in a basic British A-series), going to a header, performance exhaust, performance intake, K&N, and a rejet... gains 12-15% on a dyno... a not insignificant increase.

Of course, the better designed the system is, the less improvement in efficiency is possible.

On my carbed '78 308, I went to the individual K&N primarily for looks and for the sound... but the seat of the pants performance difference (including cat removal and rejetting) is significant.... while there was no appreciable improvement over the K&Ns alone.

Bill

 

The NSX must have a fuel leak problem that the more restrictive stock filter masks whereas the K&N doesn't.

 

I would say this holds true for any intake/exhaust modification. When I got new, larger diameter headers, I ran really lean and hot with backfires. A carb tweak fixed that and it does have a bit more HP. Yet my electronic ignition didn't require any tweaks although it runs smooth all the way to redline (6800 rpms) and starts better when cold. But no HP gain.

Ken

 

That's my thoughts as well.

As for K&N taking it back no questions asked... Well, they're a good company who stand behind their product and will do just about anything to make a customer happy. 100% satisfaction guaranteed. You weren't satisfied... they took it back.

As far as sound is concerned, it just goes to show how restrictive a paper filter can be. Modern air boxes are designed to hide intake noise. That noise you heard with the K&N is still there with the paper filter. You just can't hear it because the sound waves don't pass through the paper as they do the K&N.

 

Yes they do help with a small amount of HP but as a K+N user for MANY years in my race cars, off road cars street cars and bikes THEY DO WORK.
After 7 years on 2 of my cars both injected no dirt on the inside of the air cleaner. That is why you use a K+N
Buzz