Just got back from my first dyno pulls, and had some interesting info regarding K&N air filters and actual performance. In spite of being on this Forum for about a year, I have made NO engine mods to my car, and with a new dyno shop opening near me, thought it was time I got off my rear and started something. JCL told me about the place and I met him there. The shop was staffed by the owner and Chuck Mallett's tuner, so we were in good company today!

I had a total of 6 pulls on my car. The only thing different from dog stock on this car is a K&N air filter I installed about 5,000 miles ago. I have not cleaned or oiled it since, and it was perfectly clean for the tests.

Pulls 1 and 2 were with the K&N filter - 293.7 rwhp and 297 ft/lbs torque average. Not bad, I thought, for a '99 with 40K and no mods. I was asked what air filter I was running - "K&N". "Let's take it off..."

Pulls 3 and 4 were with no air filter at all. After a brief computer learning curve, I recorded 304 rwhp and 314 ft/lbs torque. :eek: 10 hp gain and 17 ft/lbs of torque by taking off the filter!

To see if there was a difference in hp with a paper filter, I ran next door to the auto parts store and bought what they had - a Hastings brand paper filter. Never heard of them... $11.58.

Pulls 5 and 6 were with the new paper filter - 295 rwhp and 304 ft/lbs of torque.

I was also told by the tuner that the oiled filters have a tendency to spread a thin coating of oil throughout the intake system and that I should clean the MAF sensor when I got home. Sure enough, there was a light coating on the inside of the sensor that I cleaned out with carb cleaner, as recommended.

SO - where are the hp gains claimed by K&N? Nowhere as far as this car is concerned. In fact, the cheapest filter I could find did a better job of flowing air to the engine. It was recommended that I go pick up the AC/Delco filter and I sure will as long as I have the stock air box in the car.

So now I have a baseline from where to start. I can't wait to start posting the gains I get as I add different items. Should be fun! :cheers:

 

Interesting data point. I have never liked the oiled cloth filters. I put a 2002 Z06 Air Filter Cover on my '98 Coupe, but I stayed with the stock paper filter. Your runs just show there is nothing wrong with the paper filter.

You should change your air filter cover, cheapest performance increase for $48.

 

Your test actually could show why the K&Ns are so superior. That's a 5000-mile dirty filter vs. a brand new paper filter and there's only a 2hp and 6tq difference. Try the same comparison after the paper filter gets 5000 miles on it. The K&N's advantage is exactly in that its airflow doesn't sharply decrease as it gets dirty, unlike a paper filter.

Sam

 

Well, the filter was clean as could be, and the paper filter didn't leave a coating of oil where oil shouldn't be. The way we ALL saw it was that the K&N would never show a sharp decrease in power when dirty because it blocked so much air coming through in the first place. The way I read the K&N info, they claim better air flow and better hp through their filter. Ten hp increase when I took their filter off. TEN. And I will do many more runs with a paper filter. I hear the AC/Delco is as fine as there is for this setup, so that's what I'll run. And the K&N goes on eBay - I wouldn't sell it to anyone here. :nonod: Let me quote from the K&N web site (and this is copied and pasted from there directly): "Our air filter is designed to achieve high, virtually unrestricted air flow..." and "The result is an air filter that allows dramatically more air into an engine..." Throw up the BS flag. While I will not question the filtering capabilities of their products, I will challenge any of their claims that their product for the Corvette does either one of the above items. And I have the dyno results and the witnesses to go along with it.


[Modified by BSiegPaint, 1:08 AM 2/9/2003]

 

And also from the K&N site:

"20. How do I know when to clean the filter?

The general rule of thumb is that the filter needs to be cleaned when the dirt build up gets as thick as the wire mesh. The usual interval is 30,000 - 50,000 miles depending on driving conditions. We recommend that you check your filter about once a year in normal usage."

At 5,000 miles, I was nowhere near the recommended cleaning time.

 

I have never seen a "live" test where a K&N filter showed more power output on a C5. And the last data I saw on filter perofrmance showed K&N to be slightly less effective in actual filtering. My question has always been why bother? BTW my last dyno showed 316 RWHP with just a Z06 air box and a Fram paper filter on an MN6 2000.





[Modified by Richin Chicago, 6:46 AM 2/9/2003]

 

It was a sight to see. I would have never thought that would be the outcome. I believe the EX GM tech that told us the info on the air filter test stated that it was for fuel injection set ups. Carbs are fine, although.............
I do know tomorrow mine comes off my Z71, and the AC goes back on. JCL :yesnod:

 

K&N has a very effective little model at my local car store:

They have a ping pong ball in a tube that is contected off of a fan and the only air intake is a cut out in the plastic surround. You can place different filters in this hole, and then turn the fan on. With no filter the ball slams the top, with the K&N the ***** float to almost the top, and with the paper filters (3 DIFFERENT ONES) the ball never moves upward.

Now I am not a science major, and maybe its something special, but this does show me that there COULD be an advantage to the K&N filter in some instances. I consider my Supercharged Regal to be similar in that it has forced induction (ala fan) and can pull far more air with the aid of this filter.

On the Vette.....I have a blackwing !

 

I seen the same little model :smash:

On my Vette I have a Blackwing also :cool:

 

Well, I personally have seen good HP/TQ gaines with a K&N (and other aftermarket oiled filters) on other platforms (not the 'Vette). It may be just part of the marketing hype done by K&N to call all of their products superior, but I wouldn't call all of their products crap though just because you saw no gain in your test.

This is all really just conjecture, as I have no data to support my theories, but..... I would still consider the K&N superior if it achieved the same flow rate as the paper filter, but filtered a higher percentage of particles. If you're just replacing the filter element but keeping the same air box, the filter is likely not where the largest restriction is.

 

The other scenarios to consider are:

1. stock air filter cover, AC Delco 917c filter with enough holes drilled in the stock air filter cover to decrease restriction (no material cost) net hp and ft# torque gain: app 10-15. Over stock

2. take off stock filter cover, use AC Delco 917C filters and stock filter frame and secured to the stock clamp points with cable ties and/or shortening the factory banding. (no material cost) net hp and ft# torque gain: app 10-15.over stock. Can replace cover for any reason at any time.

I personally wanted the snow and water prophilatic option, so I changed from a 2001 air filter cover to the 2002 air filter cover. (43 dollars) and stock AC Delco 917c, net hp and ft# torque gain: app 5-10. over stock

Best of luck! Your posting indicates that you see past the myths!!





[Modified by ruking1, 9:28 AM 2/9/2003]

 

I would have to agree with you that K&N makes quality products, and far be it from me to call their products crap. If the C5 replacement filter indeed could achieve the same flow rate as the paper filters, I would still have to consider its use on my car. You can't be everything to everybody, however, and I just see that the filter they make for the C5 application is not as good as they claim, and I've never seen anyone challenge their claims until now. Mine wasn't over-oiled - it had the same oil on it from when I got it - I haven't even cleaned it. It's just as it came from K&N, so I have to assume it is oiled to its optimum level and should achieve optimum air flow rates. And it still deposited a film of oil inside the air intake and sensor. Maybe their filters in a 14" round configuration do indeed flow more oil than the paper filters of the same style - I don't know. No evidence to support that. And I'm sure that the demonstration models they put out for their marketing efforts work superbly. All I'm saying is that those of us who use the stock airbox setup should think twice before spending lots of money on a filter that may not work for us with our current setups. And then maybe we should save our pennies and get a Blackwing if we want more air flow...? Anyone dyno a Blackwing??? :D

 

Thanks, ruking1 - good tips. I assume you got the 2002 cover at the dealer? Is the opened Z06 cover the same or similar? I need to watch for snow and water also here in Ohio - I drive mine all year 'round.

 

Yes you can get it at the dealer, I actually got mine from Ken Fichtner's place in Montana (supporting vendor). You can also get it from GM Parts Direct, etc. I have seen the already cut out (retangular) air filter housing in a Mid America catalog. They appear fully stock except the retangular cut outs obviously do not provide as much prophalatic protection as the 2002 air filter housing.


[Modified by ruking1, 1:26 PM 2/9/2003]

 

I hope we continue to be alowed free choice in america. But if I had seen your test I would have come to a differant opinion than you did from the imfo you gave here. To me it obviousley shows air cleaners need to be cleaned more often in the inviroment you drive in, for maximum performance, ANY FILTER. It's also not a bad idea to use an apropriate cleaner, carefully, on the maf wire and throtle body regularly in an era of incressing air polution. I never dyno, but do drag race regularly. The K&N did give me better times than the stock filter in vettes and other cars. I use a K&N on my 555BB in my camaro and run 8.8's. I think there OK. :blueangel: Ric

 

There is more to the function of a filter than increasing your HP. I'd run a cheap paper filter or no filter if I was only looking for HP and intended to rebuild my engine often. If you want to run a test; put a K&N in for an oil change interval and analyze your oil for contaminants, then do the same with the "equal" HP paper filter. I've done this test on other cars and I buy K&N for cars I want to keep. I'm less worried about oil in the intake than I am about dirt in the intake. I intend to keep my C5 for a while.

 

I'm not sure if you are still discussing a air filters, but if you are, the tests I have seen show K&N be slightly less effective in filtering effectiveness.

"When it comes to filtering efficiency, or the amount of dirt stopped by the filter, paper is in the 98-99% range when new, cotton gauze will best around 96%, while some foam filters are as bad as 50%."
http://www.fordmuscle.com/archives/2...rs/index.shtml

 

Rich,
A good article, thanks. They also mention there is a broad variance between good and bad paper filters. My point was since most of us can't measure particle pass through on a flow bench at home, an indrect way to measure that is amount of contaminants, particularly silica, in your oil. My experience has been less with K&N. YMMV. :)

 

Thanks for this discussion, as I was just about to install the K&N and was not so happy about the hood mod's, but will now send it back and get a Blackwing instead...... I had thought that having the complete airflow kit is what gives this unit an advantage over just a filter replacement but your numbers do not support it.
:p:

 

I've never liked cloth filters -- a tuner once told me: "hold it up to the light, if you can see through it, imagine what can get through it" Can intake pieces like Blackwing be used with a paper filter? (I just got my Vette, and haven't made any mods yet.)