K&N Filter Tops

[Nova70]

I noticed a lot of people are running the K&N Air Filter tops on their truck. I've been reading about them a little bit and thought I would fill everyone in on the findings. The filter top is actually robbing horsepower from your engine, the losses are up to 30-50hp with the filter tops. What happens is the air entering the carb while using an extreme lid causes air flow disturbance over the air bleeds and this causes the carb not to work properly.

I have tested these twice, and the results were the same. You LOOSE 5 to 7 HP with the lid over a regular K & N filter with a steel top. I also found that the air turbine on a S F dyno will pick about 7 or 8 HP more than when you run the carb without it..I have heard the same thing from other dyno shops.

JOE SHERMAN RACING ENGINES

Quote above is from this link- http://speedtalk.com/forum/viewtopic.php?f=1&t=9032

YellowBullit forums has also discussed this and guys there have seen up to a 50hp loss on performance built engines.

Just thought everyone might like to know the info as most of us are horsepower junkies.

Anthony

[junkyardjohn]

I had one on my 71 blazer for the 11 years i owned it & drove it everyday. I kinda like to think even i would notice either a 50 hp. Gain or loss. Never saw or felt either. The idea made sence to me or i wouldn't have spent around $55 for it. I'm 52 years old & have run open element filters on every truck or hotrod i've ever owned where possible. I like to go by peoples actual experiance for recomendations instead of articals or rumours or personal thoughts on any subject. Misleading advice is everywhere on the internet. (not saying this artical is... I just don't know??) common sence just tells me that if someone could invent an air cleaner of any kind that would majically add 50 h.p. All by itself..... Well... That inventer would be an instant jillionaire. john

[leddzepp]

Originally Posted by junkyardjohn

I had one on my 71 blazer for the 11 years i owned it & drove it everyday. I kinda like to think even i would notice either a 50 hp. Gain or loss. Never saw or felt either. The idea made sence to me or i wouldn't have spent around $55 for it. I'm 52 years old & have run open element filters on every truck or hotrod i've ever owned where possible. I like to go by peoples actual experiance for recomendations instead of articals or rumours or personal thoughts on any subject. Misleading advice is everywhere on the internet. (not saying this artical is... I just don't know??) common sence just tells me that if someone could invent an air cleaner of any kind that would majically add 50 h.p. All by itself..... Well... That inventer would be an instant jillionaire. john

x 2. Very well put.

[Nova70]

Originally Posted by junkyardjohn

I had one on my 71 blazer for the 11 years i owned it & drove it everyday. I kinda like to think even i would notice either a 50 hp. Gain or loss. Never saw or felt either. The idea made sence to me or i wouldn't have spent around $55 for it. I'm 52 years old & have run open element filters on every truck or hotrod i've ever owned where possible. I like to go by peoples actual experiance for recomendations instead of articals or rumours or personal thoughts on any subject. Misleading advice is everywhere on the internet. (not saying this artical is... I just don't know??) common sence just tells me that if someone could invent an air cleaner of any kind that would majically add 50 h.p. All by itself..... Well... That inventer would be an instant jillionaire. john

I will find the dyno printouts again. They're on YellowBullit forums. People have actual dyno proven numbers that proves they loose power.

These filters loose power on 95% of applications.

[Longhorn Man]

do some research on K&N... they aren't the best thing for your engine.
If they did what they say, and protected your engine, then big trucks would run them.

[sv10001975]

i have seen the same loss results on the dyno everytime we have run these. There is no 30-50 HP loss but there is a 7-10 HP loss everytime. A carb is not designed to have air entering from straight above and it really does disturb the air flow characteristic of the carb. if you want to see a serious loss in HP put one of these on a Q-Jet. I have seen almost 20 HP loss on 450-475HP motors with a filtered top and Q-Jet. these are definately a waste of money, and i am not ashamed to say that K&N got me on this one as well.

[nightmare]

So . . . What about normal open air elements, like below? Are they a hindrance to an engine as well? I would think that an engine is going to perform more efficiently if it can breathe, and expel the spent fumes, better. Is it better to run a filter that is encased like the factory?

[oldblue1968chevy]

interesting, I liked the look of the filter on the top also..

[Nova70]

Originally Posted by nightmare

So . . . What about normal open air elements, like below? Are they a hindrance to an engine as well? I would think that an engine is going to perform more efficiently if it can breathe, and expel the spent fumes, better. Is it better to run a filter that is encased like the factory?

This style filter is what we're comparing the tops to. The dome on the top creates an airflow that the carbs like, therefor more horsepower. The biggest horsepower gains are from the domed tops.

[petey-pablo]

Filter top like mine,So are you saying I am loosing HP?

[SOON2BLAZE]

Originally Posted by petey-pablo

Filter top like mine,So are you saying I am loosing HP?

I'm guessing your not coming up short on HP with that!

[Nova70]

Originally Posted by petey-pablo

Filter top like mine,So are you saying I am loosing HP?

Yes, you're loosing horsepower. A few guys' have said they felt the power in the butt dyno, others said they couldn't feel much but saw a difference in the dyno numbers. You will also notice your idle going a little higher switching to the domed top so you'll probably have to adjust her back down a hair.

Edit- This is the thread I discovered most of this: http://www.nastyz28.com/forum/showth...extreme+filter

[leddzepp]

Originally Posted by petey-pablo

Filter top like mine,So are you saying I am loosing HP?

I wouldn't lose any sleep over it.

[nightmare]

I see. Does this also affect fuel consumption, and possibly the MPG's?

[Bad70sbchevy]

No, it doesn't hurt your horsepower, you might actually will gain a couple actually using the k&n exteme tops. Hot Rod did an article back in 2004 when they were comparing different air filters on a 454. On one of the dyno runs they picked up 1-2hp when comparing the xtreme top to the traditional setup. I believe the article was in one of the 2004 issues. I'll put up the link if I ever find it. Even if it does hurt horsepower, I extremely doubt if you would notice it (I think on some of the dyno runs they might of lost 5hp at most). Lookin at the numbers, those tops are only makin hp with taller air filters (with the 4" tall and up) and hurt you on the smaller ones. As for the k&n filters in general, they will not hurt your engine at all, they will actually make horsepower because the more air entering your engine, the more horsepower you'll get out. Thats why when you are buying an air filter, the bigger the better, since the larger the surface area, the less resistance there is for the air entering the engine, this is why the extreme tops "should" make more horsepower. If you are seeing problems though, use a substack which helps to smooth the airflow into the carburator, thus making more power also. Then again I could be wrong, haven't took fluid dynamics yet:lol. Like I said before, these are usually small fluctuations in power, nothing to worry about and shouldn't notice anything when it comes to fuel consumption. Another site referenced the article I was talkin about at http://www.camaros.net/forums/showthread.php?t=120807.

[68Stepbed]

Actually a larger air filter(taller than 4") will start to rob HP. Carbs and engines rely less on the amount of air, but the velocity. Look at runner designs in heads. A smaller runner creates a higher velocity, making more torque. Whereas a large runner flows more air but with less velocity, making less low end torque but better for top end HP. That's why a head and cam mismatch can make for an engine that won't run good. For example, Petey-Pablo's filter setup may be robbing some torque, but may make better top end HP. On a big block, it's worth the trade off. A small block, however, would not benefit at all from a taller air filter.

Back on the topic at hand, I can see where the Xtreme top can disturb the airflow. In theory, it should make more power, but airflow characteristics are kinda wierd and hard to understand.

[Sinister]

Originally Posted by 68Stepbed

Actually a larger air filter(taller than 4") will start to rob HP. Carbs and engines rely less on the amount of air, but the velocity. Look at runner designs in heads. A smaller runner creates a higher velocity, making more torque. Whereas a large runner flows more air but with less velocity, making less low end torque but better for top end HP. That's why a head and cam mismatch can make for an engine that won't run good. For example, Petey-Pablo's filter setup may be robbing some torque, but may make better top end HP. On a big block, it's worth the trade off. A small block, however, would not benefit at all from a taller air filter.

Back on the topic at hand, I can see where the Xtreme top can disturb the airflow. In theory, it should make more power, but airflow characteristics are kinda wierd and hard to understand.

X2. I've experimented in the past with different air cleaner sizes and bigger was not necessarily better. Lost a lot of torque down low when I went too big.

[sv10001975]

for maximum results you want the air cleaner top a minimum of 3 1/2 inches above the carb top. all i can say is that i have seen these top cause way more losses in horsepower than I have seen gains. not to say in some application that it wouldn't increase horsepower, but based on my experience it will not increase horsepower. like i said i was fooled by K&N as well, have a filtered top sitting on the shelf that has about two minutes on the dyno before we yanked it off. it causes major disturbances on the air entry points and this always causes a drop in power. just my 2 cents worth

[Bad70sbchevy]

OK, that makes sense about the air velocity, but I'm just throwin this out there, even if you are running a huge air filter, won't your air velocity still speed up if your using the right carburator (not oversized) when the air encounters the smaller passeges of the carburator assuming that the amount of air is not changing? It would be just like running a carb without an air filter if you take it to an extreme. Or are you still looking at velocity issues like you said?

[sv10001975]

the size of the air filter is not changing the velocity the carb size, and design in conjunction with the motor are what changes velocity. remember unless it is a forced induction application the motor is pulling air in. as the air is pulled in the venturi size and design can change the velocity of the air and the motor pulls the volume of air in and through the carb. the motor is only going to pull in a certain amount of air regardless of carb size. in reality the carb restricts the motor from pulling in air and keeps it from being as efficient because of this restriction. in reality running a carb without a filter can cause a decrease in power as well in regards to a "clean" high flow filter. in the days of paper filters running without a filter probably did increase HP but not with todays high flow air filters. without the filter you can still get the vertical turbulance as similar with the K&N top

[junkyardjohn]

Originally Posted by sv10001975

for maximum results you want the air cleaner top a minimum of 3 1/2 inches above the carb top. all i can say is that i have seen these top cause way more losses in horsepower than I have seen gains. not to say in some application that it wouldn't increase horsepower, but based on my experience it will not increase horsepower. like i said i was fooled by K&N as well, have a filtered top sitting on the shelf that has about two minutes on the dyno before we yanked it off. it causes major disturbances on the air entry points and this always causes a drop in power. just my 2 cents worth

WELL... IT'S KINDA LIKE THE OIL FILTER DEBATE, OR THE GASKET DEBATE, LONGBED VERSUS SHORTBED, FLEET VERSUS STEP... YADDA YADDA... I'M NOT ANY KIND OF AIRFLOW GURU. I JUST KNOW WHAT WORKS FOR ME ON MY TRUCKS. THAT BEING SAID... I'LL GLADLY PAY YOU $20 FOR YOU'RE WORTHLESS 14" K&N TOP, & IT WONT BE IN YOU'RE WAY + YOU'LL BE ABLE TO RECOUP PART OF THE INVESTMENT THAT K&N FOOLED YOU OUT OF. P.M. ME FOR PAYMENT. JOHN

[sv10001975]

Yeah it's funny how some people can make stupid comments on this site and then when called out on it, they step down. My counter offer is more than fair, but you really didn't want it in the first place you just wanted to make a stupid comment, and you accomplished that.

[oldblue1968chevy]

So they add hp or take it away I really like the looks of em lol...

[Nova70]

You're loosing horsepower using them. I just posted because most of us are horsepower junkies and want everybit we can squeeze out.

[Bad70sbchevy]

Yes and no, it all depends on what kind of carb your runnin and the size of the airfilter. Unless your comparing off the dyno its hard to tell. The increased surface area of the filter helps the air to pass easier through the air filter, on the other side on some carburators it causes turbulance causing a decrease in horsepower but gains or losses are small. If your really worried about a couple horsepower, slap it on a dyno and see what happens (personally, someone is going to throw rocks at me for this, but just get a bigger air filter if you want more hp). If not and your just want the cool factor, throw it on top and dont worry about it (you shouldn't feel a difference), worse come to worse you can always take it back.