My local drag strip requires the use of an air filter for safety reasons. I'm going to replace the air filter on my single 4 barrel, small block, street/strip 55 Chevy, and could use some advise as to which one to buy. Some companies claim that their air filters can actually add horsepower. Any thoughts or opinions would be appreciated.
Air filter enclosure can give carb an area of calm air, usually seen as beneficial. Any filter can potentially cause minor changes in mixture by changing path and velocity of air, and of course major changes if it is restrictive. A big, clean paper filter can be essentially totally unrestrictive. A filter offers the opportunity for a planned ramp from filter area to carb throat...look at late 60's corvette ones, with smooth ramp trying to compensate for the transition from too low to carb height. Height from carb top to lid is also very important...too close can give a lot of trouble for several different reasons!
air filters cannot ADD horsepower. they just restrict available airflow. a free-er flowing filter frees up available airflow. more air = more fuel = more available horsepower. we use K&N on our racer.
well I think they would eventually or I guess they prevent the loss of HP due to crap wrecking your cylinder walls.
Yes, they can ADD horsepower. They do this by smoothing and directing the airflow into the carburetor. That's why you can get better power with a well-designed air cleaner than with no air cleaner at all. But I'll grant you we're probably talking a very, very small number here. The goal should be minimum restriction, tall filter (and therefore lid) height, AND a nicely-contoured base that will actually help the air find it's way into the carb throat with a minimum of turbulence.
I've seen tests of tall Delco 14" paper filters showing no measurable flow change at 750 CFM. Once restriction is eliminate, there is lots possible with can design.
Just like the gravity-tuned fuel tank fillers used by some pit crews, the shape and flow path do make a difference. Seems that if the pressure drop is minimal across the filter element, then improving the shape-flow rate is adding HP.
I think the differences are pretty minimal. Really the difference between filters is how much less they restrict airflow than another one. Ive always heard that K&N's breathe the best.
hells YA i put a cold air intake on my civic and gained 75 hp !!! then i put some stickers on the outside of the car and gained 25 more !!!
i run my falcon at the track often, and i can tell you i went from a cheap paper filter 3"x14" to a k&n filter 6"x14" and gained NO mph or e.t. so i will never spend that much on an air filter again!!!
I removed the three air cleaners on my '66 GTO tri-power and it was better by 0.15 - 0.20 second. I cannot say if it added any HP, but it improved something.
Hot Rod did a dyno comparison test of a bunch of different air cleaners recently (well, within the last few years). Used big, small, thick, thin, simple and sort of exotic air cleaners. Also tested no aircleaner at all (which was not by any means the best combination). There were only minor differences (maybe less than 10 hp between the best and worst on a pretty stout motor) among all of the items tested, and some of that variation might have been tuned out had they spent more time tweaking on the particular combinations. So, yes, there are differences, but don't expect too much.
But.. can they do any better than adding just a velocity stack? Doubt it. The paper or foam is going to slow down the intake of air. Open carb with an appropriate stack is going to win. Don't get me wrong, I think it's silly to run a motor without a good air cleaner. Why rebuild sooner than you have to?
It isn't that the air filter "adds" horse power but that as other mentioned a free flowing air filter allows maximum air flow. The smooth transition of air into the top of the carb (s) when you put on a properly designed base plate probably helps a noticeable amount in some instances. Think air flowing around a smooth rounded corner as apposed to making a sharp 90 degree turn going into the carb. And one has to remember that the claims of the manufactures like K&N are in comparison to a stock and restrictive aircleaner.
The only way I can see it helping at all is if the new one will give better and colder air flow . But add HP ?
Well, they "add horsepower" relative to no air cleaner at all. If you get 3hp more with an air cleaner than with none, then I'd say the air cleaner added 3hp! (Again, it's the shape of the base that "adds" the power, not the filter element itself.) Hence the stubstacks and such. Anything that smooths the transition and points the air where it needs to go is an improvement over nothing at all.
the motor has what it has a airfilter is not a camshaft or good head work, or a supercharger, so how can it give it anything, its all about reducing your restrictions right?
Okay, one last time: If an air cleaner (the base and lid, not the filter element itself) actually AIDS the flow of air into the carburetor then you will make MORE power with the air cleaner than with nothing at all on the carb. I would call that ADDING POWER! It is a small difference, but it is a real difference. And it is the base design and lid shape, not the filter element itself, that makes the difference.
If you don't mind the look of a K&N style filter just go that route. Never replace the filter again. One of the secrets is don't clean it but every 5 years or so, dirt accumulation actually makes it a better filter. Several brands out there, maybe you can find a color that's not too horrible.
Yes--look at the top of almost any carb; do you see anything that looks friendly to air there? It's just cut off square, with ledges and vent pipes sticking out at random. There are fairly well tested plastic things to smooth and round that area, and bases designed to turn the air that is coming in horizontally from the world. Level of base in relation to carb top can be important (or require compensating ramps if there's not much room vertically) and enough space above carb is vital. A naked carb is not the best. And of course the filter itself is a neutral party if it freely flows more than the engine needs, which is generally pretty easy with tall, large diameter paper filters. Small filters (GTO above, the types used on triple Strombergs) are often bad news.
they are tuning in more horsepower with some of these new air intake systems, such as the k&n it's not just the filter they use computers to tune the shape of the intake tube and filter, think of it in the same as a tuned set of headers working in reverse. when it's done right, the shape of that intake tube and filter can flow more air then a plain filter, remember it's not a smooth flow of air coming through the filter, every time an intake valve opens, it creates a pulse of air. these pulses can be tuned to deliver more airflow. not sure how well it would work on a traditional engine with a carb though. ,
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