Here is another great link from Bob The Oil Guy regarding some air filter stuff. This is an informative read. Make sure you check the link below for the actual test information. There are many additional links with photos.
Caveat: I am not holding this guy to be any kind of expert. He is doing that himself. Read and verify yourself.
As automotive enthusiasts, we are always looking for ways to increase the power output of our motors. Many aftermarket companies now manufacture and offer high performance air filters. Most all claim a power gain through increased airflow and some claim better filtration as well. In this test, many air filters will be compared. I personally have owned various makes of performance automobiles. This particular test is being conducted using a 1992 Mazda Miata with a bone stock engine (can't wait to modify it personally). I have many different turbocharger parts and components collected waiting to modify the Miata. The air filters tested include a Napa Gold, Amsoil two stage foam, Jackson Racing two stage foam, a Baldwin fiberous, a K&N, and a Mazda factory replacement.
The air filters will be mounted in the stock air box and filtration tested by placing a 2nd filter (after filter if you will) just before the airflow meter. A picture, as you will soon see, is worth a thousand words and shows this setup. A water manometer will be used to test pressure drop across each filter. Obviously the filters with lower pressure drop flow better, and have the potential to yield more power given the engine actually needs the airflow increase. The pressure drop across each filter will be measured in inches of H2O (water). The pressure drop will be from atmosphere using the stock Miata induction system to the air box just after the filter. 1 psi of pressure = 27.7 inches of water for reference.
I have a degree in mechanical engineering and am currently pursuing a master's in engineering management. I have been around the automobile all my life, and will be obtaining certification as an ASE certified mechanic this fall (for fun). My father worked in the automotive test industry my entire adolescent life. I've also spent much of my life at the race track, either racing as an amateur or with my father who was a crew chief for a stock car racer many years. He also was a crew chief at the 24 hours of Daytona and LeMans twice. I regret not being able to go to LeMans to this day. I'm a certified gage calibration technician, certified quality assurance inspector, certified as a refrigerant worker by the EPA, and work in the Navy as a mechanic in nuclear propulsion. I like to think I know a few things about machines including automobiles, but there is always something to learn.
I choose to conduct this test because of the conflicting information I see in advertisements and have read on the internet. Everyone claims that their filter flows the best, and removes the most dirt. If you think about it, flow and filtration ability are actually linked. A solid piece of metal would prevent any particles from entering the engine, but it wouldn't flow any air at all. On the other hand, the screen used on a window screen will flow well, but won't filter well at all. So if you think about it, the best flowing and best filtering is really contradictory in claim. I wanted to find out which filter really does filter the best, and which one really does flow the best. I have used almost every brand and type of air filter over the years including K&N. I had not used a foam filter until conducting this test. I have used every manner of off the shelf fiberous or paper filter.
There are basically four types of filtration materials currently in use for automobiles: paper or other fiberous (some appear much like fiberglass), foam, cotton gauze and stainless steel mesh. This test has used the first three, but not stainless steel mess. Steel mesh bathed in oil is some of the very first filtration materials ever used in an automotive application. There is a reason they were abandoned for paper in the '60s. I find it surprising that some aftermarket manufacturers are touting them now. In the links at the end, there is an interesting test of a stainless mesh filter.
The filters in this test were tested for both flow and filtration. The pressure drop across a filter is a good indication of its ability to rob the engine of needed airflow and hence power. Obviously the air filter with the least pressure drop is the highest performing. For the filtration test, I used a secondary filter after the filter being tested to catch any particles that passed through the first filter. The secondary filters were made by cutting apart an off the shelf Fram carburetor filter. The particles passing through the filter being tested leave a deposit on the secondary filter. The lightness or darkness on the secondary filter is an indication of how much dirt is getting through the filter being tested.
The differential pressure test was performed using a water manometer where one psi of pressure is equivalent to 27.7" of water. The differential pressure was measured between atmospheric and the pressure drop after the air filter in the stock airbox. The max pressure drop in this test was seen at only 7.0 inches of water or 0.25 psi. The factory airbox and piping with no filter yielded a pressure drop of 5.0 inches of water or 0.18 psi. That means that the worst filter in this test only caused a pressure drop of 0.07 psi. In my opinion, this means that if you are picking an air filter based on performance, you probably aren't doing your car any favors. For the record, the K&N was the best flowing filter. Of the 3 types of media tested, the cotton gauze type filters flow best. There are other brands besides K&N for sale, of which most are probably made by K&N for resellers. Foam air filters flowed marginally better than paper.
The filtration test has been the cause of much argument and debate in some circles. Many contend that a color comparison (comparing shades of gray) is not scientific or appropriate. Again, this is a very low budget test, and there are other scientific analyses where color comparison is valid. In water chemistry a color comparison is often used to determine concentrations as low as parts per billion. Search for information on titrations (of which some are by color) or color comparators. In chemistry the color is compared to a known standard of specific ion concentration by color. If you have ever played with a fish tank chemistry sampling kit, then you have done color comparison yourself. In this air filter test, no attempt is made at determining actual concentration. A color comparison is used to determine real world filtration ability. Each test filter was used in the same car, on the same roads for 500 miles. The darker deposits indicate poorer filtration, and lighter ones better filtration. That said, both the cotton gauze type (K&N) and foam filters (Amsoil & Jackson Racing) showed the same levels of filtration. Both performed poorly compared to the fiberous or paper filters (Napa, Baldwin, and Mazda).
If you are interested in the filtration pictures or pressure test data, follow the links provided to my other pages. You will also find links to other tests, which I found interesting on the web. In the end, paper or fiberous filters do remove more particles from the air before they enter your engine. The cotton gauze filters indeed offer better airflow. You have to decide for yourself whether you value ever last ounce of power or filtration. I cannot, nor will I make this decision for you. I do know that on a relatively stock car with a properly sized air filter, you indeed have very little if any performance to gain by swapping filtration material.
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'97 GT with 80mm C&L MAF, C<rue-Flow CAI, MAC 70mm TB, Superchip, 180 thermo, B&M Ripper, King Cobra Clutch, FRPP aluminum quad/adj cable, MAC O/R H pipe, MIL's, Flows, Granatelli Solid control arms, FRPP 4.10's, FRPP aluminum driveshaft, Fidanza aluminum flywheel, FRPP 9mm wires, TMD aluminum U/D pulleys, Steeda full length SFC's (welded in), and 17" polished aluminum Cobra wheels with Nitto 555 Extremes, Kenwood/Alpine sound. Waiting for install: PI intake.
I bought a March "Ram Air" system a while ago and though I knew it would not work as a ram air with all the bends,the filter and the screen but I bet it works better as a cold air kit than any fender well kit ! I wanted to see how good it worked so I stuck one end of the hose out of my car window ,bent two 90* angles at 70 mph and it was almost like AC!!! And anything helps when its 100 degrees on the track.
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2003 GT 5spd ,Magnaflo mufflers ,Steeda Triax,
3.73 gears,Nitto drags 245 45 17s,70mm BBK throttle body,Dragon plenum,Steeda pulleys, Strange rear drag shocks, S&B CAI, Mac Pro Chambers,2.5 in.cat-backs, 13.63@101.67 w/ 2.091 60 ft. Best 1/8mi 8.60@83.35mph w/1.94 60 ft.
Dynoed at 263rwhp & 302 lbft trq w/ 93 sct tune.
D=1/2p V squared S Ct.
This is the empirical formula we aeronautical engineers to calculate air pressure for lift and drag. Basically, Density of air equals one-half barometric air pressure times velocity squared times size of aperature times temperature coefficient. The lower you are, the colder the air, the faster the speed, the greater the air pressure. Key factor is Velocity squared. Static air pressure is around 15 lbs per square inch. @ 30 MPH/40lbs PSI. @ 60 MPH/75lbs PSI. @ 120 MPH/140 PSI. No, it ain't 'chargin', but ram air is more effective than CAI and cheaper too. I'll take the two pounds of 'boost'.
Go figure.
lol some guy bought one of those electric 12v fans off of ebay. They are called like an "electric supercharger". Well the fan broke off and went down into his intake.. They are garbage, lol but i'm sure we have all seen that leaf blower hooked up an intake picture.
Although you might get cooler air with a ram air set up vs. a fender mounted CAI, fact of the matter is that without a S/C or turbo, you'll never "ram" air into the engine harder than the intake is going to pull it in.
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Black 2003 Mustang GT
Power = 254 rwhp/ 291 rwtq (n/a)
1/4 mile = 13.444 sec. @ 102.94
i actually work with a guy who is an engineer and i was talking to him about having a "ram air" intake one day... he is really into cars and is very knowledgeable in every aspect. he basically said that a ram air system is pretty much pointless unless you are going about 200mph.. and proved it to me. interesting i thought. i dont have all of the graphs and such that he used to explain this but yeah you get the idea. the ram air set up looks cool but performance-wise, it really doesnt do too much unless you are going ridiculously fast. anyways.. im out
Cowl induction falls under the same category as 'Ram-Air' in my book. Unless you want to drop the coin on forced induction, a good free flowing intake is the best thing you can do.
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Sometimes I think that government fits that old-fashioned definition of a baby: An alimentary canal with an appetite at one end and no sense of responsibility at the other.
- Ronald Reagan
Today's cowl hoods are more properly called "heat extraction" hoods rather than "induction" type. Great for reducing the under hood heat. With todays laid back windsheilds, no high pressure area exists like it might have in the late '60s' at the cowl area.
Dave
One reason a fan between the MAF sensor and the throttle body would not work is because that little if any extra air is un metered air and this would cause poor running conditions. As far as Ram air I would say it would help because the air charge temp would be lower. Lower by colder temp and colder air has more air then hot air. Also if you have seen a BMW M3 it has 6 throttle bodies and the intake is short acting like a ram air affect. colder air and less time to fill the cyl with air. But thats just what i think.
