I think I've found out why people have FE gains with their CAIs...
 

If you think about it, a lot of people's CAI kits are really WAI...

https://www.camaro5.com/forums/showthread.php?t=33172
...and here's what he was talking about:
https://img292.imageshack.us/img292/7038/intake1gd8.jpg

Wow- excellent point. I never thought of it that way.

So there are three types of intakes:
1. Stock- outside air (true cold air)
2. Underhood air (passively heated)
3. Warm air intake (actively heated by exhaust or radiator)

Well, there are aftermarket CAIs that actually get cold air from outside (usually they use terms like "cowl induction", "ram air", etc)...but look at a lot of them and they're getting warm air.

I'd guess that too many people never measure their IAT before and after installing their "CAI".

measure the idle consumption of 4, 6 and 8 cylinder engines. Then measure the same engines at no load and 2000 RPM.

My Insight will go 40 MPH on less fuel than a V8 uses idling.

My Echo idles on .19 gallons per hour. Average V6 is .4 to .5. Average V8 is about .7. Those amounts double at 2000 RPM with no load applied to the engine to move the vehicle.

Reciprocating mass is a major factor in the differences in consumption, beyond friction and pumping losses.

regards
gary

Precisely. K&N is the only manufacturer I have seen that offers a tried and 'true' cold air filter kit in their FIPK. Essentially it's like any other underhood cone filter with a cold air box around it fed from you guessed it, the fender well. Many people could get similar performance out of an upgraded flat panel filter, eliminating the snorkel inside the fender, and enlarging the hole from the fender.

I actually data logged my intake temps when I built a custom kit of that sort for my race car. With intercooling and one very large turbo, I never saw more than a 4 degree difference from ambient temperature and my intake temperature at the manifold while crusing at 65. So even with a best case intercooling scenario of 80% efficiency, my intake air was otherwise never more than about 5 degrees over ambient with that setup.

oh definately you need to block the heat properly to get a cai

CAI used to mean CAI, but in the last 5 years, people have been calling short ram intakes or any cone filter CAIs, so it's due to the dumbing down of the term that some "CAI"s might now seem to be WAIs.

However, a well developed CAI kit should reduce pumping loss over a stock airbox, so economy should improve a little if you can keep your foot out of it. Also should make a more economical WAI vs a stock airbox converted to WAI.

I got a bit of a boost in Wile-E from an Airhog panel filter. The thing to remember about replacement panels from K&N is that unless it's a popular performance application, it may not flow more than stock, due to them making something that fits rather than developing it much. Escort folks say the K&N panel is useless, so I went for an airhog figuring that fram knew what their paper panel filters flowed and would make the airhog flow more. I am quite happy with it, and annoyed that all the stores round here seem to have stopped carrying airhogs, because I want one for Marvin. Whether you like fram or not, their paper flows at the higher end of the range of paper filters, so I figure any application airhog is going to flow more than any paper. With K&N it depends heavily on application, and whether the owners clubs bugged them about it if it was lackluster, and I guess what paper they compared it to. Some factory paper is horrible and you'll probably notice a diff with fram paper even.

I have a hard time believing that a well developed CAI kit could increase FE for anyone who is driving for FE; though I guess the savings of pumping losses could conceivably help someone who drives anti-FE, if the cold air doesn't bring it down too much (which is possible since factory intakes often get decently cold air anyway).

As for factory paper filters vs. aftermarket, they have every reason and ability to put in one that won't reduce FE. There's plenty of monetary reasons why they should and few why they shouldn't. It's truly hard for me to believe that a manufacturer would be so negligent of their own bottom line for so little reason on a detail that is so popularly scrutinized.

And again, even if it doesn't flow well, it shouldn't affect FE for drivers who care about FE at all.

Don't forget the EPA's own testing on the matter, which showed that even a terribly clogged filter would have little effect on fuel economy:
https://www.fueleconomy.gov/feg/pdfs/...02_26_2009.pdf

That report there says Buicks OEM filter was more restrictive than the aftermarket replacement.

However, the test methods were the EPA test cycles, they've got so many speed changes in them that nothing that affects steady state FE is going to show up in them. There's quite a number of technologies that auto companies have tested that give fairly amazing highway mpg, but they never implemented them, because they didn't show up on the EPA gas-brakes-gas-brakes test schedule. Ford had a DOD tech running in the early 80s, got 20 or 30% out of it at steady cruise, but it cut in for seconds only on the EPA schedule, so didn't make a damn bit of difference to their numbers, ergo, it wasn't produced.

Oh snap, bitten by my own failure to pay attention! :D

whats really going on here is people are retarded and dont know how to use painters caulk

Flow vs. MPG vs. microns.
 

I can tell you hours of stories from the 80s about figuring how to get a big enough air cleaner under the hood to get a 3% boost and flow and some power. I myself have come up with all sort of combinations of after market air cleaners, dryer hose, and bent up pipes. Sometimes you get some nice intake noise and maybe a boost. With the latest rage of short ramming and long ram cold air intakes, when it comes to dyno numbers, most of the high flow air cleaners come in around 4000 to 5000, but if were trying to keep in the 3000's for MPG, theoretically more flow at low RPM would not boost the static compression ratio much. From published dyno charts, low RPM number are identical. Now fixing a bend in a factory intake tract can smooth out the flow, maybe get rid of some non benefitial turbulence.

The other thing I have come to realize is MICRONS! What is the amount of microns a KnN filter lets through? You cant get free filtering. A friend mechanic I'v known for 10 years at Toyota said that oil/guass filters let more dust microns through. Being that concrete and sand are abrassives, my friend insists that the only thing those filters do is wear out your rings faster. My friend would take a factory V6 air box and adapt it to a 4 cylinder to get more flow, but he says paper is the only way to go.

Is there any data on how much dust gets through on a high flow air filter?

There is data around. Here's one low-budget test:
https://bobistheoilguy.com/airfilter/airtest3.htm

I think there are other independent tests. I wouldn't trust any test that could be funded by or connected in any way to any company with a vested interest.

OTOH, as with my observations on oil change habits, I suspect that it's quite rare for a car to go to the junkyard ever having suffered from inadequate filtering.

Repeated tests over at TDIClub.com have shown that the factory paper air filter (not the STP, Wix, Purolater fitments) actually flows MORE air than the K&N recommended unit.
Remember that the diesels don't have throttle plates that cut down the volume of air per engine stroke, so that may be a difference between the diesel results and those obtained from a throttle plate equipped gasoline fueled engine.
A benefit is that the dry paper filter does not shed oil mist that damages the hot film Mass Air Flow sensor.

More air flow, better filtration, no electronics damage from oil mist.
So I have to replace it, that's a lot cleaner than re-oiling the K&N anyway.

I noticed that the replacement OE filter for my Pilot (green material) had a thin coating of some sort of oil(?). Wonder why the change from dry paper (older Hondas) version to a 'moist' filter?

Either way an OEM air box and clean filter works fine for me.


With my old ITR the AEM cold air sure did make lots of noise at 8,000+ rpm. :D

The premium truck/suv filters are oiled now.... it's supposed to stick the dust it won't block, but it's probably to keep them from being blown out...

I bought a 1997 Z-24 Cavalier/five speed a while back for commuting to work. I averaged 31-32 mpg for the first month of driving. I then decided to do spark plugs, new belt, etc. While working on the car, I went to check the air filter, only to find a mouse nest inside that literally filled the entire air box. and completely covered the filter. I decide to put a cone filter in, so I took the airbox out all together and fitted a cone in it's place. New mpg's were... 31-32 average on my daily commute. :) If you are driving sensibly to get good mileage, the type of filter and it's state of dirtyness are not all that important unless you are always on the gas in my opinion. Oh yeah, and even with the cone filter directly in the engine compartment, average intake temps were only about 10? F above ambient while moving, they go up when idling of course.

My forward facing CAI improved fuel economy especially on the highway. Its a simple setup. Removed the high beam headlight on the driver's side and ran a sealed 3.25" tube from the headlight bucket to the stock airbox. There are no leaks anywhere in the system and all the air is coming in from the front of the car. If i go to neutral at highway speed (over 65mph) the engine will idle at 1000rpm instead of the normal 750rpm. I assume this is because the oncoming air is overpowering the idle control valve. It didn't do this with the stock hot air intake. Either way, this setup was worth about 2mpg on the highway, tested over many many tanks. My all time best highway tank was 39mpg. This is a 1991 bmw 318i. Don't get your panties in the bunch. This isn't the only FE related modification.
So yes REAL forward facing cold air intakes are very effective at improving fuel economy. Autospeed did a great series of articles on forward facing intakes and the clearly quantified the fuel economy benefits. It seems their site is down at the moment but as soon as its up again I'll post the links.

Strainer keeps the larger debris out of the airbox.
https://farm3.static.flickr.com/2322/...74e4d3300e.jpg

Sealed 3.25" tube from the headlight bucket to the airbox.
https://farm3.static.flickr.com/2144/...08ed19ab8d.jpg

There is no way for hot air from the engine bay to enter the intake track even at a stop light. The aluminum intake manifold stays at ambient air temperature even when the engine is at operating temperature.
https://farm3.static.flickr.com/2018/...75e5efed22.jpg

The name of the game is to reduce the pumping losses ahead of the throttle body as much as possible. There is nothing you can do about what happens after the TB. Some people seem to think that pumping losses only happen behind the TB. They are wrong. Feeding the engine the coldest, densest air possible will yield the best fuel economy.

omg no,

The importance of getting an intake is that it replaces the slinky dryer hoses from the factory. Putting a cotton filter on some crome tube and setting it on top of your still in take air box is not a cai.



a "Ram Air" introduces outside air from either the top or bottem by means of tube. It is still pretty much the stock set up meaning the filter is in the engine compartment.

HAPPY READING
Eliminating Negative Boost - Part 1
https://www.autospeed.com/cms/A_0629/article.html
Eliminating Negative Boost - Part 2
https://www.autospeed.com/cms/A_0637/article.html
Eliminating Negative Boost - Part 3
https://www.autospeed.com/cms/A_0646/article.html
Eliminating Negative Boost - Part 4
https://www.autospeed.com/cms/A_0652/article.html
Eliminating Negative Boost - Part 5
https://www.autospeed.com/cms/A_0663/article.html

Negative Boost Revisited, Part 1
https://www.autospeed.com/cms/A_107824/article.html
Negative Boost Revisited, Part 2
https://www.autospeed.com/cms/A_107825/article.html
Negative Boost Revisited, Part 3
https://www.autospeed.com/cms/A_107826/article.html
Negative Boost Revisited, Part 4
https://www.autospeed.com/cms/A_107827/article.html
Negative Boost Revisited, Part 5
https://www.autospeed.com/cms/A_107828/article.html

Doing the Impossible
https://www.autospeed.com/A_109877/cms/article.html

Modifying the VL Turbo Intake
https://www.autospeed.com/cms/A_0779/article.html

Into the Intake - Part 1
https://www.autospeed.com/cms/A_1361/article.html

We Have a Record!
https://autospeed.com/cms/article.html?&A=109217[/QUOTE]

LOL