I have established that I am making myself a homebrew version of a Cold Air Intake System, since the leading brands cost nearly $250 for something that should cost about $150.
I'm mainly looking for anyone else whom has created a homebrew or has GOOD suggestions on piping sizes or a good Cone filter to use.

 

What vehicle.
You can go on ebay and get a couple different cold air kits cheap and fab up a system that will look and work for you.
[align=right] [/align]

 

Haha, ironic. I was just searching on Ebay and I found plenty that fit my 2003 Dodge Dakota Quad Cab 3.9L, but something just doesn't seem right. $13.99 for an entire kit? the Filter itself costs about $60.00 at any automotive shop, not to mention the other piping supplies... Can anyone confirm if this link provided is of a true cold air intake system or not?

http://cgi.ebay.com/ebaymotors/97-03...spagenameZWDVW
http://cgi.ebay.com/ebaymotors/97-00...spagenameZWDVW

Thank's for any input!

 

Sometimes they get you on the shippng.

 

It does not come with the throttlebody hat,but depending on the system and your throttlebody it may not need one.
Keep in mind you get what you pay for as far as quality goes,I got one for my wifes dakota and it was the dual filter style and the chrome is pitting on it.

 

The first key idea
is to do some 'before' tests
of acceleration, IAT sensor reading of temperature
and MAP sensor reading of pressure.

The 'foundation' on which air intake mods should be judged is:
does it improve acceleration,
lower IAT temperature and
increase MAP pressure?

Internal pipe sizes of 90 mm or more for your CAI are fine
especially when you consider the 5.7 V8 throttle body is this size.

More important is the 'surface area' of the filter used
and this can be found only by measuring the filter area
and you will quickly find that more pleats = more area
and paper filter are generally much bigger than KN like oiled-gauze cotton
which has less surface area and quickly clogs up compared to paper.

Spend some time reading this older study by some Duramax owners
who pooled their money and had an independent lab test filters:

http://home.stny.rr.com/jbplock/ISO5011/SPICER.htm

in the many graphs the key item is how the filter behaves as it gets some dirt on it and begins to clog.
the oiled-cotton and foam filters start out with slight advantages in flow but quickly lose that advantage.

more info in old posts below:

 

Page 415 of the Bosch Automotive Handbook, 5th edition

http://tinyurl.com/yplr3d

has the two equations you need
to see how horsepower and torque change
when either temperature or pressure change.

For temperature the offical equation
used by Americans (SAE) Europeans (ISO) and Japanese (JIN)
is:

{ Temperature Before + 460/Temperature After +460} raised to exponent 0.6

you need a scientific calculator to do this
but there is one built into every Windows computer
under Start...Accessories

As an example,
say that your re-locate your air inlet to a spot where the air temperature
drops to 80 degrees
when before the air coming in had been 100 degrees.

{100 +460 divided by 80 + 460} raised to exponent 0.6

={560/540} raised to exponent 0.6

= {1.037} raised to exponent 0.6

= 1.022

You mulitply this number times your horsepower or torque
so if your engine.
If your engine makes 230 hp at peak
1.022 times 230 = 235 horsepower with the 20 degree lower air temperature.

You may have heard the 'Rule of Thumb' that each 10 degree F reduction in air
temperature improves horsepower by 'about' 1% and the equation above is where
that comes from, but is more accurate

For corrections when the pressure changes
the following equation is used:

{absolute pressure after/absolute pressure before} raised to exponent 1.2

As an example
say that the weather is changing where you live
and one day the weatherman says the pressure is
29.5 inches of Mercury as a stormy "Low" passes over
then the next day a clear sky "High Pressure Area" passes over
and the pressure rises to 30 inches of Mercury

{30/29.5} raised to exponent 1.2
{1.0169} raised to exponent 1.2
= 1.0204

It is important to realize
that built right into your engine
are IAT (intake air temperature)
and MAP (manifold air pressure)
sensors.

Your IAT and MAP sensor outputs can tell you whether an aftermarket air intake
has helped or hurt your power output. You can read these sensors
yourself by using an OBD-II scanner, or a cheap electrical multimeter.

You are correct to suspect that most CAI's
only make more noise and have flashy colored parts.

Want confirmation about this from a CAI manufacturer?

Well right now KN Filters is running an advertisement in the various hot rod
magazine saying that a typical paper air filter from the factory creates a
restriction of about 2.8 inches of water....and when this filter gets really
dirty the restriction rises to about 12 inches of water restriction. The KN
advertisement has a dyno graph showing that this can cause about 11 hp power
loss on a high horsepower engine.

The pressure of the air around us is about 404 inches of water
so KN Filter is saying that the pressure is changing from
404 - 2.8 = 401.2
to a new pressure of
404 - 12 = 392 inches of water

Play around with the equations above
and you can find out what the actual horsepower of the engine KN was using
was....and then confirm it by looking at the dyno graph in the advertisement.

 

Two great American brothers
with only high school educations
had a DIY project
that they eventually called the 'Airplane'
but like the Wright Brothers
you need to do your DIY project with careful testing.

If you want a real answer you can trust about an air intake design,
then........

Go down to Sears and buy one of the $30-70 multimeters with the temperature
probe. Sometimes they are on sale for $19

http://www.sears.com/sr/javasr/produ...seBVCookie=Yes

or

http://tinyurl.com/ywcsxv

http://s7.sears.com/is/image/Sears/0...=2.56&fmt=jpeg

Later you can use this relatively cheap multimeter and its Type K thermocouple
to 'balance' your exhaust gas temperatures by swapping around the highest
flowing fuel injectors to the highest flowing intake ports....but that is
another story.

Then buy one of these $30 gauges that can measure low pressures and buy a
length of plastic tubing about 10 feet long to attach to it:

http://flw.com/olash2.htm#1490

Get the 30/30" pressure model.

If you don't want to spend this money you can also make a simple "U tube
manometer" with just a 20 foot length of clear plastic tubing and a yardstick:


Now drill small 1/16 th inch diameter holes in your stock air filter housing
and air inlet tubing,
like at:

1. at the begining of the inlet tube
2. in front of the air filter element
3. behind the air filter element
4. near the throttle body connection

Put a fresh new air filter element in your stock filter box. Go out on a road
with little traffic and measure the temperature and pressures at your small
hole test points of the stock system when the engine is at wide open throttle
through the 2000 to 6000 rpm range.

If you find between two points that the temperature goes up, then the air is
picking up heat in that length between the two points. (i predict you won't
find much heat pickup)

If you find that the pressures go down between two points then there is
restriction in that section, like across the filter element ( i predict you
will only find a small restriction across the paper element of the filter)

Now try moving the air inlet to the stock filter box from its stock location
to other places - like the grille top or bottom. Look for a place where the
pressure is highest and the temperature is lowest. (I predict you will find
that the cavity behind the firewall and below the windshield will be best -
this is also where your air vents pick up air to ventilate the truck's cabin)

Now, if you are a bit more adventurous try the following experiment:

With all the stock air system in place, put the truck in 2nd gear and measure
with a stop watch how many seconds it takes to accelerate from 3000 rpm to
6000 rpm with wide open throttle. Do this test 3 times and average the
result.

Now if you are a little more daring and have found a clean road with little
dust in the air, think about doing the following 2 tests (it is optional but
informative)

Do the same test from 3000 to 6000 rpm, but with the paper air filter removed
from the box, and the box closed back up. This is the 'no filter but cool air
pickup' test.

Then do the same test, but with the air intake system removed and the throttle
body opening sucking the hot air from underneath the hood. This is the 'no
filter hot air pickup test.'

{The above tests sound dangerous without an air filter, but I can tell you
that many highway patrol officers removed the air filters on their cars in the
1970s. I have personally seen people pour uncooked rice down carburetors to
scour out carbon deposits. Lack of an air filter over long periods will cause
the bore walls and piston rings to wear out much quicker, but a quick test has
little effect unless you are unlucky enough to get a large chunk of something
down the throttle. If you are worried you can cover the throttle opening with
some eighth inch hole window screen material or mesh stocking}

Now go order the aftermarket air inlet systems of your choice and repeat the
pressure, temperature and 3000-6000 rpm acceleration tests in 2nd gear. Send
back the systems that don't do as well as the best for a refund of your money.

Report your results to automotive forums.
You will be a hero to some,
the worst possible news to others selling junk.

 

airram.com check out the spectra, and read the about us link. looks good to me $139 cai

 

I fabricated a cold air intake for my 07.5 Ram.

Please look at http://www.gorowan.com/2007ram/mods/...l#air%20intake