I was wondering if anybody has ever do a homemade CAI for the 3.7l's?? i was thinking about doing this myself, but i dont know where to start! thanks in advanced!
:wtf: you lost me at working on the math.....Working on the math as to whether or not the Venturi Effect makes up for the air loss due to the bottleneck effect. Just posting as I go and I'll edit to finish it up (assuming I can work through all the variables). I will be basing calculations on the Spectre P4 Cone Filter (Item#8132) at sea-level at 20ºC.
Bernoulli's Principle states that the faster a fluid is moving, the lower the pressure. Therefore, fluid in areas of higher pressure will move towards the lower pressure of the faster moving fluid, causing an increase in fluid velocity.
The standard density of air (p) at 20ºC is 1.2kg/m³
Bernoulli's Principle Formula - (p₁-p₂) = [(p/2)(v₂²-v₁²)] where p=density of the fluid, v₁ is the slower velocity (before bottleneck), and v₂ is the faster velocity (into throttle body).
Replacing p with d to differentiate between pressure and density. p₀ becomes the pressure of 1 atmosphere.
(p₁-p₂) = [(d/2)(v₂²-v₁²)]
At the surface of the earth air pressure is equal to 1.01x10⁵ N/m²
p₀ = 101000
d = 1.2
p₁ = [(101000-p₁) = (.6)(v₁²-0)]
.......v₁ = velocity of incoming air at WOT
p₂ =
v₀ = 0
v₁ =
v₂ =
Difference In Pressure
(p₁-p₂) = (1.2/2)(v₂²-v₁²)
(p₁-p₂) = (.6)(v₂²-v₁²)
The formula for the Venturi Effect is - Q = (A₁)√{[(2)(p₁-p₂)]/[(p)(A₁/A₂)²-1]} = (A₂)√{[(2)(p₁-p₂)]/[(p)(1-(A₂/A₁)²]}
where A₁ is the area of the pipe before the bottleneck and A₂ is the area entering the throttle body, and Q is the volumetric flow rate.
A 3" PVC pipe (3.5" including sidewalls) is already a squeeze under the hood so I'll use that over a 4" pipe for the equations.
Non-Bottlenecked
Q₁ = (A₀)√{[(2)(p₀-p₁)]/[(d)(A₀/A₁)²-1]} = (A₁)√{[(2)(p₀-p₁)]/[(d)(1-(A₁/A₀)²]}
Q₁ = (A₀)√{[(2)(101000-p₁)]/[(1.2)(A₀/28.26)²-1]} = (28.26)√{[(2)(101000-p₁)]/[(1.2)(1-(28.26/A₀)²]}
A₀ = Area of the filter x % of air flowing through filter
Bottlenecked
Q₂ will represent the amount of air entering the throttle body using the bottleneck.
A₁ = 28.26
A₂ = 12.56
d = 1.2
p₁ =
p₂ =
Q₂ = (A₁)√{[(2)(p₁-p₂)]/[(d)(A₁/A₂)²-1]} = (A₂)√{[(2)(p₁-p₂)]/[(d)(1-(A₂/A₁)²]}
Q₂ = (28.26)√{[(2)(p₁-p₂)]/[(d)(28.26/12.56)²-1]} = (12.56)√{[(2)(p₁-p₂)]/[(d)(1-(12.56/28.26)²]}
Q₂ = (28.26)√{[(2)(p₁-p₂)]/[(d)(4.0625)]} = (12.56)√{[(2)(p₁-p₂)]/[(d)(.8025)]}
Q₂ = (28.26)√{[(2)(p₁-p₂)]/[(1.2)(4.0625)]} = (12.56)√{[(2)(p₁-p₂)]/[(1.2)(.8025)]}
Q₂ = (28.26)√{[(2)(p₁-p₂)]/(4.875)} = (12.56)√{[(2)(p₁-p₂)]/(.963)}
good info scott."Q: Why does AEM use aluminum for its intake piping?
A: Our Chief Engineer John Concialdi provides an explanation of the difference between Aluminum vs. Steel vs. Plastic in inlet piping:
The issue of heat absorption with an intake system has a degree of validity, however we have found that too much emphasis is placed on material selection, instead of the real issue of tuning the system. Our systems feature a unique shape and diameter because this is what we found to make the most useable torque and horsepower for each individual application in testing. However, for the purposes of this discussion, we will limit it to why we choose to make our systems from aluminum and the effects of heat absorption on all materials. If you do not wish to review all of this information right now, a quick synopsis of this discussion is outlined in the following bullet points, with complete topic discussions below:
We use aluminum to eliminate any chance of the system rusting, and it's lighter than steel
We limit our use of plastic because this material absorbs some of the sound energy we work to create in the inlet duct
Whether or not an inlet system is made from aluminum, steel or plastic, the thermal conductivity of the duct material has little effect on engine power
The rate at which air travels through the inlet path under open throttle, when one is asking the engine for maximum power, negates the effect of material heat soak, regardless of the material
We use aluminum—or a combination of aluminum and plastic plenums for throttle-body-injected applications that require a special plenum—for every intake we produce. This eliminates any chance of rust occurring on the inside of the inlet pipe. We have seen chrome-plated steel systems whose inner diameter became rusted over time, causing flakes of rust to travel along the inlet path. We also choose aluminum because of its lightweight properties. Heavier components place higher loads on the brackets they are attached to—or even worse, to the pipes they are attached to. We combine our lightweight aluminum design with a flexible coupling device we call a soft mount that connects the intake system to the body of the vehicle. In addition to the soft mount, we use doublers at the point where the mounting bracket is welded to the pipe for additional strength.
We limit our use of plastic because this material absorbs some of the sound energy we work to create in the inlet duct. Although we use the best plastic material for our plenums, it is still not as resilient and does not retain the visual appeal of aluminum over long-term use. Because we have to use plastic on throttle body applications, we take extra precautions to ensure that the aluminum retaining ring that attaches to the throttle body is anchored securely into the plastic plenum; this is done by making an interlocking mechanical link between the plastic and aluminum.
Whether or not an inlet system is made from aluminum, steel, or plastic, the thermal conductivity of the duct material has little effect on engine power. We have found that the tuning of the pipe, in addition to providing the coolest inlet air source, are the keys to making useable power. We perform engine inlet-air-temp studies when developing each application to determine the coolest location for sourcing inlet air. In addition to this, we determine the safest location for the inlet source to protect it from highly dusty conditions and water. To this end, we provide a stainless-steel heat shield to help minimize heat soak into the inlet area, as well as to provide protection from dust, dirt and mud.
At light throttle opening, air speed and airflow at the inlet system are relatively low. The high residence time of air in the inlet while at low-throttle settings will increase inlet charge temps when materials with high thermal conductivity are used. Typically, when someone is at light throttle they are not asking the engine to make power. Most likely, fuel economy is the issue.
When the throttle is fully opened however, air speed and airflow increase considerably. Typically, the inlet air speed of a 5.7L engine with a four-inch duct at full throttle is 34 feet-per-second, based on a volumetric efficiency of 70% and an engine speed of 3,000 rpm. Most inlet systems for every intake manufacturer for this engine are 30 inches or less. This means that the air in the duct of a 30-inch inlet length on this engine at the given rpm is 1/10th of a second—hardly enough time to transfer an appreciable amount of heat into the air stream on any system.
Basically, the rate at which air travels through the inlet path under open throttle, when one is asking the engine for maximum power, negates the effect of material heat soak, regardless of the material. We hope that this helps to clear up the issues of material heat absorption in intake systems."
So...pretty much what that is saying is this......the amount of time that charge air spends in the iping...1/10th of a second....no heat is gonna be transferred to the air. Also....I am a metallurgist and work in the aluminum industry. The time it would take to heat the entire piping up while it is being cooled by charge of air moving through it is pretty crazy. Youd pretty much have to be idling for days. there are also ways to combat any heat soak that many "think" occur...or have "read" that occur. There are plenty of simple spray on coatings for that. And please do not use PVC piping.......leave that to the sewer guys. PVC has a very low melt point...which means over time it will deform and become brittle...it is not made to withstand any heat...especially engine temps. Not to mention the TOXIC fumes it releases when heated........
If you're referring to the Venturi thing then I think there's def an advantage to be had with that design you linked.So if it abrupts the air flow and people still do it...it must do something. Is it proven or is it just a feel good butt dyno thing?