Cold Air Intake

2000WHITEGMC · December 8, 2007

I have a 2000 GMC Z71 w/5.3L, and I want to get a cold air intake but have a hard time justifying the money for one. Has anyone ever rigged one up. Looks like all they do is take the lid off the airbox, switch the tube, and put on a different filter. If anyone has any ideas I would appreciate it.

wlvrn1215 · December 8, 2007

well just removing the lid or using a system that has an open element defeats the purpose of a CAI. The hot air from your engine compartment is going into your intake...your stock air box flows more than enough air for your engine and provides cooler air that the open element systems...sure changing the tube will help due to all of the baffles in todays intake tubes. Go with a drop in quality filter, and a nice mandrel bent alum. tube. Plastic tends to heat up the air charge. Just my $ .02

Schmids5.3l · December 8, 2007

If I were to do a custom air intake, I'd just get an air raid intake tube for $100 and panel filter of choice. I'd think metal would soak heat faster than plastic, but I After a few minutes of driving around it really wouldn't matter, they would both be hot

wlvrn1215 · December 8, 2007

the only thing i dont like about the plastic ones is that they have a seam and when and if they get really hot...could seperate..but either way a free flowing tube is the way to go

Silverado4x4 · December 10, 2007

the only thing i dont like about the plastic ones is that they have a seam and when and if they get really hot...could seperate..but either way a free flowing tube is the way to go

If things are going to get that hot to melt the plastic seam then there are more things to worry about then the plastic tube.

bksavs · December 10, 2007

A guy at work made his own. He bought a filter at auto zone. then fabricated his intake tube out of 3 inch pvc pipe. Any hardware store will have the elbows and pipe cement uyou need. $100 for a tube????!!!! try $20.

wlvrn1215 · December 12, 2007

well to each is own....

wlvrn1215 · December 12, 2007

the only thing i dont like about the plastic ones is that they have a seam and when and if they get really hot...could seperate..but either way a free flowing tube is the way to go

If things are going to get that hot to melt the plastic seam then there are more things to worry about then the plastic tube.

what i meant was that the plastic tends to absorb the heat more than the alum. ones

jnpaddison · December 12, 2007

In thermal physics, heat transfer is the passage of thermal energy from a hot to a colder body. When a physical body, e.g. an object or fluid, is at a different temperature than its surroundings or another body, transfer of thermal energy, also known as heat transfer, occurs in such a way that the body and the surroundings reach thermal equilibrium. Heat transfer always occurs from a hot body to a cold one, a result of the second law of thermodynamics. Heat transfer can never be stopped; it can only be slowed down.

Convection is a combination of conduction and the transfer of thermal energy by fluid circulation or movement of the hot particles in bulk to cooler areas in a material medium. Unlike the case of pure conduction, now currents in fluids are additionally involved in convection. This movement occurs into a fluid or within a fluid, and cannot happen in solids. In solids, molecules keep their relative position to such an extent that bulk movement or flow is prohibited, and therefore convection does not occur.

Convection occurs in two forms: natural and forced convection.

In natural convection, fluid surrounding a heat source receives heat, becomes less dense and rises. The surrounding, cooler fluid then moves to replace it. This cooler fluid is then heated and the process continues, forming a convection current. The driving force for natural convection is buoyancy, a result of differences in fluid density when gravity or any type of acceleration is present in the system.

Forced convection, by contrast, occurs when pumps, fans or other means are used to propel the fluid and create an artificially induced convection current. Forced heat convection is sometimes referred to as heat advection, or sometimes simply advection for short. But advection is a more general process, and in heat advection, the substance being "advected" in the fluid field is simply heat (rather than mass, which is the other natural component in such situations, as mass transfer and heat transfer share generally the same equations).

In some heat transfer systems, both natural and forced convection contribute significantly to the rate of heat transfer.

To calculate the rate of convection between an object and the surrounding fluid, engineers employ the heat transfer coefficient, h. Unlike the thermal conductivity, the heat transfer coefficient is not a material property. The heat transfer coefficient depends upon the geometry, fluid, temperature, velocity, and other characteristics of the system in which convection occurs. Therefore, the heat transfer coefficient must be derived or found experimentally for every system analyzed. Formulae and correlations are available in many references to calculate heat transfer coefficients for typical configurations and fluids.

Thermal insulators are materials specifically designed to reduce the flow of heat by limiting conduction, convection, or both. Radiant barriers are materials which reflect radiation and therefore reduce the flow of heat from radiation sources. Good insulators are not necessarily good radiant barriers, and vice versa. Metal, for instance, is an excellent reflector( via forced convection) and poor insulator ( via natural convection)

The effectiveness of an insulator is indicated by its R- (resistance) value. The R-value of a material is the inverse of the conduction coefficient (k) multiplied by the thickness (d) of the insulator. The units of resistance value are in SI units: (K·m²/W)

Rigid fiberglass, a common insulation material, has an R-value of 4 per inch, while poured concrete, a poor insulator, has an R-value of 0.08 per inch.

The effectiveness of a radiant barrier is indicated by its reflectivity, which is the fraction of radiation reflected. A material with a high reflectivity (at a given wavelength) has a low emissivity (at that same wavelength), and vice versa (at any specific wavelength, reflectivity = 1 - emissivity). An ideal radiant barrier would have a reflectivity of 1 and would therefore reflect 100% of incoming radiation. Vacuum bottles (Dewars) are 'silvered' to approach this. In space vacuum, satellites use multi-layer insulation which consists of many layers of aluminized (shiny) mylar to greatly reduce radiation heat transfer and control satellite temperature.

Basically the argument of plastic vs. metal is mute - buy it for cost / looks , assuming the routing is the same - ambient temperature will be met between the two will be imperceptible by your generic motor head ..

( Incoming air temp, humidity, atmospheric pressure and sea-level, octane level … yada yada yada )