Intake Definitions



From Nissan 350Z & 370Z Wiki

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Contents

Plenum

The plenum is the chamber located between the runners of the intake manifold and the throttle body (on top of the engine). The OEM plenum is actually made of 2 parts: lower and upper. It has been shown through countless tests that increasing the internal volume of the plenum yields significant horsepower (up to 20hp!). This can be achieved by either:
  1. Installing a plenum spacer
  2. Installing an aftermarket upper plenum
  3. Custom machining work on the lower plenum

Manifold

In generic terms, a manifold is a device designed to distribute gases evenly from a common opening to multiple openings via runners. In the case of an intake manifold the inlet charge is drawn from the plenum and distributed to the inlet ports of the cylinder heads. The exhaust manifolds inversely gather the spent gases from each individual exhaust port and merge them together into a single opening leading to the rest of the exhaust system.

Cold Air Intake (CAI)

As the name implies, a cold air intake is designed to bring cold air into the engine intake rather than sucking in the hot air from the engine bay. This is sometimes a very misleading concept as the OEM airbox is indeed somewhat of a cold air intake. It shields the air filter from the hot engine bay and funnels air from in front of the radiator. However, when someone mentions "cold air intake," they are generally referring to any number of after market intake components.
A True cold air intake will come with piping, hardware, and a filter (cone type usually). The piping will route the air from outside of the engine bay, either from in front of the wheels or radiator into the throttle body.

Throttle Body

A device containing a valve controling airflow into the plenum. The opening and closing of the valve is controlled by the driver via the accelerator pedal. In a standard vehicle the accelerator pedal is connected directly to the butterfly valve through a series of linkages. In the case of the Z/G the valve is controlled electronically (also known as Drive By Wire).

Z Tube

The Z Tube is the plastic piping running between the OEM airbox / MAF sensor up to the throttle body. The term was derived by the G35 crowd as their intake tube is designed with resonators and their have been power gains seen by swapping to the..... Z Tube.

Filter

The filter is located inside the Air Box. It serves to filter out any contaminates that might be in the air or sucked into the intake including: dust, dirt, leaves, grass, bugs, etc.. The OEM filter is made of paper and is very restrictive. Simply changing this out for a QUALITY aftermarket filter can provide a few extra horsepower. A low quality filter will let contaminants pass through and into the engine. Over a long period of time this can lead to problems.

Ram Air

Ram air is an intake concept that has been around since the muscle car days. This type of intake is designed so that while the car is moving air is forced or "rammed" into the intake system. This can be achieve in any number of ways and the affects are not easily quantifiable. This type of modification can not be accurately dynoed.

Short Ram

A short ram is more of a clever marketing term than a technical one. Typically a short ram is an aftermarket intake solution that draws in air from within the engine compartment, as opposed to air from outside of the engine compartment (as is the case with both the stock induction system and aftermarket CAI units). The short ram concept somewhat defeats the purpose of trying to get colder air into the engine, and often times the Short Ram intakes are mislabeled as Cold Air Intakes (which they are not).

Air Box

The portion of the OEM induction system which houses the air filter. The airbox is also the inlet to intake system and incorporates a resonance chamber into it’s design to suppress intake noise during operation. It also acts as a heat shield to the air filter preventing the intake of hot air from the engine bay.

MAF

MAF stands for mass airflow and pertains to a style of fuel injection, more specifically type of air meter. For the ECU to accurately inject the correct quantity of fuel, it must know the amount of air entering the engine. A MAF bases system utilizes a MAF sensor to measure the amount of air passing through it. This is accomplished by heating a wire to a specific temperature. From there the ECU will provide whatever voltage is necessary to keep the wire at that temp. Obviously the more air rushing over the wire, the more it will cool off. The more it cools off, the more voltage is required to keep it warm. By measuring the voltage that is being supplied to the MAF sensor the ECU can accurately gauge the air entering the engine. The VQ series engines make use of a MAF setup.

MAP

MAP stands for manifold absolute pressure, and like MAF, is a type of system used for electronic fuel injection. Instead of measuring the air entering the engine, a MAP sensor measures the pressure of the air in the intake manifold or plenum. From this (and other) measurements correct fuel ratios and ignition timing are calculated. MAP is the standard method used by Honda. Furthermore some tuning houses prefer to work with MAP based systems and have converted highly modified forced induction tuned Zs and Gs to the MAP format using aftermarket fuel management solutions.
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