[baldlobo]

Originally Posted by Joeggernaut

Okay first let me say I know there are ton of wai vs cai threads but none of them seem to address new technologies and account for them. School me or provide your input on cai vs wai in the different applications.


This thread is only concerning mostly gasoline engines and applications.

Few definitions first:
Stoich:
The modern engine is trying to keep a 14.7 to 1 mass ratio of air to fuel.
Air

Stoich, is a ratio of fuel to oxygen that will allow fuel to ignite; now when it comes to modern engine controls; it depends on engine coolent temp, intake temp, map/maf, tps and o2.

Cold Air Intake (CAI):
A intake designed to draw cooler air from parts of the engine bay that are cooler than the factory design air intake draw air from. Often these are located near the bottom of the engine compartment where the air is not as hot.

most cold air intakes do not go down past the engine(because lower means water getting sucked up/hydrolocking/getting sued). "cold air" is subjective.

Warm Air Intake (WAI):
A intake designed to draw warmer air from parts of the engine bay that are hotter than the factory design air intake draw air from. Often these are located near the top or exhaust of the engine compartment where the air is hotter.

most engines from the 80 and earlier had some variation of this, to help with cold start issues(too much oxygen to fuel). Still questioning why they got away from thermac's for fuel injection.

MAF/MAP Sensor
MAF sensor: measures the amount of air flow in terms of volume. It does not measure the amount of oxygen entering the engine.
MAP sensor: measures the amount of air flow in terms of volume based on predetermined calculations based on air pressure/intake temps/etc. It is not exact or a direct approach like a MAF but it does not interfere with air flow and is cheaper to service/produce.

the only maf i've seen that interferes with airflow is the spoon type that ford used in the late 80's/early 90's

MAF systems use the same sensors to calculate air flow as the map does, just uses a different way to determine fuel; it's also an indirect method.

Camshaft profile
The profile of the camshaft lobes that allow how far a valve opens or closes. Think "how wide"

nope, the camshaft profile is when it open's and how long it stays open per cycle.

LIFT is how far the valve opens and closes

Camshaft phasing
The phasing or adjust of the camshaft angle to allow for changes in duration that a valve is open or closed. Think "how long"

Camshaft phasing is the change of camshaft timing in relation to it's static position; does not change duration

Valvetronic/VEL
BMW/Nissan designed actuators that allow for infinite camshaft profiles. This means the valves open as high or as low as they want based on engine conditions allowing. It eliminates the need for typical/old camshaft profile designs that are often bought by v8 grurus to increase horsepower.

This gives the engine ability to eliminate a butterfly valve completely since the valves can now control air intake. Throttle losses essentially become minimal and efficiency is increase in terms of MPG and Power.

Note: There is often still a butterfly valve present as a backup in-case the system fails so the car can be limped home but in normal operation it is always completely open.

might want to read this

AutoZine Technical School

Intake and exhaust cam phasing is adjusted meaning retarded or advanced to allow for shorter or longer durations the valves are open or closed.

nope; duration doesn't change, phasing a cam changes when it opens and closes(eg crankshaft rotates 720 for every 360 of the camshaft; phasing means a camshaft the opens at 208 normally would move 10 or more degrees +/- so 208 could end up phased at 198 or 218 depending on the computer)

School Me Part/My Theories (Provide input or ideas on each part):

Schooled