Intake diameter and airflow question

[Kevin Thomas]

If your Maf sensor and throttle body's diameter is smaller than the diameter of your intake, what is the affect of this on your Maf sensor calculations, air/fuel ratio readings and hp/torque?

Ex: A Maf sensor and throttle body has a diameter of 2.75". The intake you have installed has a diameter of 3". I know that the airflow should slow down after the Maf sensor since the diameter of the intake is bigger.....slowing down the airflow velocity. The thing is, the throttle body diameter goes back to the same size as the Maf sensor opening. I'm wondering if this is detrimental to performance of your engine.

Will this cause you to run lean/rich? Can it throw off the Maf sensors calculations? Does the airflow get affected reducing or increasing hp/torque? Just trying to learn something here.

[XT6Wagon]

It can throw off the reading, more due to the different flow before and after. A K&N cone + smooth pipe after will have the same air flow "quality" as a factory air boxl and rough pipe.

I would not worry about the diamiter much as long as you have the power band where you want it.

[ImprezaRS dot com]

The MAF is actually a small part inside the black plastic tube that we call the MAF. All the MAF cares about is that the tube diamter it is bolted in stays the same, i.e. you could unscrew the MAF sensor from the black plastic pipe it resides in and move it to a pipe of different size and it would be a problem, but to move the whole unit to a different size pipe wont affect it. The MAF is metering the air through that one small section of known diamter pipe it resides in.

Still wondering if your A-SAFC is wired into the O2 sensor or the MAF signal.

Larry

[XT6Wagon]

Impeza RS, the pipes before and after DO have an affect on the MAF's ability to measure the air correctly. If in the stock setup the air is comming off of a 90 degree bend, that is also "flattened" it will have a far different velocity profile through the MAF than one that is straight through. Many cars "learn" a new calibration by refrencing the O2 sensor, and others are simply close enough that it doesn't matter.

[Joe Alejandro]

Originally posted by ImprezaRS dot com
The MAF is actually a small part inside the black plastic tube that we call the MAF. All the MAF cares about is that the tube diamter it is bolted in stays the same, i.e. you could unscrew the MAF sensor from the black plastic pipe it resides in and move it to a pipe of different size and it would be a problem, but to move the whole unit to a different size pipe wont affect it. The MAF is metering the air through that one small section of known diamter pipe it resides in.

Still wondering if your A-SAFC is wired into the O2 sensor or the MAF signal.

Larry

So if you do unscrew the little unit out, what happens to the screening that comes with the whole thing? I heard that if you remove the screen in the MAF, it'll cause problems.