MAF location

[jhandy]

With all the talk about oil and MAF damage, I was wondering if moving the MAF can be done.

I would like to move it because it is in the way of a custom design that I want to do with the intake tube.

Can the MAF be located closer to the throttle body?

[blue2000s]

The MAF measures air velocity at a point and through tuning, the designers were able to translate that into an air volume flow rate that is used to estimate how much fuel should be injected into the cyliners. The airflow through that section of tubing is important to the accuracy of the flow speed to flow rate conversion. There are so many variables involved that there's no way to tell if the car would run exactly the same if you move the MAF or not. Everyone who adds a new intake to the car also messes with the flow through the MAF tube a little, but the car sounds like it's still pretty happy with the results.

[Paul]

I've heard that it needs to be within 12" of the throttle body. Try to move it and closer and tell us what happens.

[jhandy]

Ok i did more research on the subject, and the consensus is that the MAF needs laminar air flow. This is done one of two ways. Inside the OEM air box there should be a screen, this screen makes the air flow laminar and thus provides a solution.

The other solution is to have at least 12 inches of strait pipe before the MAF to produce laminar air flow.

So for people like me that have a aftermarket setup, moving the MAF close to the throttle body, just before the last turn, should produce ideal flow.

So....surely some of the more dedicated guys out there have already tested this and have come up with data from dyno testing.......Raby, Navarro......anyone try this?

[insite]

if you move it a lot, you will probably have to tune it a bit to compensate. the OEM locations are RIGHT by the air boxes & RIGHT by some sharp angles. screen or no screen, the air will still be fairly turbulent.

that having been said, when i installed my 3.4L, i had to rip out the entire factory intake system & go with a custom setup that would give my DME some readings similar to the 996.

the MAF housing from the older (E39) 5 series BMW. the 540i housing is perfect for the 3.4L (it's 3.5" like the 996) and the 535i is perfect for the 2.5L/2.7L (3").

i put a boxster MAF into the housing & plumbed silicone from the air inlet on the side of the car to the throttle body. since the 3.4L's throttle body is canted over toward the right side of the car, i had to cut a 135deg elbow to make turn.

all the larger tubing you see is 3.5" and the smaller tubing is 3.25". the different size tubing is used because the 996 throttle body is 3.25", but the MAF housing is 3.5". FYI, i bought the MAF housing from someone on bimmerforums.com for like $20.

[chaudanova]

Originally Posted by insite

if you move it a lot, you will probably have to tune it a bit to compensate. the OEM locations are RIGHT by the air boxes & RIGHT by some sharp angles. screen or no screen, the air will still be fairly turbulent.

that having been said, when i installed my 3.4L, i had to rip out the entire factory intake system & go with a custom setup that would give my DME some readings similar to the 996.

the MAF housing from the older (E39) 5 series BMW. the 540i housing is perfect for the 3.4L (it's 3.5" like the 996) and the 535i is perfect for the 2.5L/2.7L (3").

i put a boxster MAF into the housing & plumbed silicone from the air inlet on the side of the car to the throttle body. since the 3.4L's throttle body is canted over toward the right side of the car, i had to cut a 135deg elbow to make turn.

all the larger tubing you see is 3.5" and the smaller tubing is 3.25". the different size tubing is used because the 996 throttle body is 3.25", but the MAF housing is 3.5". FYI, i bought the MAF housing from someone on bimmerforums.com for like $20.

Hey Insite, what kind of filter/shield is that?

[insite]

It's a bmc dia 85-150

[Paul]

My 3.6 has the same air filter.