Info on the MAF and custom intake

[TGX4776]

As some of you guys know I will be putting in a hood scoop CAI. The problem is that I have a MAF. I need to know more about the MAF and how it works on a BD GT. If anybody knows or knows of a resource that I can use that would be much appreciated. I need to calculate the length of piping needed in order to have the MAF work properly. I'd like to do this before I purchase the parts.


Thanks

[anothernord]

I have had lots of experience messing with MAF location and piping stuff. I can say that the MAF is pretty versatile in a N/A application.

That said, you want to have as much straight, smooth pipe as possible before and after the MAF to get a smooth voltage curve when the throttle opens. You don't want to have the MAF too close to the IACV inlet or breather lines, or else you'll lose the laminar flow that you need.

I couldn't tell you how to calculate the distance you need, other than to make it as long as possibly within your design constraints. But if you want my personal opinion, I would say that you should have at least 4" of straight, smooth piping after the MAF before making any bends.

[TGX4776]

^^^^^ so should I do 4 inches minimum before and after the MAF sensor of straight pipe?

[anothernord]

^^^^^ so should I do 4 inches minimum before and after the MAF sensor of straight pipe?

Before; not 100% necessary, after; definitely. Especially close to the throttle body; it causes a lot of turbulence when it opens and closes.

But mostly just try and make the whole system as smooth as possible within the space you have.

[TGX4776]

ok thanks.

[TGX4776]

https://sl-i.net/FORUM/images/imported/2010/03/57e5815b-1.jpg

here is the filter I will be using. I notice a lot of people place it right after the filter. if I place it right after a 180 degree bend but have a 4in straight after would that work just as well?

[anothernord]

That setup should work fine. In the future, you could replace the flex-pipe with aluminum for even better flow and more power.

[TGX4776]

I wil start off with aluminum. I am going to get it done when I get my exhaust done. In the image it appears that the breather lines and IACV are connected to the air filter box. am I correct in thinking this and will it work?

[anothernord]

I wil start off with aluminum. I am going to get it done when I get my exhaust done. In the image it appears that the breather lines and IACV are connected to the air filter box. am I correct in thinking this and will it work?

The breather lines and IACV lines must come in AFTER the MAF, otherwise the car will not run at all. You can probably have 2 bungs welded on the pipe right after the MAF before the throttle body to connect them.

[TGX4776]

thats what I thought. It should also be after the 4 in straight? or can I place them in there?

[anothernord]

thats what I thought. It should also be after the 4 in straight? or can I place them in there?

I would just put them as close to the throttle body and as far away from the MAF as possible. It looks like you should have enough space.

[TGX4776]

right thanks alot.

[anothernord]

right thanks alot.

Don't forget some rubber caps to seal off where the old bungs on the filter box. The reason they were there was because the intake was designed for a MAP-based car.

[green97gt]

pics when your setup is complete plz.

[TGX4776]

sure thing. Here is a before
https://sl-i.net/FORUM/images/imported/2010/05/4580027746_d5da89853e_b-1.jpg


A little worried about fitting the filter box in there.

[green97gt]

^ stock like a mofo. :lol:

looks like mine. only thing ive done is remove the silencer that sticks forward from the plastic intake tubing.

previous owner put red spark plug wires on it...whooo fancy.

EDIT: well, ive been elbow deep in it, swapped motors etc. but its still bone stock.