Laminar flow at the MAF or turbulent?

[FNK]

I am in the process of designing a Ram air/more efficient intake and I need to know if the turbulence of the air flow true the MAF can impair the reading of the MAF?

Because on the stock intake, the MAF is located just after the air filter, so the value read by the MAF is around the average velocity of the air flow, while a long CAI tube will generate a laminar flow, so the speed of the air at the center will be around twice the average velocity. This is a reason why some manufacturer use a screen right before the MAF.

But what about the Motronic Ecu... will it adapt!?

[Cristisor]

I read a little bit about the MAF design and functioning and it looks like the MAF has a sensitive surface that is being heated. Next the sensor checks the temperature of the surface to see how much it has been cooled by the intake air, and depending on this new value the sensor decided how much air made it past the MAF. Of course that the speed of the air must be taken in consideration because a higher speed means colder air. I hope that this info can help you.

[somebody5788]

Keep in mind the A4 MAF's do have a screen in front of them. Though not much of one, it does exist.

[FNK]

@Cristisor : Yes it helped, I didn't taught about reading on the way it works.

@somebody5788 : I will look at mine, but I've cleaned it a couple of time and I never saw a screen... maybe I removed it and I don't remember, but on mine I don't think theres one.

It look like this one;


Well most, if not all, the images of MAF from Audi on google image use a screen... I guess mine was removed...
A laminar flow reduce the pumping losses, thus increasing the volumetric efficiency of the engine.

[lespaulkid01]

Hah. what a coincidence, I JUST finished typing up a lab report on volumetric flow rates, Laminar vs Turbulent flow regimes, and Reynold's number.

This might help some.. im not completely sure but I think it may also depend on where exactly the position of the MAF is within the system.

http://www.v6performance.net/forums/...lent-flow.html

[somebody5788]

@Cristisor : Yes it helped, I didn't taught about reading on the way it works.

@somebody5788 : I will look at mine, but I've cleaned it a couple of time and I never saw a screen... maybe I removed it and I don't remember, but on mine I don't think theres one.

It look like this one;


Well most, if not all, the images of MAF from Audi on google image use a screen... I guess mine was removed...
A laminar flow reduce the pumping losses, thus increasing the volumetric efficiency of the engine.

Oh, hmm, I guess it's a 2.8 thing

Edit: read the end of your post lol and then also realized you do have a 2.8. Some people seem to think removing this screen that hardly stops any air will increase power. But it doesn't...

It is also possible that there is a revised version now and you have an original

[somebody5788]

http://forums.audiworld.com/showthread.php?t=233755

Might find this interesting, it's the first I've seen it. I would think of trying some of this except that I am going to be MAF less soon with the 034EFI on my supercharger.

If you just want to push your N/A a little more you can get a VR6 MAF and adapt it. It's 3.5" (I have been told, prove this first), I would accompany it with a nice cone filter and a heat shield. http://www.ecstuning.com/Volkswagen-...Mass_Air_Flow/ Then watch it with VAGCOM. The ECU should easily be able to correct for the added air but if not you could add a Split Second piggy back thing for $250

[FNK]

Hah. what a coincidence, I JUST finished typing up a lab report on volumetric flow rates, Laminar vs Turbulent flow regimes, and Reynold's number.

This might help some.. im not completely sure but I think it may also depend on where exactly the position of the MAF is within the system.

http://www.v6performance.net/forums/...lent-flow.html

Hehe me too, Fluid mechanics!

Im really supposed to have a screen!
ECS LINK

A bigger MAF, bigger TB and tubing would help reduce head loss, but it would also reduce velocity. Reduce velocity would increase the pumping losses, so the gain would be counter productive. A good compromise would be a smooth transition to a bigger tube, then a smooth transition to the normal size, but the pipe is not long enaugh to be worth it. Also rounding all the sharp edges would help reduce the pressure drop.

So In the end the answer was answered! The MAF should have a laminar diffuser right before sensor to read the Average intake velocity. So I need a maf, or a screen that fit... Damn you knowledge!

[somebody5788]

Hehe me too, Fluid mechanics!

Im really supposed to have a screen!
ECS LINK

A bigger MAF, bigger TB and tubing would help reduce head loss, but it would also reduce velocity. Reduce velocity would increase the pumping losses, so the gain would be counter productive. A good compromise would be a smooth transition to a bigger tube, then a smooth transition to the normal size, but the pipe is not long enaugh to be worth it. Also rounding all the sharp edges would help reduce the pressure drop.

So In the end the answer was answered! The MAF should have a laminar diffuser right before sensor to read the Average intake velocity. So I need a maf, or a screen that fit... Damn you knowledge!

Don't worry about velocity. That's what the runners in the intake are for! (link) The short runners for high flow and long runners for increased velocity. You can go as big as you want at the MAF =D

Although I'd want the transition from the 3.5" MAF to the 3" inlet to be a nice smooth tube.

I feel like this could gain more then anything else would on a 30v 2.8 with out going forced induction.

[FNK]

Don't worry about velocity. That's what the runners in the intake are for! The short runners for high flow and long runners for increased velocity. You can go as big as you want at the MAF =D

Although I'd want the transition from the 3.5" MAF to the 3" inlet to be a nice smooth tube.

I feel like this could gain more then anything else would on a 30v 2.8 with out going forced induction.

I'll have to furter investigate on this, or at the very least find some sort of dyno graph that will prove this!
Smoothing everything and creating an effective heat shield for my intake would definitively help with some hp.
Step by step to my unrealistic 240hp NA goal!

In the mean time, the Screenless vs Screen MAF does make a difference LINK

[somebody5788]

Doesn't hurt to try the bigger MAF. Check out the PSC1, that would help to correct fuel trims in the event the ECU wasn't correcting enough ,or at least to make it do less work and not have to adapt as much after clearing codes.

90* 3.5" to 3" reducer to go into the throttle body http://www.siliconeintakes.com/produ...deb6e911099e69

You will need a way to connect the IAT sensor into the piping but that will not be very hard as it's a screw and about 3/16" circle hole for the sensor.

There is also this option http://www.siliconeintakes.com/produ...deb6e911099e69

Plenty of things you could do if you want to try out a little fabbing.

I say do it! I want to see your results!

I'd even fab it for you if you wanted to pay me hehe.

[FNK]

Great link!
I've been looking for those parts for a while only to find ebay stuff shipped from china.

The PSC1 is good, but I could just set new value with Vagcom for free.
The ARC2 seems like the right product!? You have the PSC1?

[somebody5788]

I suppose that would work. I am not using ant piggy back. But the supercharged guys like the psc1 I guess.

I hope to see some results lol