Maff screen remove? power gains?

[01STS]

Case in point. 2000 Vette with LS1. Had a lean issue on the dyno. No real mods other than cold air intake and catback and the screen removed for the stock mass air. Replaced the now junk mass air with a new stock unit at A/F ratios when back to normal and it picked UP another 8hp. So much for the screen trick.

[Ranger]

Proof positive that removing the air flow straightener does more harm than good.

[Raze]

I wanted to throw in a little tid bit, the TB screen, which has been called an air 'straightener' is incorrect. I'm only saying this as I happen to do research on among other things jet engine aerodynamics and if it were a 'straightener' it would look more like 'turning vanes' which actually alter the exit path of the flow with as little frictional losses as possible. Turning vanes look like small airfoils placed vertically next to each other to help reduce those losses around corners. The screen everyone is refering to is actually there to improve uniformity of the airflow inside the intake manfiold which provides a more uniform amount of air into each cylinder, thus reducing the chance for one cylinder having a more or less rich/lean mix.

Just wanted to make the clarification for everyone's benefit, not trying to step on any toes.

[eldorado1]

Originally Posted by Raze

I wanted to throw in a little tid bit, the TB screen, which has been called an air 'straightener' is incorrect. I'm only saying this as I happen to do research on among other things jet engine aerodynamics and if it were a 'straightener' it would look more like 'turning vanes' which actually alter the exit path of the flow with as little frictional losses as possible. Turning vanes look like small airfoils placed vertically next to each other to help reduce those losses around corners. The screen everyone is refering to is actually there to improve uniformity of the airflow inside the intake manfiold which provides a more uniform amount of air into each cylinder, thus reducing the chance for one cylinder having a more or less rich/lean mix.

Just wanted to make the clarification for everyone's benefit, not trying to step on any toes.

I hate to disagree with your disagreement, but I do.

The "screen" is there to create a laminar flow across the mass airflow sensor, which as previously noted is a heated wire. If the screen is not there, there will be swirling and turbulent air entering the MAF sensor, which will give erroneous readings as the air flows front and back and side to side, instead of straight across the wire.

There actually is no mechanical correction for airflow uniformity in regards to cylinder filling. Nor is there any need to be. In even the most perfectly designed system, one cylinder will always steal more air than the next. It's just the nature of the beast. However, with sequential fuel injection systems, this can be compensated for by altering the fuel trims for each individual cylinder. These can be seen in LT1 systems for instance - where at idle fueling can be different by 4% or more between cylinders.

[clarkz71]

The screens are indeed there to straighten, or smooth the airflow over the heated wire of the MAF sensor.

[Ranger]

Originally Posted by eldorado1

I hate to disagree with your disagreement, but I do.

The "screen" is there to create a laminar flow across the mass airflow sensor, which as previously noted is a heated wire. If the screen is not there, there will be swirling and turbulent air entering the MAF sensor, which will give erroneous readings as the air flows front and back and side to side, instead of straight across the wire.

There actually is no mechanical correction for airflow uniformity in regards to cylinder filling. Nor is there any need to be. In even the most perfectly designed system, one cylinder will always steal more air than the next. It's just the nature of the beast. However, with sequential fuel injection systems, this can be compensated for by altering the fuel trims for each individual cylinder. These can be seen in LT1 systems for instance - where at idle fueling can be different by 4% or more between cylinders.

That is exactly what our old Guru always said.

[Raze]

Guys, I wasn't disagreeing and you missed what I was saying so let me try to clarify. I was trying to differentiate 'straightening' flow vs create uniformity in flow also known as producing 'laminar' flow. I can see why what I said was misconstrued so give me a second and I'll explain. When you use the term 'straighten' in aerodynamics it usually refers to altering the direction of an air mass relative to whatever you're going to use it for downstream. As an example, in windtunnels we use turning vanes to 'straighten' flow around corners and pass it through screens to then generate uniformity. In no way did I imply that the screen was not used to help produce laminar flow, in fact my exact words were:

"The screen everyone is refering to is actually there to improve uniformity of the airflow"

I was just trying to help you all so you don't use the terms incorrectly. Uniform and laminar flow are used interchangeably but most people stay away from the term laminar as it implies linear flow properties that don't necessarily hold true in practice. I know it sounds nit picky but I'm just trying to share my knowledge and experience.

[clarkz71]

Originally Posted by Raze

The screen everyone is refering to is actually there to improve uniformity of the airflow inside the intake manfiold which provides a more uniform amount of air into each cylinder

Actually, your exact words were "improve uniformity of the airflow inside the intake manifold" I believe it's the airflow through the MAF sensor that's being "improved".

[Raze]

Clark you're right, my bad, but just use the terms correctly from now on and I'll be happy

[codewize]

I hereby certify this thread as way out of control.

[clarkz71]

I'm glad we got that STRAIGHTENED out.