Intake plenum and 911 throttle body

[Ben006]

An engine is basically a pump, but the the air behave the same if you move it by droping the pressure on one side, or raising it on the other.
There is no such thing as vacuum, it's just a difference of pressure and that is what move the air, a fluid is never "sucked" it is always pushed from an area of high pressure to an area of low pressure.

[jsceash]

Air and water are Newtonian Fluids. A Newtonian fluid is any fluid that follow the same characteristics as a solid. Flow and velocity are base on friction and static attraction or a coefficient of viscosity. The calculations say ignore a negative number such as pressure because the value are squared so a negative pressure times itself is a positive value.

[KRAM36]

Originally Posted by Ben006

An engine is basically a pump, but the the air behave the same if you move it by droping the pressure on one side, or raising it on the other.
There is no such thing as vacuum, it's just a difference of pressure and that is what move the air, a fluid is never "sucked" it is always pushed from an area of high pressure to an area of low pressure.

Explain why on these charts the wedge makes no difference and in Pedro's video it does and he calls it pulling air and says there is an influence on the air

Originally Posted by blue2000s

I'm using Fluent in these simulations.

A Y will be more efficient than a T for airflow in a steady state, that's correct.

Keep in mind that with three cylinders to a plenum, there is a pretty much constant flow of air into the plenum when the engine is kept at a constant speed. There is always a cylinder pulling air. The pulses that influence secondary pressure waves are important, but they are secondary in nature so the influence on flow is on a much lower order than the primary vacuum pulled by the cylinders themselves.

Here are three more simulations varying on the one I posted earlier. The first one just adds a sloped wedge to the original T. The second adds a large radius to the T junction and the last one combines the radius with the wedge.





The volume flow rate results show that the T and T with wedge have almost identical flow rates. The radius-ed T with and without the wedge are both almost the same flow rates but are about 30% greater than the standard T.

We have this.

"A third factor in manifold vacuum is engine compression. If an engine has low compression in all cylinders, it creates a steady, but low, manifold vacuum. If an engine has low compression in one cylinder, manifold vacuum will be low only during that cylinders intake stroke. This will be observed as a gauge that fluctuates or quickly changes reading. Low compression in a cylinder can be caused by leaking valves or rings, leaking head gaskets, or other ways that keep the cylinder from sealing during the compression stroke."

Compression and Vacuum

Originally Posted by jsceash

The instant the air starts to move Newton's laws apply. It doesn't mater if it suck through a pipe or push through a pipe the same principles apply. The same equations are used to calculate flow loss, flow velocity.

This must be another theory that doesn't apply and can't be taught in Kansas school.

Do you know how to have a conversation without insulting someone? If you can't, you can go you know what yourself. Also read my location again smart guy, I don't live in Kansas.

[jsceash]

I give up
Believe what you want.

Sarcasm

Republican legislator from Missouri, offered a bill last month that would allow parents to pull their children out of high-school biology classes lest they be exposed to the concept of natural selection. Nearly 90 years since the public trial of John Scopes, a young schoolmaster accused of teaching evolution to Tennessee children, Missouri’s House Bill no. 1472

The earth is flat and Einstein was all wet

[KRAM36]

Originally Posted by jsceash

I give up
Believe what you want.

Sarcasm

Republican legislator from Missouri, offered a bill last month that would allow parents to pull their children out of high-school biology classes lest they be exposed to the concept of natural selection. Nearly 90 years since the public trial of John Scopes, a young schoolmaster accused of teaching evolution to Tennessee children, Missouri’s House Bill no. 1472

The earth is flat and Einstein was all wet

It's not what I believe, it's what I see. With the simulations the wedge makes no difference, then you have Pedro blowing air into the Distribution T and it makes a difference. So what is it that's making this difference? It has to be the way the air is being fed into the Plenum from Distribution T. The air is not hitting the back of the Distribution T (yes maybe a little), it's getting pulled along the side of the Distribution T's radius. That's what makes the 997 Distribution T so effective.

[Jamesp]

As an engineer, it's entertaining to watch the other engineers try to explain technical principles to non technical folks. Without a technical education folks will believe what they want to believe (suction is a great example). At some point you just have to say, "I can explain it to you, but I can't understand it for you."

[jsceash]

Originally Posted by Jamesp

As an engineer, it's entertaining to watch the other engineers try to explain technical principles to non technical folks. Without a technical education folks will believe what they want to believe (suction is a great example). At some point you just have to say, "I can explain it to you, but I can't understand it for you."

I like that

[KRAM36]

Originally Posted by Jamesp

As an engineer, it's entertaining to watch the other engineers try to explain technical principles to non technical folks. Without a technical education folks will believe what they want to believe (suction is a great example). At some point you just have to say, "I can explain it to you, but I can't understand it for you."

I don't see where you explained anything? Try me, I'm not afraid to learn.

From the simulation. "The volume flow rate results show that the T and T with wedge have almost identical flow rates." Yet Pedro's video shows the opposite.

Originally Posted by jsceash

I like that

jsceash can you explain this? Is the simulation wrong? Did Pedro sneak a magic trick in on you? I can't imagine Pedro could pull one over on a smart guy like you.

[jsceash]

I'll try a different way.

Have you ever gone fishing in a trout stream and watched a bend in the stream with a back eddy. The water spins backward and slows as it gets away from the current the speed up as it comes back around. A portion of the stream flows back continuously. It really obvious if there is a can or foam cup floating in it. That is what happens in the long radius flat back Porsche Plenum.

Now imagine the same stream and same bend if someone built a concrete barrier in the outside radius. The water would glide past at a faster speed or equal to the rest of the stream current. The IPD and or Pedro's Plenum.

Pedro's video is a bit of truth a bit of exaggeration. It exploits the defect in the stock plenum. The dead space becomes larger as the velocity of air is increased it is a principle in air flow called a "Boundary air layer". "Turbulent boundary air" is proportional to the air velocity so the turbulent area increases as the air velocity increase. Pedro uses a vacuum to blow air in the plenum which creates a higher velocity than the NA motor can produce but it is fast enough to exaggerate the flow problem. I've been trying to explain all day that turbulent air is like a plug reducing flow. The second type of boundary air layer is "Laminar Boundary air" its the drag created from the air friction with surface of the pipe. This is proportional to the square root of the velocity so it increases slowly as the velocity increases so it has little effect in the application. The big thing you see this affect is golf balls put dimples in the surface you can defeat the effect. Pedro uses a Teflon insert which has a low friction coefficient. IPD used of epoxy coat them but now the shot peen the inside so it like the dimples on a golf ball either way they negate the effect at the air flow speeds for the application

[Jamesp]

[QUOTE=KRAM36;451898]I don't see where you explained anything? Try me, I'm not afraid to learn.
QUOTE]

Wanting to learn is good! As B2000 pointed out we are discussing fluid flow which brings us to Navier-Stokes. Many years ago I had the pleasure of learning fluid dynamics and aerodynamics which just wouldn't be the same without the good old Navier-Stokes equations. The material isn't completely transparent, so I've included this wiki link to get you started. You'll want to brush up on tensors to get the full impact. Here's the link:

Navier

Now don't say I haven't tried to explain anything to you.

[jaykay]

I can see a wedge helping where you have the airflow motive force being dominated by constant "push" forces as would be present from a turbo or supercharger. The reason being that side to side pulses or draw into the engine from left to right, right to left plenums are fed positively from the turbo or super charge. The side to side pulse is not disrupted by the wedge.

When we consider NA there will pulses from plenum to plenum as the engine draws air in. This will be interrupted by the wedge. There is no positive charge to help feed this need.

Have a look at the IPD wedge. In many iterations you will see holes, relief features which I believe is a feature intended to mitigate this NA flow issue.

NA engines: wedge value is questionable

Boosted engines: wedge could help cylinder filling

> as always testing is needed to know