Maximizing Intake Flow

Paul

The "nail through the hose" would have an effect on the velocity... not the volume. Bernoulli's equation... velocity must increase, but pressure decreases.

Actually I agree with you that the overall volume of air is determined by the size of the "pump"... the cylinder displacement. In my experience, increasing the flow velocity (through laminar flow V-Stacks) improves throttle response due to an increase in VE (volumetric efficency). Removing an restriction like the secondary throttle rod enables a more laminar (smooth) flow of air to pass through the throttle bodies.

If we change the equation to a 2 stage pump (supercharger), we now have twice the volume of air being moved (at 14psi boost), at greater velocity... which would have to equate to a relatively greater pressure drop due to any disturbance. Hence my thinking that throttle response is improved even more on a supercharged R3 by removing the secondary rod.

Some guys like golf... I love discussing these things!

Paul Hyland said:

I work with centrifugal blowers and air movement systems so let me throw this out to you.
You talked about the rock in water thing, what you have to realize is that the flow in the stream never changes (has no restriction) were as in the intake you have one size opening in the first stage of the intake (filter area) then a smaller hole were it enters the motor. So unless you open that second hole VOLUME threw there is constant. So by putting the a velocity intake on you are changing pressure and speed of flow but not volume threw the secind hole so unless you have a blockage are restriction just before the second intake the rods shouldn't make any kind of noticeable difference.

Look at a garden hose one with the nozzle you adjust by turning. The hose can only deliver a constant volume of water but you can adjust the pressure and speed of flow buy opening or restricting the nozzle but the volume the hose can carry doesn’t change. So say you put a nail threw the hose about 6” up the hose volume at the nozzle with remain constant because of the restriction at the smaller end of nozzle. The small hole can’t move the same volume as the big hole so unless you can get more air threw a small hole than a big hole I don’t think you will notice any kind of difference.
Doe’s any of this make since or am I way off here.

What you need Hombre is a CFD computer modeling program the models flow. You put the design in (in this case a computer model of the R3 intake) and the program shows you how to improve flow. We have one here and it is cool watching how things can change the flow in a machine.

Click to expand...

Actually, the cheap way out would be a Dwyer Manometer. It will show the pressure/flow differential at any point where the probe is placed versus ambient pressure. While the cheapest models are analog, they are still very accurate.

If you want to get real critical, I'd re-machine the throttle plate shaft to make it totally round (rather than the visible flat that causes turbulence) and make doubly sure that the fixing screws didn't protrude at all through the rod itself, but were flush with the shaft when tightened.

We sell a lot of those Dwyer meters.

Hombre

Agreed the volume will be the same on both sides of the nail but velocity will be slowed on impact of nail while it disperses around it. Is that what you are thinking with the rods velocity is being slowed at that point?. who am I to argue I know when you port and polish a head or you go into an intake on a car and clean out some of the edges and clean it up you gain some zoom why not buy giving the R3 cleaner flowing air.

Paul Hyland said:

We sell a lot of those Dwyer meters.

Click to expand...

Here's what I use:

Paul Hyland said:

Agreed the volume will be the same on both sides of the nail but velocity will be slowed on impact of nail while it disperses around it. Is that what you are thinking with the rods velocity is being slowed at that point?. who am I to argue I know when you port and polish a head or you go into an intake on a car and clean out some of the edges and clean it up you gain some zoom why not buy giving the R3 cleaner flowing air.

Click to expand...

Yup... that's all I'm trying to do. Bernoulli explains obstructions in a flow like this:


Stagnation pressure and dynamic pressure

Bernoulli's equation leads to some interesting conclusions regarding the variation of pressure along a streamline. Consider a steady flow impinging on a perpendicular plate (figure 16).
Figure 16. Stagnation point flow.

There is one streamline that divides the flow in half: above this streamline all the flow goes over the plate, and below this streamline all the flow goes under the plate. Along this dividing streamline, the fluid moves towards the plate. Since the flow cannot pass through the plate, the fluid must come to rest at the point where it meets the plate. In other words, it ``stagnates.'' The fluid along the dividing, or ``stagnation streamline'' slows down and eventually comes to rest without deflection at the stagnation point.

Bernoulli's equation along the stagnation streamline gives



where the point e is far upstream and point 0 is at the stagnation point. Since the velocity at the stagnation point is zero,



The stagnation or total pressure, p_0, is the pressure measured at the point where the fluid comes to rest. It is the highest pressure found anywhere in the flowfield, and it occurs at the stagnation point. It is the sum of the static pressure (p_0), and the dynamic pressure measured far upstream. It is called the dynamic pressure because it arises from the motion of the fluid. The dynamic pressure is not really a pressure at all: it is simply a convenient name for the quantity (half the density times the velocity squared), which represents the decrease in the pressure due to the velocity of the fluid.
We can also express the pressure anywhere in the flow in the form of a non-dimensional pressure coefficient C_p, where



At the stagnation point C_p = 1, which is its maximum value. In the freestream, far from the plate, C_p = 0.

OK OK Hombre

I'll have to get the books out at work on that one. BUT a question???? for combustion do you not need flow not pressure. Don't you want high flow and low pressure. You can acheve high flow with out hight pressure. Like bellows to a fire high flow of air low pressure or it will blow it out. Just trying to keep you on your toes here.

Combustion of an open air flame source and combustion in a cylinder chamber are two very different things. In our case (combustion chamber), we want to pack the cylinder as full and completely as possible (including forcing out exhaust gases). So pressure and velocity are good for cylinder fill (volumetric efficency). After the valves are closed (no more flow), we'll worry about combusting it!