Reeds.. single stage vs 2 stage???

[Chaz]

Rate of pressure drop and total gradient is dependent on rpm ie piston speed.

I could send you some results if you care to learn

I didn't ask about column velocity , demand slope , point of reed hysteresis , etc.

Let me narrow the focus down to "one intake cycle" so you can concentrate on the question asked ... not on a presentation of yet another outdated , irrelevant paper you stole from someone else.

Deflection = FuMPy

BTW .. have you learned the difference between "positive" and "negative" pressure waves yet .. ????
You'll need to know this if your to keep up with the conversation ..

The question remains :

What phenomena takes place along the path , that will pull the second reed off of it's seat , instead of just open the smaller top leaf farther ... ?



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​As vacuum velocity & pressure increases, the first stage opens further. This is where resistance to deflection happens. The further the material deflects (bends) the more resistant it is to further deflection. Thats where the second stage begins to work. Because the second stage is still in a neutral position, at some point it becomes less resistant to deflection that the first stage that has already reached its maximum flexural capabilities and very resistant to further deflection. I would guess that the second stage only slightly opens to satisfy the vacuum pressure demands but it should definitely open at some point.


​At bottom dead center and for roughly 20* each side of it the reeds are closed and compared to the rotational movement , there is little to no piston ( pressure/ vacuum generator) movement.
From there business picks up to where the piston speed is the highest (for the intake stroke ) @ 90* ABDC.
From nothing to something is like a G-meter .. always more .. early , to the point of max acceleration .. then the second half , from 90 to TDC is the process of coming to a stop. ( much like flipping a quarter , you know it left your hand hard , slowed on the second half of upward travel , stopped somewhere before changing direction and coming back down)
Chaz = hoping the stragglers don't pull us backwards from here ...

OK so the little guys notices this first and opens . I understand that there is not enough area to keep up with demand , so the second reed opens .

What does the the first one do when the second one opens .. ?

How does the second one react to a high speed column of air moving over it , and a demand for air to move under it ... ?

[roadkill636]

I'm digging this ^^^^^

[Dave S]

heeHee..... looks like a chart from the heart doc.......

[Smalltownbassin]

What does the the first one do when the second one opens .. ?

How does the second one react to a high speed column of air moving over it , and a demand for air to move under it ... ?

Again, i'm only learning here so i'm gonna jump out of pocket again and provide another answer even its its wrong hahaha.

Q1- when the second reed begins to open, the first would begin to close since the volume of air supplied by opening the second (larger) reed is much greater....??? In my mind it seems like they would be clapping together at that point hahaha.
Q2- That question is describing the "phenomenon" of LIFT. Similar to the Venturi effect...???
Ok, let the crucifixion begin...

[roadkill636]

time to change gears.

Thoughts on THICKNESS of reeds for different application??

[mrichartz]

What does the the first one do when the second one opens .. ?

How does the second one react to a high speed column of air moving over it , and a demand for air to move under it ... ?

Again, i'm only learning here so i'm gonna jump out of pocket again and provide another answer even its its wrong hahaha.

Q1- when the second reed begins to open, the first would begin to close since the volume of air supplied by opening the second (larger) reed is much greater....??? In my mind it seems like they would be clapping together at that point hahaha.
Q2- That question is describing the "phenomenon" of LIFT. Similar to the Venturi effect...???
Ok, let the crucifixion begin...

Don't call it an answer call it a thesis that way it's just an unproven thesis..lol
So can't say wrong just unproven

[Merc 2.5]

time to change gears.

Thoughts on THICKNESS of reeds for different application??

This is what im thinkin bout. ^^

[Chaz]

What does the the first one do when the second one opens .. ?

How does the second one react to a high speed column of air moving over it , and a demand for air to move under it ... ?

Again, i'm only learning here so i'm gonna jump out of pocket again and provide another answer even its its wrong hahaha.

Q1- when the second reed begins to open, the first would begin to close since the volume of air supplied by opening the second (larger) reed is much greater....??? In my mind it seems like they would be clapping together at that point hahaha.
Q2- That question is describing the "phenomenon" of LIFT. Similar to the Venturi effect...???
Ok, let the crucifixion begin...

I must say , your reading and comprehension skills are impeccable ...

The only stupid people I know are the ones who were born knowing everything ..

The same way that the transfer are open lets say 55* BBDC .. They are still open for 55* ABDC . The exhaust port is still trying to evacuate the cylinder , even if it is part of the fresh charge.
The piston is creating a low pressure area . If the transfer is still open I cant help but think that it will tend to stall out the column until the transfer closes. Now it becomes part of the "leak free" crankcase. Perhaps at high RPM the column will adhere to the "an object in motion rule" . As we can also see by the graph FuMPy posted ... a steady3000 RPM averaged 21 PSI .. then going down to just above idle to 5000 RPM moved just 1 pound ( .095% ) each direction across the range.
RPM does however come into play above the torque peak , where the motor has less and less time to fill the case.
Friend and mentor .. Mr. Carson says the reed closes each and every revolution. I tend to think that we are lucky to have enough control of the petal to get it to close every second or third revolution. It would take a spintron machine and footage you could put on a big screen and play it in slow motion to know for sure. But the country boy method of looking for fuel standoff might give a hint as to what's happening. Old piston port motorcycles would drench your pants legs if you ran them with no air filters ...
To his credit , on 300x type plenum boxes , I've run them at the dock on a test wheel .. turned the key off at 6400 RPM , and looked down inside the box .. It was much dryer than I expected to find it. Perhaps at an RPM the motor could never get to or a huge reed petal .. there might be a loss of control. But as it stands, Chris builds reeds that work within the parameter the motor is capable of ...
I'm still learning too ..

Ohh yea .. # 1 )
I think the little guy opens and stays that way .. till until the is no longer a sufficient vacuum signal to keep it open . If and when the second reed opens , it wont open too much and then both them do the who's on first , what's on second routine .
I do think that the second reed makes for a poor floor for the top reed. Instead of the tear drop shape of the cage , air is sheared off by a thin blade and begins to tumble . And when the second reed opens , it tends to block the little guy as well .

#2 ) I think the air going over one , under the other tends to corrupt the total air flow . Two stage reeds had their time in the sun .. in the 1970's when you had a choice between stock steel .. or two stage reeds.
Todays reeds and blocks have been refined to the point it's a no brainer. I know Carson put a lot of time and effort putting together a data base . He put different reeds in different people hands . Some that were trolling for fish all day , every day. Some that parked big motors at 6000 RPM for hours at a time . Smaller motors that spun 9500 for a race or play .. If you ask , what reeds should I run . My answer is call Chris .. tell him your intentions , how you run the boat ... he will hit it right the first time .. <---( keys water )

Lets call this pencil .300"



Put in in between first and second .. looks OK ..



Lot of effort to open one big reed and seven little ones ... never happen ..



Even worse ...



Stripped Merc six pedal block ...





Early ~ early yellow reed , and some three pedal's that we sawed the center rib out to pick up window area. Worth a shot ..



Billet / oversized , sport-jet, 300x style blocks 11% more window area ...







I had my waterjet guy run some "shorty stops" for me out of stainless. And Chris made the pattern to cut custom reeds for them ..



One of my early adapter plates ..





Of course .. if you do this .....

[mrichartz]

How hard is it to cut the reeds with a rod like that are they consistent?
Ouch..

[FMP]

You must have a belief that the surface area of the second reed is not influenced by the low pressure lifting increase which has lifted the first reed. That once this occurs then the second reed can't respond if the rate of pressure drop vs degrees rotation continues, increasing the gradient plenum to case and meets the lift resistance of the material. That some how it all just just gets used up earlier by the small surface area of the first reed while the dynamics continue to change.

[Chaz]

You must have a belief that the surface area of the second reed is not influenced by the low pressure lifting increase which has lifted the first reed. That once this occurs then the second reed can't respond if the rate of pressure drop vs degrees rotation continues, increasing the gradient plenum to case and meets the lift resistance of the material. That some how it all just just gets used up earlier by the small surface area of the first reed while the dynamics continue to change.

Yes , how silly of me to have forgotten the :

"Hyper generacinfuzed nanodecabulator refluxinducerlawof Usayabunchofnothingasusual"

[SS Minnow]

Yes , how silly of me to have forgotten the :

"Hyper generacinfuzed nanodecabulator refluxinducerlawof Usayabunchofnothingasusual"

Watching that video is a lot like reading FuMPy's posts here. Trying to figure out what he is talking about is like trying to teach an Iguana how to speak Portuguese.

[Whaaaaat]

Your iguanas don't speak portugese?

[SS Minnow]

Your iguanas don't speak portugese?

They don't speak it but they know how to sign it.

[SS Minnow]

Your iguanas don't speak portugese?

Kind of like this, but the Iggies are better looking.