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This is all true if we assume that air behaves as a perfect gas, inlet pressure and temperatures are constant, and there are no abdiatic processes in effect. Also we must disregard some degree of fluid dynamics. Oh and I almost forgot accoustical effects.

Carry On
Ronin Z


Ok let's run with this. Robin you raise some generaly valid engineering concerns, but you do not explain how they may be relevant to the plenum issue.

All engineering studies and designs begin with the perfect or ideal model. Anomalies that may be particular to the design application are then introduced to model real-word situations.

Let's begin by stipulating that we are dealing with an engine that is at normal operating tempurature. Inlet pressures and temps may vary over the long term (minutes, even seconds), but this variation is going to be miniscule. Baring anything catastrophic, we will not be experiencing dramatic atmopheric pressure and tempurature changes. Our intake air flow does not move through or across a greatly varying change in tempurature. In the short term, crankshaft revolution to revolution, intake pressure and tempurature changes will be nill. I would have to conclude, that for this application, concerns about inlet pressures and temps changes are withou merit.

The abdiatic process is definately present. For those unfamiliar, the abdiatic process is where the system neither gains, nor losses heat as work is done. There IS heat gain and loss as as the engine goes through it combustion procces. Once the engine reaches operating tempurature thr combustion process and cooling systems allow the engine to reach and an equilibrium tempurature, i.e nornal operating tempurature. This results in a constant tempurature in and around the plenum. As a result of this, the ideal gas equation (P= nRT/V) applies without tempurature becoming a consideration. Temperature is constant, so as Volume increases, Pressure drops and the moles of air spread out to fill the increased volume.

Fluid dymanics will be applicable to any disturbances in the air flow. I do not see how this would have any increased effects in one type of plenum over the other. Ideally both types of plenums would would be constructed with smooth interior walls and a minimum nunber of seams and protrusions into the plenum cavity.

Accustical effects! In this enviornment? Typical enviornments for acoutical considerations would be space and rocket flights during take-off and re-entry and in heavy artillery combat situations. In most of these cases we are concerned about mechanical vibrations that are caused by acoustic sound waves. There are no vibrations in the car that are strong enough to disturbe the air flow through the plenum.

I believe that stock plenum uses sound engineering principles and is a valid design. I would be skeptical of non-sloping designs
 

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Inlet pressures and temps may vary over the long term (minutes, even seconds), but this variation is going to be miniscule. Baring anything catastrophic, we will not be experiencing dramatic atmopheric pressure and tempurature changes. Our intake air flow does not move through or across a greatly varying change in tempurature. In the short term, crankshaft revolution to revolution, intake pressure and tempurature changes will be nill. I would have to conclude, that for this application, concerns about inlet pressures and temps changes are withou merit.

The abdiatic process is definately present. For those unfamiliar, the abdiatic process is one where is one where the system neither gains, nor losses heat as work is done. There IS heat gain and loss as as the engine goes through it combustion procces. Once the engine reaches operating tempurature thr combustion process and cooling systems allow the engine to reach and an equilibrium tempurature, i.e nornal operating tempurature. This results in a constant tempurature in and around the plenum. As a result of this, the ideal gas equation (P= nRT/V) applies without tempurature becoming a consideration. Temperature is constant, so as Volume increases, Pressure drops and the moles of air spread out to fill the increased volume.
I would disagree with most of this. Temperature will not be constant. The temp difference between the incoming air the the temp of the plenum will be drastically different -- by as much as 50 deg C. I would argue that this alone could cause issues with the ideal gas law. Admittedly, I'm speculating and have no real data to back that up.
 

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Ok let's run with this. Robin you raise some generaly valid engineering concerns, but you do not explain how they may be relevant to the plenum issue.
It's Ronin. The Japanese word for a samurai that has lost his master. Robin is an androgynous name given to both sexes.

All engineering studies and designs begin with the perfect or ideal model. Anomalies that may be particular to the design application are then introduced to model real-word situations.
Really? Man, we do it the hard way at work. We use the equations that most accurately match the real world results. Even if it means it takes a bank of computers weeks to generate an answer.

"Oh Deep Thought, tell us the answer to life the universe and everything!"

Let's begin by stipulating that we are dealing with an engine that is at normal operating tempurature. Inlet pressures and temps may vary over the long term (minutes, even seconds), but this variation is going to be miniscule. Baring anything catastrophic, we will not be experiencing dramatic atmopheric pressure and tempurature changes. Our intake air flow does not move through or across a greatly varying change in tempurature. In the short term, crankshaft revolution to revolution, intake pressure and tempurature changes will be nill. I would have to conclude, that for this application, concerns about inlet pressures and temps changes are withou merit.
Unless you're talking about a diesel genset running at steady state operation, I can't agree with much you just said.

The abdiatic process is definately present. For those unfamiliar, the abdiatic process is one where is one where the system neither gains, nor losses heat as work is done. There IS heat gain and loss as as the engine goes through it combustion procces. Once the engine reaches operating tempurature thr combustion process and cooling systems allow the engine to reach and an equilibrium tempurature, i.e nornal operating tempurature. This results in a constant tempurature in and around the plenum. As a result of this, the ideal gas equation (P= nRT/V) applies without tempurature becoming a consideration. Temperature is constant, so as Volume increases, Pressure drops and the moles of air spread out to fill the increased volume.
And what about when we add those two pretty little words: Forced Induction? Hm?

Fluid dymanics will be applicable to any disturbances in the air flow. I do not see how this would have any increased effects in one type of plenum over the other. Ideally both types of plenums would would be constructed with smooth interior walls and a minimum nunber of seams and protrusions into the plenum cavity.
Airflow is all about fluid dynamics. Ignoring their effects, is like ignoring the problem.

As a side note you're not supposed to have perfectly smooth interior plenum/intake runner walls. It increases the boundary layer of your laminar flow, thusly decreasing intake volume. I laugh whenever I see some home garage tuner who has polished the inside of intake runners.

Accustical effects! In this enviornment? Typical enviornments for acoutical considerations would be space and rocket flights during take-off and re-entry and in heavy artillery combat situations. In most of these cases we are concerned about mechanical vibrations that are caused by acoustic sound waves. There are no vibrations in the car that are strong enough to disturbe the air flow through the plenum.
So there are no accoustic resonance effects at play? None? You really need to stop an think about that one. Seriously.

I believe that stock plenum uses sound engineering principles and is a valid design. I would be skeptical of non-sloping designs
Agreed, when you take into account all of the non-performance related concerns, the stock plenum is an acceptable design. But that is the story with most factory inlet systems. Those poor engineers have to factor in cost/ease of production, ease of assembly(fitment), ease of repair/replacement(service), performance, emissions/economy, not to mention NVH issues... it's amazing the thing works as well as it does. That being said, the design does have slight flaws.

Regards,
Ronin Z
 

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Ronin,

I appologize for getting the spelling on your name incorrect. My mistake.

With respect to the inside of the plenum being smooth, this was an oversimplification on my part. A smooth object will have increased surface tension and therefore more resistance to the meduin through which it travles or that which travels around it. An example of this is the dimpled golf ball. The dimples give the ball a lower co-efficient of friction and therefore allow it to travel farther than if it were smooth.

Forced induction. The same rules apply. As you decrease the number of moles of air, you must reduce your volume to maintain equal pressure throught the system. As air passes through the plenum and enters each cylinder the number of moles of air available at the next cylinder is dereased, and pressure will drop, unless volume is decreased. Any reputable HVAC guy will attset to this. In residential and commercial air handling systems air is blown through the system by a fan. Let's all say FORCED INDUCTION. As the air runs the length of the supply plenum, lines will branch off to supply heating and A/C to individual rooms. At a point shortly beyond where the supply lines branch off the plenum will be reduced in size. This reduction in size is done to keep the pressure up in the remainder of the downline system. Anyone wishing to see an example can go to any commercial business with an exposed ceiling and examine the duct work.

As far as cost and ease of production, it would have been less expensive and easier for Nissan to produce a flat plenum than one with a sloping design.


I stand by my arguements regarding sloped vs. flat plemuns. I have offerd evidence, both scientific and anecdotal. Maybe I am missing something, but if this is to be a discussion I need to get back more than just meaningless quips and "Oh Yeas!!" that lack any meaningfull information.
 

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dm4,

Congrats, you win. I'm done.

:clap:

Regards

RZ
 

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I officially offer the first persone in the NJ area to scedule an install with me a FREE DYNO run to prove this plenum does nothing but flow "LESS" air than stock..
 

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Julian,
Are you sayin the Kinetix plenum flows less air then the stock plenum?



376 people have viewed this thread to this point. I am surprised that no one has offered a challege, backed by evidence or explanation, to my conclusions on this plenum issue. Even though I believe that the sloping plenum is a valid design, I can think of one fundamental engine function that might cause me to re-examine my conclusions.
 

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I offered you to explain why most of the FI failures are with the front two cylinders. It is the general consensus that the sloped plenum is the cause, and if the Kinetix prevents that failure, that is good enough for me.
 

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I offered you to explain why most of the FI failures are with the front two cylinders. It is the general consensus that the sloped plenum is the cause, and if the Kinetix prevents that failure, that is good enough for me.
Actually most F/I failures are the REAR 2 cylinders closes to the fire wall, and the conclusian appears to be more "heat soak" related than the plenum design.To say the Kinetix plenum would prevent a Failure would be at least "irresponsible"
 

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Julian,
Are you sayin the Kinetix plenum flows less air then the stock plenum?
376 people have viewed this thread to this point. I am surprised that no one has offered a challege, backed by evidence or explanation, to my conclusions on this plenum issue. Even though I believe that the sloping plenum is a valid design, I can think of one fundamental engine function that would cause me to re-examine my conclusions.
Yes I am, I am actually saying that the Kinetix plenum was designed in somebody's back yard shed and never flowbenched or tested.Kinetix is not a legitimate company IMO and produces second hand junk, that has undergone R&D at their customers expense..We have had failures on EVERY SINGLE KINETIX PRODUCT we installed from day one 3 years ago.From test pipes to suspension parts..We refuse it SELL or INSTALL their products. We believe in selling QUALITY and PROVEN parts..How can it be that there are 100's of these plenms sold and yet ZERO conclusive tests done independant of the company selling them?
 

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Toykila,

I saw that and I appologize for not responding. I really can not offer an explanation as to why most of the engine failures are in the front two cylinders. What kind of evidence has the engine teardowns revealled? It would be interesting to see if there is a cause and effect related to the plenum.
 

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Discussion Starter · #33 ·
Toykila,

I saw that and I appologize for not responding. I really can not offer an explanation as to why most of the engine failures are in the front two cylinders. What kind of evidence has the engine teardowns revealled? It would be interesting to see if there is a cause and effect related to the plenum.

I have been around a long time and I don't think I have seen where "MOST" engine failures are confined to the front two cylinders???


I completely agree with Julian's comments. I had my doubts about kinetix and then had a chance to get a hands on with their products working on a locals car. If they were the only company making products, that would be one thing, and if that was the case, I would remain stock. But the fact is, there are numerous other manufacturers out their putting out good products that dont' have a crap track record like kinetix.
 

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I have been around since the first procharger was strapped on a Z and went "KABOOM". It was the general findings that most of the failures were the front cylinders. I dont know if this is still the case, but I would be it is.
 

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Discussion Starter · #35 ·
I have been around since the first procharger was strapped on a Z and went "KABOOM". It was the general findings that most of the failures were the front cylinders. I dont know if this is still the case, but I would be it is.
links?

from what I remember, most blown motors were from poor timing control,
 

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Yes I am, I am actually saying that the Kinetix plenum was designed in somebody's back yard shed and never flowbenched or tested.Kinetix is not a legitimate company IMO and produces second hand junk, that has undergone R&D at their customers expense..We have had failures on EVERY SINGLE KINETIX PRODUCT we installed from day one 3 years ago.From test pipes to suspension parts..We refuse it SELL or INSTALL their products. We believe in selling QUALITY and PROVEN parts..How can it be that there are 100's of these plenms sold and yet ZERO conclusive tests done independant of the company selling them?


Hooray,

It is refreshing to see that others are willing to question conventional wisdom and bandwagon beliefs. Just because a product is polular does not mean it is effective and /or offer any advantages. I do not believe in being cynical, but it can be benificial at times to be skeptical and ask questions.
 

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links?

from what I remember, most blown motors were from poor timing control,
yes, timing played a factor, but the FRONT CYLINDERS were the failure point.

Hooray,

It is refreshing to see that others are willing to question conventional wisdom and bandwagon beliefs. Just because a product is polular does not mean it is effective and /or offer any advantages. I do not believe in being cynical, but it can be benificial at times to be skeptical and ask questions.
You dont know me very well.. I am one of the biggest questioners of conventional beliefs. When i get an opportunity I will run extensive tests on this manifold.
 

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Discussion Starter · #39 ·
I haven't even been banned from a site yet, and most would lead others to beleive I do nothing more than start sh!t and bash people and products.

How did you get banned?
 
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