2V spring upgrade - final word?
02-03-2010, 05:17 PM
#16
Rennlist Member
No, I saw this post as well. It talks about valve float in that one sentence, but there is no clear reason why it would be do to boost.
It probably pertains to the losses might being greater at valve float in a boosted environment. do you know??
mk
It probably pertains to the losses might being greater at valve float in a boosted environment. do you know??
mk
02-03-2010, 05:19 PM
#17
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FWIW, in one of the WSM or suplimental issues the process for doing rings on a 4.5 said: "bore out to 4.7 and use those rings" or something like that.
Did you whack your head this morning? That’s the entire point of this thread Mark.
02-03-2010, 05:43 PM
#18
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02-03-2010, 05:58 PM
#19
Rennlist Member
No, the point was that you might not have valve float with our engines running at lower RPM with our stock valve springs. Also, the other and MAIN point is that boost doesnt cause valve float. Iwould think that the little 4 bangers twisting up at 1000 to 2000rpm higher than our engines would be the reason that valve float would be an issue.
02-03-2010, 06:02 PM
#20
Rennlist Member
Here you talk about what I was responding to. The valves are not being forced open via the 20-30psi. there is never 30psi trying to keep them open as the intake valve is closing.
If the main point of the issue is the effects of valve float being greater on a boosted engine. Sure, I completely agree. BUT, I dont belive the issue is how you called it below in your post, nor would any of the boosted guys.
Are you sure you didnt bang YOUR head this morning?
If the main point of the issue is the effects of valve float being greater on a boosted engine. Sure, I completely agree. BUT, I dont belive the issue is how you called it below in your post, nor would any of the boosted guys.
Are you sure you didnt bang YOUR head this morning?
02-03-2010, 06:24 PM
#21
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Tell you what Mark, lets take a torn down head, you move the valve open and closed with your fingers (acting as the valve springs). Then I'll pressurize the back side of the valve with 20lbs of boost.
So you are trying to say the amount of force needed to close the valve is the same with / without the boost?
Nowhere in Brendon's initial post (or any of mine) did he mention at what RPM this was a concern. No kidding at higher RPM's there is a greater chance of valve float especially when combined with boost.
Some of the 951 guys have seen on they dyno, the head pulling away from the block under high boost. But somehow this amount of pressure cannot overcome a valve spring????
Where did anyone say the valve was being forced open, even in the quote you copied I clearly stated: “keep them open”.
Valve float is when the valve does not have enough return spring when trying to close. The more force you exert on the valve, be it from inertia, boost, or in this case both……..how on earth is this so complicated to you?
That’s the whole point of the discussion……….
So you are trying to say the amount of force needed to close the valve is the same with / without the boost?
Nowhere in Brendon's initial post (or any of mine) did he mention at what RPM this was a concern. No kidding at higher RPM's there is a greater chance of valve float especially when combined with boost.
Some of the 951 guys have seen on they dyno, the head pulling away from the block under high boost. But somehow this amount of pressure cannot overcome a valve spring????
Valve float is when the valve does not have enough return spring when trying to close. The more force you exert on the valve, be it from inertia, boost, or in this case both……..how on earth is this so complicated to you?
That’s the whole point of the discussion……….
02-03-2010, 07:51 PM
#22
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Thread Starter
****, I go to work, have a three hour meeting with no money made, and get back for this? Let me digest.
02-03-2010, 07:54 PM
#23
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Thread Starter
02-03-2010, 08:05 PM
#24
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Thread Starter
A valve that follows the cam properly at all experienced RPMs is a better situation than one that doesn't keep up with the ramp.
Remember - the only thing closing that valve as the ramp recedes on the cam IS the spring.
Yes, there is no reason to worry about springs at all. I'll just reuse the one who have been raped and pillaged for 30 years:
Remember - the only thing closing that valve as the ramp recedes on the cam IS the spring.
Yes, there is no reason to worry about springs at all. I'll just reuse the one who have been raped and pillaged for 30 years:
02-03-2010, 08:08 PM
#25
Rennlist Member
Thread Starter
Okay - does everyone here see the air charge come in the cylinder - if that is at a high positive pressure, it will sort of push at the valve, as its trying to close:
02-03-2010, 08:10 PM
#26
Rennlist Member
Thread Starter
Nah, the valve springs aren't one of the most under-duress parts of an engine:
02-03-2010, 08:12 PM
#27
Rennlist Member
you did bang your head, didnt you?
how can you pressureize the back side of the valves, if the valve is open?
below, you mention that the boose would really be trying to open closed valves right?
and to answer your question, yes, there would be no difference in closing the valve with and without boost. think about it. boost is the ambient air now, the valve opens, differential pressure moves the air mass into thecylinders. at the bottom of the stroke, probalby both sides of the valve will have the same pressure on them, so there would be NO extra forces on the intake valve against it to open it, close near bottom-dead-center.
yes, brendan didnt mention rpm, but my point was that at that point, thats were valve float can happen, and with boost, it can be more of a detrimental factor than with a non boosted engine.
so, to your last point, you said: "Mark, Brendon is trying to close the valves with 20-30psi of manifold pressure trying to keep them open."
Yet again, if the valves are starting to close, the air pressure on all sides of the valve will be the same. the pressure in the cylinder is 20psi and the pressure in the manifold is 20psi. (more or less) there is no "force" on the valves trying to "keep them" open
You said it, its inertia, momentium, speed that can cause valve float. why cant YOU understand that boost is not a factor in valve float, and its all about the spring pressure acting on those forces. There are no boost forces acting on the back of the valves as they begin to close. why is that so complicated for you to understand??
I suppose valve float is worse with boosted engines, as they can lose more of a percentage of their mass flow, because the mass is 2X more dense, and during float, you blead off the fuel air charge back out the intake valve as the piston is coming up.
how can you pressureize the back side of the valves, if the valve is open?
below, you mention that the boose would really be trying to open closed valves right?
and to answer your question, yes, there would be no difference in closing the valve with and without boost. think about it. boost is the ambient air now, the valve opens, differential pressure moves the air mass into thecylinders. at the bottom of the stroke, probalby both sides of the valve will have the same pressure on them, so there would be NO extra forces on the intake valve against it to open it, close near bottom-dead-center.
yes, brendan didnt mention rpm, but my point was that at that point, thats were valve float can happen, and with boost, it can be more of a detrimental factor than with a non boosted engine.
so, to your last point, you said: "Mark, Brendon is trying to close the valves with 20-30psi of manifold pressure trying to keep them open."
Yet again, if the valves are starting to close, the air pressure on all sides of the valve will be the same. the pressure in the cylinder is 20psi and the pressure in the manifold is 20psi. (more or less) there is no "force" on the valves trying to "keep them" open
You said it, its inertia, momentium, speed that can cause valve float. why cant YOU understand that boost is not a factor in valve float, and its all about the spring pressure acting on those forces. There are no boost forces acting on the back of the valves as they begin to close. why is that so complicated for you to understand??
I suppose valve float is worse with boosted engines, as they can lose more of a percentage of their mass flow, because the mass is 2X more dense, and during float, you blead off the fuel air charge back out the intake valve as the piston is coming up.
Tell you what Mark, lets take a torn down head, you move the valve open and closed with your fingers (acting as the valve springs). Then I'll pressurize the back side of the valve with 20lbs of boost.
So you are trying to say the amount of force needed to close the valve is the same with / without the boost?
Nowhere in Brendon's initial post (or any of mine) did he mention at what RPM this was a concern. No kidding at higher RPM's there is a greater chance of valve float especially when combined with boost.
Some of the 951 guys have seen on they dyno, the head pulling away from the block under high boost. But somehow this amount of pressure cannot overcome a valve spring????
Where did anyone say the valve was being forced open, even in the quote you copied I clearly stated: “keep them open”.
Valve float is when the valve does not have enough return spring when trying to close. The more force you exert on the valve, be it from inertia, boost, or in this case both……..how on earth is this so complicated to you?
That’s the whole point of the discussion……….
So you are trying to say the amount of force needed to close the valve is the same with / without the boost?
Nowhere in Brendon's initial post (or any of mine) did he mention at what RPM this was a concern. No kidding at higher RPM's there is a greater chance of valve float especially when combined with boost.
Some of the 951 guys have seen on they dyno, the head pulling away from the block under high boost. But somehow this amount of pressure cannot overcome a valve spring????
Where did anyone say the valve was being forced open, even in the quote you copied I clearly stated: “keep them open”.
Valve float is when the valve does not have enough return spring when trying to close. The more force you exert on the valve, be it from inertia, boost, or in this case both……..how on earth is this so complicated to you?
That’s the whole point of the discussion……….
02-03-2010, 08:22 PM
#28
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02-03-2010, 08:25 PM
#29
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Thread Starter
how can you pressurize the back side of the valves, if the valve is open?
below, you mention that the boose would really be trying to open closed valves right?
and to answer your question, yes, there would be no difference in closing the valve with and without boost. think about it. boost is the ambient air now, the valve opens, differential pressure moves the air mass into thecylinders. at the bottom of the stroke, probalby both sides of the valve will have the same pressure on them, so there would be NO extra forces on the intake valve against it to open it, close near bottom-dead-center.
yes, brendan didnt mention rpm, but my point was that at that point, thats were valve float can happen, and with boost, it can be more of a detrimental factor than with a non boosted engine.
so, to your last point, you said: "Mark, Brendon is trying to close the valves with 20-30psi of manifold pressure trying to keep them open."
Yet again, if the valves are starting to close, the air pressure on all sides of the valve will be the same. the pressure in the cylinder is 20psi and the pressure in the manifold is 20psi. (more or less) there is no "force" on the valves trying to "keep them" open
You said it, its inertia, momentium, speed that can cause valve float. why cant YOU understand that boost is not a factor in valve float, and its all about the spring pressure acting on those forces. There are no boost forces acting on the back of the valves as they begin to close. why is that so complicated for you to understand??
Its not even worth attempting to explain to you why you are wrong and what details you are missing.
But, if you weren't paying attention to the actual words we were saying before, please do so now:
from: http://www.magnumpowers.com/light_spring.php
Additional Valve Spring Requirements:
There are two distinct additional requirements a supercharged engine places on valve springs. These requirements are not recognized by leading valve spring manufacturers or most race engine builders and are therefore a new concept to most people looking for increased performance. Firstly supercharged engines require stronger valve springs then NA engines do to a force applied to the valve head that is associated with manifold pressure and the engine’s volumetric efficiency (VE). If for instance a supercharged engine running 20-psi manifold pressure has a volumetric efficiency of 100% when the piston reaches the bottom of the intake stroke and the intake valve closes there will be 20-psi on both sides of the valve head, i.e., 20-psi on the intake manifold side and 20-psi on the cylinder side because the cylinder fully filled with air during the intake cycle. Since the air pressure in this case are the same on both sides of the valve no force is applied to the valve head. If however the engine has a volumetric efficiency of only 50% there will be 20-psi pressure on the manifold side but only 10-psi on the cylinder side when the valve closes, because the cylinder did not completely fill, a net pressure of 10-psi will be present across the valve head. If the intake valve has a surface area of 2.5 square inches a force of 25 pounds (2.5x10) will be generated that will be trying to open the valve thus reducing the effective valve spring pressure by 25 pounds. Since engine manufacturers install valve springs that are only strong enough to support proper valve action to their RPM limit any reduction in effective valve spring strength will lower the useful power band RPM limit. If the valve spring does not have enough strength to keep the valve following the camshaft profile the valve is said to “float”.
The second additional requirement arises during the exhaust cycle. During the exhaust cycle the cylinder pressure drops to zero or can even go negative do to exhaust header-savaging effects. During the exhaust cycle the intake valve spring must be strong enough to hold the intake valve closed against manifold pressure. If the manifold pressure is 20-psi and the valve head has 2.5 square inches of surface area the force attempting to open the valve will be 50 pounds (2.5x20). If the intake valve opens during the exhaust cycle the air/fuel intake charge will flow through the intake valve and out the exhaust valve during the exhaust cycle and will not be used by the engine to develop power.
There are two distinct additional requirements a supercharged engine places on valve springs. These requirements are not recognized by leading valve spring manufacturers or most race engine builders and are therefore a new concept to most people looking for increased performance. Firstly supercharged engines require stronger valve springs then NA engines do to a force applied to the valve head that is associated with manifold pressure and the engine’s volumetric efficiency (VE). If for instance a supercharged engine running 20-psi manifold pressure has a volumetric efficiency of 100% when the piston reaches the bottom of the intake stroke and the intake valve closes there will be 20-psi on both sides of the valve head, i.e., 20-psi on the intake manifold side and 20-psi on the cylinder side because the cylinder fully filled with air during the intake cycle. Since the air pressure in this case are the same on both sides of the valve no force is applied to the valve head. If however the engine has a volumetric efficiency of only 50% there will be 20-psi pressure on the manifold side but only 10-psi on the cylinder side when the valve closes, because the cylinder did not completely fill, a net pressure of 10-psi will be present across the valve head. If the intake valve has a surface area of 2.5 square inches a force of 25 pounds (2.5x10) will be generated that will be trying to open the valve thus reducing the effective valve spring pressure by 25 pounds. Since engine manufacturers install valve springs that are only strong enough to support proper valve action to their RPM limit any reduction in effective valve spring strength will lower the useful power band RPM limit. If the valve spring does not have enough strength to keep the valve following the camshaft profile the valve is said to “float”.
The second additional requirement arises during the exhaust cycle. During the exhaust cycle the cylinder pressure drops to zero or can even go negative do to exhaust header-savaging effects. During the exhaust cycle the intake valve spring must be strong enough to hold the intake valve closed against manifold pressure. If the manifold pressure is 20-psi and the valve head has 2.5 square inches of surface area the force attempting to open the valve will be 50 pounds (2.5x20). If the intake valve opens during the exhaust cycle the air/fuel intake charge will flow through the intake valve and out the exhaust valve during the exhaust cycle and will not be used by the engine to develop power.
Addresses the issues inherent in a high pressure turbo - it complicates the exhaust side of the equasion even more.
Valve Spring Theory Proven by Test Results:
A plate was fabricated and bolted across the intake port in place of the intake manifold at Magnum Powers’ laboratory and then the intake port was pressurized to simulate boost pressure. Air pressure was increased slowly until at 18-psi the valve opened and air started leaking past the valve seat revealing for the first time, by testing, that the Lightning’s valve spring pressure is inadequate. These tests were later collaborated by others within the Lightning community. As air pressure as increased further air leakage pass the valve seat became very significant on the order of 5-10cfm.
A plate was fabricated and bolted across the intake port in place of the intake manifold at Magnum Powers’ laboratory and then the intake port was pressurized to simulate boost pressure. Air pressure was increased slowly until at 18-psi the valve opened and air started leaking past the valve seat revealing for the first time, by testing, that the Lightning’s valve spring pressure is inadequate. These tests were later collaborated by others within the Lightning community. As air pressure as increased further air leakage pass the valve seat became very significant on the order of 5-10cfm.
02-03-2010, 08:54 PM
#30
Rennlist Member
you dont read my posts do you? Its funny how you blast someone for being an expert when they are just asking questions. Brendan, get a reality check. you are no expert either. The things you say sometimes, come from way out in the left field bleachers. Now, moving on.
I mentioned that on the exhaust stroke, there could be leaking out the intake valve which is being held closed by the spring pressure and boost pressure reduces that. by how much. anyones guess.
I also mentioned that at the bottom of the intake there couldnt be any forces. now, you and the article is talking about the pressure at the piston. at the valve, front and back there is a differnet story. there are things called pressure gradients and they are present in this type of example.
do we have 50% volumetric effciency? say we do, that means the pressure at the piston face willl be certainly MUCH different than at the valve face.
I dont think anyone would think that the boost pressure in our case would be acting on the valve to where that would be an issue with valve float or delay of valve closing. however, as I had said, on the exhaust stroke, there would be pressure to crack it open and leak boost out the intake and out the exhaust
now, again, i wasnt talking about nor was hacker talking about valve leaks. we said that that is a possibility. However, are our valve springs like "Lightening" valve springs? I dont know, I'm not the expert, that could be on a lawn mower for all I, or you , know.
point is, until you know, you shoudlnt tout like you do! as far as leaks, just pressurize the valve port with 30psi and see if we have a leak in our intake valves. Or for grins, put 50lbs of pressure on the valve and see if it leaks.
I mentioned that on the exhaust stroke, there could be leaking out the intake valve which is being held closed by the spring pressure and boost pressure reduces that. by how much. anyones guess.
I also mentioned that at the bottom of the intake there couldnt be any forces. now, you and the article is talking about the pressure at the piston. at the valve, front and back there is a differnet story. there are things called pressure gradients and they are present in this type of example.
do we have 50% volumetric effciency? say we do, that means the pressure at the piston face willl be certainly MUCH different than at the valve face.
I dont think anyone would think that the boost pressure in our case would be acting on the valve to where that would be an issue with valve float or delay of valve closing. however, as I had said, on the exhaust stroke, there would be pressure to crack it open and leak boost out the intake and out the exhaust
now, again, i wasnt talking about nor was hacker talking about valve leaks. we said that that is a possibility. However, are our valve springs like "Lightening" valve springs? I dont know, I'm not the expert, that could be on a lawn mower for all I, or you , know.
point is, until you know, you shoudlnt tout like you do! as far as leaks, just pressurize the valve port with 30psi and see if we have a leak in our intake valves. Or for grins, put 50lbs of pressure on the valve and see if it leaks.
you did bang your head, didnt you?
how can you pressureize the back side of the valves, if the valve is open?
below, you mention that the boose would really be trying to open closed valves right?
and to answer your question, yes, there would be no difference in closing the valve with and without boost. think about it. boost is the ambient air now, the valve opens, differential pressure moves the air mass into thecylinders. at the bottom of the stroke, probalby both sides of the valve will have the same pressure on them, so there would be NO extra forces on the intake valve against it to open it, close near bottom-dead-center.
yes, brendan didnt mention rpm, but my point was that at that point, thats were valve float can happen, and with boost, it can be more of a detrimental factor than with a non boosted engine.
so, to your last point, you said: "Mark, Brendon is trying to close the valves with 20-30psi of manifold pressure trying to keep them open."
Yet again, if the valves are starting to close, the air pressure on all sides of the valve will be the same. the pressure in the cylinder is 20psi and the pressure in the manifold is 20psi. (more or less) there is no "force" on the valves trying to "keep them" open
You said it, its inertia, momentium, speed that can cause valve float. why cant YOU understand that boost is not a factor in valve float, and its all about the spring pressure acting on those forces. There are no boost forces acting on the back of the valves as they begin to close. why is that so complicated for you to understand??
I suppose valve float is worse with boosted engines, as they can lose more of a percentage of their mass flow, because the mass is 2X more dense, and during float, you blead off the fuel air charge back out the intake valve as the piston is coming up.
how can you pressureize the back side of the valves, if the valve is open?
below, you mention that the boose would really be trying to open closed valves right?
and to answer your question, yes, there would be no difference in closing the valve with and without boost. think about it. boost is the ambient air now, the valve opens, differential pressure moves the air mass into thecylinders. at the bottom of the stroke, probalby both sides of the valve will have the same pressure on them, so there would be NO extra forces on the intake valve against it to open it, close near bottom-dead-center.
yes, brendan didnt mention rpm, but my point was that at that point, thats were valve float can happen, and with boost, it can be more of a detrimental factor than with a non boosted engine.
so, to your last point, you said: "Mark, Brendon is trying to close the valves with 20-30psi of manifold pressure trying to keep them open."
Yet again, if the valves are starting to close, the air pressure on all sides of the valve will be the same. the pressure in the cylinder is 20psi and the pressure in the manifold is 20psi. (more or less) there is no "force" on the valves trying to "keep them" open
You said it, its inertia, momentium, speed that can cause valve float. why cant YOU understand that boost is not a factor in valve float, and its all about the spring pressure acting on those forces. There are no boost forces acting on the back of the valves as they begin to close. why is that so complicated for you to understand??
I suppose valve float is worse with boosted engines, as they can lose more of a percentage of their mass flow, because the mass is 2X more dense, and during float, you blead off the fuel air charge back out the intake valve as the piston is coming up.
Jesus. You seriously have a fundamental misunderstanding of many things which you espouse on as if you are some sort of expert. NONE of us here are actually certified experts. Especially you. Honestly, you bring such confusing, mis-directed, and non-sequitorial information to threads, I wish I could bar you from posting in them.
Its not even worth attempting to explain to you why you are wrong and what details you are missing.
But, if you weren't paying attention to the actual words we were saying before, please do so now:
from: http://www.magnumpowers.com/light_spring.php
And this thread here: http://www.4btswaps.com/forum/showthread.php?t=7092
Addresses the issues inherent in a high pressure turbo - it complicates the exhaust side of the equasion even more.
OKAY! This will hurt your ego when I say this - "Are we done here?
Its not even worth attempting to explain to you why you are wrong and what details you are missing.
But, if you weren't paying attention to the actual words we were saying before, please do so now:
from: http://www.magnumpowers.com/light_spring.php
And this thread here: http://www.4btswaps.com/forum/showthread.php?t=7092
Addresses the issues inherent in a high pressure turbo - it complicates the exhaust side of the equasion even more.
OKAY! This will hurt your ego when I say this - "Are we done here?