Heavy valve springs don't use more HP
06-14-2002, 02:53 PM
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Heavy valve springs don't use more HP I've heard argued on here that heavier valve springs rob HP.
I was reading an article in Car Craft that made a very sharp observation on this point: For every spring that is being compressed by a lifter there is another spring that is forcing a lifter back down. In other words the work springs do always cancels out, regardless of the force it takes to open those springs.
Of course lash, weird lobes, and what have you will effect this, but the basic idea here is heavier springs do not cost HP!
I was reading an article in Car Craft that made a very sharp observation on this point: For every spring that is being compressed by a lifter there is another spring that is forcing a lifter back down. In other words the work springs do always cancels out, regardless of the force it takes to open those springs.
Of course lash, weird lobes, and what have you will effect this, but the basic idea here is heavier springs do not cost HP!
06-14-2002, 03:01 PM
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Re: Heavy valve springs don't use more HP For you physics nuts I know you lose 4-5% in heat and noise, I'm just making a general observation. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
06-14-2002, 03:44 PM
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Re: Heavy valve springs don't use more HP You are much more respectable when you stick to tech talk like this <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />
06-14-2002, 05:22 PM
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Re: Heavy valve springs don't use more HP I agree 100% with Terry. We have done A-B-A engine dyno tests, and you do not lose HP with heavier springs. However, too light (seat pressure) can be VERY bad for the valve train, especially the roller lifters themselves.
06-17-2002, 02:07 AM
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Re: Heavy valve springs don't use more HP I disagree indirectly. Stiffer springs may not reduce HP, but they are usually bigger and thus more weight. Heavier valvetrain costs ya. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
<small>[ June 17, 2002, 02:08 AM: Message edited by: Jantzer98SS ]</small>
<small>[ June 17, 2002, 02:08 AM: Message edited by: Jantzer98SS ]</small>
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06-17-2002, 02:23 AM
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Re: Heavy valve springs don't use more HP </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Jantzer98SS:
<strong>I disagree indirectly. Stiffer springs may not reduce HP, but they are usually bigger and thus more weight. Heavier valvetrain costs ya. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Jantzer98SS,
They are not always bigger.
Next, if you ARE putting in bigger springs, then they MAY weigh more (than a comparable spring, if same material). However, that is not all in moving weight, and none of this weight is weight such as a lifter, pushrod, valve, etc.
So what do you mean by it 'costs ya' ??
<small>[ June 17, 2002, 02:24 AM: Message edited by: Will Race 4 Food ]</small>
<strong>I disagree indirectly. Stiffer springs may not reduce HP, but they are usually bigger and thus more weight. Heavier valvetrain costs ya. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Jantzer98SS,
They are not always bigger.
Next, if you ARE putting in bigger springs, then they MAY weigh more (than a comparable spring, if same material). However, that is not all in moving weight, and none of this weight is weight such as a lifter, pushrod, valve, etc.
So what do you mean by it 'costs ya' ??
<small>[ June 17, 2002, 02:24 AM: Message edited by: Will Race 4 Food ]</small>
06-17-2002, 05:36 AM
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Re: Heavy valve springs don't use more HP Scott is right, springs wieght shows up in direction changes of valves, this slows valvetrain, costing accelleration,not the same as hp but still important. The extra friction from stiffer springs costs power and is only beneficial if its needed to control cam profile in usable rpm range.Loose valve guides from extra spring pressure can really cost you hp , because valve job and seal gets beat to hell also. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
06-17-2002, 08:52 AM
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Re: Heavy valve springs don't use more HP I'm not sure how you guys can "theorize" your way through this one. One sure fact is that, in all the motors I've put together, I've found that higher seat and open pressures make it WAY harder to lash valves. One must turn the motor to the next valve 16 times (often with a second run, "just for kicks")
The hardest motors I've ever lashed were FULL roller motors (roller cam bearings, roller lifters, roller rockers) with seat pressures at 300lbs (obviously pro-stock motors). These had low tesion oil rings to boot.
There is most DEFINITELY more power required to overcome heavy valve springs. That's the entire reason Chevy uses such weak springs on stock motors, for an increase in valvetrain efficiency.
That's also the reason they use the beehive geometry, for a lighter seat pressure and heavier open pressure.
SC
The hardest motors I've ever lashed were FULL roller motors (roller cam bearings, roller lifters, roller rockers) with seat pressures at 300lbs (obviously pro-stock motors). These had low tesion oil rings to boot.
There is most DEFINITELY more power required to overcome heavy valve springs. That's the entire reason Chevy uses such weak springs on stock motors, for an increase in valvetrain efficiency.
That's also the reason they use the beehive geometry, for a lighter seat pressure and heavier open pressure.
SC
06-17-2002, 01:15 PM
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Re: Heavy valve springs don't use more HP Interesting topic Terry, but the work put into compressing the spring is not completely conserved like you also pointed out. The non-conservative loss between a larger spring and something like a 918 would be minimal though.
06-17-2002, 03:10 PM
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Re: Heavy valve springs don't use more HP I can see the point that CC is making, but I believe there is a slight loss. You have to take all things in to account (I'm sure I'm going to miss some), Spring pressure, weight, Cam style, duration, ramp rates, lift ect..
In a perfect work a ball rolled down a 10 foot ramp from the top would roll to the top of the other side of that same 10 foot ramp. There is energy wasted some where. There is never a perfect equal to energy input vs energy out put.
In a perfect work a ball rolled down a 10 foot ramp from the top would roll to the top of the other side of that same 10 foot ramp. There is energy wasted some where. There is never a perfect equal to energy input vs energy out put.
06-17-2002, 03:36 PM
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Re: Heavy valve springs don't use more HP Maybe this will go nowhere..... But it proves to total geeks like me the point that heavier springs will slow the valve train.
F = MA (Force = Mass * Accelleration)
F = KX (Spring Force = Spring Factor * Distance Compressed)
MA = KX (Spring Force is relative to the inertial relationship)
M = KX / A
(Mass = Spring Constant * Distance Compressed / Accelleration)
This shows that for every increase in mass, there is going to be a decrease in acceleration (inverse relationship). The only way to compensate for this is to increase the spring force (K factor) or to increase you lift (X distance compressed). Bigger springs will ALWAYS decrease valve acceleration if the spring force and lift remain equal. <img border="0" alt="[judgement]" title="" src="graemlins/gr_judge.gif" />
F = MA (Force = Mass * Accelleration)
F = KX (Spring Force = Spring Factor * Distance Compressed)
MA = KX (Spring Force is relative to the inertial relationship)
M = KX / A
(Mass = Spring Constant * Distance Compressed / Accelleration)
This shows that for every increase in mass, there is going to be a decrease in acceleration (inverse relationship). The only way to compensate for this is to increase the spring force (K factor) or to increase you lift (X distance compressed). Bigger springs will ALWAYS decrease valve acceleration if the spring force and lift remain equal. <img border="0" alt="[judgement]" title="" src="graemlins/gr_judge.gif" />
06-17-2002, 03:49 PM
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Re: Heavy valve springs don't use more HP quote]
Maybe this will go nowhere..... But it proves to total geeks like me the point that heavier springs will slow the valve train.
[/quote]
Your argument fails to consider that automotive camshafts work in a black and white environment, and overstates the significance of the springs "mass".
A lifter is either ridding the cam profile properly and the engine is accelerating, or its not and the engine is in a valve float condition. As long as the lifter is riding the cam profile properly we're only talking about the force to accelerate the springs "mass".
Sure it will slow the engine down in a theoretical sense, just like adding a gram to each piston will, but the springs mass is small and its travel short in relation to the other moving parts in an engine (IE pistons).
Usually if you're buying titanium parts titanium valve springs are the last thing you get. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
Maybe this will go nowhere..... But it proves to total geeks like me the point that heavier springs will slow the valve train.
[/quote]
Your argument fails to consider that automotive camshafts work in a black and white environment, and overstates the significance of the springs "mass".
A lifter is either ridding the cam profile properly and the engine is accelerating, or its not and the engine is in a valve float condition. As long as the lifter is riding the cam profile properly we're only talking about the force to accelerate the springs "mass".
Sure it will slow the engine down in a theoretical sense, just like adding a gram to each piston will, but the springs mass is small and its travel short in relation to the other moving parts in an engine (IE pistons).
Usually if you're buying titanium parts titanium valve springs are the last thing you get. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
06-17-2002, 06:17 PM
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Re: Heavy valve springs don't use more HP </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Terry Burger:
<strong>
Your argument fails to consider that automotive camshafts work in a black and white environment, and overstates the significance of the springs "mass".
</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I am talking for non-float conditions.
Overstating the significance of the spring mass, depends on how heavy you are talking about. I think you are understating the significance of valve acceleration.
It is common knowledge that increasing the weight of your valvetrain (no matter where you do it) is going to make it more difficult for the valve to accuratly follow it's intended motion.
At the RPM's that most of us operate at, I doubt we will be able to see any significant losses from (slightly) heavier valvetrains. The higher in RPM you go though, the more apparent these losses are going to become. It's all relative, just depends on where you are going with it <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
<strong>
Your argument fails to consider that automotive camshafts work in a black and white environment, and overstates the significance of the springs "mass".
</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I am talking for non-float conditions.
Overstating the significance of the spring mass, depends on how heavy you are talking about. I think you are understating the significance of valve acceleration.
It is common knowledge that increasing the weight of your valvetrain (no matter where you do it) is going to make it more difficult for the valve to accuratly follow it's intended motion.
At the RPM's that most of us operate at, I doubt we will be able to see any significant losses from (slightly) heavier valvetrains. The higher in RPM you go though, the more apparent these losses are going to become. It's all relative, just depends on where you are going with it <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
06-17-2002, 11:50 PM
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Re: Heavy valve springs don't use more HP I've seen as much as a 7 rwhp loss going from one spring type to another.
The theory of one spring pushing up while another is being compressed will work if there is one lobe for another lobe at a given time working in conjuction with the other(there still is a effeciency loss). And that the lifters are in similar respects to its "paired up" other at a given point on the lobe as far as position, but that isn't the case. (for example both lifters being at the midpoint of the lobe or at the end of there opening and closig cycles for each verse one lobe nearing it's end of closing while it's supposed other is only halfway through the lift cycle). Plus seat pressures aren't the same as the pressure of a compressed spring. Also have to figure in ramp rate differences and the differnce in exhaust lobes to intake lobes. The lobes aren't perfectly like each other nor are they always similar in opening verse closing rates within the same given lobe.
I still think that higher spring rates are going to hurt power. And how much power loss is related to the type of cam you are running as well as the spring rate.
Hope this helps.
Max
The theory of one spring pushing up while another is being compressed will work if there is one lobe for another lobe at a given time working in conjuction with the other(there still is a effeciency loss). And that the lifters are in similar respects to its "paired up" other at a given point on the lobe as far as position, but that isn't the case. (for example both lifters being at the midpoint of the lobe or at the end of there opening and closig cycles for each verse one lobe nearing it's end of closing while it's supposed other is only halfway through the lift cycle). Plus seat pressures aren't the same as the pressure of a compressed spring. Also have to figure in ramp rate differences and the differnce in exhaust lobes to intake lobes. The lobes aren't perfectly like each other nor are they always similar in opening verse closing rates within the same given lobe.
I still think that higher spring rates are going to hurt power. And how much power loss is related to the type of cam you are running as well as the spring rate.
Hope this helps.
Max
06-17-2002, 11:55 PM
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Re: Heavy valve springs don't use more HP Think of it kinda like an uneven seesaw where one side is shorter than the other. take two kids of identical weight and place them on either end, and it won't balance out. Sorta kinda like that, lol, but not.
If spring rates didn't hurt, than why do most engine builders live by the rule of thumb, that the best spring pressure is just enough. If that isn't the case then we should just slam in the heaviest spring we can find, and whalla no more valve float for anyone.
If spring rates didn't hurt, than why do most engine builders live by the rule of thumb, that the best spring pressure is just enough. If that isn't the case then we should just slam in the heaviest spring we can find, and whalla no more valve float for anyone.
06-18-2002, 03:46 AM
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Re: Heavy valve springs don't use more HP </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by No Go:
<strong>quote]
Maybe this will go nowhere..... But it proves to total geeks like me the point that heavier springs will slow the valve train.
</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Your argument fails to consider that automotive camshafts work in a black and white environment, and overstates the significance of the springs "mass".
A lifter is either ridding the cam profile properly and the engine is accelerating, or its not and the engine is in a valve float condition. As long as the lifter is riding the cam profile properly we're only talking about the force to accelerate the springs "mass".
Sure it will slow the engine down in a theoretical sense, just like adding a gram to each piston will, but the springs mass is small and its travel short in relation to the other moving parts in an engine (IE pistons).
Usually if you're buying titanium parts titanium valve springs are the last thing you get. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> </strong>[/QUOTE]by Terry Burger
Terry,
Still you are right. Again!
OK, to finish this argument up, instaed of posting our experience and findings, we have researched another race shop, actually in Texas. Pro Stock points leaders, Chevy engine builders for 30 years, and most of their engines go to Sportman customers.
To quote David Reher, of Reher-Morrison Racing engines, Texas, QUOTE:
The most COMMON mistake I see in engine building is to use valve springs with inadequate pressure. Not all springs are created equal; just because a set of coils is described as 'roller springs' in a catalog or advertisement does not mean that the springs will produce enough pressure to do their job..........
In fact, too little spring pressure is almost always the root cause of valvetrain failures. We spent A YEAR studying valve springs using an Optron, a sophisticated electronic device that can presicely record valve motion and reveal valve float. We learned some shocking truths about valvetrain behavior at high RPM. Even with a RELATIVELY MILD camshaft profile, the valves bounce on their seats before they close. If the spring is too light, the valve bounces uncontrollably. The valve hits the seat, rebounds, hangs in the chamber awhile, and the valve bounces erratically several more times. Imagine how hard this is on the valve and the rest of the valve train.....
**ANOTHER EXCUSE I've heard for not using stiff valve springs is that they take more horsepower to compress. My reply is that each spring stores energy, and for every valve that is opening another one is closing. Anyone who has been whacked by a torque wrench while turning a crankshaft can testify that the valve springs exert considerable force on the closing ramps.
**I have NEVER installed stiffer valve springs on an engine and lost power; the improvement in valvetrain dynamics more than offsets whatever additional power is required to overcome the springs resistance." END QUOTE.
Couldn't have said it better!
These guys have built thousands of Chevy performance street and pure racing engines. They have two dyno's etc etc. Have won World Championships (and likely again this year).
Anyone who thinks they are engine building/racing guru's (store bought guys don't apply within please) want to argue with the above?? Takers?
To those that originally agreed, Cheers! <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
To those that disagreed, keep on learning and take advise from those that have the experience. That's why this board is here. Enjoy the ride.
I and our crew don't profess to know everything about LS1's, but logic and experience count.
Oh, and BTW, Reher-Morrison do LS1 engines for you 'all in Texas... <img border="0" alt="[Burnout]" title="" src="graemlins/burnout.gif" />
<strong>quote]
Maybe this will go nowhere..... But it proves to total geeks like me the point that heavier springs will slow the valve train.
</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Your argument fails to consider that automotive camshafts work in a black and white environment, and overstates the significance of the springs "mass".
A lifter is either ridding the cam profile properly and the engine is accelerating, or its not and the engine is in a valve float condition. As long as the lifter is riding the cam profile properly we're only talking about the force to accelerate the springs "mass".
Sure it will slow the engine down in a theoretical sense, just like adding a gram to each piston will, but the springs mass is small and its travel short in relation to the other moving parts in an engine (IE pistons).
Usually if you're buying titanium parts titanium valve springs are the last thing you get. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> </strong>[/QUOTE]by Terry Burger
Terry,
Still you are right. Again!
OK, to finish this argument up, instaed of posting our experience and findings, we have researched another race shop, actually in Texas. Pro Stock points leaders, Chevy engine builders for 30 years, and most of their engines go to Sportman customers.
To quote David Reher, of Reher-Morrison Racing engines, Texas, QUOTE:
The most COMMON mistake I see in engine building is to use valve springs with inadequate pressure. Not all springs are created equal; just because a set of coils is described as 'roller springs' in a catalog or advertisement does not mean that the springs will produce enough pressure to do their job..........
In fact, too little spring pressure is almost always the root cause of valvetrain failures. We spent A YEAR studying valve springs using an Optron, a sophisticated electronic device that can presicely record valve motion and reveal valve float. We learned some shocking truths about valvetrain behavior at high RPM. Even with a RELATIVELY MILD camshaft profile, the valves bounce on their seats before they close. If the spring is too light, the valve bounces uncontrollably. The valve hits the seat, rebounds, hangs in the chamber awhile, and the valve bounces erratically several more times. Imagine how hard this is on the valve and the rest of the valve train.....
**ANOTHER EXCUSE I've heard for not using stiff valve springs is that they take more horsepower to compress. My reply is that each spring stores energy, and for every valve that is opening another one is closing. Anyone who has been whacked by a torque wrench while turning a crankshaft can testify that the valve springs exert considerable force on the closing ramps.
**I have NEVER installed stiffer valve springs on an engine and lost power; the improvement in valvetrain dynamics more than offsets whatever additional power is required to overcome the springs resistance." END QUOTE.
Couldn't have said it better!
These guys have built thousands of Chevy performance street and pure racing engines. They have two dyno's etc etc. Have won World Championships (and likely again this year).
Anyone who thinks they are engine building/racing guru's (store bought guys don't apply within please) want to argue with the above?? Takers?
To those that originally agreed, Cheers! <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
To those that disagreed, keep on learning and take advise from those that have the experience. That's why this board is here. Enjoy the ride.
I and our crew don't profess to know everything about LS1's, but logic and experience count.
Oh, and BTW, Reher-Morrison do LS1 engines for you 'all in Texas... <img border="0" alt="[Burnout]" title="" src="graemlins/burnout.gif" />
06-18-2002, 03:04 PM
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Re: Heavy valve springs don't use more HP The comparison wasn't of a bad set of springs where valve float is present, but rather a set of springs that have enough pressure verse a set that has more pressure than the set being compared to it.
Lets over exagerate the situation. Assemble a engine's top half only(no crank, rods, or pistons). In the first test place in a set of 1lbs springs. you'd probably be able to spin the cam by hand. Now for the second test take all those springs and replace them with a set that have a force of 300lbs, good luck spinning that by hand.
There is a difference in association to spring pressure. Now take that difference in pressure and imagine having it when the engine is spinning at 6300 rpm. There is going to be a power loss.
Not that there is a 299lbs difference between spring types, but that there is a difference when you switch from one set to another.
Some of the power is lost in friction.
Lets over exagerate the situation. Assemble a engine's top half only(no crank, rods, or pistons). In the first test place in a set of 1lbs springs. you'd probably be able to spin the cam by hand. Now for the second test take all those springs and replace them with a set that have a force of 300lbs, good luck spinning that by hand.
There is a difference in association to spring pressure. Now take that difference in pressure and imagine having it when the engine is spinning at 6300 rpm. There is going to be a power loss.
Not that there is a 299lbs difference between spring types, but that there is a difference when you switch from one set to another.
Some of the power is lost in friction.
06-18-2002, 03:11 PM
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Re: Heavy valve springs don't use more HP </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">
Lets over exagerate the situation. Assemble a engine's top half only(no crank, rods, or pistons). In the first test place in a set of 1lbs springs. you'd probably be able to spin the cam by hand. Now for the second test take all those springs and replace them with a set that have a force of 300lbs, good luck spinning that by hand.
</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">There are three states here. Adding to the springs, taking from the springs, and neutral (no give or take). Sure if you go to spin the engine by hand from a neutral position you need to put in all the work to compress those springs. The big picture that you're missing here is you get most of that work back as the engine turns! It appears you are naive enough to believe that all the energy that went in to compressing the springs just disappears in to heat. The fact here is that most springs are 95% efficient.
Lets over exagerate the situation. Assemble a engine's top half only(no crank, rods, or pistons). In the first test place in a set of 1lbs springs. you'd probably be able to spin the cam by hand. Now for the second test take all those springs and replace them with a set that have a force of 300lbs, good luck spinning that by hand.
</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">There are three states here. Adding to the springs, taking from the springs, and neutral (no give or take). Sure if you go to spin the engine by hand from a neutral position you need to put in all the work to compress those springs. The big picture that you're missing here is you get most of that work back as the engine turns! It appears you are naive enough to believe that all the energy that went in to compressing the springs just disappears in to heat. The fact here is that most springs are 95% efficient.