Valve spring tech. . . .
04-19-2004, 08:09 AM
#1
Valve spring tech. . . . Due to the post on which springs to use I thought I would give a few pointers. I have helped develop 3 valvetrain lines so I have a little background on the stuff.
You have 3 major players that wind the cam companies springs to their specs. . .some share common springs because they are proven coils.
This will just be some basic info with some info on increasing spring life:
Materials:
Vanadium Chrome Silicon: Std OEM type material used by the big 3. Has excellent indurance but lacks high spring load pressure for radical drag and circle track applications. Spring rate fades over a long period of time. It is not breakage prone. Will take initial set of around 5%
H-11 Tool Steel: Long used as the choice for high lift radical cam combinations, this material has a high spring load rate. Excellent for drag and circle combinations that have good maintenance checks. Negative side is that the spring is prone to breakage after cycle time with no warning. Does take an initial set of 10% average during start up.
Super Clean Chrome Silicon: New material developed some 10 years ago, most of the production in out of Kobi Japan. Material was developed to have the longevity of Chrome Silicon and the spring rate of tool steel. This was accomplished by adding 2 more degassing processes to rid the spring of impurities. The impurities in the metal are what causes a spring to break. Spring has great endurance and does not take an initial set. Down fall is that it is expensive, costing on average 6 X more then a Chrome Silcon.
Process:
Cryo seems to work well in increasing spring life. Would recommend.
Meta-laxing is what I would recommend. This is vibrational stress relief. Imagine a sugar bowl full of sugar with a mound in the center. . . now shake the bowl back and forth. . .the sugar spreads out evenly. This is what the molecules do in the spring material. I have logged spring life increases as much as 5 X longer then another set of the same springs.
Electo Polishing: This process is a surface enhancement that smooths the surface of the spring. This reduces the friction between coils and allows the spring to run cooler. Heat is a killer on springs. We have measured a difference of 20 degrees after this has been done to a spring. Highly recommened.
Deburring. Stress builds in sharp edges. Before springs are installed you can take a dremel with sand rolls, mild grit, and smooth and round the sharp edges on either end. This reduces stress possiblities and increase life.
Types of Breakage.
If a spring breaks and it is a clean break. . .butter knife...then this is a heat treat failure. The spring did not get the proper about of heat cycling. NOt common. Fix is get another set.
If a spring breaks and it is jagged.. . very rough probly angled...this is harmonics. The spring has failed due to valvetrain frequencys affecting the springs frequency and putting stress on it. Very common. Fix is the go through valvetrain and diagnose problem. . .if a dual was used may want to go to a spring with a dampener to absorb the harmonics.
Enough for me this morning. . .any other "q's you can e-mail me.
Chris
You have 3 major players that wind the cam companies springs to their specs. . .some share common springs because they are proven coils.
This will just be some basic info with some info on increasing spring life:
Materials:
Vanadium Chrome Silicon: Std OEM type material used by the big 3. Has excellent indurance but lacks high spring load pressure for radical drag and circle track applications. Spring rate fades over a long period of time. It is not breakage prone. Will take initial set of around 5%
H-11 Tool Steel: Long used as the choice for high lift radical cam combinations, this material has a high spring load rate. Excellent for drag and circle combinations that have good maintenance checks. Negative side is that the spring is prone to breakage after cycle time with no warning. Does take an initial set of 10% average during start up.
Super Clean Chrome Silicon: New material developed some 10 years ago, most of the production in out of Kobi Japan. Material was developed to have the longevity of Chrome Silicon and the spring rate of tool steel. This was accomplished by adding 2 more degassing processes to rid the spring of impurities. The impurities in the metal are what causes a spring to break. Spring has great endurance and does not take an initial set. Down fall is that it is expensive, costing on average 6 X more then a Chrome Silcon.
Process:
Cryo seems to work well in increasing spring life. Would recommend.
Meta-laxing is what I would recommend. This is vibrational stress relief. Imagine a sugar bowl full of sugar with a mound in the center. . . now shake the bowl back and forth. . .the sugar spreads out evenly. This is what the molecules do in the spring material. I have logged spring life increases as much as 5 X longer then another set of the same springs.
Electo Polishing: This process is a surface enhancement that smooths the surface of the spring. This reduces the friction between coils and allows the spring to run cooler. Heat is a killer on springs. We have measured a difference of 20 degrees after this has been done to a spring. Highly recommened.
Deburring. Stress builds in sharp edges. Before springs are installed you can take a dremel with sand rolls, mild grit, and smooth and round the sharp edges on either end. This reduces stress possiblities and increase life.
Types of Breakage.
If a spring breaks and it is a clean break. . .butter knife...then this is a heat treat failure. The spring did not get the proper about of heat cycling. NOt common. Fix is get another set.
If a spring breaks and it is jagged.. . very rough probly angled...this is harmonics. The spring has failed due to valvetrain frequencys affecting the springs frequency and putting stress on it. Very common. Fix is the go through valvetrain and diagnose problem. . .if a dual was used may want to go to a spring with a dampener to absorb the harmonics.
Enough for me this morning. . .any other "q's you can e-mail me.
Chris
