Valve Spring Life
10-13-2005, 10:40 PM
#1
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Valve Spring Life Cam Masters:
A technical challenge. With the LS7 reporting to have .590 plus lift, how is it Chevorlet can design a 100,000 mile serviceable high-lift cam application when the rest of us are changing valve springs every 20,000 or so miles with aftermarket cam and head packages.
With that in mind, the challenge is: What are the factors which impact valve spring life and what existing commericial off the shelf combinations provide the optimum balance of power, torque and valve spring life?
Sure the LS7 is a 7.0 litre engine, but the technology can't be secret.
Your thought would be appreciated
A technical challenge. With the LS7 reporting to have .590 plus lift, how is it Chevorlet can design a 100,000 mile serviceable high-lift cam application when the rest of us are changing valve springs every 20,000 or so miles with aftermarket cam and head packages.
With that in mind, the challenge is: What are the factors which impact valve spring life and what existing commericial off the shelf combinations provide the optimum balance of power, torque and valve spring life?
Sure the LS7 is a 7.0 litre engine, but the technology can't be secret.
Your thought would be appreciated
10-13-2005, 11:17 PM
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This makes me think too, but some of it has to do with valve spring material. GM has a lot more money to wrap up into R&D than Comp does. Who knows how many different types or spring/cam combinations were tested before they were happy.
10-14-2005, 06:07 AM
#4
It comes down to repetitive stress levels in the material and the material fatique capability. A taller spring that will have a lower outer fiber stress level at peak lift is probably a good start. We are forced to deal with the limitations of 1.8 installed height, I wouldn't be surprised to find the installed height on the LS7 is higher.
10-14-2005, 08:50 AM
#5
Originally Posted by vettenuts
It comes down to repetitive stress levels in the material and the material fatique capability. A taller spring that will have a lower outer fiber stress level at peak lift is probably a good start. We are forced to deal with the limitations of 1.8 installed height, I wouldn't be surprised to find the installed height on the LS7 is higher.
10-14-2005, 11:04 AM
#6
If you can achieve desired seat and open pressures with a smaller diameter valve spring you are better off. A valvetrain no matter what will have harmonics. The larger valve spring will amplify these harmonics. Larger coils will make more harmonics smaller coils less harmonics.
I'm sure GM has done their homework on these springs. I would speculate these are a Super Clean Vanadium Chrome Silicone material and that the spring has been cycle tested for at least 100K miles.
Chris
I'm sure GM has done their homework on these springs. I would speculate these are a Super Clean Vanadium Chrome Silicone material and that the spring has been cycle tested for at least 100K miles.
Chris
