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

 

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.

 

Hmmmmm.. That is a very good question. I like to see some of the other members insight on this topic.

 

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.

 

A larger diameter would acomplish the same as well, no?

 

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

 

paging J-ROD, your thoughts??

 

Spring material diameter is a bigger player, and it becomes a trade-off between spring force and coil bind height.

 

This is a little off topic but how long do you think valve springs will last when I get my Fm13 put in? Im gonna go with comp 918s btw. Also any other springs that would last long than the 918's? Thanks!

 

Are they using real light valvetrain parts? That would allow the spring to be less stiff and have less stresses.

 

IIRC, yes, the ls7 valve train utilizes a few lightweight parts

 

Valves themselves are titanium.