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lvporschepilot lvporschepilot is offline
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Join Date: Jul 2005
Location: Atlanta
Posts: 896
Originally Posted by MST0118 View Post
I’m wondering if anyone has tried hollow stem valves in their engine and if so how they’re holding up. Their weight is about 20% lighter than stainless steel but not as light as titanium which is probably 40% less than SS.

I think hollow stem are not recommended for turbo but may be an alternative to Ti valves for NA motors since they’re quite a bit cheaper. I’m curious for what type of engine is it recommended to use a hollow stem or Ti valve.

For instance, is recommended to use these valves with appropriate springs in an engine that regularly spins to 8000 or 9000 rpm? Are there benefits to engines that rev lower or is it a waste of money? Also, at what point or RPM level would hollow stem be inadequate when compared to Ti?
Hollow stem stuff is somewhere between SS and Ti valves, but minus having to change valve seats for Ti valves which is a nice bonus. I have not used them but many have with great success due to significantly reduced stresses to the valve spring which allows less valve spring force required to control the valve (highly cam dependent, different discussion). Subtracting 20-30% valve weight is huge and creates again far less burden on the valve spring. Less parasitic drag = more power. Nothing but win as I see them.

I would not run them in a turbo without more information. Get with whoever is making them and have a discussion.
No physical quantity completely explains its own existence
Old 09-04-2018, 12:22 PM
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