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Neil Harvey Neil Harvey is offline
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Join Date: May 2004
Posts: 157
We use hollow stem valves on many of our engine projects. As the valve stem diameters get smaller and smaller, the heat rejection becomes a greater need. But these are made for us on a custom basis and the costs are extreme.

Titanium valves are expensive too, and as previously stated, you have to be prepared to inspect at regular time periods to ensure their integrity. Titanium requires a different seat material to transfer the heat out of the valve quicker or the valve margins will degrade rapidly. Alloy 25 and 3 are the typical materials used and this stuff is also not cheap, along with the actual replacement costs.

My suggestion for these 2V engines, would be to consider steel, 8.0mm or 7.0mm stems, wasted lower stems behind the face head, and try a lower back angle. Flow testing will show which angle is best. Going in and coming out requires different back angles and radius's. You may be limited by the forgings available unless you go with a custom valve and then the costs climb again.

The stock filled valves are expensive, and limited to sizes, so any "hot rodding" has to be done with solid stem valves typically.
Old 09-09-2018, 02:30 PM
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