Titanium valves

[beetle1303]

What bugger said is totaly correct. Just to add a bit
titanium isn't stronger than stainless. it has greater impact strength thus its more brittle, but due to it's advanced molecular grid is superior to the stainless (this brittleness will eventualy appear at very high load conditions, compared to stainless). This means that it can sustain higher continous loads over stainless steel. thus is better for high impact applications. also it has much better heat capacity, thats why its used primarily for ex valves

Chris