Custom Valves to Your Specification
Intake and exhaust valves are used for sealing the combustion chamber that controls the gas exchange process in the internal combustion engine. The intake valves are cooled by the incoming gases. In contrast, exhaust valves are subject to extremely high temperatures and harsh chemical corrosion during the exhaust cycle. To compensate for this, Summit uses a wide range of materials and geometries in our design and manufacturing of exhaust valves. A well design valve plays a critical part in engine performance and durability. The proper valves, matched to the proper valve seat can impact flow and compression in the combustion chamber. This immediately translates into lost or gained horsepower.
Several design choices such as valve stem size, material, and backcut are important aspects not only in the design, but the manufacturing tolerances of the finished valve. As far a valve material selection, a few variants of stainless steel (due to its price point durability) are pretty typical when it comes to passenger and light duty racing applications. For maximum performance and very heavy duty applications, custom alloys and titanium is required because of the materials lighter weight and strength.
From a valve seat perspective, keep in mind that titanium is a basically a soft metal. A traditional cast or hard seat easily make a groove into the valve. This is why a nickel or even a bronze seat is recommended.
Keep in mind, the higher quality of EV8 stainless valves are an excellent choice for regular use as well as mid-level racing engines. Titanium accommodates high engine speeds in race engines that don’t need extreme heat tolerances.
More information on our Valve Seat Selection:
SODIUM-FILLED Sodium-filled valves feature stems that are precision-gun-drilled and filled with a specially formulated sodium. This achieves weight reduction (the result of the gun-drilling to create a hollow stem) and better heat dispersion. There is some debate concerning the efficiency of this heat transfer, due to concerns that the heat transfer to the guides increases guide wear. Even with these concerns in mind, it’s interesting to note that the Chevy LS7 engine features sodium-filled exhaust valves (along with titanium intake valves). The hollow space in the head/stem of a sodium-cooled valve is filled to about 60% of its volume with metallic sodium, which melts at about 206 degrees F. The inertia forces that result during valve opening cause the liquid sodium to migrate upwards inside the stem, transferring heat to the valve guide and subsequently to the water jacket.
HOLLOW STEM Hollow-stem stainless steel or titanium valves (no sodium-fill) features gun-drilled stems to create hollow stems, strictly for weight reduction (this reduces valve weight by approximately 10% as compared to a comparable solid-stem valve). Citing Ferrea as an example, their hollow stem valves are gun-drilled and micropolished, and feature friction welded tips, shot-peened and rolled lock grooves, “avionics” chrome plated stems, and feature face hardness up to 42 HRc. This micropolishing reduces the risk of stress risers in the I.D. walls of the stem.
STAINLESS STEEL - These valves are offered in a varying of grades and configurations and are known for high performance which means they are mostly used in heavy duty or racing. Most are made from a one-piece forging, and some configurations offer a stronger stainless steel form with even higher heat resistance.