RPM Tech - Stainless Steel Valves

Stainless Steel Valves and Combustion Temperatures

An upgrade to performance valves is going to be money well spent

Your engine relies on it’s valves to control the flow of air and fuel into the cylinder, seal the combustion in, and allow the spent exhaust gasses to exit. Seems simple enough, but engine rpm range, combustion temperature, exhaust gas temperature and other factors will place special demands on the valves, and as Mom used to say, if you can’t take the heat stay out of the kitchen.

The choices available include stock valves, stainless steel valves and Titanium valves. Each has properties which are suited to particular applications.

Stock valves are typically made from lower carbon steels, which work well in standard passenger car applications. Low carbon valves are actually harder than stainless steel at room temperature, but their strength decreases as combustion temperatures go up. Stock valves can often work in mild performance situations, but if an engine is showing signs of valve burning or premature valve failure, an upgrade to performance valves is going to be money well spent.

Stainless steel valves, on the oth-

er hand, increase in hardness and strength at elevated temperatures. Erson’s stainless steel valves are our most popular valves for street, dirt track and drag racing engines because of their ability to maintain their strength at high temperatures and their enhanced flow characteristics. They are available in two styles to suit varying levels of engine performance.

Erson Sportsman Race (2000) Series valves are made from a one-piece forging of EV8 high strength stainless steel alloy. These valves are popular for street performance and sportsman racing applications. They are far superior to stock valves with much higher heat resistance.

Erson Competition (1000) Series valves are made from a one-piece forging of PS824 premium stainless alloy which can withstand temperatures up to 1600 degrees Fahrenheit.

Erson 1000 series valves are great for roller cam/high spring pressure applications and for higher temperature power adder use.

Erson 2000 Series onepiece stainless valves are popular for performance street use and sportsman racing.

Competition Series valves are recommended for roller cam applications or valve springs with 130 psi seat pressure / 450 psi open spring pressures or greater. These are popular valves for serious dirt track and drag racing engines, with alloys that can handle the high temperatures resulting from power adders.

In addition to their superior high temperature durability, one of the advantages of using a high grade stain-

less such as EV8 or PS824 is that the margin on the valve head can be made thinner with less danger of cracking or burning, making for a lighter weight valve.

Erson valve stems are hard chrome plated to reduce stem and guide wear. Chrome has the added benefit of microscopic surface pores that retain oil and help to reduce wear. Hard chrome plating is much thicker than flash chrome, making it far superior for valve stems because it is more durable and lasts much longer.

Both 1000 and 2000 series stainless valves feature hard stellite tips, so that lash caps are not necessary. Stainless is not hardenable, so a hardened tip must be welded onto the stem to prevent wear, otherwise hard lash caps are required.

(see photos A & B at right)

Both series feature an undercut stem design which increases airflow and reduces valve weight by as much as 10%. The valve head is swirl polished and features a back cut which further improves the flow characteristics.

For turbocharged, supercharged or nitrous engines, you may want to upgrade to an even higher temperature alloy exhaust valve for added protection. These applications may require Inconel exhaust valves. Inconel is a superalloy with high levels of nickel and chromium and a small amount of titanium, designed for use in highheat environments. It is also more dimensionally stable than steel under high-heat use, so it doesn’t tend to creep or grow as much at high temperature. Inconel requires high temperatures to perform correctly. The material is more brittle at lower temperature and becomes more elastic and stronger with elevated temps, so these are not a good choice for engines that will operate at a lower temperature.

Titanium valves are designed to reduce valve train weight for high-rpm and extended high-rpm applications

where valve weight is important and cost is not a consideration, as they are very expensive. However, for extreme-temperature situations such as blown, turbocharged or nitro engines, titanium may not be the ideal choice, particularly on the exhaust side. Titanium is also not a good choice for most street engines that won’t be torn down and serviced regularly.

Stainless steel valves are the most commonly used types for the majority of performance and racing engines, offering great performance and durability at an affordable cost. Good quality valves which are correct for your application will be an investment you won’t regret.