Engine builders constantly chase higher RPM to unlock more horsepower. To achieve this, reducing valve train mass remains a key strategy. Utilizing valves with smaller, lighter stems is one of the many options engine builders opt for.

However, with the racing parts industry becoming so competitive, sourcing perfectly matched components presents challenges. SI Valves aims to simplify that process by expanding its custom size valve program, offering complete packages tailored around reduced-stem diameters.

Recognizing the growing trend among racers and builders adopting stem sizes ranging from 9mm down to a tiny 5.5mm, SI Valves announced increased support for these high-RPM applications.

The company now provides comprehensive “Valve/Retainer Packages” built around custom-specified valve dimensions, ensuring builders get properly matched components for their specific cylinder head projects.

The foundation involves SI Valves expanding its inventory of valve “blanks.” These unfinished valves serve as the starting point, and they are available in either premium stainless steel or exotic Inconel alloys suitable for extreme heat applications like turbo or nitrous builds.

SI offers these blanks across the wide 5.5mm to 9mm stem diameter range. Builders can then have these blanks finished to their precise length, head diameter, and seat angle requirements.

To properly support these reduced-stem valves, SI Valves include matching valve guides in their packages. The company manufactures these guides in-house using a proprietary manganese-bronze alloy formulation.

SI stated that this fortified material offers enhanced wear characteristics and improved heat transfer capabilities compared to standard bronze guides, which are important factors for reliability in high-RPM racing engines. These guides remain compatible with various modern valve stem coatings and finishes.

While specific details vary by application, the packages also include corresponding valve retainers designed to work with the specified valve stem size and spring requirements, providing the core components needed for a custom size valve train assembly.

SI Valves confirmed that these custom packages support a wide variety of popular domestic and import engine platforms. They specifically mentioned the availability of common choices like the Chevy LS, Ford Coyote, and Godzilla V8, as well as numerous Toyota, Nissan, and Mitsubishi engine families.

For racing engine builders pushing the envelope with lightweight valve trains and reduced-diameter stems to maximize RPM potential, SI Valves’ expanded custom program offers a solution.

It provides a convenient way to source high-quality, precisely matched valves, guides, and retainers specifically designed for these demanding, high-performance builds.