One of the questions we are often asked is, "why are your boost controllers made of Brass"?
With all of the materials available, people often wonder why we don't make our boost controllers out of something like anodized aluminum. We'll pick on aluminum, since that is the material that most of the low-cost (or high-margin) suppliers have chosen to use. While aluminum (especially when anodized in a pretty blue, or red) offers advantages in look and cost (in machining and materials), it lacks in other areas. Specifically, in lubricity. Because brass is made of copper and zinc, threaded brass sections are easier to turn. Also, brass naturally inhibits corrosion by developing a patina with age. Our ancestors realized this long before it was practical to forge aluminum, let alone anodize it. Although anodized aluminum will resist corrosion, once the anodizing is scratched, it corrodes rapidly. Also, the anodizing wears off of the threads if you make frequent (more than a few?) adjustments. So a year later, when you go to make an adjustment, you find that the various parts have locked themselves together. Complicating the situation is that often these aluminum parts are sourced from various suppliers, using different alloys of aluminum. The process of electrolysis then takes over and speeds the corrosion even more. We discovered this for ourselves in 1998, when we tried to have an aluminum product manufactured locally. The Detroit machine shops are saturated with reclaimed and recycled aluminum of dubious origin. We actually had to go outside the area (still in the US, though) to ensure that our materials are not from unknown sources. Our Boost Controllers are made of Virgin Brass (meaning, it has not been sourced from recycled materials). All components are machined from the exact same batch of brass, eliminating the potential of electrolysis.
Another quality of brass is that it is hard enough to endure, but pliable enough to provide a good seat seal. As the steel or ceramic ball (in the case of the Hybrid) repeatedly strikes the seat, during operation, it peens the seat to the shape of the ball. This provides a good seal. More importantly, it holds that shape over time. Aluminum is also soft enough to peen. However, as aluminum is repeatedly struck, its properties change and it tends to flake off. So, you have a constantly changing seating surface. This is not what you want for consistent boost control. Some manufacturers use stainless steel, which eliminates most of the corrosion issue, but it is too hard (metal hardness, not difficulty, though one follows the other) to peen into a good sealing surface.
Last, aluminum, although cheaper to purchase and machine, can be difficult to machine precisely. It tends to stick to the drill and lathe, making it more difficult to make an EXACT product. For that reason, threads and such tend to be designed to a coarser pitch. That means it can be more difficult to make fine adjustments in the boost (although this is also application dependent, to a degree).
So, in a nutshell, here are some pros and cons of Brass and Aluminum Boost Controllers:
Pros: Cheap, easy to machine, provides a low cost product (or high margin, in the case of some sellers), looks nice when anodized.
Cons: Thin anodizing scratches easily, corrodes if anodizing does not reach the threads or is scratched, seat does not hold a peen.
Pros: Provides its own patina to limit corrosion, stays pliable and will not seize, holds a peen on the ball seat, easier to machine accurately
Cons: Brass is expensive (more and more so every day, as copper prices go up), it is less attractive than aluminum (although, if you polish and then clear-coat, it looks pretty flashy!)
Hopefully, this answered a question in some of your minds and provided food for thought, for the rest of you. As always, feel free to email us with questions, or comment in the blog.
Thank you for being one of our customers and a part of our family!
--3 Bar Racing Inc.