Hello everyone - I would like to jump in and provide some factual information to help anyone looking to make a piston choice. The advantages of forged aluminum are greater strength, ductility (which means the material will bend before it breaks), feature aligned grain structure, and resistance to impact and fatigue. Cast material is much less dense, the constituants and materials are more randomly placed, and there are voids and inclusions throughout the structure, which can weaken the material and shorten the fatigue cycles.
Generally, most forged pistons do require slightly more warm up time versus a cast part. Cast pistons are manufactured with a higher content of silicon (20% or higher), which does lower the expansion rate, but also weakens the material as compared to forged aluminum. Forged aluminum can only contain a certain level of silicon and still be able to be forged; this resides in the low teens in percentage. Knowing this, it is possible to cold sieze or damage a cast or forged aluminum piston by riding too hard too soon, the piston will expand faster than the cylinder causing the piston to scuff or sieze. Using a forged part only means a little more warm up time.
All that being said, the chioice of a piston depends really on the rider and the usage. In a racing situation, a forged material piston is logical due to the greater strength and ability to take more abuse (temperatures, compression, and damaging affects from detonation for example). Watch any form of motorsports racing, and the vast majority of engines are powered using a forged aluminum piston (and this includes moto). Cast pistons are an affordable option depending on the usage, but we like to let people know the reasons why forged pistons can provide performance and a long service life.
Wiseco does manufacture our pistons (and clutch baskets) at our plant in Mentor Ohio, we purchase the raw material, forge it, heat treat it, machine and skirt coat the piston, all under one roof. Wiseco also supports the local and national race scene by sponsorship of events and riders, we are a very "grass roots" driven company. Please keep that in mind!
Glad to answer anyones questions regarding pistons and materials, you can email me at
dsulecki@wiseco.com and I will try and answer your questions!
Dave </SPAN>