Supertech Mazda Miata 1.8L 85mm Bore -3.5cc Dome 9:1 CR Pistons - Set of 4 (Excl Rings)

If you're rebuilding the engine in your Mazda Miata and looking for a solid set of pistons to handle increased performance or just want to refresh the internals, this set from Supertech is a strong contender. These are forged pistons, meaning they start as a solid block of aluminum that's heated and hammered into shape under immense pressure. This process creates a much stronger and more durable piston than cast ones, making them ideal for engines that see hard use or have been modified for more power. This specific set is designed for the 1.8L engine, features an 85mm bore, and has a -3.5cc dome volume, which results in a 9:1 compression ratio. This compression ratio is a good balance for many naturally aspirated or mildly boosted builds, offering improved response without being overly sensitive to fuel quality.

Supertech is known for making well-built engine components, and these pistons are no exception. The forged construction means they can withstand higher cylinder pressures and temperatures compared to cast pistons. The 85mm bore is the standard size for many 1.8L Miata engines, so these are a direct replacement in terms of bore diameter, though they are a significant upgrade in terms of material and strength. It's important to note that these pistons are sold as a set of four and do not include piston rings. You'll need to purchase a separate set of rings that are compatible with the 85mm bore and the piston groove dimensions. This is a common practice when building an engine, allowing you to choose the ring set that best suits your specific build requirements, whether that's for a naturally aspirated setup or a forced induction application.

When installing these pistons, remember that proper engine assembly procedures are critical. This includes ensuring the cylinder walls are honed correctly for the new piston size and that the correct ring gap is set according to the manufacturer's specifications for your chosen rings and intended use. While these pistons are a significant upgrade for performance and durability, they are not CARB approved and cannot be shipped to California. Always consult your engine builder or a trusted mechanic to ensure these pistons are the right choice for your specific engine build and performance goals.