2013–2020 Subaru BRZ / 2013–2016 Scion FR-S / 2017–2020 Toyota 86 2.1L FA20
21003-AT004
Overview:
The HKS Low Compression Stroker Replacement Pistons are engineered specifically for the Subaru BRZ, Scion FR-S, and Toyota 86 equipped with the 2.1L FA20 stroker upgrade. Designed as a direct replacement for the pistons in the HKS 21004-AT003 and 21004-AT004 stroker kits, these pistons are not compatible with rods or crankshafts outside the HKS 2.1L capacity upgrade.
Built for enthusiasts seeking enhanced durability and the ability to run higher boost levels, these pistons optimize compression ratios to support increased power output while maintaining reliability. Whether you are upgrading for spirited street driving or track use, these pistons provide a solid foundation for your engine build.
Key Features:
These replacement pistons incorporate advanced materials and design to meet the demands of high-performance FA20 stroker engines:
Construction & Design:
The pistons are crafted from high-quality forged materials to withstand the increased loads of a stroked 2.1L FA20 engine. The recessed design ensures compatibility with HKS high-lift camshafts, preventing valve-to-piston interference. The piston crown features a sophisticated 3D shape that complements the stock direct injection system, promoting efficient air-fuel mixing and combustion.
The molybdenum coating on the piston skirts reduces friction against the cylinder walls, enhancing wear resistance and contributing to smoother engine operation. By retaining the factory bore size, the pistons allow for a straightforward installation without the need for additional machining, preserving the structural integrity of the engine block.
Installation & Fitment:
This piston kit is intended exclusively as a replacement for the pistons included in the HKS 2.1L FA20 stroker kits (part numbers 21004-AT003 and 21004-AT004). It is not compatible with other rods or crankshafts outside of the HKS 2.1L upgrade.
Installation is simplified by the retention of the stock 86mm bore, eliminating the need for boring, honing, or installing sleeves. This reduces labor time and cost, making it an efficient upgrade for those maintaining or refreshing their stroker build.
What's Included:
Ideal For:
This piston kit is ideal for Subaru BRZ, Scion FR-S, and Toyota 86 owners who have upgraded to or plan to upgrade to the HKS 2.1L stroker kit and require durable, high-performance pistons capable of handling increased boost and power levels. It suits enthusiasts focused on maximizing engine strength and reliability while maintaining cost-effective installation.
HKS is a Japanese company specializing in high-performance aftermarket automotive parts, including turbochargers, exhaust systems, suspension kits, and electronic control units. Their products are designed for enthusiasts seeking to enhance vehicle performance, offering reliable and precise components for various builds and driving scenarios.
PART # 21003-AT004
Upgrade your 2.1L FA20 stroker with HKS Low Compression Replacement Pistons, designed for 2013-2021 Subaru BRZ, Scion FR-S, and Toyota 86. Forged for durability and optimized for high boost, these moly-coated pistons reduce friction and maintain stock bore size for a cost-effective, hassle-free install. Perfectly engineered for HKS camshafts and direct injection, they deliver reliable performance and flexible compression ratios without boring or honing.
ETA stands for Estimated Time of Arrival. The date shown is calculated using our Available-to-Promise (ATP) system, which tracks real-time supplier commitments to determine when a product is expected to be available for delivery. Specifically, the date is calculated by adding 9 business days from the date a supplier has committed to ship the product, representing a worst-case scenario for when we can expect to receive inventory.
Please note: The ETA is an estimate, not a guarantee. While we work closely with our suppliers to keep dates as accurate as possible, delays due to shipping carriers, weather, customs, or supplier-side issues may occasionally push the actual arrival beyond the date shown. Likewise, inventory may arrive sooner than the ETA in many cases. If you would like to be notified for when this item arrives, sign up for our back in stock notifications!
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2013–2020 Subaru BRZ / 2013–2016 Scion FR-S / 2017–2020 Toyota 86 2.1L FA20
21003-AT004
Overview:
The HKS Low Compression Stroker Replacement Pistons are engineered specifically for the Subaru BRZ, Scion FR-S, and Toyota 86 equipped with the 2.1L FA20 stroker upgrade. Designed as a direct replacement for the pistons in the HKS 21004-AT003 and 21004-AT004 stroker kits, these pistons are not compatible with rods or crankshafts outside the HKS 2.1L capacity upgrade.
Built for enthusiasts seeking enhanced durability and the ability to run higher boost levels, these pistons optimize compression ratios to support increased power output while maintaining reliability. Whether you are upgrading for spirited street driving or track use, these pistons provide a solid foundation for your engine build.
Key Features:
These replacement pistons incorporate advanced materials and design to meet the demands of high-performance FA20 stroker engines:
Construction & Design:
The pistons are crafted from high-quality forged materials to withstand the increased loads of a stroked 2.1L FA20 engine. The recessed design ensures compatibility with HKS high-lift camshafts, preventing valve-to-piston interference. The piston crown features a sophisticated 3D shape that complements the stock direct injection system, promoting efficient air-fuel mixing and combustion.
The molybdenum coating on the piston skirts reduces friction against the cylinder walls, enhancing wear resistance and contributing to smoother engine operation. By retaining the factory bore size, the pistons allow for a straightforward installation without the need for additional machining, preserving the structural integrity of the engine block.
Installation & Fitment:
This piston kit is intended exclusively as a replacement for the pistons included in the HKS 2.1L FA20 stroker kits (part numbers 21004-AT003 and 21004-AT004). It is not compatible with other rods or crankshafts outside of the HKS 2.1L upgrade.
Installation is simplified by the retention of the stock 86mm bore, eliminating the need for boring, honing, or installing sleeves. This reduces labor time and cost, making it an efficient upgrade for those maintaining or refreshing their stroker build.
What's Included:
Ideal For:
This piston kit is ideal for Subaru BRZ, Scion FR-S, and Toyota 86 owners who have upgraded to or plan to upgrade to the HKS 2.1L stroker kit and require durable, high-performance pistons capable of handling increased boost and power levels. It suits enthusiasts focused on maximizing engine strength and reliability while maintaining cost-effective installation.
HKS is a Japanese company specializing in high-performance aftermarket automotive parts, including turbochargers, exhaust systems, suspension kits, and electronic control units. Their products are designed for enthusiasts seeking to enhance vehicle performance, offering reliable and precise components for various builds and driving scenarios.
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Need to return an item? We make it easy. Email us and we'll send you a free return label with instructions on how to return.
Free Standard Shipping on orders over $250. Select “Free Shipping” at checkout.
Need to return an item? We make it easy. Email us and we'll send you a free return label with instructions on how to return.
