HKS BCD HC-TT STEP3 Pistons and Rods for G16E-GTS Toyota GR Corolla [21004-AT011]
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HKS BCD HC-TT STEP3 Pistons and Rods for G16E-GTS Toyota GR Corolla
HKS’s Pistons and Rods for G16E-GTS pair three BCD pistons with HKS I-beam connecting rods and matching pins for the three-cylinder engine in the GZEA14H GR Corolla, keeping the factory 87.5mm bore and 89.7mm stroke. The pistons are A2618 high-temperature alloy with a Triple Tumble crown for knock resistance, and HKS rates the machined nickel-chrome steel rods 25% stronger than stock. This kit suits an owner who wants stronger internals at the factory 1,618cc; for more displacement, the HKS 1.75L capacity upgrade kit is the better choice.
Features
- Bridge Concept Design piston structure for rigidity with reduced weight
- Triple Tumble crown shape developed to improve knock resistance
- Nickel plating above the top ring groove, a two-layer anti-seizure coating and a titanium coated top ring
- Machined nickel-chrome steel I-beam rods with WPC treatment to raise fatigue strength
- Matching 24mm piston pins supplied with the set
Specifications
- Bore: 87.5mm (factory size)
- Stroke: 89.7mm (factory crankshaft)
- Displacement: 1,618cc
- Piston weight: 352g
- Piston pin: 24mm diameter, 56mm long
- Compression ratio: 10.7 factory 0.69mm gasket, 10.6 HKS 0.8mm gasket, 10.3 HKS 1.0mm gasket
- Piston-to-wall clearance: 0.029 to 0.054mm
What’s Included
- BCD Piston Kit G16E HC-TT STEP3 87.5mm (21003-AT009)
- Conrod Set G16E STEP3 (23004-AT003)
- Piston Pin Set 24mm (21005-AK011)
Applications
- Toyota GR Corolla: GZEA14H | 2023-2025 | G16E-GTS
Notes
- No crankshaft is included and displacement does not change
- Professional installation by an experienced engine builder is required
- Engine management tuning is required, and no ECU or tune is included
- Boring and honing are not required, but HKS specifies a chamfer on the bottom edge of each cylinder
- HKS states that the piston kit or the connecting rod set can be installed alone, but either combination causes vibration from imbalance, which is why the Pistons and Rods for G16E-GTS are supplied together
- HKS developed the kit on a Japanese-market vehicle and states that it has not yet been tested in other markets
- This part is intended for off-road or competition use where emissions laws apply, and the buyer is responsible for checking local regulations
Frequently Asked Questions
- Do the Pistons and Rods for G16E-GTS include a crankshaft or add displacement? No. The HKS Pistons and Rods for G16E-GTS keep the factory 87.5mm bore and 89.7mm stroke, so displacement stays at 1,618cc. HKS sells its 1.75L capacity upgrade kits, with an 88.0mm bore and a 95.7mm stroke crankshaft, as separate products.
- Can the pistons or rods be installed on their own? Yes, but HKS does not recommend it. HKS states that the piston kit or the connecting rod set can be installed alone, but either combination causes vibration from imbalance. This kit supplies the BCD pistons, the STEP3 rods and the matching pins together.
- What compression ratio does the kit produce? With the factory cylinder head and the stock 0.69mm head gasket, HKS lists a compression ratio of 10.7. An HKS 0.8mm gasket gives 10.6 and an HKS 1.0mm gasket gives 10.3, so the gasket choice lets the builder set the ratio for the planned fuel and boost.
- Does the block need machining? No boring is needed. HKS states that boring and honing are not required at the factory 87.5mm bore, although honing is allowed to reach a piston clearance of 0.029 to 0.054mm. Each cylinder needs a small chamfer at the bottom edge of the bore.
- Is a tune required after installation? Yes. The new pistons change the crown shape and compression ratio of the G16E-GTS, so the engine management must be tuned by a qualified tuner. The kit includes no ECU or tune, and HKS specifies a break-in of 1,000 to 3,000 km.
About HKS
HKS is a Japanese performance engineering brand founded in 1973 and headquartered in Fujinomiya, Shizuoka, with a long-standing reputation for developing high-quality aftermarket parts and motorsport-proven technology for enthusiast and professional applications. Known for innovations in turbocharging and engine performance, HKS produces a broad range of components including exhaust systems, turbo kits, electronics / engine management, and suspension solutions, with product development heavily influenced by decades of involvement in racing disciplines such as circuit time attack, drag, and drifting.
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- Please review the product dimensions carefully to ensure the right fit for your space
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- Some items may require simple assembly upon delivery
- Perfect for both everyday use and long-term comfort
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Product Size Guide
Please refer to the general size reference below to better understand how this product may fit into your space. Dimensions may vary slightly depending on the design and materials.
| Category | Small | Medium | Large |
|---|---|---|---|
| Decor & Accessories | Up to 10″ | 10″ – 20″ | 20″+ |
| Tables | Up to 30″ | 30″ – 60″ | 60″+ |
| Seating | 1 Seater | 2–3 Seater | 4+ Seater |
| Storage Units | Compact | Standard | Large Capacity |
| Lighting | Small Fixture | Standard Fixture | Large Fixture |
Note: For exact product dimensions, please refer to the specifications section above. This guide is intended as a general reference only.
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HKS BCD HC-TT STEP3 Pistons and Rods for G16E-GTS Toyota GR Corolla [21004-AT011]
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