Radium Rotary Engine Injector Seat (Single) - Mazda RX-7 FD/Cosmo JC (13B/20B)

Radium Rotary Engine Injector Seat (Single) – Mazda RX-7 FD3S / Cosmo JC (13B / 20B)

Suits:

• Mazda RX-7 FD3S — 13B-REW
• Mazda / Eunos Cosmo JC — 13B-RE
• Mazda / Eunos Cosmo JC — 20B-REW

The Radium Engineering Rotary Engine Injector Seat is the same machined aluminium seat used in Radium fuel rails for Mazda and Eunos Cosmo and RX-7 rotary engines. It converts the OEM 16mm injector seat counterbore to the more common 14mm lower O-ring specification used by popular aftermarket injectors. The seat simply presses into the OEM injector bore and is designed to be compatible with or without the OEM fuel injector diffusers installed. It seals to the machined injector counterbore using the included Viton O-ring.

Suitable for both primary fuel injector iron ports and OEM intake manifold secondary injector ports.

Note: Most aftermarket lower intake manifolds are already machined with 14mm lower injector O-ring ports — check before ordering.

Sold individually. Quantity required per engine:

• 13B-RE — 4 total (2 primary + 2 secondary)
• 13B-REW — 4 total (2 primary + 2 secondary)
• 20B-REW — 6 total (3 primary + 3 secondary)

Features

• Converts OEM 16mm injector seat to 14mm lower O-ring specification
• Compatible with or without OEM fuel injector diffusers
• CNC-machined billet 6061 aluminium
• Type-II black anodised finish
• Laser etched logo
• Viton O-ring included — boost and fuel compatible

Part Number:

• 20-0444 — Radium Rotary Engine Injector Seat, Single (Mazda RX-7 FD3S / Cosmo JC, 13B / 20B)

Why Radium Engineering?

• ✅ Manufactured in the USA to motorsport-grade tolerances
• ✅ CNC-machined billet aluminium components built for performance and longevity
• ✅ Trusted by high-power build tuners and race teams worldwide
• ✅ Press-fit installation — no cutting, drilling, or permanent modifications required
• ✅ Viton O-ring sealing — compatible with E85, methanol, and all exotic fuel types