Koyorad HH060643 Racing Radiator for 1989-1992 Mazda RX-7 FC 1.3L MT

Vehicle Fitment

• 1989-1992 Mazda RX-7 (FC3S) -- Series 5, 1.3L 13B Rotary, Naturally Aspirated
• 1989-1992 Mazda RX-7 (FC3S) -- Series 5, 1.3L 13B-T Rotary, Turbo II

Fitment Notes

• MANUAL TRANSMISSION ONLY
• Late FC chassis (Series 5) ONLY -- NOT for 1986-1988 Series 4
• Uses OEM side brackets -- brackets are Series 4 or Series 5 specific
• Retains coolant level sensor provision (top)
• Increased core thickness may require minor modification to OEM intake snorkel
• OEM fan shroud compatible
• Factory radiator cap will NOT fit -- Koyo Hyper cap recommended
• Aftermarket electric fans recommended for best results
• Can be used with automatic transmission if external trans cooler is added
• N-FLO dual pass version: HH060643N (requires OEM shroud trimming)

Features

• 48mm HH Series Hyper Core -- ultra high fin density
• 40%+ increase in core thickness over OEM
• Up to 35% increased cooling performance over stock
• All-aluminum construction -- aircraft quality
• Nocolok-R furnace brazed core
• Hand TIG welded tanks
• Precise tube and fin alignment
• Billet aluminum filler neck
• 1/8" NPT female accessory fitting with plug (for temp sensor)
• Direct-fit OEM replacement -- retains factory mounting points
• Compatible with OEM fan shroud and coolant hoses
• Triple pressure tested for quality

Specifications

• Part Number: HH060643
• Brand: Koyorad
• Product Line: HH Series (Hyper Core)
• Type: All-aluminum performance racing radiator
• Core Thickness: 48mm (1.89")
• Core Design: Single pass (standard); N-FLO dual pass available as HH060643N
• Material: Aluminum (core, tanks, end caps)
• Brazing: Nocolok-R
• Welding: Hand TIG
• Accessory Port: 1/8" NPT female (plugged)
• Transmission: Manual (external cooler needed for automatic)
• Installation: Direct bolt-in
• Warranty: Koyorad manufacturer warranty

Included Components

• 1x All-aluminum HH Series racing radiator
• 1x 1/8" NPT threaded plug (for accessory port)

Product Description

The Koyorad HH060643 is a 48mm HH Series all-aluminum racing radiator for the 1989-1992 Mazda RX-7 (FC3S Series 5) with manual transmission, fitting both naturally aspirated 13B and Turbo II models. The 48mm Hyper Core provides over 40% more thickness than the OEM radiator with ultra high fin density, delivering up to 35% improved cooling performance -- ideal for spirited street driving, track days, and forced induction applications. The core is Nocolok-R furnace brazed with precise tube and fin alignment, while the tanks are hand TIG welded from aircraft quality aluminum for maximum strength and durability.

This radiator is a direct bolt-in replacement that retains all factory mounting points, fan shroud compatibility, and coolant hose connections with no engine bay modifications. A 1/8" NPT female accessory port is integrated for aftermarket temperature sensor installation. OEM side brackets are required and must be transferred from the factory radiator -- note that Series 4 and Series 5 brackets are not interchangeable. The factory radiator cap will not fit; a Koyorad Hyper cap (1.3 bar) is recommended for increased system pressure. For maximum cooling, an N-FLO dual pass version is available as HH060643N. Manufactured in Koyorad's ISO 9001 certified facilities.