Mazda MX5 / Miata Billet Main Cap Set – 5-Cap Upgrade for Boosted Builds

🛠️ Strengthen Your Mazda MX5 Bottom End

Did you know that factory cast main caps in Mazda MX5/Miata engines often start to fail around 280–320 HP (210–240 kW)? At this point, boosted or high-RPM builds risk cap walk, crank misalignment, and even catastrophic block damage. If your turbo or track build is aiming anywhere near this range, billet main caps are cheap insurance to keep your bottom end together.

When building power in your Mazda MX5 or Miata engine — especially with forced induction or high RPM — the factory main caps become a known failure point. This 5-piece Billet Main Cap Set offers the reinforcement needed to handle serious stress, helping to protect your crankshaft and block under extreme conditions.

💡 Why Upgrade to Billet Main Caps?

• OEM cast caps can flex or shift under boost or high RPM
• Billet caps maintain critical alignment and reduce cap walk
• Cheap insurance for turbocharged, high-horsepower, or track-focused builds

✅ Key Features:

• 5-piece billet steel main cap set
• Direct replacement for factory caps
• Precision CNC-machined in South Australia
• Zinc-coated for corrosion resistance and longevity
• Strengthens the bottom end of your MX5 engine

📦 Fitment:

• Mazda MX5 / Miata engines (NA/NB series – contact us to confirm fitment)

🔧 Installation Notes:

• Line boring/honing required after installation
• ARP main studs recommended for best performance
• Installation by a qualified engine machinist is essential

🇦🇺 Made in Australia by Milton Engine Developments

Each set is CNC-machined in South Australia by Milton Engine Developments, trusted by performance builders and race teams nationwide.

📦 Availability & Support

• Stocked and shipped from Adelaide
• If your build is time-sensitive, contact us before ordering to confirm lead time
• Need a custom part? Contact us — we may be able to make it