The Mazda MX-5 Miata ND is a benchmark for lightweight sports cars, offering a near-perfect balance of chassis dynamics and power. While the 2.0-liter Skyactiv-G engine is peppy from the factory, many enthusiasts quickly crave more thrust without sacrificing the car’s inherent reliability or daily drivability. Installing a performance camshaft is one of the most effective bolt-on modifications to unlock significant horsepower while retaining full OEM compatibility. This article provides an in-depth, authoritative guide on performance camshaft installation for the ND Miata, covering the expected 25 hp gain, the factors that influence it, and every detail you need to execute a successful upgrade.

Understanding Performance Camshafts for the Skyactiv-G

To appreciate what a performance camshaft does, you need a basic understanding of valve timing. The camshaft controls when the intake and exhaust valves open and close, along with how far they lift off the seat. Stock cams are a compromise between low-end torque, emissions, fuel economy, and wide power delivery. Performance cams alter these parameters to shift the powerband higher in the rev range, increasing peak horsepower and improving volumetric efficiency.

The ND Miata’s 2.0-liter Skyactiv-G engine uses a dual overhead cam (DOHC) design with variable valve timing (VVT) on both intake and exhaust cams. Aftermarket camshafts are designed to work with the factory VVT phasers, maintaining OBD-II compliance and proper idle quality when paired with a suitable tune. Key spec changes include increased lift (typically 0.5–1.0mm more), longer duration (10–20 degrees more), and sometimes a tighter lobe separation angle (LSA) to boost overlap for better scavenging at high rpm.

Benefits of Upgrading to a Performance Camshaft

  • Increased Horsepower and Torque: The primary goal is a substantial power gain—up to 25 whp at the wheels with supporting mods. The gain is most noticeable from 5,500 rpm to redline.
  • Improved Throttle Response: Aggressive lobe profiles reduce valve reversion, making the engine feel snappier under part-throttle acceleration.
  • Enhanced Engine Sound: A more aggressive cam profile gives the exhaust a deeper, more purposeful note without being obnoxious.
  • OEM Compatibility: Drop-in fitment with no modifications to the cylinder head, valve springs, or pistons—provided you choose a mild to moderate cam profile. Stock valve springs are adequate for lifts up to approximately 11.0mm; beyond that requires upgraded springs and retainers.
  • Potential for Better Fuel Efficiency: While not the main objective, improved volumetric efficiency at cruising speeds can yield a modest reduction in fuel consumption when paired with proper calibration.

Expected Horsepower Increase: The 25 HP Claim

Many well-known ND tuners and parts suppliers, such as Flyin’ Miata and Goodwin Racing, have documented gains of 20–28 wheel horsepower from a camshaft upgrade alone, depending on the specific cam profile and supporting modifications. The often-cited 25 hp increase is a realistic median for a stage 2 or “street” cam profile when combined with a free-flowing intake, exhaust header, and a proper tune. Without those supporting mods, real-world gains hover closer to 15–18 hp.

Factors Influencing Horsepower Gains

  • Camshaft Profile: A mild drop-in cam (e.g., 11.0mm lift, 275° duration) will yield less peak power but retain near-stock idle and low-end torque. An aggressive high-lift cam (11.5mm+ lift, 285°+ duration) can hit 30 hp but may require upgraded springs, a higher redline, and will have a lumpier idle.
  • Supporting Modifications: A camshaft alone is like a bigger straw—you need free-flowing intake and exhaust to let the engine breathe. A high-flow cat or catless header, cold-air intake, and a 2.5-inch exhaust system amplify cam gains significantly.
  • Tuning and Calibration: The stock ECU cannot fully utilize aftermarket cam profiles. A reflash via VersaTuner or OpenFlash Tablet is mandatory to adjust VVT timing, fuel maps, and ignition advance. Gains are lost without proper calibration.
  • Engine Condition and Mileage: A high-mileage engine with carbon buildup or worn valve seals will see reduced gains. Ensure the engine is healthy before installation.

OEM Compatibility: What “Drop-In” Really Means

One of the biggest concerns for ND owners is whether a cam upgrade will require head machining, variable valve timing deletion, or sacrificing daily drivability. The best aftermarket cams are designed for direct bolt-in to the stock cylinder head:

  • They use the same journal diameters and bearing clearances as OEM.
  • They are compatible with the factory VVT phaser actuators and oil control solenoids.
  • They require no changes to the cam sprockets or timing chain tension.
  • They maintain stock valve clearances (shim-over-bucket) within spec, though mild lapping is sometimes needed.

This OEM compatibility means you can install performance cams in a single afternoon, with no irreversible modifications. If you ever decide to return the car to stock, the original cams can be reinstalled without any permanent changes to the head or block.

Several manufacturers offer proven ND Miata camshafts. When selecting, consider your power goals, tolerance for idle quality, and willingness to upgrade valvetrain components. Below are some of the most popular choices.

Flyin’ Miata “Stage 2” Cam

Flyin’ Miata’s cam offers 11.0mm lift and 275° duration. It is designed for use with stock valve springs and requires no idle or vacuum compromises. Expected gain: 18–22 whp with tune and exhaust mods. Ideal for daily drivers.

Goodwin Racing “RoadsterSport” Cam

Goodwin Racing’s cam set uses similar specs but with a slightly tighter LSA for better high-rpm scavenging. Requires a tune but no spring upgrade. Gains are 20–25 whp with supporting parts.

Supertech / Kelford “Track” Cam

These high-lift options (11.5mm+ lift, 285°+ duration) demand upgraded valve springs and titanium retainers to avoid valve float above 7,500 rpm. Gains of 28–32 whp are possible but idle quality is rougher. Best for track-focused builds.

Installation Process: Step-by-Step Guide

Installing cams on the ND Miata is a job best undertaken by an experienced home mechanic or a professional shop. The engine is a chain-driven DOHC, meaning the timing chain must be properly aligned and tensioned. Follow this detailed procedure.

Tools and Parts Required

  • Socket and ratchet set (metric, including 10mm, 12mm, 14mm, 17mm, 21mm)
  • Torque wrench (range 10–100 ft-lb)
  • Camshaft holding tool (to prevent rotation during sprocket removal)
  • Timing chain wedge or pin to secure tensioner
  • Valve cover gasket (new)
  • RTV silicone for cam cap and spark plug tube seals
  • Engine oil and filter (for post-install fill)
  • Coolant (if draining for access)
  • Shop rags and degreaser
  • Magnetic pickup tool (to retrieve dropped bolts)

Step-by-Step Installation

  1. Prepare the Vehicle: Disconnect the battery negative terminal. Remove the engine undercover and drain engine oil and coolant if you need to remove the water pump or lower radiator hose for access.
  2. Remove Intake and Exhaust Components: Take off the intake manifold, throttle body (for clearance), and the exhaust header if necessary. The camshaft cover/vario intake manifold may need removal to reach all cam cap bolts.
  3. Remove the Valve Cover: Unbolt the valve cover using a T30 Torx bit (cover bolts are captive). Carefully lift the cover; if stuck, gently pry from the front corner. Replace the gasket with a new OEM unit.
  4. Set Cylinder 1 to TDC Compression Stroke: Rotate the crankshaft clockwise using a 21mm socket until the timing marks on the crank pulley align with the indicator on the front cover. Verify that the intake and exhaust cam alignment marks on the cam sprockets point upward and are aligned with the marks on the back of the cam caps.
  5. Remove the Timing Chain Tensioner: Use a pin or small drill bit to lock the tensioner in its compressed state. Remove the two 10mm bolts securing the tensioner and pull it out. The chain will go slack.
  6. Mark the Chain and Sprockets: Use a paint marker to align chain links with the sprocket timing marks. This makes reassembly easier even if the chain slips.
  7. Remove the VVT Sprockets: For the intake cam, unbolt the VVT phaser using the cam holding tool to prevent rotation. The exhaust cam sprocket is fixed but remove it with the gear. Carefully slide each sprocket off its camshaft. Keep the sprockets in order.
  8. Remove the Cam Caps: Loosen the cam cap bolts in a criss-cross pattern from the outside in. Lift the caps and note their numbering (do not mix them). Remove the old camshafts.
  9. Install the New Camshaft: Apply a light coat of assembly lube to the cam journals and lobes. Place the new intake and exhaust cams into the head, aligning the bearing surfaces. Install the cam caps in their original positions and torque to specification (typically 8–10 ft-lb in two passes). Ensure smooth rotation by hand.
  10. Reinstall Sprockets and Timing Chain: Position the VVT phaser and exhaust sprocket onto the cams, aligning the pin/tab. Hand-tighten the sprocket bolts. Thread the timing chain around the sprockets, aligning your painted marks. Reinstall the timing chain tensioner and release the pin. Rotate the engine two full revolutions by hand and recheck timing marks.
  11. Reassemble: Replace the valve cover with new gasket and RTV at specific corners (per Mazda service manual). Reinstall intake manifold, exhaust, and other components. Refill oil and coolant.
  12. Initial Start and Check: Start the engine and let it idle for a few minutes. Check for oil leaks at cam caps and valve cover. Listen for unusual noises. If everything is quiet, proceed to tuning.

Tuning and Calibration: Unlocking the Full Potential

After installation, the stock ECU will compensate for the altered airflow but will not deliver peak power. A custom tune is essential. Use a handheld flashing device such as VersaTuner (popular for Mazda) or an OpenFlash Tablet. Many tuners offer base calibrations for specific cam profiles, then refine via data logging and dyno runs.

Key adjustments in the tune include:

  • VVT timing map: Align cam phasing for maximum volumetric efficiency at each rpm/load point.
  • Fuel injection timing and duration: Optimize for new cylinder filling characteristics.
  • Ignition timing: Avoid knock while extracting maximum torque.
  • Idle speed and throttle control: Adjust to maintain stable low-rpm operation with a lumpy cam.

Without a tune, you risk running lean under high load, potentially causing detonation. Always prioritize professional calibration.

Post-Installation Considerations

  • Break-In Procedure: Run the engine at varying rpm (2,500–4,500 rpm) for the first 100 miles, avoiding sustained high loads. This allows the cam lobes to mate with the lifter faces.
  • Monitor Oil Pressure and Temperature: After a hard run, check oil pressure via the gauge or a dedicated sender. If pressure drops unusually, suspect incorrect cam cap torque or an oil restriction.
  • Dyno Tuning Session: Book a session with a reputable tuner experienced in ND Miatas. A final tune can net an additional 5–10 hp over a generic base map.
  • Regular Inspection: Every oil change, inspect the cam lobes through the oil fill cap for scoring or excessive wear. Also check for cam cap bolt tightness (though they should stay in spec).

Real-World Results and Owner Experiences

ND owners on forums like Miata.net and Facebook groups consistently report satisfaction with cam upgrades. One common feedback is that the car feels significantly faster above 6,000 rpm, with the engine pulling hard to redline. Many owners combine cams with a header and tune to reach 190–195 whp on a Dynojet, from a baseline of 155 whp.

However, some caution that overly aggressive cams (e.g., 11.5mm lift) can cause the engine to idle poorly and require frequent tuning adjustments. For a daily-driven sports car, a moderate street cam is the sweet spot.

Conclusion

Installing a performance camshaft in your ND Miata is a high-reward modification that delivers a genuine 20–25 whp increase while maintaining full OEM compatibility. By choosing the right cam profile, supporting it with proper intake/exhaust upgrades, and investing in professional tuning, you can transform your Miata’s top-end power without sacrificing reliability. With careful installation and a thoughtful approach, this upgrade turns an already delightful car into an even more thrilling companion for weekend drives and track days alike.