Upgrading the camshafts in your Nissan S13 240SX is one of the most effective engine modifications for unlocking significant power gains. The KA24E (single cam) and KA24DE (dual cam) engines found in these cars respond exceptionally well to improved valve timing profiles, often yielding a genuine 20-30 horsepower increase with the right camshaft selection and supporting modifications. This article provides a comprehensive guide to selecting, installing, and tuning aftermarket camshafts to get the most out of your S13 build.

Understanding Camshafts and Your S13’s Engine

Camshafts control the opening and closing of the intake and exhaust valves. Their lobe profiles—specified by lift, duration, and lobe separation angle (LSA)—directly influence how much air enters the cylinder, how long it stays there, and how efficiently exhaust gases exit. Factory camshafts are designed for a broad powerband, emissions compliance, and fuel economy, leaving a great deal of performance on the table. Aftermarket units prioritize airflow at higher RPMs, increasing volumetric efficiency and net horsepower.

Key Camshaft Specifications

  • Lift: The maximum distance the valve opens from its seat. Higher lift allows more air to pass through, but requires adequate valve-to-piston clearance and stronger valve springs to prevent float.
  • Duration: The amount of crankshaft rotation (in degrees) that the valve remains open. Longer duration shifts the powerband higher, often at the cost of low-end torque.
  • Lobe Separation Angle (LSA): The angle between the intake and exhaust lobe centers. A tighter LSA creates more overlap, increasing top-end power but making idle rougher; wider LSA smoothes idle and improves low-RPM response.

For the KA24DE, typical stage 2 camshafts offer around 0.455”–0.480” lift and 256°–264° duration at 0.050” lift. These specs provide a healthy power increase while still being streetable with proper tuning. Always match camshaft profiles to your engine’s compression ratio, turbo or naturally aspirated setup, and intended usage.

Benefits of Aftermarket Camshafts for the S13

Installing aftermarket camshafts delivers multiple performance and driving experience improvements beyond raw horsepower.

  • Measurable Horsepower Gains: With a proper exhaust, intake, and tune, expect 20–30 hp at the wheels. Some aggressive profiles combined with head work can add even more.
  • Improved Torque Curve: Mid-range torque often improves, making the car more responsive during daily driving and on track. The powerband shifts upward, but many stage 1 cams retain good low-end.
  • Sharper Throttle Response: Better airflow reduces lag, especially in naturally aspirated builds. The engine feels more eager to rev.
  • Distinctive Idle and Sound: A more aggressive camshaft profile gives the S13 a lumpy, aggressive idle that many enthusiasts enjoy—sound is a subjective but real benefit.
  • Custom Tuning Potential: Aftermarket camshafts allow you to tailor the powerband to your driving style, whether you prioritize autocross, drift, or street driving.

Choosing the Right Camshaft for Your S13

Selection depends on your engine type, existing modifications, and performance goals. Below are key considerations and popular options.

Camshaft Types and Stages

  • Stage 1 (Mild): Slight increase in lift and duration; works with stock valve springs. Best for daily drivers seeking a modest gain (10–15 hp) without sacrificing drivability.
  • Stage 2 (Moderate): More aggressive profile; requires upgraded valve springs and retainers. Ideal for street/strip use with bolt-on modifications. This is the sweet spot for most S13 owners.
  • Stage 3 (Aggressive): High lift and long duration; needs extensive head work, adjustable cam gears, and likely a standalone ECU. Best for race applications where low-end torque is secondary.

Compatibility and Supporting Mods

Aftermarket camshafts must work with your engine’s valve train. For KA24DE engines, the following are strongly recommended when upgrading camshafts:

  • Upgraded Valve Springs and Retainers: Prevent valve float at high RPM. Stock springs are not sufficient for lift above 0.460” or high-RPM use.
  • Adjustable Cam Gears: Allow you to dial in the cam timing for optimal powerband placement. Essential for fine-tuning performance.
  • New Timing Chain and Guides: While not always required, it is wise to replace the timing chain and tensioner during camshaft installation to avoid premature wear.
  • Performance ECU Tune: Stock ECU maps will not take advantage of the new camshafts. A reflash, Nistune board, or standalone ECU is necessary to adjust ignition timing and fuel maps.

Popular brands for S13 camshafts include BC Racing, Kelford Cams, Tomei, and JUN Auto. Each offers specific profiles; consult with a knowledgeable tuner or engine builder to match cam choice to your entire setup.

Tools and Materials Needed for Installation

Gathering the right tools before starting saves time and prevents headaches. You will need:

  • Socket and wrench set (metric, 10mm–22mm)
  • Torque wrench (ft-lb and in-lb scales)
  • Camshaft removal/installation tool (or a hex key for the KA24DE cam sprocket bolts)
  • Timing chain tensioner tool or zip ties to hold the chain
  • Dial indicator and magnetic base for degreeing camshafts (highly recommended)
  • Feeler gauges to check valve clearances
  • Crankshaft pulley socket (often 22mm or 24mm)
  • Engine assembly lube
  • New valve cover gasket, camshaft seals, and gasket sealant (e.g., RTV)
  • Fresh engine oil and filter

Installation Process: Step-by-Step

Below is a simplified but thorough outline for installing aftermarket camshafts on a KA24DE engine. Always refer to the manufacturer’s instructions and service manual for your specific vehicle.

Preparation

  1. Disconnect the negative battery terminal. Drain engine oil and coolant (if distributor is in the way).
  2. Remove the intake manifold, throttle body, and any brackets that obstruct the valve cover.
  3. Label and disconnect ignition coils, spark plug wires, and vacuum lines. Remove the valve cover.

Removing the Old Camshafts

  1. Rotate the crankshaft to align the timing marks – typically TDC on cylinder #1. The timing chain sprocket marks should align with the cylinder head surface.
  2. Lock the timing chain in place using a chain clip or zip tie to prevent it from dropping into the oil pan.
  3. Unbolt the cam sprockets (note which side is intake and exhaust). Use a cam holding tool to prevent the cam from turning.
  4. Remove the camshaft bearing caps in a crisscross pattern, loosening each bolt evenly. Lift the camshafts straight out.

Installing the New Camshafts

  1. Clean the cam journals and bearing surfaces thoroughly. Apply a thin coat of assembly lube to the new cam lobes and journals.
  2. Place the new camshafts into the cylinder head in their correct positions (intake has a distinct shape vs exhaust on some brands).
  3. Install the bearing caps hand-tight, then torque them in two or three steps to the manufacturer’s specification (typically 10–15 ft-lb). Use a crisscross pattern to ensure even load.
  4. Reinstall the cam sprockets, aligning the dowel pins. Ensure the timing chain is correctly meshed with both sprockets. Do not tighten the sprocket bolts fully until after timing verification.

Degreeing ensures the camshaft is installed at the correct timing relative to the crankshaft. This step maximizes power and prevents valve-to-piston contact. Use a dial indicator on the lifter of cylinder #1 intake valve and rotate the crank to find the .050” lobe center. Adjust the cam gear position as needed. Most aftermarket camshafts include a degree card with target numbers.

Reassembly

  1. Once timing is verified, torque the cam sprocket bolts to spec (often 40–50 ft-lb). Reinstall the timing chain tensioner.
  2. Install new camshaft seals and the valve cover with a fresh gasket. Torque the valve cover bolts in sequence to prevent oil leaks.
  3. Reattach the intake manifold, ignition components, and all previously removed parts. Fill the engine with oil, install a new filter, and refill coolant.

Tuning After Installation

Camshafts change the engine’s airflow characteristics dramatically. The stock ECU will not provide optimal ignition timing or fuel mixture, potentially causing rough idle, poor performance, or even engine damage. Tuning is mandatory.

  1. ECU Reflash or Chip Tune: For KA24DEs, a Nistune board or a custom ROM tune is cost-effective. Many tuners offer base maps for common camshaft profiles.
  2. Standalone ECU: For aggressive cams or forced induction, a standalone like Haltech, MegaSquirt, or AEM EMS gives full control over timing, fuel, and idle control.
  3. Dyno Tuning: A dyno session allows the tuner to dial in the air-fuel ratio and ignition advance across the RPM range. Expect a power increase of 10–15% over a base tune.
  4. Idle and Cold Start Adjustments: Aggressive cams may require higher idle speed (800–1100 RPM) and increased fuel enrichment on startup. Modern ECUs can compensate with special maps.

Common Mistakes and Tips

  • Neglecting Valve Clearance: Always check and adjust valve lash after installing new camshafts. Incorrect clearances cause noise or premature wear.
  • Using Stock Valve Springs: This is the most common failure. Upgraded springs are essential for any camshaft with more than 0.460” lift. Stock springs will float at high RPM, causing power loss and possible valve damage.
  • Skipping Camshaft Degreeing: Even quality aftermarket camshafts can be off by a few degrees. Degreeing ensures you get the advertised power gains and avoid piston-to-valve contact.
  • Ignoring Timing Chain Condition: A stretched or worn timing chain can skew cam timing. Replace it during the cam install.
  • Overtightening Valve Cover: The KA24DE valve cover is prone to warping if bolts are overtightened. Use a torque wrench and follow the factory spec (typically around 4–7 ft-lb).

For further reading, refer to technical discussions on Zilvia.net and the NICO Club forums, which have extensive build threads and tuning advice from experienced S13 owners.

Conclusion

Aftermarket camshafts are one of the highest-value upgrades for the S13 240SX. With the right selection, proper installation, and a professional tune, you can reliably add 20–30 hp while making the car more responsive and enjoyable to drive. Whether you are building a street machine, a drift car, or a weekend track toy, camshafts offer a proven path to increased performance. Take your time with the installation, invest in supporting mods like valve springs and tuning, and you will unlock the true potential of the KA engine.