Understanding the F20C Engine and Its Performance Potential

The Honda F20C engine is a legendary powerplant, originally found in the AP1 and early AP2 S2000 models. It is renowned for its high-revving nature, producing 240 horsepower (in US spec) from just 2.0 liters without forced induction. This achievement is largely due to its advanced design, including a dual-overhead camshaft (DOHC) valvetrain with VTEC, a high compression ratio of 11.0:1, and a lightweight, free-revving reciprocating assembly. However, factory camshaft profiles are a compromise between emissions, drivability, and peak power. Upgrading to a Toda Racing camshaft kit unlocks the engine’s latent potential, allowing for increased valve lift and duration, which in turn improves volumetric efficiency and pushes the power band higher. For serious track enthusiasts or those chasing a naturally aspirated edge, this modification is a cornerstone of F20C performance.

Before diving into the installation, it’s critical to understand that camshaft replacement is an intermediate to advanced mechanical task. It requires attention to detail, familiarity with engine internals, and proper timing procedures. This guide expands on the basics to ensure a successful outcome.

Why Choose the Toda Racing Camshaft Kit?

Toda Racing has been a leading Japanese manufacturer of performance engine components for decades, trusted by professional race teams and grassroots builders alike. Their camshaft kits for the F20C are engineered with proprietary lobe profiles, billet steel construction, and precise hardening treatments. The kit typically includes two racing camshafts (intake and exhaust), valve springs with titanium retainers, and sometimes shims. Key benefits include:

  • Increased lift and duration: Typical Toda F20C cams offer around 12.5 mm lift (up from 11 mm stock) with duration around 270 degrees, shifting the power curve upward by 500-800 RPM.
  • Improved mid-range torque: Despite the peaky reputation, these cams actually broaden the usable power band when paired with proper tuning.
  • Durable construction: Billet steel and nitrided surfaces reduce wear and withstand high RPM operation.

For more details on the specific part numbers and dyno charts, visit the Toda Racing official product page.

Tools and Materials: Expanded List

The original list covers basics, but a comprehensive installation requires additional specialized items to avoid frustration. Here is a complete inventory:

  • Toda Racing Camshaft Kit (camshafts, valve springs, retainers, shims if included)
  • Socket set (3/8" and 1/2" drive), including deep sockets for head bolts
  • Torque wrench with foot-pounds and inch-pounds scales (critical for cam cap bolts)
  • Camshaft alignment tool (or improvised method with timing pin and protractor)
  • Valve spring compressor (overhead style for F20C)
  • Silicone sealant for valve cover and timing cover gaskets
  • Thread locker (medium strength) for cam cap bolts and timing gear bolts
  • Engine assembly lube (moly-based preferred for cam lobes and bearing journals)
  • New OEM gaskets: valve cover gasket, spark plug tube seals, timing chain tensioner gasket, and front cover gasket (if removing)
  • Gasket scraper and brake cleaner for surface prep
  • Dial gauge and magnetic stand for checking valve-to-piston clearance (recommended)
  • Timing chain wedge or cam holding tool to prevent rotation during work
  • Shop rags, safety glasses, nitrile gloves

A full factory service manual for the Honda S2000 is indispensable; many are available online at Honda Parts Now or enthusiast forums like S2KI.com.

Preparation Before Installation: Deep Dive

Workspace and Safety

  • Park the vehicle on a level, well-lit concrete floor. Use jack stands if you need to remove wheels or access the engine from below.
  • Disconnect the battery negative terminal and wait at least 10 minutes for the ECU capacitors to discharge.
  • Remove the engine undercover and drain the engine oil (oil change is recommended after cam installation anyway).
  • If the engine is hot, allow it to fully cool (below 100°F / 38°C) to prevent warpage.

Access and Component Removal

  • Remove the intake air box and mass airflow sensor tube to clear the valve cover area.
  • Disconnect the ignition coils, spark plug wires, and PCV hoses. Label each connector for reassembly.
  • Remove the throttle cable bracket and any wiring harness clips secured to the valve cover.
  • If the vehicle has a supercharger or turbo kit, you may need to remove the charge piping or intercooler ducting – plan extra time.

Once the valve cover is exposed, take a moment to clean the surrounding area with brake cleaner to prevent debris from entering the engine.

Removing the Old Camshafts: Step-by-Step Expanded

Timing Chain Removal Consideration

The F20C uses a timing chain, not a belt. The chain does not need to be completely removed unless you are also replacing the chain tensioner or timing guides. However, you must release tension from the chain to allow camshaft removal. Follow these refined steps:

  1. Rotate the engine to Top Dead Center (TDC) on cylinder #1. Align the crankshaft timing mark with the indicator on the oil pump housing.
  2. Remove the crankshaft pulley and lower timing cover to access the timing chain tensioner.
  3. Compress the tensioner and install a lock pin (or use a zip-tie technique) to hold it retracted. Do not let the chain jump teeth on the crank sprocket.
  4. Remove the camshaft sprocket bolts. Counterhold the sprockets with a chain holding tool or by using a large crescent wrench on the hexagonal boss behind the sprocket.
  5. Carefully slide each sprocket off the camshaft and set aside, keeping the chain taut on the crankshaft side.

Camshaft Bearing Cap Removal

  • Label each cam bearing cap with its position (intake side has marks like "I1, I2" and exhaust "E1, E2") – they are not interchangeable.
  • Unbolt caps in a reverse tightening sequence (outside-in) incrementally to avoid binding the cam.
  • Lift the old camshafts straight out. Inspect the bearing surfaces for scoring or pitting; if present, the cylinder head may need machining.

This S2KI DIY thread provides detailed photos of the removal process.

Installing the Toda Racing Camshafts

Preparation of New Components

  • Apply a generous amount of assembly lube to the camshaft lobes and bearing journals.
  • If your kit includes new valve springs and retainers, now is the time to install them. Use a valve spring compressor to remove the old springs and retainers, then install the higher-rate Toda springs. Note: the F20C uses shim-under-bucket style tappets; you may need to adjust shim thickness to achieve proper valve lash after cam installation. Measure the current clearance and order shims as needed.
  • Clean the camshaft bore in the cylinder head with brake cleaner and compressed air.

Positioning and Torquing

  1. Carefully lower the new Toda intake camshaft into its journals. Ensure the keyway or dowel pin on the cam aligns with the appropriate location for timing.
  2. Repeat for the exhaust camshaft.
  3. Install the cam bearing caps in their correct positions and orientations (arrow direction toward timing chain).
  4. Hand-tighten the cap bolts, then use a torque wrench in three steps: first 7 ft-lb (10 Nm), then 14 ft-lb (20 Nm), and finally to the factory specification of 22 ft-lb (30 Nm). Work from the center caps outward in a crisscross pattern.
  5. Reinstall the camshaft sprockets onto the new cams. Note: Toda cams may have a different keyway position relative to stock – check the timing marks on the sprocket teeth. Some Toda kits require adjustable cam gears for fine-tuning. Install the sprocket bolts with thread locker and torque to 65 ft-lb (88 Nm).

Timing Verification

With the chain tensioner still compressed, confirm that the crankshaft is still at TDC and the camshaft lobes for cylinder #1 point upward (intake and exhaust lobes up) or outward depending on engine rotation. Many builders use a protractor and dial gauge to verify the lobe centerline angle matches Toda’s specifications. If the cam timing is off by even one tooth, the engine may run poorly or suffer valve contact.

After timing is verified, release the chain tensioner by removing the lock pin. Rotate the engine manually by two full turns using a socket on the crank pulley bolt. Recheck TDC alignment and cam marks to ensure timing didn't jump.

Reassembling the Engine

Valve Cover and Sealing

  • Clean the valve cover gasket mating surface thoroughly. Apply a thin bead of silicone sealant at the corners where the timing chain cover meets the cylinder head.
  • Install the new valve cover gasket and spark plug tube seals into the valve cover.
  • Position the valve cover and tighten the bolts in the manufacturer’s specified sequence to 9 ft-lb (12 Nm). Do not overtighten – the cover is aluminum.
  • Reattach the ignition coils, spark plugs, throttle cable, PCV hoses, and air intake assembly.

Reconnecting Systems

  • If you removed the radiator or fans for access, refill with coolant and bleed the system.
  • Reconnect the battery.
  • Fill the engine with fresh high-quality 10W-30 or 10W-40 oil (synthetic recommended). The F20C requires about 5.2 quarts with filter.

Final Checks and Start-Up Procedure

Pre-Start Verification

  • Double-check that all bolts are tightened: cam caps, sprockets, valve cover, timing cover, and crankshaft pulley.
  • Ensure that no tools, rags, or loose bolts remain in the engine bay.
  • Prime the oil system: disable the fuel pump or ignition, then crank the engine for about 10 seconds in two-second bursts until oil pressure builds (indicated by the oil light turning off). Alternatively, use a pressurized oil primer tool.

Initial Start and Break-In

  • Start the engine. It may take a few extra cranks to fill the lifters. Listen carefully for any ticking or knocking. A slight valvetrain noise is normal until lifters pump up.
  • Let the engine idle until it reaches operating temperature (about 180°F / 82°C). Monitor for oil leaks at the valve cover and cam plugs.
  • Perform a static throttle test: rev the engine gently to 3000-4000 RPM, then release. The engine should return to idle smoothly.
  • Drive the vehicle lightly for the first 500 miles (800 km) without exceeding 5000 RPM. Use engine braking to help seat the rings and cam lobes. After this break-in period, change the oil and filter again.

Post-Installation Tuning and ECU Considerations

Upgrading to aggressive camshafts will require a professional ECU tune to realize full gains. The stock ECU will likely experience idle instability, reduced low-RPM torque, and potential lean conditions at partial throttle. Consider these steps:

  • Install a standalone ECU (e.g., Motec, Haltech, or AEM) or reflash the stock ECU with a specialized tune from a recognized Honda tuner.
  • Adjust valve lash: After the initial break-in, recheck valve clearances. Toda recommends 0.18 mm intake and 0.23 mm exhaust (cold) for their racing cams; vary by specific kit.
  • Consider adjustable cam gears if not included. Toda offers degrees-adjustable sprockets that allow intake and exhaust timing to be dialed independently for maximum power.

For tuning resources and dyno results, the community at Hondata offers excellent guidance and calibration files for the FlashPro system.

Common Mistakes and Troubleshooting

  • Incorrect cam timing: The most frequent issue is misalignment of the cam sprockets. Always verify TDC after rotating the engine manually.
  • Overtightening cam caps: Torque spec is critical; excessive force can distort the cam bore and cause seizure.
  • Failure to replace valve springs: Stock springs may coil-bind at higher lift values, leading to valve float and potential piston interference. Always install the springs included in the Toda kit.
  • Neglecting valve-to-piston clearance: With high-lift cams, especially on a stock engine, there is a risk of contact if the valves have not been pocketed. Check with clay or a dial gauge.

Conclusion

Installing the Toda Racing Camshaft Kit on your F20C engine is a transformative upgrade that rewards careful preparation and precise execution. By following this expanded guide and consulting factory service resources, you can safely achieve a significant increase in peak horsepower and an exhilarating, high-revving character that defines the S2000 experience. Remember that tuning and break-in are just as important as the mechanical installation – invest in a quality tune to match the hardware. For continued performance, monitor oil condition and valve lash at regular intervals. With the right approach, your Toda camshafts will deliver reliable, track-ready performance for years to come.