Introduction: A Cost-Effective Path to 50 Horsepower

The Acura RSX Type S remains one of the most accessible platforms for front-wheel-drive performance. With its K20A2 engine, the car already delivers a respectable 200 horsepower from the factory. But for many enthusiasts, the desire for more power—without spending thousands on turbocharging or supercharging—leads to one of the most effective naturally aspirated upgrades: a camshaft swap. Using a Civic Type R camshaft, specifically the one from the DC5 Integra Type R (K20A), is a proven way to gain roughly 50 horsepower at the wheels. This article breaks down the true cost of that upgrade, covering parts, labor, and supporting modifications needed to realize the full gain.

Understanding the Camshaft Upgrade on the K20 Platform

The K20 engine family is known for its robust valvetrain and i-VTEC system, which provides both variable timing and variable lift. The camshaft controls when the intake and exhaust valves open and close, as well as how far they open (lift). In the RSX Type S, the stock camshaft profile is tuned for a balance of low-end torque and mid-range power. The Civic Type R (DC5 or EP3) camshaft features more aggressive lobe profiles—higher lift and longer duration—that shift the power band upward while drastically improving airflow in the upper RPM range.

Because the K20A2 and K20A (Type R) share the same basic architecture, the Civic Type R camshaft is a direct mechanical swap. The i-VTEC mechanism, cam chain sprockets, and bearing caps are compatible. However, the stock ECU cannot fully exploit the new camshaft’s potential without recalibration. The Type R camshaft alone won’t deliver 50 horsepower unless the engine management is adjusted for the increased airflow and changed VTEC engagement point.

The Civic Type R Camshaft: Specifications and Compatibility

Camshaft Profile Differences

The RSX Type S (K20A2) camshaft has intake lift of approximately 11.5 mm, exhaust lift of 10.5 mm, and duration around 236 degrees on the intake and 220 on the exhaust (at 1 mm valve lift). The DC5 Civic Type R (K20A) camshaft increases intake lift to 12.5 mm and exhaust to 11.5 mm, with correspondingly longer duration. This increase in lift and duration is responsible for the significant horsepower gains, but it also shifts the power peak upward by about 500-800 RPM.

Expected Power Gains

When installed on an otherwise stock RSX Type S with a proper tune, the Civic Type R camshaft can add 30-50 horsepower at the wheels. The wide variance depends on the condition of the engine, the quality of the tune, and any supporting modifications (intake, exhaust, header). Many owners report gains in the 40-50 hp range after tuning, with peak power occurring around 7,800-8,000 RPM.

For a reference point, check the Hondata K-Manager tuning documentation, which covers VTEC engagement and fuel maps for camshaft upgrades.

Detailed Cost Breakdown: Beyond the $400 Claim

The original article states a total cost of $400. While a used Civic Type R camshaft can often be found for $300, and basic gaskets for $50, that figure ignores several critical expenses required to achieve a reliable 50-horsepower gain. Below is a more realistic cost breakdown that accounts for all necessary parts, fluids, and labor or tool purchases.

  • Used Civic Type R (K20A) Camshaft: $250-$350. Prices vary on forums like k20a.org and eBay. Ensure the camshaft is from a DC5 EP3 or FD2 Type R (K20A/K20Z) to guarantee compatibility.
  • Valve Cover Gasket Set: $25-$40. Includes the spark plug tube seals and valve cover gasket. Reusing old gaskets risks oil leaks.
  • Camshaft Seal (front and rear): $15-$25 each. Often overlooked but essential to prevent oil seepage.
  • Timing Chain Tensioner (optional but recommended): $80-$120. The tensioner can weaken over time; replacing it ensures proper chain slack and avoids potential engine damage.
  • Head Studs (ARP or similar): $100-$150. Not strictly required for a cam-only build, but if you plan to raise the rev limiter, upgraded studs provide extra clamping force and reliability.

Labor and Tuning

  • DIY Labor: $0, but you need tools like a torque wrench, camshaft lock tool, and a pulley puller. If you lack tools, budget $50-$100 for rentals or purchases.
  • Professional Installation: $200-$400 at a shop familiar with K-series engines. This includes R&R of the valve cover, camshaft replacement, and gasket installation.
  • ECU Tuning: $400-$600. This is the single most important cost for achieving 50 horsepower. A flash or standalone ECU (e.g., Hondata K-Pro or K-Tuned) must be tuned on a dynamometer. Expect $300-$400 for a base tune plus $100-$200 for dyno time.
  • Dyno Fees: $100-$200 per hour, typically 2-3 hours for a thorough day.

Total Realistic Cost

  • Minimal DIY (used cam, no tuning, reused gaskets): ~$350. You will not see 50 hp. The car will likely run lean and may throw knock codes.
  • Complete setup with tune (DIY install): $1,000-$1,200.
  • Full shop install with tune: $1,400-$1,800.

The original $400 figure is a bare-minimum parts cost. To truly gain 50 horsepower safely, you must budget for tuning and proper installation.

Installation Process and Considerations

Swapping the camshaft in a K20 engine is a straightforward job for someone with moderate mechanical skills, but several steps require precision.

Tools Required

  • Socket set (8mm, 10mm, 12mm, 14mm, 17mm)
  • Torque wrench (capable of in-lb and ft-lb)
  • Camshaft locking tool (or a partner to hold the cam)
  • Harmonic balancer puller
  • RTV silicone for any reused cover gaskets

Step-by-Step Overview

  1. Disconnect the battery and remove the intake duct, airbox, and any wiring harness clips on the valve cover.
  2. Remove the valve cover by unscrewing the 10mm bolts. Lift carefully to avoid damaging the gasket.
  3. Lock the camshafts using a tool or by marking the chain-to-sprocket position. On K20 engines, the timing chain does not need to be removed for a camshaft swap, but you must ensure the chain does not skip teeth.
  4. Remove the camshaft bearing caps in the correct sequence (center outward) to avoid bending the camshaft. Note that the caps are numbered and must go back in the same orientation.
  5. Lift out the old camshaft and replace with the Civic Type R camshaft. Apply assembly lube to the lobes and journals.
  6. Install new camshaft seals on the front and rear before placing the bearing caps. Torque caps to factory specs (about 14 ft-lb in two stages).
  7. Reinstall the valve cover with a new gasket. Torque the bolts in sequence to the specified in-lb (typically 8 Nm or 71 in-lb).
  8. Reconnect all components, battery, and start the engine. Check for oil leaks around the seals and cover.

One critical detail: the Civic Type R camshaft uses the same VTEC spool valve as the RSX Type S, so no modifications to the VTEC solenoid are needed. However, the ECU will need to be reprogrammed to delay VTEC engagement to around 5,500-6,000 RPM (instead of the stock 4,500 RPM) to match the new cam profile.

Supporting Modifications for Full Power

The camshaft upgrade flows more air, but the stock intake, exhaust manifold, and exhaust system can become restrictive. To maximize the 50-horsepower gain, consider these supporting modifications:

  • Cold Air Intake (CAI): $150-$300. A larger-diameter intake tube and high-flow filter reduce inlet restriction. The popular AEM or Injen CAI systems work well.
  • RBC Intake Manifold: $200-$400 (used). The larger plenum and shorter runners from the Civic Type R intake manifold complement the camshaft’s top-end flow. This is one of the best bolt-on upgrades for any K20.
  • Aftermarket Header (race or street): $300-$600. The stock RSX Type S header has restrictive catalytic converter and small primaries. A 4-1 or 4-2-1 header with a high-flow cat or test pipe frees up exhaust flow.
  • Exhaust System (3-inch or 2.75-inch): $400-$800. A free-flowing cat-back exhaust reduces backpressure. Pair with a larger downpipe if using a header.

Without these supporting mods, the camshaft alone might only net 20-25 horsepower, because the engine cannot expel exhaust gases effectively. A fully built naturally aspirated RSX with RBC manifold, header, exhaust, and camshaft can produce over 240 wheel horsepower, representing a gain of 50+ horsepower over stock.

Tuning Requirements: The Key to 50 Horsepower

No camshaft upgrade on a modern Honda engine will reach its potential without recalibrating the engine control unit. The stock ECU is programmed for the stock cam’s airflow characteristics and VTEC timing. Installing the Civic Type R camshaft alters the volumetric efficiency curve. The consequences of not tuning include:

  • Lean air/fuel ratios at high RPM, risking detonation and engine damage.
  • Poor driveability due to incorrect VTEC engagement causing a flat spot in power delivery.
  • Check engine light and error codes for camshaft position or knock.

ECU Options

  • Hondata K-Pro: $900-$1,200 (new). This standalone ECU replaces the stock unit and offers full control over fueling, ignition, VTEC, and variable timing. It is the gold standard for K-series tuning.
  • Hondata FlashPro: $695 (for RSX Type S). A reflash option that allows custom maps but does not offer full standalone capability. Sufficient for a cam-only build.
  • K-Tuned K1 or K2 ECU: $900-$1,100. Alternative to Hondata with similar features.
  • Mail-in Tune: $200-$300 (plus ECU). Some tuners provide a base map based on your mods, but dyno tuning is strongly recommended for maximum power.

Plan on spending a minimum of $500 for tuning. Insist on a dyno session to verify horsepower gains and ensure safe air/fuel ratios. The Hondata K-Pro product page provides details on features for the K20A2 engine.

Potential Challenges and Solutions

Camshaft Wear and Inspection

Used Civic Type R camshafts are often removed from engines with high mileage. Inspect the lobes for pitting or scoring. If the camshaft shows uneven wear, it will not perform optimally and could damage the lifters. Replace worn camshafts for $350-$400 new (through Honda or aftermarket suppliers like Skunk2 or K-Tuned).

Valve Spring Concerns

Stock K20A2 valve springs are adequate for a mild cam upgrade like the Type R camshaft, which has only slightly higher lift. However, if you plan to increase the rev limiter beyond 8,200 RPM, consider upgrading to K20A2 Type R valve springs (or aftermarket ones) to prevent valve float. Budget an additional $100-$200 for springs and retainers.

Oil Consumption

With increased lift and duration, the PCV system may not handle blowby as effectively. Install a catch can to reduce oil ingestion into the intake manifold. A simple baffled catch can costs $30-$80.

Smog and Emissions Compliance

Depending on your region, a camshaft upgrade may still pass visual inspection if you keep the stock catalytic converter and vacuum lines. However, tuning that removes the secondary O2 sensor feedback may cause a readiness failure. Research local emissions laws before proceeding.

Conclusion: Is $400 Realistic?

Achieving a 50-horsepower gain on an RSX Type S with a Civic Type R camshaft is entirely possible, but the original $400 figure represents only the camshaft and basic gaskets. To realize the full gain reliably, you must invest in ECU tuning ($500+) and likely supporting modifications like an intake and header ($300-$600). The total investment for a safe, powerful upgrade will fall between $1,000 and $1,800. For many enthusiasts, that remains a strong value proposition compared to forced induction, which can easily exceed $4,000 for parts and tuning.

The Civic Type R camshaft swap remains one of the most cost-effective power-adders for the K20 engine, provided you approach it with realistic expectations. A dyno-tuned car with the right supporting mods will deliver the advertised 50-horsepower gain, transform the driving experience, and retain the naturally aspirated character that makes the RSX Type S so enjoyable.

For further reading, the K20A.org camswap guide offers community-tested advice, and Modded Hondas K20 engine specs page provides comprehensive data on all K20 variants.