Why Camshaft Upgrades Matter for the RSX Type S

The Acura RSX Type S, with its high-revving K20Z1 engine, is a beloved platform among Honda enthusiasts. While the car delivers respectable power from the factory, the camshaft profile is a major restriction that holds back significant torque, particularly in the mid-range. Upgrading the camshaft is one of the most effective mechanical modifications you can make to unlock additional power. By altering valve lift, duration, and lobe separation, a performance camshaft allows the engine to breathe more efficiently, resulting in measurable gains. In this guide, we will examine the best camshaft upgrades for the RSX Type S that can deliver a genuine increase of 15 lb-ft of torque or more at the wheels.

Understanding Camshaft Basics and Torque Production

To appreciate what a camshaft upgrade does, it helps to understand how the cam profile influences engine performance. The camshaft controls when the intake and exhaust valves open and close, as well as how far they open. Stock camshafts are designed for a balance of fuel economy, emissions compliance, and broad power delivery. They typically have conservative lift and duration figures that leave power on the table.

When you install a performance camshaft with higher lift and longer duration, you allow more air-fuel mixture into the cylinder and expel exhaust gases more effectively. This directly increases volumetric efficiency, which is the primary driver of torque output. For the K20Z1, which already has excellent cylinder head flow characteristics, the camshaft is a bottleneck. Upgrading it can shift the torque curve upward, often filling in the dreaded dip between 4,500 and 5,500 RPM that many RSX owners experience with bolt-on modifications.

It is important to note that camshaft selection must match your overall build goals. A cam that is too aggressive can sacrifice low-end drivability and may require supporting valvetrain components. For a target of 15 lb-ft of additional torque, a moderate street-performance camshaft is typically the sweet spot.

Top Camshaft Upgrades for the RSX Type S

After extensive research and real-world owner feedback, three camshaft families consistently deliver the best torque gains for the RSX Type S. Each has distinct characteristics that suit different driving styles and engine configurations.

Skunk2 Alpha Series Camshafts

The Skunk2 Alpha Series is arguably the most popular aftermarket camshaft for the K20 platform. These camshafts are designed with aggressive intake and exhaust profiles that prioritize high-RPM power without completely sacrificing mid-range torque. The Alpha Series offers multiple stages, from Stage 1 to Stage 3, allowing you to choose the aggressiveness that fits your setup.

Key Specifications and Torque Gains: The Stage 2 Alpha camshafts feature 0.375-inch intake lift and 0.350-inch exhaust lift with 272 degrees of duration. In dyno tests on a naturally aspirated RSX Type S with intake, headers, and exhaust, these camshafts have shown torque increases of 12 to 18 lb-ft between 5,500 and 7,500 RPM. The peak torque gain often arrives around 6,200 RPM, flattening the torque curve significantly.

Valvetrain Compatibility: Skunk2 recommends using their matching dual valve springs and titanium retainers with the Alpha Series camshafts, especially for Stage 2 and 3 profiles. The stock valvetrain can handle Stage 1 at moderate RPM, but for reliable high-rpm use, upgraded springs are essential to prevent valve float. Check the Skunk2 product line for the latest fitment details and compatible spring kits.

Driving Characteristic: Expect a noticeable lope at idle with Stage 2 or 3 camshafts. The engine will pull strongly from 4,500 RPM to redline, and the torque increase in the upper mid-range is immediately felt during spirited driving. The car requires a proper tune to run correctly, as the stock ECU calibration cannot compensate for the altered cam timing.

Brian Crower Stage 2 Camshafts

Brian Crower (BC) offers a line of camshafts that are engineered for enthusiasts who want strong torque gains without extreme idle characteristics. The Stage 2 camshafts are a common recommendation for RSX Type S owners who daily drive their cars but still want to track them on weekends.

Key Specifications and Torque Gains: The BC Stage 2 camshafts provide 0.370-inch intake lift and 0.360-inch exhaust lift with 272 degrees of duration. The lobe separation angle is optimized for mid-range torque production. Independent dyno results from multiple RSX owners show torque gains of 13 to 16 lb-ft in the 5,000 to 6,500 RPM range, with a particularly strong improvement from 5,200 to 5,800 RPM, where the stock camshaft tends to fall flat.

Valvetrain Compatibility: Brian Crower explicitly recommends aftermarket valve springs with the Stage 2 camshafts. The stock springs lack the seat pressure needed to control the more aggressive lobe profile at high RPM. BC offers a complete valvetrain package that includes springs, retainers, and seals. Visit the Brian Crower website for compatibility details and dyno charts for the K20 platform.

Driving Characteristic: The idle is slightly choppier than stock but still acceptable for daily driving. The torque increase in the mid-range makes the car feel noticeably faster during normal acceleration. The power delivery is linear, making it easier to drive smoothly on the street compared to more aggressive camshafts.

Comp Cams Xtreme Energy Camshafts

Comp Cams is a well-known name in the American performance industry, and their Xtreme Energy line for the K20 engine has gained a loyal following among RSX Type S owners. These camshafts are designed with a unique lobe profile that emphasizes fast ramp rates and increased area under the curve, which translates directly to torque production.

Key Specifications and Torque Gains: The Comp Cams Xtreme Energy camshafts for the K20Z1 feature 0.365-inch intake lift and 0.355-inch exhaust lift with 268 degrees of duration. The slightly reduced duration compared to Skunk2 or BC designs helps preserve low-end torque while still delivering strong gains up top. Users report torque increases of 14 to 17 lb-ft across a broad RPM band from 4,800 to 7,200 RPM.

Valvetrain Compatibility: Like the other options, Comp Cams recommends their own valve spring kit for proper operation. The Xtreme Energy profile is aggressive enough that stock springs will likely cause valve float at high RPM, leading to power loss and potential engine damage. A set of aftermarket retainers is also recommended for long-term reliability.

Driving Characteristic: The Xtreme Energy camshafts offer a very broad power band. The torque comes on early and stays strong throughout the rev range. This makes them an excellent choice for autocross or road course driving, where maintaining momentum through corners is critical. The idle is slightly rougher than stock but not intrusive. Explore the Xtreme Energy range for complete specifications and application notes.

Supporting Modifications for Maximum Torque Gains

A camshaft upgrade alone will not deliver the full 15 lb-ft of torque you are targeting. The engine needs to be able to move more air in and out, and the fuel system must be able to supply the additional fuel required. If you are installing camshafts on an otherwise stock RSX Type S, you will still see gains, but they will be limited by the restrictive intake manifold and exhaust system.

To maximize the torque increase, consider pairing your camshaft upgrade with the following modifications:

  • Cold Air Intake: A high-flow intake system reduces restriction on the intake side. The stock airbox is designed for quiet operation and limits airflow above 5,500 RPM. A cold air intake from brands like AEM or Injen can add 3 to 5 horsepower on its own and becomes even more effective with upgraded camshafts.
  • Header Upgrade: The stock exhaust manifold on the RSX Type S is cast iron and has restrictive primary tube diameters. A 4-1 or 4-2-1 header with larger primaries (1.75-inch is a good match for mild camshafts) reduces exhaust backpressure and allows the engine to scavenge exhaust gases more effectively. This alone can add 8 to 12 lb-ft of torque when combined with a cam upgrade.
  • Exhaust System: A 2.5-inch cat-back exhaust system with a high-flow catalytic converter or test pipe reduces restriction on the exhaust side. The stock exhaust is 2.25 inches and has a restrictive muffler design. A well-designed exhaust system can add 3 to 5 lb-ft of torque and improve throttle response.
  • Intake Manifold Spacer: A thermal intake manifold spacer, such as those from HPS or Skunk2, reduces heat transfer from the engine to the intake manifold. This lowers intake air temperature, which increases air density and can add 2 to 4 lb-ft of torque in hot weather conditions.
  • Upgraded Fuel Injectors: If you are using the most aggressive camshafts and supporting modifications, the stock 310cc fuel injectors may run out of capacity. Upgrading to 410cc or 550cc injectors from an RDX or aftermarket supplier provides the headroom needed for higher RPM fuel delivery.

Installation Guide and Critical Considerations

Installing camshafts in a K20Z1 engine is a moderate-to-advanced mechanical task. It requires precision, the correct tools, and careful attention to timing marks. If you are not confident in your mechanical skills, professional installation is strongly recommended. A mistake during camshaft installation can result in bent valves, damaged pistons, or catastrophic engine failure.

Essential Tools and Parts: Before beginning the installation, gather the following: a torque wrench, camshaft holding tool (or a strap wrench if you are careful), new valve cover gasket, new camshaft seals, assembly lube, and a timing chain tensioner tool. You will also need a set of feeler gauges if you plan to check valve clearances.

Critical Steps:

  1. Timing Chain Alignment: The K20 engine uses a timing chain, not a belt. You must align the crankshaft to top dead center (TDC) on cylinder one and ensure the camshaft sprockets are aligned with the timing marks. Do not rotate the crankshaft after removing the timing chain without the camshafts installed, or you risk piston-to-valve contact.
  2. Valve Spring Replacement: If you are upgrading valve springs, you will need a spring compressor tool designed for the K20 cylinder head. The valve keepers are small and easy to lose, so work carefully over a clean surface.
  3. Valve Clearance Adjustment: After installing the new camshafts, you must check and adjust the valve clearances. The K20Z1 uses mechanical adjusters (shim-over-bucket design). The recommended clearance for most aftermarket camshafts is 0.006 to 0.008 inches on the intake side and 0.008 to 0.010 inches on the exhaust side. Use a feeler gauge and a shim kit to achieve the correct clearance.
  4. Camshaft Break-In Procedure: After installation, the engine should be started and run at 2,000 to 3,000 RPM for approximately 20 minutes. This allows the camshaft lobes to wear-in against the valve buckets. Use a high-zinc break-in oil or a dedicated assembly lube on the camshaft lobes before startup.

Common Mistakes to Avoid: Do not reuse the old valve cover gasket. Do not overtighten the camshaft cap bolts (use a torque wrench with the specified torque value). Do not install the camshafts without verifying the timing chain alignment twice. Do not forget to replace the camshaft position sensor O-ring if it is old and brittle.

Tuning Your RSX Type S After Camshaft Installation

Installing a performance camshaft without tuning is a waste of money. The stock ECU is calibrated for the factory camshaft profile and cannot adapt to the altered valve events. Your engine will run rich at idle, potentially lean at high RPM under load, and will not achieve the torque gains the camshaft is capable of delivering. Tuning is not optional; it is mandatory.

Available Tuning Methods:

  • K-Tuner: This is the most popular tuning solution for the RSX Type S. The K-Tuner V2 unit plugs into the OBD-II port and allows you to flash custom calibration files to the ECU. Many tuners have pre-built base maps for common camshaft profiles, which provide a safe starting point for dyno tuning.
  • Hondata FlashPro: Similar to K-Tuner, the FlashPro system allows precise control over fuel maps, ignition timing, camshaft angle, and other parameters. It is a robust platform for professional tuning and includes datalogging capabilities.
  • Professional Dyno Tuning: For the best results, take your car to a reputable Honda-specific tuning shop with a dynamometer. A professional tuner will adjust the fuel and timing maps in real-time while monitoring knock sensors and air-fuel ratios. This is the only way to guarantee safe operation and maximum torque output.

Tuning Parameters to Optimize: After a camshaft upgrade, the tuner will focus on adjusting the fuel map to target an air-fuel ratio of approximately 12.8:1 at wide-open throttle. The ignition timing map will be advanced in areas where the camshaft improves airflow, often reducing the need for aggressive timing. The camshaft angle control (i-VTEC engagement point and phasing) may also be adjusted to match the new camshaft profile. Learn more about the K-Tuner platform and its compatibility with the RSX Type S.

Expected Performance Gains and Dyno Results

Real-world dyno tests from RSX Type S owners who have installed aftermarket camshafts with supporting modifications provide a clear picture of what you can expect. Here are representative results from a typical build:

  • Stock RSX Type S (baseline): 160-165 whp, 115-120 lb-ft wtq
  • With intake, header, exhaust, and tune (no cams): 185-195 whp, 125-130 lb-ft wtq
  • With Skunk2 Stage 2 cams, supporting parts, and tune: 210-220 whp, 140-145 lb-ft wtq

In this scenario, the camshafts alone (compared to the bolt-on-only setup) contributed approximately 20 to 25 horsepower and 12 to 16 lb-ft of torque. The torque gain is most pronounced between 5,500 and 7,000 RPM, where the stock camshaft begins to lose steam. The peak torque figure of 140 lb-ft may not sound enormous, but on a lightweight car like the RSX Type S, it translates to a significantly faster acceleration feel. The 15 lb-ft target is not only achievable but can be exceeded with the right combination of camshaft and supporting modifications.

Frequently Asked Questions

Will a camshaft upgrade damage my stock engine? Not if installed correctly and tuned properly. The K20Z1 engine has a robust bottom end with forged connecting rods and a strong cylinder head. With a moderate camshaft like those discussed here, the engine will operate well within safe limits.

Do I need to upgrade the valve springs? For Stage 2 and more aggressive camshafts, yes. The stock valve springs are designed for the factory camshaft profile and can experience valve float above 7,500 RPM with higher-lift camshafts. Upgraded springs provide the necessary seat pressure to keep the valves under control.

How much does a camshaft upgrade cost? A set of camshafts ranges from $600 to $900. Valve spring kits add $200 to $400. Professional installation and tuning typically cost between $1,000 and $2,000 depending on the shop and region. The total investment is usually between $1,800 and $3,300.

Can I pass emissions with aftermarket camshafts? In most cases, yes, with a mild camshaft and a good tune. The car must still meet idle and cruising emission standards. However, some regions with strict visual inspections may fail a car with non-OEM camshafts. Check local laws before proceeding.

Will the car still be reliable for daily driving? With a mild camshaft like the BC Stage 2 or Comp Cams Xtreme Energy, daily drivability remains good. The idle will be slightly rougher, and low-RPM torque may be slightly reduced, but the car remains perfectly usable for commuting. Aggressive camshafts (Stage 3 and above) significantly reduce low-end torque and make the car less pleasant to drive in traffic.

Conclusion

Upgrading the camshaft in your RSX Type S is a proven path to achieving a genuine 15 lb-ft torque increase. The Skunk2 Alpha Series, Brian Crower Stage 2, and Comp Cams Xtreme Energy camshafts are all excellent choices that deliver measurable gains when paired with appropriate supporting modifications and a professional tune. Each option has its own character, from the top-end rush of the Skunk2 cams to the broad mid-range torque of the BC Stage 2 or Comp Cams designs. Regardless of which camshaft you choose, the key to success lies in careful installation, upgraded valvetrain components, and a custom calibration that fully exploits the new cam profile. With the right approach, you can transform the driving experience of your RSX Type S and unlock the performance potential that Honda left on the table from the factory.