Understanding Cams and Intercoolers

To maximize power and efficiency from a Subaru WRX built engine, two of the most impactful upgrades are the camshafts and the intercooler. These components work in tandem to optimize the engine’s air-handling capabilities. Camshafts control the precise timing of when intake and exhaust valves open and close, dictating how effectively the engine breathes at different RPM ranges. The key specifications—duration (how long the valve stays open), lift (how far it opens), and lobe separation angle (overlap between intake and exhaust)—directly shape the power curve. A more aggressive cam profile increases top-end horsepower but can reduce low-end torque and idle quality.

Intercoolers, on the other hand, reduce the temperature of compressed air from the turbocharger before it enters the engine. Cooler air is denser, containing more oxygen per volume, which allows for more fuel to be burned and higher power output. Charge air temperature can drop by 50–100°F with an efficient intercooler, reducing the risk of knock and enabling more aggressive timing. According to engineering principles, every 10°F reduction in intake temperature can yield roughly 1% more horsepower. For a comprehensive overview of intercooler theory, EngineLabs provides an excellent technical walkthrough.

Best Cams for WRX Built Engines

Selecting the right camshafts for a built WRX engine depends on your specific goals—whether you prioritize daily drivability, peak track power, or a blend of both. Below are some of the top-performing options available, each with distinct characteristics for different build profiles.

GSC Power-Division S2 Cams

The GSC Power-Division S2 cams are a popular choice for enthusiasts seeking a balance between significant power gains and manageable street manners. With a 272-degree duration and around 10.3 mm of lift, these cams provide robust mid-range to top-end power without completely sacrificing low-end torque. They are designed for engines with upgraded turbochargers and supporting fuel systems. Many tuners report gains of 30–40 horsepower on a well-prepped EJ25 or FA20 platform. These cams require upgraded valve springs and retainers to handle the higher lift, so budget for that during installation. For an official spec sheet and application notes, GSC Power-Division’s Subaru page is a reliable resource.

BC Racing Stage 2 Cams

BC Racing Stage 2 cams are known for their aggressive profile, making them ideal for high-horsepower builds aimed at track days or drag racing. With a 272-degree intake and exhaust duration and 10.5 mm lift, these cams shift the powerband higher into the RPM range—typically above 4,500 RPM. This aggressive profile creates noticeable lope at idle and can reduce low-speed drivability. They pair well with large-frame turbos (GT35 or larger) and ported cylinder heads. BC Racing offers these cams as part of a complete valvetrain package, including springs and retainers, ensuring compatibility. Expect to invest in a standalone engine management system to tune the newly aggressive cam profile.

Grimmspeed 272 Cams

Grimmspeed’s 272 cams are engineered for improved airflow across the entire RPM band, making them suitable for both street and track applications. They feature a proprietary lobe design that reduces valvetrain noise and wear compared to some competitors. With 10.8 mm lift and a conservative lobe separation angle, these cams provide a noticeable power boost—typically 25–35 horsepower—while retaining acceptable idle characteristics. They are compatible with stock-style valve covers and require only upgraded springs. Grimmspeed includes detailed installation instructions and recommends a professional tune. Their ability to work with both top-mount and front-mount intercooler setups makes them versatile for various builds.

HKS 264 Cams

For those looking for a moderate performance increase without compromising reliability and smooth operation, the HKS 264 cams are a solid choice. With a 264-degree duration and 9.5 mm lift, they offer a mild increase in lift and duration over stock, improving top-end flow while maintaining excellent low-end torque. These cams are often used in stage 1 or stage 2 builds where the engine remains mostly stock internally. They work well with the factory valvetrain and require minimal supporting modifications. While power gains are modest—around 15–20 horsepower—the HKS 264s are plug-and-play for daily drivers who want a subtle performance edge and a more aggressive exhaust note.

Additional Cam Options

Other noteworthy cams include the Kelford 272 (Australia-made, known for extreme lift and high-RPM power) and the Brian Crower Stage 2 (similar specs to BC but with a focus on reliability). For extremely high-output builds (800+ horsepower), custom-ground cams from Comp Cams or Web Camshafts can be tailored to exact engine specs. Always verify compatibility with your engine block (EJ207, EJ255, EJ257, FA20DIT, etc.) and valvetrain components.

Best Intercoolers for WRX Built Engines

Intercooler choice is equally critical, as it directly affects intake air density and engine knock resistance. The two main types are top-mount intercoolers (TMIC), which sit on top of the engine, and front-mount intercoolers (FMIC), which are mounted at the front of the vehicle. TMICs offer shorter charge piping and faster spool, while FMICs provide larger cooling capacity and lower intake temperatures, especially at high power levels.

Process West Verticooler

The Process West Verticooler is arguably the gold standard for top-mount intercoolers on Subaru WRX and STI models. Its vertical-flow core design maximizes surface area within the confines of the engine bay, allowing it to cool charge air more effectively than traditional horizontal-flow TMICs. Process West claims up to 60% greater cooling capacity than the stock intercooler, with pressure drops as low as 0.5 psi at race gas levels. It fits under the stock hood with minimal trimming, making it a direct upgrade for built engines aiming for 450–550 wheel horsepower. The Verticooler includes a billet adapter plate and comes with all necessary hardware. For more details on construction and testing data, Process West’s official site provides extensive dyno charts.

Grimmspeed Top Mount Intercooler

Grimmspeed’s TMIC is a lightweight but robust option, constructed from cast aluminum end tanks and a bar-and-plate core. It offers a 50% increase in core volume compared to the stock unit, translating to consistent power gains across the RPM range. The design prioritizes minimal pressure drop (less than 1 psi at 400 horsepower) while reducing intake temperatures by 20–30°F on a hot day. It is compatible with stock charge piping and requires no permanent modifications. This intercooler is a favorite among enthusiasts who want a proven upgrade without the complexity of a full front-mount system. Combined with a Grimmspeed 272 cam and a built short block, this TMIC supports reliable daily-driven builds around 450 wheel horsepower.

ETS Front Mount Intercooler

For high-horsepower builds, the ETS (Extreme Turbo Systems) Front Mount Intercooler is a leading choice. It features a massive 3.5-inch thick core with cast aluminum end tanks and a bar-and-plate construction that excels in heat dissipation. ETS offers various core sizes (from 3-inch to 5-inch thickness) to match specific power goals, ranging from 500 to over 800 wheel horsepower. The kit includes mandrel-bent charge piping with smooth transitions to reduce turbulence and pressure drop. A splitter and shroud set is available for optimal airflow. Installation requires cutting the bumper beam, so it is a permanent modification best suited to track-oriented cars. The ETS FMIC, paired with aggressive cams like BC Stage 2, can support over 600 wheel horsepower with proper tuning.

COBB Tuning Front Mount Intercooler

COBB Tuning’s FMIC is engineered for balanced performance and ease of installation. It uses a 3-inch thick core with a high-density fin design to optimize heat rejection and airflow. The kit includes all necessary piping, couplers, and clamps, with pre-drilled mounting brackets for a direct fit on 2015+ WRX and STI models. COBB has focused on reducing overall weight (about 30% lighter than some competitors) while maintaining a low pressure drop of 0.8 psi at 500 horsepower. This intercooler is ideal for street-focused built engines where a blend of responsive spool and high cooling capacity is desired. COBB’s Accessport tuning can be used to dial in the setup for maximum reliability.

Additional Intercooler Options

Other respected choices include the Perrin Performance TMIC (known for its cast end tanks and durability) and the Mishimoto FMIC (offers a budget-friendly option with good core quality). For extreme builds, PWR offers custom FMIC cores that can be integrated into dedicated piping setups. Regardless of choice, ensure the intercooler core size is matched to your turbo and horsepower targets—oversized FMICs can cause lag, while undersized TMICs may heat soak in sustained WOT pulls.

Factors to Consider When Choosing Cams and Intercoolers

Selecting the optimal camshaft and intercooler combination requires careful consideration of several factors. Below are key elements to evaluate before making a purchase.

Engine Build and Compatibility

The camshaft and intercooler must align with your engine’s displacement, rotating assembly, and turbocharger. A built engine with forged pistons, rods, and a billet crank can handle more aggressive cam profiles and higher boost levels made possible by a larger intercooler. For instance, a closed-deck EJ block is better suited for the extreme lift of Kelford 272 cams, while an open-deck block may benefit from milder cams like HKS 264 to reduce stress on cylinder walls. Always check valve-to-piston clearance, especially with high-lift cams and aftermarket pistons. Confirm that the intercooler piping diameter matches your turbo outlet and throttle body to avoid restrictions.

Driving Style and Performance Goals

Your intended use heavily influences component choice. For daily driving with occasional spirited runs, a moderate cam like the GSC S2 combined with a Process West Verticooler provides responsive power and good low-end torque. For autocross or time attack, a FMIC like the ETS with mild cams ensures consistent cooling during short bursts of high boost. For drag racing or high-speed track days, aggressive cams (BC Stage 2) paired with a massive FMIC (COBB or ETS) will unlock top-end power at the cost of idle quality and low-RPM response. Define your peak horsepower goal (e.g., 400, 500, or 600+ horsepower) as this dictates the intercooler core volume and cam profile aggressiveness.

Budget and Total Cost

Cam and intercooler upgrades are not isolated costs. Cams require new valve springs and retainers ($200–$500), and often professional installation ($500–$1,000). Intercooler kits range from $800 (TMIC) to $1,500+ (FMIC with piping). Installation of an FMIC may require body modifications (cutting the bumper beam) and additional labor ($300–$700). Furthermore, both upgrades necessitate a custom ECU tune ($500–$1,000) to optimize air/fuel ratios and ignition timing. Set a realistic budget that covers all supporting modifications. For example, a complete GSC S2 cam setup with springs and a Grimmspeed TMIC plus tune may cost around $2,500, while a BC Stage 2 cam setup with ETS FMIC could exceed $4,000.

Installation Complexity

Installing cams is an involved process that requires removing the timing belt, sprockets, and valve covers, and often replacing seals and gaskets. It is recommended for experienced DIYers or professional shops. Intercooler installation varies: TMICs are generally bolt-on within 2–4 hours, while FMICs require bumper removal, cutting, and routing charge pipes, taking 4–8 hours. Check if the kit includes detailed instructions and all hardware. Some FMIC kits require custom fabrication for cold-side piping, especially on older WRX models. Factor in installation time and potential hidden costs like additional couplers or brackets.

Supporting Modifications

To fully exploit the potential of upgraded cams and intercooler, ensure the rest of the engine is prepared. This includes a upgraded fuel system (higher flow injectors, fuel pump, and regulator), a larger turbocharger (if aiming for 450+ horsepower), and an aftermarket intake and exhaust system. The intercooler’s cooling capacity must match the turbo’s airflow and boost level; an FMIC with a 4-inch core may be excessive for a small turbo running 20 psi but essential for a Garrett GTX3582R at 30 psi. Similarly, cams with 280+ degree duration require a standalone ECU (e.g., Haltech, Syvecs) or at least a fully custom ECU calibration like Cobb Accessport with ProTune. Do not skip a dyno tuning session—improperly matched cams and intercooler can lead to knock, high EGTs, and engine damage.

Installation and Tuning Tips

Professional vs. DIY Installation

While both cam and intercooler installations can be performed by experienced DIYers, cams require precise timing alignment. Use a factory service manual and timing tools (camshaft sprocket holder, timing pin set) to avoid valve-to-piston contact. For the intercooler, ensure all charge pipe couplers are tightened evenly to prevent boost leaks. Invest in a boost leak tester to verify integrity after installation. If you are not comfortable with engine internals, hire a Subaru specialist to avoid costly mistakes.

Break-In Procedure for New Cams

After installing new cams, follow a break-in procedure to seat the lifters and ensure long-term reliability. Start the engine and idle at 2,000–3,000 RPM for 20–30 minutes using high-zinc break-in oil (adequate for flat-tappet cam designs). Vary the RPM slightly to promote oil splash. Check valve lash after initial cooldown. For overhead cam designs like the WRX, break-in primarily involves verifying proper timing and listening for abnormal noise. After 500 miles of gentle driving, perform an oil change and inspect the valvetrain.

Dyno Tuning and Data Logging

A reliable tune is non-negotiable. Cams shift the torque curve and alter the engine’s VE (volumetric efficiency), requiring adjustments to fuel and spark maps. The intercooler improves charge density, so boost levels may need to be recalibrated to avoid overboosting. Use a dyno with a wideband O2 sensor and knock detection. Many tuners recommend a ECU calibration from a known platform like Cobb Accessport, EcuTek, or OpenECU. Data log during the first few pulls to monitor intake temperature, knock correction, and air/fuel ratios. For built engines, consider a conservative tune initially and slowly increase boost to allow the engine to break in fully.

Conclusion

Upgrading the camshaft and intercooler in your Subaru WRX built engine is one of the most effective ways to increase power and efficiency. By matching the cam profile to your driving style and turbo setup, and pairing it with an intercooler that can effectively cool the increased boost, you can achieve a reliable and powerful engine. Whether you choose the moderate power gains of GSC Power-Division S2 cams with a Process West Verticooler for a responsive street car, or the aggressive top-end of BC Stage 2 cams with an ETS front mount intercooler for track dominance, each combination requires careful planning. Research your specific engine model, consult with experienced tuners, and invest in quality components and installation. With the right setup, your built WRX will deliver thrilling performance for years to come.