BC8810-1 – Mitsubishi 4G63/Evo VIII/Evo 9 Adjustable Cam Gear (Exhaust Gear only)

In the relentless pursuit of power and efficiency from the legendary Mitsubishi 4G63 engine, control over valve timing is non-negotiable. The Brian Crower BC8810-1 Adjustable Exhaust Cam Gear represents a fundamental upgrade for the serious tuner, transforming a fixed component into a precise tuning instrument. Engineered specifically for the Mitsubishi Evolution VIII and IX platforms, this exhaust-only gear allows for independent adjustment of exhaust cam timing, unlocking critical horsepower gains, broadening the powerband, and optimizing engine behavior for both street and track. Constructed from 6061-T6 aerospace-grade aluminum and finished with a hard-anodized, laser-etched surface, the BC8810-1 is built to withstand the punishing environment of a high-performance valvetrain while offering repeatable, accurate adjustments measured in precise degree increments. This is not an accessory; it is a core component for advanced engine tuning, enabling you to correct factory tolerances, compensate for aftermarket camshaft profiles, and fine-tune the exhaust scavenging process to extract every last ounce of performance from your turbocharged 4G63.

Technical Design & Manufacturing Excellence

The Brian Crower BC8810-1 is a paradigm of function-over-form engineering. Its core is machined from a solid billet of 6061-T6 aluminum, a material chosen for its exceptional strength-to-weight ratio and resistance to fatigue. This is not a cast piece; the billet construction ensures a uniform grain structure free from potential weak points, providing absolute reliability at sustained high RPM. The final step in its manufacturing is a hard-anodized finish. This process electrically bonds a dense, ceramic-like layer to the aluminum surface, dramatically increasing surface hardness for superior wear resistance against the timing belt teeth and providing a corrosion-resistant barrier against moisture and contaminants. The laser-etched degree markings and brand logo are permanent, ensuring legibility throughout the life of the component, even in oily, high-heat engine bays. The gear interfaces directly with your OEM or aftermarket exhaust camshaft, utilizing the standard dowel pin and bolt pattern for a direct, slop-free fit.

Precision Adjustment Mechanism

The defining feature of this adjustable cam gear is its triple-bolt locking hub system. Unlike crude slot-and-pin designs, the BC8810-1 employs a precision-machined center hub that rotates independently of the outer, toothed ring. Three high-grade, hex-head cap screws secure this relationship. To adjust timing, the tuner simply loosens these three bolts, rotates the inner hub (and attached camshaft) relative to the fixed outer gear, and re-torques to specification. This design provides immense clamping force, completely eliminating any chance of slippage under load—a critical failure point in inferior designs. The outer ring features clearly marked degree indicators, typically in one-degree increments, allowing for adjustments with an accuracy far beyond the factory fixed setting. This system enables tuners to make fine, repeatable changes to dial in engine performance with laboratory-level precision.

Performance Tuning Benefits & Application

Installing an adjustable exhaust cam gear like the BC8810-1 is one of the most cost-effective modifications for realizing the full potential of other engine upgrades. Its primary function is to alter the phasing of the exhaust valve events relative to the crankshaft and piston position.

• Optimize Scavenging & Spool: Advancing the exhaust cam timing can help initiate the exhaust pulse earlier, improving turbocharger spool response by harnessing exhaust energy more effectively at lower RPM.
• Increase Top-End Power: Retarding the exhaust timing can allow for greater cylinder fill at high RPM by keeping the valve open later, supporting increased airflow from larger turbochargers and camshafts.
• Correct Aftermarket Cam Installation: Performance camshafts often have altered lobe separation angles or centerlines. An adjustable gear is essential to dial the camshaft back to its intended position, ensuring you gain the power characteristics you paid for.
• Compensate for Mechanical Variance: Manufacturing tolerances in blocks, heads, and timing components can lead to cam timing that is several degrees off from the factory blueprint. This gear allows you to correct these errors, ensuring optimal baseline timing.
• Tune for Fuel & Emissions: Fine-tuning exhaust valve overlap can influence exhaust gas recirculation (EGR) effects within the cylinder, allowing a skilled tuner to manage combustion temperatures and efficiency.

For a deeper technical understanding of cam timing theory and its effects on turbocharged four-cylinder engines, we recommend this authoritative resource on camshaft tuning principles from MA Performance.

Vehicle Fitment & Compatibility

The BC8810-1 is engineered as a direct, bolt-on component for specific applications. Correct fitment is paramount for proper timing belt alignment and engine operation.

Primary Fitment:
Mitsubishi Lancer Evolution VIII (2003-2005) – All models
Mitsubishi Lancer Evolution IX (2006-2007) – All models
Note: This gear is designed for the exhaust camshaft position only on the 4G63 (DOHC, turbocharged) engine found in these vehicles.

Compatibility Notes: This gear is compatible with OEM timing belts and most aftermarket belts. It is mandatory to use a compatible aftermarket adjustable intake cam gear if adjusting intake timing is desired. Always verify clearance with aftermarket valve covers or other ancillary components. Installation requires specialized tools, including a timing belt tool kit, torque wrench, and harmonic balancer holder.

Technical Specifications

Installation & Final Tuning Note

Installation of the BC8810-1 Adjustable Cam Gear is a task that coincides with a timing belt service or camshaft upgrade. Absolute attention to detail is required. The engine must be set to Top Dead Center (TDC) on cylinder #1 compression stroke, and the factory timing marks must be meticulously aligned before removing the OEM gear. After installation and initial torquing of the locking bolts to the manufacturer’s specification (typically 18-22 ft-lbs), final timing adjustment must be performed with a dial indicator or degree wheel to measure actual camshaft movement, not by relying solely on the markings on the gear. Final tuning should always be validated with a wideband air/fuel ratio meter and knock monitoring system on a dynamometer or during careful road tuning to ensure safe, optimized performance. The Brian Crower BC8810-1 provides the tool; the final power curve is crafted by the skill of the tuner.