Mahle MS Piston Set Chevy SB 389ci 4.135in Bore 3.625/3.75 Stroke 6.125/6 Rod .927 HD Pin 9cc 13.5CR

This Mahle MS Piston Set is built for Chevy Small Block engines displacing 389 cubic inches. You get a complete set of pistons, designed to handle the demands of a performance engine build. The set includes pistons with a 4.135-inch bore, a 3.625-inch stroke, and are intended for use with a 6.125-inch connecting rod. These pistons are crafted from 2618 aluminum, a strong material commonly used in high-performance applications for its durability and heat resistance. They feature a 0.927-inch heavy-duty pin for added strength and a valve relief volume of 9.0cc, which contributes to a 13.5:1 compression ratio when paired with the correct cylinder heads and deck height.

Mahle has engineered these pistons with a specific focus on performance and reliability. The 4.135-inch bore size is crucial for achieving the 389 cubic inch displacement, and the 1.062-inch RCH (rod center height) is matched to the specified rod length. The 0.927-inch heavy-duty pin is designed to withstand higher cylinder pressures and stresses compared to standard pins. The 9.0cc valve reliefs are precisely machined to provide adequate clearance for most common performance camshaft profiles, preventing piston-to-valve contact while helping to achieve the target 13.5:1 compression ratio. Each piston weighs approximately 445 grams, which is a notable consideration for engine balancing.

When undertaking an engine rebuild of this caliber, proper balancing of all rotating and reciprocating components is essential for longevity and smooth operation. These Mahle pistons are a solid option for builders looking to maximize performance from their Chevy Small Block. Please note that this piston set is not CARB approved and cannot be shipped to California. Always refer to the manufacturer's installation instructions for critical details regarding piston ring installation, pin fitting, and cylinder wall preparation.