ZRP RODS – PISTONS SET BMW 1.8L M42

BMW 1.8L M40/M42 pistons are designed for moderate to high-performance tuning, primarily for road racing or club cars looking to develop their engines for high mileage and/or street use. Designed by ZRP engineers and manufactured in Germany from a high-silicon, low-expansion 4032 (T6) alloy. This allows the engine builder to use a closer piston-bore clearance, resulting in better sealing. This minimizes the slapping noise during cold starts, common among engines using forged pistons, ensuring quiet operation and low oil consumption.
We chose a full-round skirt design with a lower reinforcing band, with oversized and deeper valve pockets to allow the use of high-lift camshaft profiles. They have offset pins for quiet operation, and the wrist pins are made of 9310 alloy. Other features include anti-knock grooves to protect the first rings, and a gas pressure accumulator groove for improved ring sealing and vibration reduction. A pack of premium Japanese-quality 1.00 mm x 1.20 mm x 2.80 mm rings is included.Product Features and DesignAnti-knock grooves for long life and high performanceGas pressure accumulator groove in the second ring for increased wear resistance.Horizontal slots in the pin bore designed to allow oil to penetrate between the pin and the pin bore area.Precision CNC-machined ring groovesHigh-silicon/low-expansion 4032-T6 alloyHoned pin holesClip-on cutouts on the intake side edgeFull-round skirt with lower reinforcement band for high HP/boost applicationsValve pockets designed to accommodate oversized valves and high-lift camshaftsPistons designed to optimize squish for longer engine life and increased power potential.Optional coatings offered upon request.Blast Off Bronze Thermal Barrier Coating.Stealth Black Side-Skirt and Under-Crown Moly Coating.Additional Information.Application. 1.8L, 1.8L M42.Bore Size. 84.00mm, 84.50mm, 85.00mm.Weight. 323, 325, 327g.Stroke. 81.00mm.Compensation Ratio. 8.8:1.Reduction Ratio. OEM compensation10.0:1Comp. height 31.50mmAction 139.95 mmPin diameter 22.00 mmBridge Clearance -0.05CCS dome -14.30cc, -15.50cc, -15.60ccSet of rings 21-GNH8400, 21-GNH8450, 21-GNH8500Wrist Pin Pn WP098