Description Reviews Mahle MS Piston Set 07+ Mini 77.50mm Bore 85.8mm Stroke 138.2mm Rod 20mm Pin 1cc 10.3 CR Set of 4 The Mahle PowerPak is a complete race-proven piston assembly kit composed of hand deburred, forged, performance coated pistons, high-quality steel pins, round wire locks and low drag performance rings. It may seem crazy, but you really can get 8, 14, or even 22 more HP with Mahle pistons and rings. The secret is in Mahle's ultra flat ring grooves and low drag rings. Improved sealing minimizes parasitic drag to create ''free'' horsepower. Performance coatings include a phosphate dry lubricant (not to be confused with a thermal film coating) that is used to protect against ring micro-welding and pin galling during initial start up and break-in. For additional performance, Mahle applies its proprietary Grafal anti-friction coating to each piston skirt. Features: Forged Aluminum Pistons CNC-machined crown Hand deburred finishing Forced pin oiling with machined drain backs Lightweight slipper skirt forgings CC-finished pin bores Forced Pin Oiling Reliable round wire locks standard with every kit Pre-fitted German steel pins noted for their high strength, light weight, and durability Phosphate coating is a dry lubricant that provides Mahle pistons' grey appearance Piston crown remains machinable Mahle's Grafal skirt coating reduces piston noise, drag, scuffing, friction, and cylinder bore wear Note: 77.5mm Bore, Stock Compression. Special order at this time, with a 2 week lead time. Includes: Pistons, Pins, c-clips, & All Rings. Actual Piston not shown in photo. Mahle's Grafal skirt coating reduces drag, scuffing friction and cylinder bore wear as well reduces piston noise.Phosphate coating provides the grey appearance to the Mahle pistons. This dry lubricant (not to be confused with a thermal film coating) provides a lubricant film in the pin bores and ring grooves until the oiling system of the engine reaches operating pressure, particularly useful during initial start-up or break-in of engines to protect against galling and microwelding. The piston crown is still machinable.M142 alloy is used by Mahle for increased strength and less thermal expansion. In fact M142 is an Aluminum alloy which allows for tighter cylinder to wall clearances and improved temperature stability. It's a cast of an eutectic aluminum/silicon alloy which contains small amounts of copper and nickel.