Piston: Description and Operation

Pistons





The pistons are made of light alloy and have grooves for two compression rings and one oil scraper ring.

The plain top compression ring is chromium- or molybdenum-coated and the bottom compression ring has oil scraping characteristics. The actual oil scraper ring is in three parts. The pistons are tin-coated.

The engines are fitted with reinforced pistons, the tops of which are hard-anodized, of slightly lower dimensions that previous models to give lower compression. The pistons have been adapted to take connecting rods with trapezoid little ends. They are also fitted with nitrogen case-hardened gudgeon pins. All 2.0 liter engines have a compression ratio of 8.8:1 and 2.3 liters engines 9.3:1.