Pistons And Rings - BMW N55 Manual

Pistons and Rings

A full slipper skirt type piston with a diameter of 82.5 mm is used. The first piston ring is a
plain rectangular compression ring with a chrome-ceramic coating on the contact surface.
The second piston ring is a tapered faced Napier type ring. The oil scrape ring is
designed as a steel band ring with spring that is also known as VF system.
N55 piston with piston rings
Index
1
2
3
4
5
6
7
8
9
18
N55 Engine
Explanation
Plain rectangular compression ring
Tapered faced Napier ring
VF system ring
Steel inlay for first piston ring
Groove for first piston ring
Groove for second piston ring
Groove for oil scraper ring
Hole for lubricating oil drain
Graphite coating