
Workshop Manual, TPD 1353E, Issue 3
51
4
Peregrine EDi and 1300 Series EDi
Piston and connecting rod assemblies
4
General description
The aluminium alloy pistons have a cast iron insert for the top piston ring.
The two-piece pistons have an aluminium alloy skirt and a steel piston crown. The steel crown compensates
for increased combustion pressures, and can be removed from the piston skirt, when the piston assembly is
dismantled.
Both types of piston have recesses in the crown to allow clearance for the inlet and exhaust valves. The
combustion bowl is off-centre.
A variation in the aluminium alloy along the length of the piston skirt controls expansion of the piston.
Each piston has two tapered compression rings and an oil control ring. The grooves for the piston rings have
the same shape as their rings. The top compression ring is marked "TOP-UP" on its upper face, the second
compression ring is marked “2nd-UP” on its upper face. The oil control ring is not marked, and new rings may
be fitted either way up. The top compression ring has a round edge, the edge of the second compression ring
is at an angle.
Combustion pressure is allowed to pass through the ring gaps to the underside of the compression rings. This
maintains the correct contact between the face of the piston rings and the cylinder bore, to improve
performance and reduce oil loss.
Axial location of the fully floating gudgeon pin is by circlips.
The connecting rods are "H" section forgings of steel. The small end is wedge shaped to improve strength and
reliability. The overall length of the connecting rod is reduced by an angle of tilt to the big end bearing.
Jets fitted in the cylinder block spray lubricating oil onto the inner surface of the piston to cool the piston.
This document has been printed from SPI². Not for Resale
Содержание 1300 EDi Series
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