944 S L4-2479cc 2.5L DOHC (1987)
Piston: Testing and Inspection
Checking pistons and cylinder bores
Compression: 10.9 : 1
Nominal dia. 100.00 mm
An arrow pointing toward the belt pulley indicates the installation position.
1 - Plain compression ring, chrome-plated
2 - Oil scraper ring
3 - Three-part oil wiper ring
Repair Stage
Piston
Cylinder bore dia. tolerance group
(mm)
(mm)
code
Standard size
99.980
100.000
0
99.990 ± 0.005
100.010 ± 0,005 1
100.000
100.020
2
Oversize 1
100.480
100.500
I 0
100.490 ± 0.007 100.510 ± 0.005 I 1
100.500
100.520
I 2
Checking pistons
Measure approx. 61 mm from piston crown, 90 offset from piston pin axis.
Checking cylinder bores
Measure approx. 61 mm from upper edge of cylinder bore, transverse to engine block. Mount lower crankcase section and tighten bolts to specified
torque for measuring.