SAAB WIS ONLINE

Pistons

Pistons

General data

Different makes of piston must not be fitted in the same engine.


Piston class and cylinder travel

Piston class is stamped on piston crown.

Classification codes Piston diameter
Category A mm 81.920 - 81.930
Category B mm 81.930 - 81.940
Category C mm 81.940 - 81.950
Oversize mm 0.4
Piston clearance mm 0.1


The possible cylinder classes are

Classification codes Cylinder bore
Class A mm 82.000 - 82.010
Category B mm 82.010 - 82.020
Category C mm 82.020 - 82.030
Oversize mm 0.1
Cylinder bore conicity mm < 0.005
Cylinder bore ovality mm ± 0.05


Max weight difference between pistons g 5


Piston rings


Upper compression ring Lower compression ring Oil scraper ring
Piston ring gap Z19DT mm 0.20 - 0.35 0.25 - 0.50 0.25 - 0.50
Piston ring opening Z19DTH/DTR mm 0.20 - 0.35 0.60 - 0.80 0.25 - 0.50
Piston ring play in groove mm 0.0985 -0.130 0.025 -0.070 0.030 -0.070
Piston ring thickness mm 1.970 - 1.995 1.970 - 1.990 1.970 - 1.990
Piston ring, groove in piston mm 2.080 - 2.100 2.020 - 2.040 2.020 - 2.040


They can all occur in the same cylinder block.

The piston ring working gaps must be displaced 120° to each other.

Gudgeon pin and pin bearing

Outside diameter of gudgeon pin mm 25.982 - 25.987
Gudgeon pin, length mm 56.4 - 56.8
Inside diameter of piston bearing mm 25.999 - 26.004
Gudgeon pin's bearing play in piston mm 0.003 - 0.014
Gudgeon pin's bearing play in connecting rod mm 0.003 - 0.019
Inside diameter of bearing bushing, piston end mm 26.006 - 26.014
Gudgeon pin in relation to connecting rod mm Floating bearing


Gudgeon pin and pin bearing DTR

Outside diameter of gudgeon pin mm 29.975 - 29.980
Gudgeon pin, length mm 66.7 - 67.00
Inside diameter of piston bearing mm 29.993 - 29.998
Gudgeon pin's bearing play in piston mm 0.013 - 0.023
Gudgeon pin's bearing play in connecting rod mm 0.026 - 0.039
Inside diameter of bearing bushing, piston end mm 30.006 - 30.014
Gudgeon pin in relation to connecting rod mm Floating bearing