Troels Dyhr Pedersen.indd - Solid Mechanics

ENGINE MODIFICATION
To increase the room for the various geometries, the engine block and cylinder head were separated by a ten
millimeter thick steel plate. The cylinder liners were kept in their original position. Apart from longer pushrods,
no further modifications were necessary. Figure 9 shows the assembly.
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Engine block
Gasket
Steel plate
Gasket
Cooling water jacket
Copper ring
Cylinder liner
Cylinder head
6 mm bolts
(8 pcs) Steel plate
Piston
crown
Copper ring
Original
piston
Copper ring
Cylinder liner
Cooling water jacket
Gasket
Gasket
Engine block
O-ring seals
Figure 9: Modification of engine block and piston
Gaskets were used on both sides of the steel plate. The surface against the cylinder head was furthermore sealed
with a copper ring resting in a groove in the plate. The alignment of the plates 85 mm holes is accurate enough
for the pistons to pass, but piston rings cannot move across the gap.
The cylinder liner is made of cast iron. The liner is inserted from the top of the engine and is surrounded
completely by the cooling water. It rests on a shoulder on top of the engine. The bottom seal is provided by two
o- rings. Therefore only the top end of the cylinder liner is capable of transferring high frequency vibrations
directly to the engine block. Vibrations transferred to the water will however also transfer sound efficiently to
the engine block due to the incompressibility of water.
The cylinder in which the piston crowns were tested was equipped with a cylinder pressure transducer
positioned in the steel plate as shown on figure 10. The steel plate can be seen in position on figure 11.