tech mail

PISTON CROWN DESIGN

During the mid-1980s, Renault had a 9 and an 11 series on the market in South Africa. Both were available with a 1,4- and 1,7-litre engine. The 1,4-litre motor was a pushrod unit, tried and trusted. The 1,7-litre was a single overhead cam with two valves per cylinder. Some characteristics about the latter were and remain most intriguing:

• The pistons were machined like that of a typical diesel engine; concave with the combustion chamber in the piston crown.

• The cylinder head face was 100% flat.

• The cylinder head face looks as if an additional head gasket has been “glued” to the face.

• Apparently, the head cannot