
70 LIGHT AND HEAVY VEHICLE TECHNOLOGY
On the other hand the plug electrodes also need to be
cooled and scoured of any residual exhaust products by
the incoming fresh cylinder charge.
With regard to the siting of the fuel injector nozzle in
diesel engines, this depends upon the type of combus-
tion system used, as described later. In general terms, a
centrally disposed nozzle is required for direct-injection
engines with open combustion chambers, whereas for
indirect-injection engines an offset nozzle spraying into
a combustion antechamber of either the precombustion
or swirl type is employed.
Cooling provision
If a high volumetric efficienc