From V8X
http://www.v8x.com.au/cms/A_100988/article.html
"Engine Change
The engine fitted to a car at each meeting must not be changed without prior express approval of the Category Technical Director. Approval to change an engine will only be given if it can be verified by the Category Technical Director that the engine has suffered a mechanical failure.
For the avoidance of doubt, an engine change is defined as:
- the removal and replacement of an engine; or
- the breaking of any seals attached to the engine so as to allow the removal of either cylinder head/s or the sump.
On a maximum of two (2) occasions only during the course of the Championship, at a Sprint Round, a team will be permitted to conduct an engine change in a car prior to the commencement of the first qualifying session without incurring a penalty. If an engine change is approved by the Category Technical Director following any subsequent race, the relevant car will be placed at the back of the starting grid for the next race of that meeting."