Engine Bay Ambient Temperature
It is the air temperature to which an electronic component is exposed on or near the engine. Control units mounted in the engine bay are typically designed for ambient temperatures reaching 110 degrees Celsius. Since temperature is the single biggest cause of electronic failures, it is the decisive criterion in choosing the mounting position.
Heat arrives by two routes: the temperature of the surrounding air and the heat radiated from hot surfaces. The second is often underestimated; a housing a few centimetres away from the exhaust manifold or the turbo heats up considerably by radiation even if the air is not hot.
The practical mounting rules are these:
- Stay away from the exhaust manifold, the turbo and the run of the exhaust pipe; if possible put a barrier in between.
- Prefer a point with air circulation, one that is not closed in.
- Apply the same criterion to the cable and the cable sheath as well; the liner hardens with heat.
An operating temperature range is not declared in the GS740 and GS740-3P documentation. For that reason the values above are general engine bay design data, not a product specification. Only for the AS5600 encoder used in the position feedback is a component-level operating range given by its manufacturer, as −40 to +125 degrees Celsius.
Context in which this term is used: Electronic speed and throttle control on a diesel engine