combustion reactions are exothermic or endothermic

'10 February. The Peregrine flew north across the valley. He was half miles away, but I could see the brown and black of his wings, the shining gold of his back. The pale cream of his tail coverts looked like a band of straw twisted across the base of his tail. Thinking he'd return downwind, I went into fields with the river to watch for him. I stood in the lee of the hawthorn hedge, looking through it on the north, sheltered in the bitter wind' Next to contact breaker, spark plug has become the weakest section of the ignition system. It is mounted within the combustion chamber of the engine, where working conditions are- severe. During peak combustion conditions the temperature inside combustion chamber in the modern car engine could possibly be around 2500 ºC along with the pressure about 7 Mpa. Moreover a spark plug can also be encountered with thermal and load cycling fatigue on account of sudden adjustments to temperature and pressure-from the high temperature of burnt gas for the relatively low temperature with the air/fuel mixture and from your underhand during explosion with the air/fuel mixture to low pressure during induction. In addition, the spark plug has got to endure high voltage, mechanical vibration along with the corrosive atmosphere of combustion gages. A modern spark plug comes with an economical life of about 10,000-16,000 km.