Automobile Engineering in ME
The compression ratio in petrol engine is kept less than in Diesel engine because

It is just customary to have less compression ratio in petrol engines
It makes petrol engines lighter
Higher or equivalent compression ratio in petrol engines is not possible due to pre-ignition
Less compression ratio gives better performance

ANSWER DOWNLOAD EXAMIANS APP

Automobile Engineering in ME
The auto ignition in a spark ignition engine means

Ignition of the charge before the passage of flame front
Ignition induced by the passage of a spark
Ignition induced to supplement the process of normal combustion
Automatic ignition of the charge at the end of compression

ANSWER DOWNLOAD EXAMIANS APP