Answer / pushkar

Hi Syed.
Your first answer is correct & second one is wrong.
Because Calorific value which is also called as heating
value for petrol is arround 47.3MJ/kg & for diesel it is
44.8MJ/kg

Answer / abhishek prakash

hi frndz.
according to me the rate of power depends on combustion. In
S.I engines more amount of fuel get burnt as compare to
diesle engine.But in petrol engine due to turbulance a rich
mixture burnt more lively n smoothly and in deisel engine
only compression is there,so d mixture gets not proper
turbulance and amount of burnt mix. is little bit lesser
than petrol engine.
therefore petrol engines have more power than diesel engines
of same capacity.

Answer / techyy

It's true that the Diesel engine generates more torque than
that of Petrol engines due to higher working pressures, but
the speed of Diesel engines is less as compared to Petrol
engines because of rate of combustion of those fuels &
Diesel engines being very heavy.

Power = Torque * RPM.
This makes petrol engines more powerful as compared to
Diesel engines because of very high speeds.

Answer / alankrit shukla

Firstly calorific value of petrol is greater than that of
diesel.
Secondly, ignition temperature of diesel is greater than
that of petrol,so for compression ignition process in diesel
engine high compression ratio(required pressure is about
50-60bar) is needed to ignite diesel hence much amount of
power is spent in compression process.
As a result petrol engines have more power than that of
diesel engines.

Answer / syed waqas hashmi

due to high calorific value of petrol is one of the
important reason in my opinion.

Answer / r balakrishnan

The calorific value of petrol is higher than diesel
engine.The value for petrol is arround 47.3MJ/kg & for
diesel 44.8MJ/kg.The rate power depond on combustion.petrol
engines have more power than diesel engines

Answer / gaurav

am also agree with the answer of techyy but here ialso want to add the concept of calorific value of petrol and diesel. may u also agree with me.

Answer / techyy

I am not sure about the relation with calorific value here, because even though calorific value of petrol is higher than diesel it's just by 4MJ/kg. And when we compare petrol and diesel engines of same capacity, diesel engines have longer strokes and hence bigger diameter crankshaft. This results in a diesel engine actually producing more torque than a petrol engine of same capacity.
Hence, as stated above, I feel it's just the relation between Torque, speed and power which results in a petrol engine generating more power than a diesel engine.

Answer / syed waqas hashmi

hi singh.
i also discussed the same point as you did. but i dont know
who mark this answer as incorrect

Answer / dev parmar

calorific value of petrol is higher than diesel because
amount of heat produce during combustion of petrol is higher
than diesel ...in other words petrol is highly volatile
because it vaporizes at a relatively low temperature of 40
degree Centigrade. than diesel.

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