Answer / amit

because of high copression ratio of desial engine and
efficency of desial engine increases with load

Answer / rakesh

in case of petrol engine compression ratio is <10.
that is very small for large power output.suppose u hav to
drive a big ship by usin a petrol enine,the enine size will
be less half of the ship,where as the size of the disel
engine will be very small as compared to that of petrol enine.
for all these reasons for heavy machinery disel engine is
used,not the petrol.

Answer / deependra singh parihar

We use diesel engine for heavy purpose because it has the
compression ratio (11:1-13:1)more than patrol engine (9:1-
11:1).so the thermal efficience of diesel engine will be
higher compared with petrol engine,

Answer / sanjay

The Compression ratio is calculated by the following
formula:
CR= ((3.14*b^2/4*s+Vc)+VC) / Vc
, where
b = cylinder bore (diameter)
s = piston stroke length
Vc = clearance volume.

In deisel Engine the compression ratio is in the range of
20:1 to 25:1, which is very high as compared to Petrol
engine. for same bore dia, the stroke is bigger in case of
a diesel engine that is why for heavy engine diesel engine
is suitable than petrol engine.

Answer / swayang

a diesel engine follows on diesel cycle and a petrol on otto
cycle.as diesel engine have greater compression ratio than
petrol therefore it has more thermal efficiency than petrol

Answer / arup kr borah

Heavy machinaries requires greater torque....diesel engine
having greater compression ratio gives more torque..

Answer / jegan

petrole is used for sudden pickup purpose and smoothness
not in heavy machinery lifting,so diesal only used for
lifting heavy machinary,

Answer / mohankumar

The higher compression ratio is helpful in raising fuel
efficiency. Diesel engines are much more efficient than
petrol engines when at low power and at engine idle. Diesel
engines, unlike the petrol engine, lack a butterfly valve
(throttle) in the inlet system, which closes at idle. This
creates parasitic loss and destruction of availability of
the incoming air, reducing the efficiency of
petrol/gasoline engines at idle. This mechanism makes the
diesel engine an attractive choice for many. Diesel engines
are left idle for many hours or sometimes days in many
applications, such as marine, agriculture, and railways.
The engines are more efficient when compared to petrol
engines of the same power. They consume significantly lower
fuel and offer better mileage.

Answer / aditya tripathi

same compression ratio petrol engine give higher efficincy
compare to diesel engine but if we increse the compression
ratio detonation start in petrol engine hence efficiency
reduces causes we use diesel engine in place of petrol
engine....also cost is high and petrol is not available at
large amount.....

Answer / dinesh

yes,

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