Question

Select the best answer for the question. 7. Which one of the following statements about diesel engines is true? A. The temperature of the fuel in a diesel engine has an effect on the power output. B. Diesel engines deliver usable torque through a much wider rpm range than gasoline engines. C. Diesel engines run quieter than gasoline engines. D. Acceleration is faster with a diesel engine compared to a gasoline engine.

Answer 1

Power = Speed * torque

Torque is the abilty of a engine to pull a load. More the torque , it can pull more.

Why does petrol engine accelerate faster.

We know that ,Diesel engine's reciprocating parts are much heavier than petrol , this is because the engine is built robust as the compression ratio and peak pressures are high for diesel.

More mass = more inertia, so a diesel engine will need to spend more energy to reciprocate its piston.
Also petrol engines have mostly squared engine i.e. stroke = bore in dimension. So the stroke length is less and can rev at higher RPMs.

Another reason lies in nature of fuel

Petrol is well refined than a diesel , The flame speed of petrol is much faster than diesel. Since flame speed is high all of its energy is released in sudden.

But diesel burns steadier , it takes more time to release all energy.
Hence lesser reciprocating weight and faster combustion gives petrol engine its better acceleration , also its torque curve is almost linear. So as you increase speed , the torque is getting increased.

But in diesel engine , the torque curve is not linear , it has good low rpm torque , but the torque vanishes after crossing that rpm.

Why diesel engine gives out more Torque

Common reason is the compression ratio and pressure at end of compression being higher.
Another thing is that diesel fuel has higher Lower calorific value. Also the diesel fuel is more denser than petrol.
Another reason is that diesel burns steadily than petrol ( it burns faster within fraction of seconds)
So higher compression ratio ( more stroke length) , better fuel ( with higher LCV) and higher peak pressure and steady burning diesel gives more torque .

So final summary
1.Petrol engine accelerates faster due to its lesser reciprocating mass and faster energy release.
2. It produces more power as the torque curve is linear and ability to rotate at higher max speed combines to give more power.
3.Diesel engine produces more torque as the compression ratio is large ( so larger stroke ) and combined with more energy which is released steadily .

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I hope it will help