Designs of diesel and gasoline engines differ significantly. The increased noise of a diesel engine is explained by the peculiarities of its structure, including the high degree of compression and the lack of classic spark plugs.
In addition, they have different fuel mixture preparation schemes. If a gasoline engine has gasoline and air mixed in advance and the mixture is injected into the combustion chambers in a finished form, the heavy fuel engine initially compresses the air, and the solarium is sprayed into the cylinder in the final compression phase, approximately 10-20 degrees of crankshaft rotation.
In the combustion chamber, it mixes with the air and an ignition occurs. In this case, the time allocated for mixing and blasting, about ten times less than in gasoline units, which makes the diesel engine runs harder.
High compression ratio
In gasoline engines, the compression ratio of the fuel-air mixture in the combustion chamber rarely exceeds 12:1. Whereas in diesel engines this parameter sometimes reaches 18:1. This means that the air is compressed much harder, and when the mixture ignites, a more powerful release of energy occurs.
When fuel is burned, it is possible to achieve high efficiency of the motor, and the shaft creates almost twice as much torque. It is not surprising that at the moment of ignition a part of energy goes into the hull, creating second order oscillations, which bring the motor out of the equilibrium state.
Modern diesel engines have outstanding characteristics. They are able to pull well even at low speeds, making them suitable for tractors and SUVs that need high engine traction at low speeds.
The stiffness of the diesel motor depends on the pressure build-up speed along the crankshaft angle. The higher this index is, the stronger is the shaking.
However, the diesel engine is less comfortable than gasoline. To compensate for this shortcoming, the manufacturers increase noise insulation, put engine supports with soft cushions and hydraulic expansion joints, as well as introduce counterweights that compensate for second order vibrations.
Meanwhile, they do not always help. Rigid, non-metallic crackling, which gives a bell in the exhaust system, is able to suppress, but the vibrations penetrate the body, cause irritation and not everyone is evaluated positively.
The cause of unpleasant vibrations can also be technical failures of the power unit.Noise of the diesel engine is influenced:
malfunction of injectors and fuel pump of high pressure;
contaminated engine oil and filter;
incorrect operation of the oil pump;
valve wear and increased valve clearance;
early fuel injection, resulting in premature detonation;
camshaft knocking due to bearing wear;
crankshaft knocking due to bearing wear;
damage to engine support cushions.