Why are diesel engines louder than gasoline ones?



Why are diesel engines louder than gasoline ones?

In: Engineering

Good question. I really don’t know, for sure, but I have a couple theories. I’m sure a diesel mechanic will chime in.

1. Diesel has significantly more energy per unit volume than gasoline. Perhaps the explosive force is greater?

2. The clearances between reciprocating parts in Diesel engines are significantly greater than in gasoline engines (especially newer designs). Perhaps more “slap”

3. Gas engines can be tuned to advance or retard the ignition spark. Diesel engines can’t adjust their timing, since the fuel / air mixture ignites as soon as the pressure of the compression strike reaches critical value. This may be before top-dead center. This would result in the explosion trying to drive the piston back before the crank is in the proper position. I suppose the momentum of the crank keeps it running in the correct direction, but I’m sure there is some opposition to this force and it could create noise.

Diesel engines tend to have way higher pressures than gas engines. This makes them more efficient, as well as requires more weight. It also allows them to generate significantly more force and thus comparable power to gas engines at lower rpms. Higher pressures result in louder noise.