Why do gas and diesel engines sound different? From my understanding they’re both internal combustion engines but they have different ways of igniting. Is the ignition process why it sounds different or is it a more mechanical reason? I.e. more moving parts or mufflers etc.
Im talking about normal stock gas and diesel engines. No whistlers, aftermarket cams or exhaust.
In: Other
While I’m no expert my assumption would be that it is down to three factors.
First and most obviously, diesel engines tend to run at a lower speed. That fact will lend them a less smooth sound as each combustion event can be heard more distinctly rather than blending into an overall drone.
Secondly, the combustion process. Diesel engines are CI. That means that you tend to get lots of fuel droplets within the combustion volume that will ignite nearly simultaneously, causing a pressure wave that will ignite the surrounding area. This would cause a swifter/more violent combustion event than the smooth outward progression you get from the spark plugs in an SI engine.
Thirdly. CI engines run at a higher compression ratio than SI engines so they will more actively expel exhaust from the cylinder. This is because the amount of volume left in the cylinder with the piston at TDC in relation to the volume in the cylinder with the piston at BDC on smaller.
As I said, I’m no expert but I think these are likely the main causes.
Latest Answers