What affects the "volume" of a diesel?

[ghunt]

And by volume I mean how loud the "clattering" is while it runs.

I ask because, well, Powerstrokes are loud, which I have been told is because of the HEUI injection system.

However, 12V cummins are also pretty loud...we have a Ford F800 here at work that has a 12V in it, and you have to almost yell to have a conversation when you're standing next to it and it's running.

My truck isn't nearly as loud as most Cummins or PSD's that I hear...

[Pocket]

The injectors, the fuel system, the injection timing, and more all play a role.

Take 7.3L Powerstrokes for example. The OBS 7.3L PSD's, 94-97 (except 97 Cali models) are louder at idle than the 99-03. The reason is that the 94-97's are single shot injectors, and the 99-03 and 97 California trucks are split shot injectors. The split shots mean there is a smaller pilot injection before the main injection. This helps to quiet the sound of the 7.3L.

That's just one example. There are many more over countless engine configurations. Your truck is an IDI (Indirect Injection), where the Powerstrokes are DI (Direct Injection). That also changes the idle tone and how loud the engine is.

[strokin_it7.3]

Also take into consideration the 16:1 to 20:1 compression ratio. Taking air under boost, compressing it that many times smaller than it's original volume, injecting fuel into that, it's gotta make some serious noise.