Eli5: why do diesel engines tend to be turbocharged rather than supercharged or even N/A?
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Diesel engines work by filling the cylinder full of air, compressing it so its really hot, then injecting the desired amount of fuel which combusts and pushes the piston down.
In a diesel the cylinder is *always* filled with air and the amount of fuel inject varies unlike in a gasoline engine where a throttle plate restricts the amount of air in the cylinder. If you can ram more air into the cylinder then you can add more fuel and get more power
For gasoline engines a turbo generally requires lower compression ratios to avoid preignition and a stronger engine block to handle the increased pressures but diesels are starting with high compression ratios and injecting fuel last second so there really isn’t extra strengthening required so a turbo is just a free way to get more power out of a smaller volume
Superchargers are kinda bleh. They suck power from the engine *all the time* so anything meant to run at relatively low load ends up burning significantly more fuel with a supercharger. Their main benefit is low RPM boost pressure for gasoline engines since they’re not relying on large volumes of exhaust to spin them up, but again, a diesel is always filling its cylinders completely with air so it has a large exhaust volume even at low RPMs to spin up the turbo
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