Holy cats.
https://www.soundingsonline.com/feat...s-largest-ever
At first I assumed it must be a twelve cylinder evolution of a cam in block LSx, but nope! It’s a quad cam 7.6L, based on Mercury’s 4.6L DOHC V8. My initial thought there was Ford or maybe Volvo (didn’t they punch that V8 out to 4.6?), but other reading suggests it’s a bespoke design based on their V6. And it sounds like for packaging reasons it’s a hot vee.
https://www.powerboatandrib.com/2018...nd-v8-engines/