The biggest engines in the world
To top 100,000 horsepower
These are the Värtsilä–Sulzer RTA96-C and a new improved version of it called the Wärtsilä RT-flex96C.
Wärtsilä-Sulzer RTA96-C - Wikipedia
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The RTA96-C was reportedly first installed in the Emma Mærsk, then the largest container ship ever built, owned by the Danish shipping and logistics company A.P. Moller–Maersk A/S.
It is apparently a turbocharged two-stroke straight-14 with a bore of 96cm and a stroke of 250cm.
The total displacement may be calculated
14 × 0.962 × π/4 × 2.5 = 25.33m3
Like most two-stroke engines it does run on a mix: in this case heavy crude fuel oil with added engine cylinder lubricant. The massive crankshaft scarcely tops 100 rpm.