A few elementary calculations reveal how feasible this might be. A typical ICE produces a few hundred horsepower using 4-8 cylinders rotating at a few thousand RPM. 1 HP = 745 watts. Figure out how much energy is released per cylinder on each cycle, and compare that to the energy released in a typical fusion ignition. Also note the cycle time of an ICE rotating at a few thousand RPMs, and compare that to the cycle time of a current state-of-the-art fusion reactor. (Hint: the former is measured in milliseconds, the latter currently in months if not years.)
I'm a layman and so its possible I am missing some limiting factors but I do feel as though this rebuttal does not take into account the possible ranges of values that can be configured when tweaking things like scale and operating speed. For example the Wärtsilä-Sulzer RTA96-C operates at 15-102 RPM generating 100,000 HP (or 74.5 megawatts for your comparison) [0].
Nor does it take into account the difference between a prototype investigation being constantly modified for experimentation and analysis and a production system built to purpose.
Yes, I probably should have used numbers from a large diesel rather than an automobile engine. Wow, the Wärtsilä-Sulzer RTA96-C operates at speeds as low as 15 RPM! That is just mind-boggling. I found this video:
Still, I think you will find that even this doesn't help all that much. A cycle time measured in seconds rather than milliseconds is still orders of magnitude away from what can presently be achieved.
> the difference between a prototype investigation being constantly modified for experimentation and analysis and a production system built to purpose.
AFAICT, no one has ever built an ICE that is within even an order of magnitude of realistic operating parameters of a fusion ICE. It's a whole 'nuther level of engineering challenge beyond just getting the fusion itself to work. I'm not saying it's impossible, but I'll give you long odds against seeing it happen in any of our lifetimes.
