To be perfectly honest, a well-tuned turbo or supercharged engine really shouldn't suffer any catastrophic failure until you're pushing the limits way harder than can be used on the street. My supercharged Saleen has been a custom project for years, and is currently running at 15psi. The block should hold up to 30psi. Beyond that, you're really stressing the materials, and if you build the materials strong enough, you'll introduce all new problems. The key is a proper tune. Run too close to stoichiometric ratio, and you're toast. Spark too early, and you're toast. There's a pattern to be seen there.. The moral of my story is that the engine materials can really handle a lot of abuse, and don't really need to be changed. Especially not for t sakehe of not having to accurately control combustion, because no matter how strong you make it, it'll never be strong enough to withstand detonation with any frequency.
I haven't spent a ton of time researching hydrogen-only engines, but have looked quite a bit into hydrogen supplementation on a gasoline engine. When you switch over to hydrogen only, timing becomes your largest issue. With gasoline, you can normally ignite within 20 degrees of TDC, but with hydrogen, you need to push that spark way later. The number 70 is floating in my head, but don't quote that. To my understanding, the problem is that the expansion rate of hydrogen/oxygen combustion is much higher than that of gas/oxygen. It was explained to me as saying that the gas/air mix gives more of a soft/gradual push compared to the hydrogen, which would be more like smacking the piston with a hammer. I'm sure that's an overexaggeration, but it got the point across to me.. Whether it was right or not though, I can't tell. :) Like I said, the common solution I've seen so far hasn't been to try to contain the intense expansion, but delay it so that the cylinder volume is larger and the expansion is less critical. The average pressure in each cylinder really isn't going to change much no matter what fuel you burn. You can run an ICE on air pressure, if you want to.
The trick is figuring out how long to wait before igniting the mixture so that the pressure created meets the demands of the power desired. You could go higher and have a much stronger motor, but you end up hitting the limits of materials available. If you make it so strong it can handle high pressure, the rotating mass will limit power, and that much mass won't shed heat fast enough no matter how good your cooling system. It's a problem that compounds itself, and you'll chase it forever.
I would really like to see someone experiment with a hydrogen powered rotary engine. Getting the seals to hold up would be tricky, but you don't have reversal like an ICE has, and the design of the engine is much more hydrogen friendly.
I really think you'd have your work cut out for you, trying to harness maximum efficiency in a hydrogen-only engine. There are videos of guys running 2 cycle engines on HHO after modifying the magneto to spark much, much later than gasoline requires. If there are people out there doing it already, do you have links to any of it? I'd really like to see how far people are coming with it.
