was just kinda contemplating the hydrogen rotary and compairing a few things to the normal rotary:

1) does it still require oil/burn oil? and wouldnt this make it a little less environmentally friendly than just water and heat as exhaust?

2) would we be running cat-less? dunno how loud it runs compaired to with gasoline... guessing it wouldnt be too different but I honestly dont know

3) same question kinda, but on the muffler... would it have to be re-designed to accommodate water or could it just fill up and over flow when it needs?

just a few random questions seeing as mazda just made the claims about hydrogen-fueled rotary cars in the future... feel free to answer or ask more questions, figured it'd be an interesting topic of discussion

1) Yes it does still need oil injection.
2) Technically you need a cat to pass emissions standards, even if it is capable of passing without one.
3)Good question.

I'd assume, or at least hope, that with the advancement of alternative fuels that they would change regulations on stuff like the cat... how much would the oil used increase emissions? I'd assume it's not too much, especially since hydrogen would basically get rid of most, I think. Would a cat be a bit restrictive for exhaust flow if it was liquid? I dont exactly know how fast the exhaust flow would be for the engine, so not sure if that would be an issue.

The exhaust isn't any more liquid than it is now- water is a byproduct of gasoline combustion too. Once the engine heats up the exhaust is hot enough that it comes out as steam and doesn't condense inside the muffler. Hydrogen is not any differant.

The cat is used to clean up and nitrogen-oxygen byproducts, and those are still there with hydrogen too. Most of what the engine inhales is nitrogen and there's no way around that. You just have no significant CO or CO2. Its a lot like burning propane but without the carbon.

yeah, thought about the fact it'd be hot shortly after posting... makes sense.

Fortunately laws regarding catalytic converters are changing. They need to with the hybrids and other technologies coming out.