Preliminary questions about engine conversion

[Bishop]

I have been considering converting my car to a hydrogen system, not not some hokey ebay bullshit. but the problem is, they do not recommend using the system on an engine with a higher then 9.5 to 1 compression ratio. I have a 2007 Yaris, its all stock. So the engine has a 10.5 to 1 compression ratio. The issue is because hydrogen burns much faster then gas, which can cause predetonation at higher compression ratios. I am hoping that because the engine is aluminum instead of cast iron it may not have the issue as much? If not, any ideas as to what would be a good engine to swap it with that has a 9.5 to 1 ratio (or lower)?

[fnkngrv]

wow...sounds like a hell of a project. I have no useful information for you, but I wanted to truly wish you best of luck...very cool.

[why?]

swapping the engine sounds like it would cost a ton. You could also look at getting lower compression internals. Rods and pistons I believe.

[markitect]

You might be able to get a head spacer made to drop it enough, but I haven't seen anyone with one on a yaris, some of the boosted people might use one.

[Astroman]

Yeah the boosted guys would know more. Sounds like a neat project!

[cali yaris]

Swap CP 9.5:1 pistons into it.

you won't need aftermarket rods unless you're going to make MORE than stock power.