[bluGill]

The total amount you can get from changing the timing isn't very much. Even if you put in a whole new camshaft. Not to mention timing effects emissions as well.

The more typical way to do this is have a turbocharger (supercharger... I can never remember the difference and which you want when). You and run more boost which increases the compression ratio. However this requires an expensive turbo and so isn't a popular option.

I'm not sure why turbo cars have not made these modifications though. There are probably other trade offs I'm not aware of.

[jgust]

Exactly. More ICE cars are coming standard with turbochargers which would enable more to take advantage of the extra octane, but it's an optimization problem with constraints: fuel efficiency, reliability, drive-ability, emissions to name a few.