Your car will die!
No, not really.
Parts stores around here carry octane booster. You can add that, but mostly I'd just take it easy, don't run it hard. Higher octane means less detonation (so lower would mean more chance of detonation), but as long as you don't run it hard it will be just fine. Probably would be even if you did, as long as you don't have a lot of mods (UP,DP, engine management highly tuned for 93).