At what pressure will regular gasoline spontaneously explode/ignite? Would it be safe to pressurize it to 100 PSI in a tank or would I blow up my house?
Vapor alone - not mixed with oxidizer - is not a problem.
Fuels can spontaneously ignite with enough pressure if oxygen is present: temperatures can get quite hot inside a vessel if pressure is high enough! That's how diesel engines and fire pistons work.
OK, now that idea is horrible.
Don't do it. You're asking for something to go wrong. In fact, that is combining a number of dangers in one.
What I was building is a pulse furnace where a large amount of fuel is injected in an extremely short time into a small superheated space along with air to melt sand into glass and melt other normally non meltable things like rocks and crystals.