SpudFiles

It's a simple question. Will heating up the fuel/gas mixture produce a better explotion/shot/more presure?

Simply, no.

Theoretically it may add an extra few psi, but nothing worthwhile.

In a pneumatic, though, it is possible to achieve supersonic velocities if the gas is heated.

Heating the pipe will reduce it's strength. Besides this has been covered before either on here or on SpudTech.

I would suspect that heating the air in an atmopheric-pressure combustion gun would decrease preformance in most situations; it would significantly decrease the amount of air in the chamber, maybe 30-50% (hot air is less dense) and only slightly elevate the post-reation temperature (less than 8-12%), so the resulting pressure will probably be some 20-40% lower.

However, the rate of reaction will be increased too. The auto ignition temperature of propane is 435*C, so if you heat the air in the chamber to 350*C (the higher temperature gain; it resulted in a 50% air mass reduction), I'm geussing (no training/study/whatnot here) that the flame front will propogate about 4 times faster.
Take that number with a large crystal of halite (salt), but the concept - that it'll be faster - is correct. That's probably mostly a bad thing, though, as it makes DDT (the switch from burning to detonation) more likely.

Although not benificial for use in the chamber, it could help in a jet-ignition system.

I think i understand what your talking about, your answer really answered my question, thanks blb.