SpudFiles

which doesn't really even apply to spudguns anyway (since gasoline reacts very differently when compressed than propane or MAPP gas do)

propane motors exist too last time i checked

Commonly everybody say ddt will happen at 5x or 6x mix...
Well im shooting my cannon at 7.5 x.... did it burst nope !
My chamber is now regular plumbing pipe rated at 150psi

my message isnt take your gun to 30x

most people think 10x isnt safe
remember lucky took his sch 80 plastic gun up to 8X
the idea is 10X is NOT going to break steel

I'm baaaaaaaaaaaaack
pyro: the shockwave would only act on the walls of the cylinder and the cylinder itself won't burst because that would require enough force to blast open the engine block, which CAN NOT be generated because the detonation moves the piston and releases the excess gas at the end of the stroke.
not on a 4 stroke the piston pushes the exaust out the valve[/quote]

turbohacker wrote:Sorry, most engine blocks are cast steel or iron.

No, almost all modern engine blocks are made of aluminum due to it's significant weight advantage over steel. Who said anything about V8 engines, or automobiles in general?

Found this from a PPT on SI engines

Note that the pressure spikes for "pinging" is only perhaps 2x the normal peak pressure.

From:
Mechanical and Materials Engineering
McLaughlin Hall, Queen's University
http://me.queensu.ca%2Fcourses%2FMECH435%2Fnotes%2FCombustion_in_IC_Engines.ppt

A 30x hybrid mix, even without detonation would risk the rupture of the chamber. With detonation, you'd have a lethal failure.

But, please don't take the word of several highly knowledgable and intelligent people in this field...

If you are certain that a repeated 30x mix would not harm the steel, then please try it. But stand back 100 feet behind a 6 foot wall of earth with full body armour on. Oh, and mark your experiment with: "THIS IS NOT A SPUDGUN", to avoid bad rep for spudguns.

Firstly, get a set of calipers, and measure the OD and ID of your chamber. Then after you've managed to solve the difficulties you will have igniting that mix, stand well back, and try a few mixes.

I guarantee that your chamber will have either ruptured, exploded, or have expanded in diameter and length quite significantly.
None of these situations are a good thing.

If you can safely say (with proof - photos and video.) that after a dozen mixes or so at that strength, your chamber is intact, undamaged, and could be X-ray inspected to prove all of this, then I'm sure you could redeem that as an apology from everyone else here who is trying to advise against it.

But I think you'll end up with a pile of scrap metal.

pyro86 = banned, for editing moderator edits to his post, then for editing my edits.