chamber radius caomparisons?

[Hashbrowwns 4flip]

Hi guys I am a noob and I did try and find answers before I asked this but since I was un successful has anyone done or notice any difference between short fat chambers and longer thin ones in a combustion gun? I am designing my first propane injected and have some 3inch and know I am using a 1 .5 inch barrel but if a fatter chamber packs more punch I will rethink what I am doing.

[mattyzip77]

3 inch chamber about 18 inches long is plenty big enough for what you want to do. Make the barrel 3 to 4 feet of 1 1/2 inch.

[Hashbrowwns 4flip]

I ordered a 4ft 10inch rifled clear PVC barrel so it will look cool on night ops so my math figures roughly a 22 inch chamber but, if I go with the barrel over chamber design I think I need to in clude the turn as part of the chamber which I haven't done the math on.

[Fnord]

Unless your chamber is unusually long and skinny/short and fat, you won't notice the difference, especially if you add a chamber fan. If in doubt, use additional spark gaps. 3" pipe is fine; make the barrel about the same total volume as the chamber.

The turn/u-bend won't make a huge difference. When I figure precise numbers, I usually only include half the bend volume, since fuel doesn't mix well within them.