curious question

[jon_89]

does the diameter of the combustion chamber matter? does a one inch chamber have a different effect than a two inch chamber.

[frankrede]

obviously.
ha.
Yes it makes a big difference.
Essentially, bugger is better.

[jon_89]

i now bigger is always better but i mean if they are the same volume.

[Lentamentalisk]

what matters more, is how instantaneously the gas is lit, though that is not very much.

i do however suspect that having an incredibly skinny chamber wouldn't be too good.

[spudgunnerwryyyyy]

It has to do with the speed of the flame front. Combustion occurs more rapidly in a short fat chamber than in a long skinny chamber. The ideal shape is a sphere but that would be way too expensive.

[CannonCreator]

you need to have a good Cahmber to barrel ratio. Haveing a huge chamber and small barrel is wasting power. And if you have a extremely long barrel and small chamber, thats just bad. Get a C:B calcualtor off of http://www.BurntLatke.com

[MrCrowley]

i now bigger is always better but i mean if they are the same volume.

I do remember I think it was BoilingLeadBath saying that the diameter does matter even if it is the same volume, I can't remember if he said bigger diameter is better or smaller, but I'm pretty sure the bigger diameter is better so the combustion is as close to spherical as possible.

Anyone feel free to correct me, this is just my memory saying this

[mark.f]

spudgunnerwry.... and MrCrowley brought up the key point.

A flame front travels faster in spherical mode. If the ignition is in the center of the chamber, and the chamber is as close to the same diameter as the length, while keeping the right volume, then the flame front travels more in spherical mode, and progresses faster before transitioning to laminar mode.

Jimmy101 made a great series of articles on things like this that can be found on the Spudtech archives. I have to admit I c/p'ed each to word and printed them out, (Don't worry Jimmy, it's because it's good information, not any *other* reasons), after he made them each.

[Redcoat]

bugger is better.

One could take that in a different context, frank. .

Anyway, yes bigger is better but to a degree you don't see many people with Chambers the size of a Truck.

[jackssmirkingrevenge]

One could take that in a different context, frank.

It depends on which side of the Atlantic you're on, "buggery" doesn't mean much in America... on the other hand, sucking on a fag isn't a big deal in the UK, but doing it in the US is something entirely different

Anyway, yes bigger is better but to a degree you don't see many people with Chambers the size of a Truck.

The topic isn't bigger or smaller chamber volumes here, but how that volume is distributed. A 1/2 inch diameter chamber 50 inches long has the same volume as a 5 inch diameter chamber 2 inches long, but the latter will give you more power.

[jon_89]

thanks for the answers. any ideas for a sphere chamber?

[jackssmirkingrevenge]

any ideas for a sphere chamber?

have a look here.

[jimmy101]

You really don't need a spherical chamber. Just use a chamber that has length approximately equal to the diameter. Much easier than a spherical chamber.

With a cylinder of length=diameter the percent of fuel burned in the spherical mode is;
(4/3)PiR³
----------- = (4/3)/2 = 67%
2PiR³

For a more typical chamber shape, say 3"ID by 12"L, about 34% of the fuel is burned in the spherical mode.

A chamber fan running during combustion probably does more to speed things up than does a spherical chamber.