Butane Injection

Boom! The classic potato gun harnesses the combustion of flammable vapor. Show us your combustion spud gun and discuss fuels, ratios, safety, ignition systems, tools, and more.
flamerz14
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Mon Jul 02, 2007 3:45 am

I read a topic on injecting butane from a can using a syringe. I was wondering...:

1.How do I calculate the correct amount of fuel?
2.How can I directly link a butane refill can to a spudgun?

help appreciated.
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jackssmirkingrevenge
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Mon Jul 02, 2007 3:51 am

1) calculate the total volume of your chamber, multiply by 4 and divide by 100 and that's the amount you need to meter in.

2) butane refill cans come with a variety of adapters to suit various different lighters - one of them should be an easy push-fit in the nozzle of the syringe, simple as that.
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flamerz14
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Mon Jul 02, 2007 3:54 am

ok thanks for 1st answer.. for the second I meant to link the butane canister directly to the chamber..Like the AMC.
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boilingleadbath
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Tue Jul 03, 2007 12:54 pm

Eh, jack, that's a 4% mix.

Which is wrong for butane.

Rather, don't we want a 3.1% mix? (that'd be "multiply by 3.1, devide by 100" for flamerz)
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joannaardway
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Tue Jul 03, 2007 2:16 pm

It's a 3.22% mix IIRC.

The AMC'sfuelling mechanism is basically a simple metering system, but it uses a blowgun modified to have three ports. The modification is the hard part.

A much better choice, and far easier to construct, would be conventional propane metering using two ball valves instead.
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jackssmirkingrevenge
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Wed Jul 04, 2007 2:15 pm

you're bound to lose some using a syringe so 4% should do nicely :)
hectmarr wrote:You have to make many weapons, because this field is long and short life
flamerz14
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Fri Jul 06, 2007 7:17 am

wait. 4% or 3.1% ??
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Fnord
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Fri Jul 06, 2007 8:34 am

Around 3.2%
You probably won't notice much difference between 3-4%, so dont worry too much.
It might help to measure the volume of your chamber by filling it with water and measuring the water volume. Mini chambers tend to be oddly shaped and curved(pill bottles).
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