Login    Register
User Information
Username:
Password:
We are a free and open
community, all are welcome.
Click here to Register
Sponsored
Who is online

In total there are 48 users online :: 4 registered, 0 hidden and 44 guests


Most users ever online was 218 on Wed Dec 07, 2016 6:58 pm

Registered users: Bing [Bot], Google [Bot], MSNbot Media, Yahoo [Bot] based on users active over the past 5 minutes

The Team
Administrators
Global Moderators
global_moderators.png CS

Fuel-Injection Method

Discuss miniature cannons built from things such as pill bottles and pen caps.
Sponsored 
  • Author
    Message

Fuel-Injection Method

Unread postAuthor: Spudinator » Wed Aug 22, 2007 6:21 pm

I recently discovered a great way to fuel minis, I think you guys will like it. You dont have to worry about getting a good fuel mixture, and if you do it right you dont even have to vent the chamber. It uses the Venturi system from a mini-torch, like the ones you find in gas stations (not a regular lighter, the ones that have a hot blue flame). The parts you'll need for it are the torch, a long-stem lighter (for the fuel canister and tubing), and a few small screwdrivers to disassemble the lighter.


First off, you need to seperate the venturi (just so you know, the end of the venturi is where the flame comes out) from the body and fuel canister of the lighter. Most mini-torches have a small phillips screw at the bottom, this usually will allow most of the lighter to come apart.

From there, seperate the butane canister from the venturi (usually connected by a small rubber hose), then unscrew the venturi from the torch body. If you did it right, you should have what is showing in the pic labeled "Venturi".

To use it in a gun, you'll need to drill a hole just a bit smaller than the threads in the chamber (Pill bottles will do great with these), then use a small wire stuck in the end of the venturi to guide it into that hole from the inside of the chamber. When you have it through, use a pair of pliers to twist the threads in from the outside. Connect the fuel hose to the small barb at the bottom of the venturi, and thats it.

Make sure the chamber isn't sealed when you inject fuel, the back pressure prevents the venturi from injecting the correct fuel:air ratio.



Any Questions? Comments?
  • 0

Attachments
100_1644.jpg
Fuel Canister with valve lever, Fuel Hose, and Venturi
VENTURI.JPG
Venturi Close-up

Heheh, gotta love 5 Megapixels
"This is so fun it should be illegal... Oh wait..."
User avatar
Spudinator
Donating Member
Donating Member
 
Posts: 70
Joined: Sun Feb 13, 2005 4:50 pm
Location: WA
Reputation: 0

Unread postAuthor: jackssmirkingrevenge » Wed Aug 22, 2007 10:18 pm

Since ratio is so critical on a smaller scale, how do you calculate the volume you're injecting?
  • 0

User avatar
jackssmirkingrevenge
Donating Member
Donating Member
 
Posts: 24225
Joined: Thu Mar 15, 2007 11:28 pm
Country: Holy See (Vatican City State) (va)
Reputation: 66

Unread postAuthor: f.c » Thu Aug 23, 2007 3:14 am

i think it would work. though id be more likely to just use my propane torch. and yes i have made a propane powered mini :twisted:
  • 0

User avatar
f.c
Captain
Captain
 
Posts: 340
Joined: Sun Jul 08, 2007 2:40 am
Reputation: 0

Unread postAuthor: jimmy101 » Thu Aug 23, 2007 11:48 am

Jacksmirk..., I believe what Spudinator is going for is to not have to calculate anything at all.

The venturi supplies an air + fuel mixture in the correct ratio. To use, you need to flush the chamber several times with the gas mix this produces. Or, install it on one end of the chamber, open the other, and just flush fuel mix through for a while. Not exactly fuel efficient but in a mini it really wouldn't matter much.

Like f.c. said, the same thin has been done with a standard Benzomatic torch head. A torch head, and this "venturi" are both the same thing as a Bunsen Burner, which should also work.

I've always wondered if the gas flow through the nozzle is dependent on the thing actually being lit. Does a Benzomatic torch suck as much air in through it's vents when the flame is not lit as it does when it is lit?
  • 0

Image

jimmy101
Lieutenant General
Lieutenant General
 
Posts: 3129
Joined: Wed Mar 28, 2007 9:48 am
Location: Greenwood, Indiana
Country: United States (us)
Reputation: 7

Unread postAuthor: jackssmirkingrevenge » Thu Aug 23, 2007 12:10 pm

*blink*

I completely missed the "venturi" bit.

I need to get away from this PC :?
  • 0

User avatar
jackssmirkingrevenge
Donating Member
Donating Member
 
Posts: 24225
Joined: Thu Mar 15, 2007 11:28 pm
Country: Holy See (Vatican City State) (va)
Reputation: 66

Unread postAuthor: Spudinator » Thu Aug 23, 2007 10:26 pm

Jimmy~ You are correct, once you fire you can either blow into the chamber to vent it then inject fuel, or simply inject fuel after firing, but you have to run the venturi for a bit longer.

The entire reason I posted this was so you don't have to use a propane torch, they are way to bulky and incovenient to use in a mini (although I do swear by them with large combustions). With the venturi system, you can have the fuel cansister and everything onboard the gun, which would make it much more convenient to use, you simply have to push that little lever on the butane canister (or, like I am doing, rig up a system that loads a BB, vents the chamber, and fuels it all at the same time) to fuel your mini.

I can probably get several hundred shots out of one of those butane canisters (and they are refillable too, you unscrew the adjustment lever out a ways so it flows fast, then stick the butane refill canister over the brass barb and push it up with the lever), so I dont think efficiency is a big issue here either.

You guys should try it out, it really is a great fueling system. I'd like to see how other people like it...
  • 0

"This is so fun it should be illegal... Oh wait..."
User avatar
Spudinator
Donating Member
Donating Member
 
Posts: 70
Joined: Sun Feb 13, 2005 4:50 pm
Location: WA
Reputation: 0

Unread postAuthor: jimmy101 » Fri Aug 24, 2007 11:00 am

Spudinator: How many chamber volumes do you think you need to flush through to get a reasonably complete fueling?

Best case scenario would say one chamber volume would only give you 50% fueling. Two chamber volumes 75%...

Ten chamber volumes would certainly give you ~100% but that is a heck of a lot of waste.
  • 0

Image

jimmy101
Lieutenant General
Lieutenant General
 
Posts: 3129
Joined: Wed Mar 28, 2007 9:48 am
Location: Greenwood, Indiana
Country: United States (us)
Reputation: 7

Sponsored

Sponsor
 


Unread postAuthor: Hubb » Fri Aug 24, 2007 11:35 am

I just built and posted a mini that operates with butane. It hasn't misfired but I have gotten inconsistent shots with it. This seems like a good idea for me to use, since it will ratio the fuel properly (luckily I saved this little piece when I disassembled the lighter).

Thanks for this info.
  • 0

User avatar
Hubb
Major General
Major General
 
Posts: 2390
Joined: Mon May 28, 2007 8:39 am
Location: South Georgia
Reputation: 2

Unread postAuthor: Spudinator » Fri Aug 24, 2007 10:50 pm

Jimmy~ Really, all you have to do is give it a couple seconds to run, as long as there is a vent port (the barrel will do as long as its a decent diam, think 3/8+) to eliminate backpressure. If you set the venturi up so that the gases flow around the chamber a bit, say like the port of a vortex BB gun, it fills the chamber rather thoroughly. The gun I have been using this on has a somewhat small chamber, 1.5" x 2", so it may take a tad longer for larger chambers, but not by much. I think you'd be surprised by how much gas comes out of it, especially if you turn the flow rate up on the butane canister.


Hubb017~ In the beginning I also got inconsistent shots, I fixed the problem by increasing the vent size and giving it a bit of a longer fueling, try that and see if it fixes the problem.
  • 0

"This is so fun it should be illegal... Oh wait..."
User avatar
Spudinator
Donating Member
Donating Member
 
Posts: 70
Joined: Sun Feb 13, 2005 4:50 pm
Location: WA
Reputation: 0

Unread postAuthor: SpudBlaster15 » Sat Aug 25, 2007 1:22 am

This thread reminds me of everyone's favorite forum member, Affliction. :lol:
  • 0

People should not be afraid of their governments. Governments should be afraid of their people.
User avatar
SpudBlaster15
Major General
Major General
 
Posts: 2385
Joined: Wed Oct 18, 2006 11:12 pm
Location: Canada
Country: Poland (pl)
Reputation: 3

Unread postAuthor: Spudinator » Sat Aug 25, 2007 8:43 pm

Uhh, how are you correlating my post with Mr Douche? I posted this for mini spudguns (I'm pretty sure you arent going to find ball valves, regulators, and fittings to make a metered propane system for a mini heh), and I'm not an asshole like Affliction. I'm not sure if many know this, but I was one of the mods on Spudtech for some time, so I HATE assholes/douchebags/Afflictions...



Anybody else tried the system?
  • 0

"This is so fun it should be illegal... Oh wait..."
User avatar
Spudinator
Donating Member
Donating Member
 
Posts: 70
Joined: Sun Feb 13, 2005 4:50 pm
Location: WA
Reputation: 0

Unread postAuthor: frankrede » Sun Aug 26, 2007 12:00 am

Spudinator wrote:Uhh, how are you correlating my post with Mr Douche? I posted this for mini spudguns (I'm pretty sure you arent going to find ball valves, regulators, and fittings to make a metered propane system for a mini heh), and I'm not an asshole like Affliction. I'm not sure if many know this, but I was one of the mods on Spudtech for some time, so I HATE assholes/douchebags/Afflictions...



Anybody else tried the system?

I haven't tried it, but its something I plan to try soon.


And don't worry, you are in no way like affliction.
Affliction said his system was better and denounced all other systems.
  • 0

Current project: Afghanistan deployment
User avatar
frankrede
Lieutenant General
Lieutenant General
 
Posts: 3220
Joined: Thu Jul 20, 2006 9:47 pm
Reputation: 0

Return to Miniature Cannon Discussion

Who is online

Registered users: Bing [Bot], Google [Bot], MSNbot Media, Yahoo [Bot]

Reputation System ©'