DIY Flamethrower wiring

jamnajar · Dec 4, 2012

Hi guys! I am looking to add flamethrowers to my brother's Ratrod. I am not interested in washing down the cylinder walls with fuel and am going to go with shooting fuel into the exhaust. I have a question about the following image. Specifically about the condensor/capacitor: most ignition condensors are one wire. Should it just be attached (via the one wire) to the 30, 85, and the balast resistor? The diagram implies two wires. I figured I would ask before I went all trial and error. I also attached a fuel setup that I am going to run, except I am going to run a separate fuel tank for the flamethrowers (so we can play with the fuel compound), so I am looking at running one electronic fuel pump and one fuel solenoid. Do you think that running a fuel solenoid is necessary in that application? Amy spark plug recommendations for this application? For reference I am looking to run .025 jets in the NOS fuel sprayers @ 5lbs of fuel pressure, and these are going in lake style headers about 8" from the end.

21willys · Dec 4, 2012

I've ran flame throwers the original way without hurting the engine for years. Just change the oil when it needs it. Plus a lot of compitions won't allow injected systems to compete.

sgtpontiac · Dec 5, 2012

I've never had flame throwers before so excuse my

lack of knowledge.....wouldn't a propane injection be a bit safer? I'm sure you've taken into consideration all the issues.....the igniter system would work regardless.....like I said, I'm no expert on these things so pardon my questions.....

sneakysnake · Dec 5, 2012

A one wire condenser has the wire as +pos and the case as -neg so the wire will need to go on 30 and insolate the case and hook it to 85.You will want to use a fuel solenoid to give precise and clean fuel cutoff.

jamnajar · Dec 6, 2012

sneakysnake said:
A one wire condenser has the wire as +pos and the case as -neg so the wire will need to go on 30 and insolate the case and hook it to 85.You will want to use a fuel solenoid to give precise and clean fuel cutoff.

Thank you sneakysnake, you have confirmed my recent assumptions about the condensor (after staring at diagrams vs the parts they use) I am planning on making a how to and posting it when i am finished so others in the future can build their own. I think that I will build a system with a solenoid and without to compare the shutoff of each.

sgtpontiac said:
I've never had flame throwers before so excuse my
lack of knowledge.....wouldn't a propane injection be a bit safer? I'm sure you've taken into consideration all the issues.....the igniter system would work regardless.....like I said, I'm no expert on these things so pardon my questions.....

IMO gasoline injection would be easier to work with, with propane you don't need an ignition source, but it burns very fast (very bright-yellow flame) with running gasoline in it's own tank we can play with the compound (like add diesel, or something to slow down the burn, or add chemicals to change the color of the flame!) Safety wise I think if you are running propane you need to have a flash arrestor so you dont blow the tank if you have a leak, but they can both be setup safely. Gasoline is just easier for me to work with.

Alot of people don't inject anything into the exhaust at all, they simply ignite fuel that is unburnt by revving the engine, shutting of the engine's coil and filling the exhaust with raw fuel, then igniting the fuel. Some people (like 21willies) have been running this method for years. I don't like the idea of the gasoline washing the cylinder walls with fuel (removing the layer of oil) and diluting the oil with gas. But people have been running that method for years and attest it doesn't hurt the engine.

I am looking to try something different.

440Clark · Dec 6, 2012

I am interested to see how this works out. I don't have a lot of experience with these systems, although I wired up one for a friend using the old-school method of cutting spark to the engine and redirecting it to the plugs in the tail pipe. It works freaking great. The thing I am curious about is; is there enough oxygen in the exhaust with your method to support combustion of the fuel? Old school way uses an air/fuel mixture-not just fuel. We need one of the old pro's around here to chime in on this.

sgtpontiac · Dec 6, 2012

I did know how the old school ones worked....

jamnajar said:
Thank you sneakysnake, you have confirmed my recent assumptions about the condensor (after staring at diagrams vs the parts they use) I am planning on making a how to and posting it when i am finished so others in the future can build their own. I think that I will build a system with a solenoid and without to compare the shutoff of each.

IMO gasoline injection would be easier to work with, with propane you don't need an ignition source, but it burns very fast (very bright-yellow flame) with running gasoline in it's own tank we can play with the compound (like add diesel, or something to slow down the burn, or add chemicals to change the color of the flame!) Safety wise I think if you are running propane you need to have a flash arrestor so you dont blow the tank if you have a leak, but they can both be setup safely. Gasoline is just easier for me to work with.

Alot of people don't inject anything into the exhaust at all, they simply ignite fuel that is unburnt by revving the engine, shutting of the engine's coil and filling the exhaust with raw fuel, then igniting the fuel. Some people (like 21willies) have been running this method for years. I don't like the idea of the gasoline washing the cylinder walls with fuel (removing the layer of oil) and diluting the oil with gas. But people have been running that method for years and attest it doesn't hurt the engine.

I am looking to try something different.

But it's only recently that people have been setting this stuff up to run on other "fuel"......thanks for the info...I'm interested in seeing the how to when your done....[P

21willys · Dec 6, 2012

Mearly a guess but I bet you build a bomb out of your exhaust. I hope not tho.

You can do most everything you mentioned about messing with the fuel when you do it the old school way. A little 2 cycle oil never hurt anything either.

If your wanting different flame colors it's easier to put things in the pipes instead of the fuel.

jamnajar · Dec 7, 2012

21willys said:
Mearly a guess but I bet you build a bomb out of your exhaust. I hope not tho.

You can do most everything you mentioned about messing with the fuel when you do it the old school way. A little 2 cycle oil never hurt anything either.

If your wanting different flame colors it's easier to put things in the pipes instead of the fuel.

The premise of a bomb is having something expand rapidly, then having that pressure contained for a bit to make it more powerful. I will certainly have gas ignited and very rapidly expanding but it will have an outlet (the open end of the lake header), so it "shouldn't" blow up. I have heard of people injecting fuel before the mufflers and blowing them off the car! That is a bomb!

I will definitely have to try putting things in the exhaust..(for sparkly and color change)

440Clark said:
The thing I am curious about is; is there enough oxygen in the exhaust with your method to support combustion of the fuel? Old school way uses an air/fuel mixture-not just fuel. We need one of the old pro's around here to chime in on this.

There is some oxygen left on your exhaust even after combustion but not much. I am looking to atomize the fuel, mix it with the hot exhaust gases and provide spark. The little bit of oxygen left over from the initial combustion should ignite the fuel. The oxygen will mostly come from the air as this heated mix of exhaust and fuel exits, hitting the air outside of the header. I'm hoping most of this combustion happens outside of the header but we will see, I will do some initial testing on my VW baja bug with the final product to appear on my brother's Rat. I picked up a somewhat high speed camera (GoPro3 120fps @720P) so we should at least get some great footage!

440Clark · Dec 8, 2012

I think you are going to have to install your plugs very close to the ends of the exhaust pipe as I do not think the remaining oxygen alone will be enough to support combustion. You may even consider small holes drilled into the tail pipe a couple feet before the exit to allow oxygen into the pipe.

Please proceed with caution.

21willys · Dec 8, 2012

Are you planning on doing this on just headers?

jamnajar · Dec 17, 2012

Initially we are going to install these on lake-style headers. I am going to build a prototype on my VW baja that has a merged header into a open pipe, so I can test the spark plug placement, fuel nozzle location and possibly adding holes to encourage combustion. Attached is a pic of the headers

21willys · Dec 17, 2012

Having had cars with flame throwers and being around them a lot I'm going to strongly suggest against putting flame throwers on just those headers. Way to close to the doors and the engine. It don't take much of any breeze to blow the flames over your ride.

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