Used to, before catalytic convertors, a spark plug welded in-line at the exhaust tip would be hooked to the coil and the excess fuel would be ignited (hope I'm not wrong on this). Nowadays, the catalytic convertors burn off the excess gas so a seperate source has to be used, like propane. see http://www.flamethrowers.com/
We have a local car club in Sothern Ohio called " Keepers of the Flame" Some really cool old Cogers.They all drive slammed 50's Mercs.etc. There is a car show once a year in Oxford Ohio (home of Miami Univ.) Thses guys all come and have a flame thrower contest.When they really get going,they have kind of a rythm they use.Kind of a thump...da da...thump.da da...thump.They start off slow and keep getting faster and faster.It really is something to see.From what I could tell they do something with their choke too,maybe using it to sort of flood their motor to pass thru unused gas.I've seen flames shoot out 20 feet from these cars.You got to remember these are the guys who did this stuff in the fifties,they don't use any new technology.You have to see it,very impressive (and illegal in Ohio ) The local cops look the other way during the show,but I bet they would bust them in a heart beat in they saw them using them as they were going down the road.
The name is BOND. James Bond. The flamethrower switch is right next to the ejection seat and oil slick switches.
My grandpa told me they used to use old Ford Model A coils to do it back in the 50's. You use a seperate coil, not the same one the car is running on. He said, you hook the second coil to the points just like the first one, and for the positive side, you run a wire to the battery then to a switch and then to the coil so that when you throw the switch it puts power to the coil. He said it was hard on the points. Don't know where you would find a Model A coil now days.
The down side is all the raw fuel washing the oil off the cylinder walls and causing the engine to wear out quicker, also dilutes the oil in the crankcase.
its funny....everyone talking about how safe it is...but honestly......why the heck do you want to crank the enigine to 4500-5000 rpms ??!?!?!??!?! this is certainly hurting the engine to just have a flame out the back... and most importantly.....if gas is in the muffler ( ie...turbo muffler) and a spark gets inside it the gas will want to "vent" and BOOOOM there goes your muffler... thats not very safe.....with shrapnel flying under your car ....take it from experiance watching a friend shrapnel his exhaust trying to make his truck backfire. which is the same thing......engine braking and turn off the exhaust.....pipes fill up with gas...turn the ignition back on...boom.... but it blew his muffler off.....LOL....classic good luck....
Freespinning a motor to 5000 and doing it under stress are two different things. I have seen many motors let go at 5500 rpm in neutral cause someone was showing off.. Not for me.. But maybe if I was driving Lonnies old truck!
THey are cool. Dual exaust throwing flames is well.... awesome. But check with local car clubs and cops. In floida it is illegal. Ten days in jail is not worth in in the long run.
Just put an electric pump to a EFI nozzle and a venturii adapter that sucks air into the pipe about 8 inches from the exit. Weld a tab to mount a spark plug to and wire to a vibrator circuit. Depending on the nozzle you can get flames 3 to 8 feet behind the car. As long as the pipes exit below the rear axle the draft keeps the flames away from the car.
I thought they had kits to inject gas near the spark plug to shoot flames out. Then you don't have to shut engine off an flood cylinders. Anyone seen these?