Simply put, how do I get a small but eye-catching flame to peek out of my car’s tailpipe. I dont want anything that will catch the road on fire. Just something like the bounty hunter in Raising Arizona. Is it even legal? Or is my simple-minded dream one step away?(if it matters: I have a V-8 grand cherokee). Thanks for your help, peter
IIRC, the devices that you see in the older moves (Grease) actually put a small shot of gas into the tailpipe, along with a spark plug or some other source of ignition. I’m guessing they have since been outlawed in most areas. If you search on google for “exhaust flame thrower”, you’ll find a bunch of sites that tell you how. These sites seem to indicate you don’t need fuel at all though. You’ll have to check with your local officials to find out if this is legal though.
The easiest way…
1)Take two spark plugs (one from each head) and hammer the gap closed. (make sure they are not succesive firing order)
2)Replace plugs - do not replace spark plug wire.
2.5)If you have lots of time, you can experiment and close the gap enough to give you a fair amount of pre-ignition. This will give you a bit more power than if the plugs are completely closed and may allow the engine to actually run.
3)drill hole in each exhaust pipe ~ 8 inches from end.
4)screw good, firing spark plugs into holes.
5)Run spark plug wires from distributor to spark plugs in exhaust pipes.
5.5)It is a wonderful idea to interrupt this very long wire with a push button switch, preferrably mounted on the dash.
when the engine runs (very rough) the unburned fuel makes its way into the exhaust system where it can be burned when it hits the good spark plugs.
big caveat…
This works best in large block engines (350, 351, you get the idea). Nothing personal, but your little grand cherokee probably doesn’t have the displacement necessary to overcome two cylinders misfiring. What do you have, a 302 or something?
Your gas mileage will suck even worse than it does now.
Your power output will suck even worse than it does now.
The cool effect is so not worth the problems.
If you want a more technologically sound solution, keep all plugs in working order and add two working plugs to the exhaust pipes as stated above. Now, however, you have to set up a double switch that, when activated, will bypass the spark to the two selected cylinders and shunt it to the plugs in the back. A bit tougher to do, but you won’t lose as much power or gas mileage.
It’s still not worth it, though.
whatever it takes.
very interesting, a huge buzz-kill, but interesting. thanks
The flames generally result from igniting the emissions of people with methane-producing bacteria in the colon.
Oh, sorry! I thought I was still in the intestinal gas question thread. Never mind.
QtM
Spritle, out of curiosity, why do you need to hammer the gap closed on the spark plugs in the dead cylinders? If they’re disconnected from the ignition wires, they’re not going to fire anyway.
Good point. If you disconnect the wires, you don’t need to hammer the gap closed. In my listing, I guess I hit on a means to keep the plug from firing (closing gap) then did so again with the wire removal. A big point is that you don’t want to leave the cylinder open (remove the plug completely.)
FWIW those are both standard engine sizes, for Chevy small block and Ford respectively, not just a guess.
This can’t be legal. Imagine what’s going to happen to that car in back of you waiting at a stop sign & you forget to turn those flames off. lol
To get a flame you need something to burn. There is some resdual unburned fuel in the exhaust under some operating conditions. However, it will not burn because all of the oxygen has been used up. If it hadn’t been the fuel would already have burned.
The catalytic converter is specifically designed to reduce the amount of unburned fuel in the exhaust. Here is a cite: http://www.howstuffworks.com/catalytic-converter1.htm
To get a flame you might need to introduce a little fuel and some air into the tail pipe. This is probably not a good idea.
Well, some of us got it! Good movie!
If you have a car with a manual choke and no catalytic, weld bungs into the tailpipes that will allow you to stick sparkplugs into the exhaust flow (you can probably make the bungs out of “spark plug anti-foulers”, or whatever you want to call those extensions that plug into your head to move the spark plug away from the cylinder.) Insert the spark plugs, and wire them up to use a siamesed coil (like off of a Harley or a performance coil for a Japanese sport bike.) Insert a double throw switch into the ignition primary wire with the common going to the points. Run one switched line from the switch to the engine’s coil, and run the other to the coil you added.
When you want flames flip the switch, pull the choke and floor the gas. The fuel will go through the engine unburned and should be ignited by the spark plugs in the tailpipe.
You should get the sputtering flames you want. You will also get plenty of flames from people standing around when you do this and from the people standing on whatever grass you start burning. It’s not always considered the cool thing that people think it is. It is also illegal for street vehicles just about anywhere.
Thanks, Weeks. Glad to know I’m not a complete write-off. 
They make kits, I’ve seen them for sale at hot rod swap meets. Try searching Google for tailpipe flamethrowers. Here’s one kit (with a photo gallery), there are others. That would probably be the easiest way, rather than trying to hack something together on your own.
These kits generally require replacing the catalytic converter with a straight pipe. Needless to say, they are not legal on emission-controlled vehicles. Also, they don’t work so well on cars with modern, electronic fuel injection.