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How to Inject Propane Into Exhaust

by Andrea Walk

Exhaust flame kits were popular in the 1950s, and then began to regain popularity following the 2000 motion picture "Gone in 60 Seconds." The older flame kits were installed on vehicles that used carburetors, as opposed to fuel injectors. These kits used a spark plug and toggle switch that ignited the fuel emissions from the exhaust. The bulk of these flame kits were used before the Environmental Protection Agency made it mandatory to install catalytic converters. Some kits today use propane to help boost the flame after the catalytic converter.


Connect the regulator and the hose to the propane tank. Drill a hole either in the floor board or fender well in the trunk.


Run the propane tank hose through the hole and then drill another hole about 4 inches behind the catalytic converter. Attach the brass fitting with the nut and bolt and attach the propane tank hose to the exhaust pipe.


Mount a toggle switch on the passenger side dash. Run the negative wire to a ground and connect it. Run the positive toggle switch wire to the positive battery terminal and connect it with an adjustable wrench. Connect an old coil to the spare toggle switch terminal.


Drill a second hole in the exhaust pipe about 5 inches from the end. Insert the spark plug with the gap end facing inward into the hole. Thread it into place. Attach the other end of the coil to the exhaust pipe with a crew right next to the plug.


Connect one end of a spark plug wire to the coil and the other end to the spark plug.


Start the vehicle and flip the toggle switch on. Open the propane tank valve to shoot the flame from the exhaust.


  • The addition of flame thrower kits might be illegal in your state. Check with the state department of motor vehicles before installation to make sure it is legal.

Items you will need

About the Author

Andrea Walk began writing in 2001, authoring user guides for technical software. She holds a Bachelor of Arts in political science from Loyola University, where she was a member of the Dean's Grade Review Committee for English. Walk is a member of the Automotive X-Prize team Global-E.

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