Friday, October 23, 2009

No Tailpipe Flames

So unfortunately, after doing a ton of research, we will not be having tailpipe flames on Wendy for reasons of safety (we live dangerously, not stupidly).

So the traditional method of having flames shoot out your tailpipe is to dump extra fuel into the exhaust and then use a spark plug about 6" from the end of your exhaust that will light the unburned fuel when you push a button or something similar. Two problems with this, we have a catalytic converter and a fuel injection system. The whole point of a catalytic converter is to burn unused fuel, so we would have to rip that out. The O2 sensor on the fuel injector would have to go as well, as it keeps your engine from dumping extra fuel without hacking the ECU.

So this leaves the alternative of pumping propane into the exhaust line after the cat converter. The problem with this is that the flame can chase back up into the propane tank and blow up unpredictably. Now don't get me wrong, we are all about explosions, but we prefer it when we can control them. So if anyone knows a lot about propane routing, let us know!


  1. Don't you need oxygen to blow up a tank? It seems to me that as long as you are flowing, you should be fine. Those tanks self-pressurize, so as long as you are not flowing too fast and you have fuel, you should probably be fine.

  2. All you need is a flame trap on the propane line like they use on oxy-fuel welding rigs.

  3. Propane is liquid in the tank, plus there is a one-way check valve you should install, if it were to blow up then every gas propane grill n America would blow up.
    Diesel engines use propane injection the same way gas engines use NOS. Fumes mixed with oxygen cause explosions, same as gasoline, the liquid does not burn the fumes burn. Thats why it must atomized to burn.

  4. I agree with the last post - use a check valve. Additionally, downstream of the check valve and solenoid valve (I'm assuming that is how you are controlling on/off), put in a sonic venturi sized for the mass flow rate your want.