I hate to jock your flow as far as the liquid comment goes, but getting liquid is easy. You just need the right type of cylinder to do it is all. The liquid's in the bottom, so all you need to do is have a tank with a tube that runs to the bottom (I'd reccomend either a forklift tank, a tank off of a camper if it's got a liquid tap or a buffer tank if you can find one with a liquid tap) The buffer tank would probably be best for the track, the forklift tank or the camper tank would be best for daily drivability. The forklift and buffer tanks also come in alluminum so they're lighter as well. The tanks can be laid either horizontally or stood up vertically, so clearance isn't as much of a concern. The gas pressure pushes the liquid out without a pump or anything like that. Keep in mind that one volume of liquid in such a setup is equal to 272 times the volume of vapor, so you're getting a lot more fuel then you would otherwise. There are a few issues with LPG in my book though, a biggie being how to keep the pressure constant. Using liquid would alleviate some of these issues since the boiling of LPG is a cooling action, the pressure decreases as you draw off the vapor. Far as using it goes, I'd lean out the gasoline as much as possible replacing it with LPG vapor, or just run more boost with the liquid because the more liquid you dump in the higher the cooling action. Another thing to keep in mind is that LPG gives you LESS fuel per set energy volume, so for every gallon of gasoline you need about 1.35 gallons of propane liquid. There's special hosing required for liquid versus vapor, as well as special solenoids (find a place that does bulk trucks or an LPG plant to get the solenoids, hoses and that stuff for you) I've got a project I'm working on, I'm planning on a 3 stage system using a nitrous fogger nozzle (cheap easy to get jets) along with a homebrew electronic controller for it. What I'm thinking about right now is having it set up to displace about 50 hp worth of fuel, then it'll switch to a 100 hp nozzle then it'll open both of them.