Propane injection, when properly tuned, can produce as much as 80RWHP increase. It may increase fuel economy but any savings are offset by the cost of propane.
There are two basic types: Vapor (gas) phase systems and Liquid phase systems.
Liquid phase systems are most common. Liquid propane is taken from the tank to a vaporization chamber where it turns into propane gas the gas is metered into the intake air thru a jet or series of jets. In a multi (usually 3 or 4) jet system the amount of propane being delivered is controlled by opening and closing jets. The result is incremental (step stair) increases in propane as need increases. Single jet systems provide a constant flow of propane no matter what the need. Both of these systems produce periods of excess propane and other periods of insufficient propane.
Vapor phase systems draw propane gas from the storage tank. A constantly variable regulator delivers the propane in amounts proportional to the need at that moment.
As need increases the propane flow is ramped up as need decreases the flow ramped down, its like turning on a faucet you can adjust the amount of water to suit your requirement.
Vapor phase systems are safer because there is no way droplets of liquid can enter your intake air flow. Liquid phase systems can allow liquid propane droplets to enter the air flow should certain critical components fail. Liquid propane in your engine will ruin the engine and your day.
My system is the Powershot 2000 a vapor phase system. I use it when I tow my fifthwheel trailer in hilly terain. It helps a lot.
Last edited by Phydeaux88; 09-27-2007 at 02:54 PM.
I have also seen a post where one propane user said that he got reduced propane pricing on tank refills since he was using it as vehicle fuel. The price difference he quoted was pretty big, which would certainly justify the expenditure in the long haul if he is right about the discount. Otherwise, what I've heard is that propane is economically justifiable as long as the price for proane is equal to or less than the price of diesel (roughly).
Here's the other thing. You've got to have gauges to protect the engine. It can get awfully hot awfully fast if you're not aware of what's happening, and then you're faced with damaged parts that aren't cheap to replace.