I'm throwing this in for my dad so don't fault me for not having a clue! Dad has an 86 350 crew with 6.9 and a banks turbo. He wants to know about adding propane injection if possible or is this a danger to the turbo? Any test regarding this set up would be greatly appreciated.
depends on how you do it and the system it self. No leaks(probably the most important of the things you maybe able to do wrong) and dot approved containers and injecting the propane in an appriote spot, having tank mounted correctly will determine how safe any propane system is.
The propane is injected as a vapor before the turbo. With mine, it is a lean air/propane mixture that is injected into the air intake, before the turbo. Boost pressure is picked up by teeing into an existing boost gauge, or by drilling and tapping into the manifold. It makes more power with a turbo diesel due to the increased air.
It is easier and much more driveable to control the flow of propane with boost pressure, as opposed to all or nothing, like other manufactured and homemade systems. The proper tank in the proper orientation is also very important.