You have to be very careful with adding propane to diesel because of the danger from detonation and DIY diesel-LPG systems are very risky. Commercial fuel-map based systems tightly control propane addition, which maximizes propane use and minimizes any danger. The price of LPG in the BBQ cylinder is ~$3.26/gal (~$5.02/DGE - Diesel Gallon Equivalent) so that is just about the most expensive way to buy propane. You can get bulk propane for about $1.55/gallon (~$2.39/DGE).

Diesel-CNG dual fuel makes more sense, especially if you're near a public CNG station. Often, CNG sells for ~$1.00/GGE (~$1.12/DGE). For example, the price of CNG in St Louis, MO is $0.96/GGE ($1.07/DGE) compared with $2.80 for diesel. Universal diesel-CNG kits typically substitute about 40% of your diesel consumption.

 

do any of yall know if this would work on a 86 6.9 international? and if so what kind of complications am i looking at and whats the good out of it?