We are all aware that propane is a safe and convenient fuel for heating homes, drying clothes, and cooking steaks on the grill, but did you know that propane can also be used to safely add power, torque, and range to your Cummins-powered Dodge truck? That's right, diesel engines actually respond very well to propane injection as a power adder and the Cummins is no exception. The Cummins engine is powerful in stock form, but who can leave anything stock?
With so much aftermarket power-adding equipment available, we just couldn't leave well enough alone. It started with wanting to add just enough power to our '01 dualie so the transmission wouldn't downshift when towing our car trailer up inclines, but like most gearheads once we started exploring how much power these engines can make, we couldn't stop. After adding an Edge computer, wastegate controller, and free-flowing exhaust, and burning up our torque converter, requiring it to be replaced with a beefier unit, we still wanted more. Our research led us to MSD ignition's web site where we learned about their Digital Propane Injection.
Propane has been used as an automotive fuel for quite some time in gasoline engines and though slightly less efficient than gasoline is an extremely clean burning fuel. A diesel engine operates somewhat differently than a gasoline engine taking in the maximum amount of air possible during each intake stroke. Engine speed is then determined by varying the amount of diesel fuel injected into the cylinders. The result is that there is nearly always extra oxygen in the cylinders that has not been used up in the combustion process. When propane is injected into the cylinders through the intake system it bonds with the additional oxygen and combusts with the rest of the fuel resulting in substantial gains in power and torque. The same power can be attained by adding more diesel fuel, which is the premise used by computer programmers or "chips," but the extra amount of diesel necessary to make the same power as propane is usually not feasible without making costly fuel system modifications. Diesel fuel also burns at a slightly higher temperature than propane, so exhaust temperature can limit the amount of power that can be attained through increasing the amount of diesel fuel injected into the engine. An additional benefit of using propane to increase power is that propane is a clean burning fuel, not adding the soot or emissions that diesel fuel does. Considering our power adding options, we decided to try MSD's new system and find out for ourselves how it worked.