Our test mule is an F-350 powered with Ford's 6.0L Power Stroke. The hauler is equipped with a completely enclosed drop-in service toolbox that keeps our electrical contractor's tools and supplies organized. The utility body is heavy enough by itself, but if JD (electrical contractor) packed the bed with all the wire it could hold, it would easily surpass the max load of the one-ton dually axle.

Rants and raves fill bulletin boards with controversy over propane as an additive for diesel power plants. The addition of propane into the diesel combustion engine increases power by adding an additional oxidizing fuel to the chemical combustion process. The problem is propane has been known to escalate exhaust temperatures well over 1700 degrees F. So is propane an engine killer, or has its bad rap come from getting greedy for cheap and quick power?

We were anxious to get to the bottom of this controversial power modifier, so we asked Bully Dog to send out their basic bare bones kit to see what was involved with the installation and setup. Since the system is made as mileage enhancer, we chose a worse case scenario and installed the propane kit on a truck with the aerodynamic properties of a two 4x6 foot sheets of plywood. In addition, the utility truck of choice also maxed the rear differential's load rating.

Installation was a snap and the system was set to the minimum setting as instructed. The system only passes gas (pardon the expression) into the intake when the engine is under boost. A pressure switch installed into the intake regulates the on/off status of the propane. On initial setup, the pressure switch is jumped to force the propane solenoid to the open position. After checking to ensure the propane regulator was completely closed, the regulator was slowly turned up until enough propane started to trickle into the intake to disrupt the engine idle. We're not sure exactly what pressure the regulator is set at to produce this situation, but we did instantly notice a difference in the truck's exhaust smell. The propane kit did not come with a meter on either the injection pressure or a tank fill level, but a large noticeable increase in throttle response verified the system was operating. Even though this setup is designed to affect fuel mileage, it was obvious some of the savings was going to come in the form of additional power.

After monitoring the truck for a couple weeks, we found the mileage average fluctuated depending on city or highway traffic conditions and vehicle load. With all the variables, it's hard to say why our fuel mileage fluctuated, but we documented an average between 10 to 12 additional miles to each gallon of fuel. Because the truck was outfitted with a remote filler valve, it was obvious the propane was for highway use so we were able to purchase it for $1.38 a gallon as opposed to the barbeque refill price of $2.76. With the regulator set at the minimal setting, we never tripped a high exhaust temp code on the ECM and we burned one and a half tanks of fuel to every six-gallon tank of propane.

For this test at least, we found propane used in moderate proportions will provide a huge benefit in mileage. Stay tuned next issue for the results of propane used for power. We already know it enhances power, but at what price? 

Proof positive the manufacturer doesn't always get everything right. When we started working on the one-ton we found this bottle jack you'd find in a half-ton model. There is no way this jack would safely lift the front of this diesel-powered truck, let alone the rear with the utility box in it.	We did get one option with the basic propane kit. We opted for a remote refill system so we wouldn't have to remove the tank from the bed for refilling. We removed the license plate and found a spot for the refill lines behind the plate. With the bracket holes marked, a self-tapping screw was used for holes to fit the bracket to.	The lines fit perfect here. A spring-loaded license plate hinge from a late '60s or early '70s muscle car will make refilling a easy and convenient.
One of the tasks of the propane regulator is to ensure the liquid propane has been converted to its gas form. This is done by tapping into the heater lines and circulating engine coolant through the regulator. We found that fitting the propane regulator to the passenger side of the engine compartment, just above the valve cover, would make hooking up the coolant line easier.	We fed the propane line down the fender well to the frame, and used a couple of the 10mm studs on the valve cover to hold the regulator bracket.	We didn't even need to cut the stock heater lines. We simply took the coolant hose supplied in the kit and cut some to fit the lengths we needed to circulate hot water through the regulator.
The stock heater line comes from the engine and runs down the passenger side to this remote valve. This vacuum-controlled valve shuts coolant off from going into the cab, but has full pressure up to that point. We disconnected the heater line on the front side of the valve and hooked the heater pressure line to one side of the regulator. Then we cut one long piece of hose to circulate the water all the way back to the climate control vacuum valve.	You don't want the propane blowing cool gas over your mass airflow sensor or interacting with any input node that might change the engine programming. Plus, the propane opens and closes according to intake pressure, so you want the system to react as quickly to the off/on operation as possible. If the propane injector nozzle was mounted at the beginning, the engine would still have propane in the intake after the system decided it should be off. This is why it's suggested you mount the propane injection nozzle no more than three inches away from the front of the turbo.	After we drilled the intake tube, it was decided that we probably should have just removed it to prevent any particles from flowing down the turbo. We felt comfortable with just using a rag stuffed in the intake because the soft rubber intake wasn't going to make small metal particle shavings. To prevent harmful shavings from entering the engine, we suggest you just pull the intake off.