Mobile Turbodiesels
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Our CNG kits for mobile turbodiesels work much like our stationary kits do. The main difference is the pressure of the gas entering the conversion kit. Our stationary kits are designed to run on ½ psi of pressure from a gas pipeline, but the CNG kits draw gas from a fuel tank pressurized to 3600 psi. It then feeds the gas into the engine via a venturi tube which is inserted into the air intake pipe on the suction side of the turbocharger.
Obviously, it takes a special tank and special plumbing to deal with gas under that kind of pressure. People often ask if it’s safe to have gas under that much pressure on a vehicle. The answer is yes. When a CNG system is properly installed, it is safer than gasoline. Anyone who has transported or used an oxy-acetylene torch has dealt with combustible gases under similar pressures.
There are three pressure regulators in our CNG kits. The first two regulators are designed to decompress the gas from 3600 psi to less than 1 psi. The final regulator in the system is a demand regulator. It will only let gas flow to the engine when there is suction on the venturi nozzle. There is also an electrically activated solenoid which prevents any gas from flowing to the final regulator unless the engine is running. It is not possible for gas to leak into the engine while it is shut off.
At idle your engine will not suck any gas. When you press on the accelerator pedal, the turbo begins to spool up and raise the vacuum inside the air intake pipe. The final regulator begins metering gas into the engine. You will notice a very quick and dramatic throttle response as the gas begins flowing. Natural gas will increase the available horsepower between 15% and 25% and will increase available torque by 15-20%, depending on the application. You will notice greater towing power and hill climbing ability.
Natural gas will not combust by itself in the engine. The heat of compression is not sufficient to ignite it. It needs some diesel to act as a “liquid spark plug” and start the ignition process. However, it does not take much diesel fuel to ignite the gas. Because of the way a diesel engine works, the diesel fuel governor will meter the minimum amount of diesel fuel necessary to achieve the engine RPM’s demanded by the driver. The diesel engine’s fuel governor will automatically reduce the amount of diesel fuel that is sent to the fuel injectors in response to the presence of the gaseous fuel in the airflow. Basically your engine thinks you are rolling downhill for 400 miles and adjusts the diesel flow accordingly. Your lift pump, injector pump, and injectors are all lubricated by the fuel as they normally would be. Sufficient diesel fuel is still present in the combustion chamber for any lubrication that might be needed there. Pickup trucks will generally get 40-50 diesel mpg and get from 20-22 mile per dge of gas. Heavy trucks will achieve 30-50% fuel substitution rates and generally get between 3-5 extra miles per gallon on their diesel. Results will vary depending on driver, terrain, and load.
Because natural gas combusts so much more quickly than diesel fuel, you get a very complete ignition, and a very, very clean burn. The soot going into the crankcase is dramatically reduced. Therefore you can safely double your oil change intervals.
Natural gas is safe for a diesel engine if it is properly metered and controlled. One concern that has to be addressed in any diesel dual fuel conversion is exhaust temperatures. It is quite possible to generate engine damaging high exhaust temperatures on straight diesel fuel, especially while towing. Because more fuel energy is available to the engine when running dual fuel, that danger is increased. That is why all of our kits come with a digital pyrometer (exhaust temperature gauge) which has a special circuit that is designed to shut off the natural gas flow when exhaust temperatures get too high, and then turn the gas back on again when temperatures are in the safe range again.
If your heavy truck or equipment has a PTO function, we have a special kit that is designed to help you maximize fuel economy during PTO operations. During these operations your engine will act much like a stationary diesel engine does, with the same (generally light) constant load characteristics. An extra gas circuit with a high flow solenoid on the kit allows the engine to run on a high percentage of natural gas during these operations.
Some manufacturers are claiming to be able to safely substitute 90+% of the diesel fuel with natural gas in heavy trucks. Perhaps they can do so, but there are other issues to take into consideration.
First and foremost is the cost of the conversion. These conversions are quite expensive. It will take a lot of miles to pay for a conversion.
Secondly, there are fuel storage density issues. CNG is not a very space efficient fuel to store on a vehicle. A GGE of gas takes up more than 2.5 times the space that a liquid gallon does. A DGE (Diesel Gallon Equivalent) represents an even larger storage volume. That is the reason why many of the larger over the road trucks will be using Liquified Natural Gas (LNG) in the near future.
A 15 gge tank of compressed natural gas is 73” x 16”. To get 60 gge onboard a heavy truck, you will need four of those tanks behind the cab. There are 50 gge saddle tanks available, but they cost around $8,000 apiece, and you have to remove one of your diesel tanks.
If you substitute 90% of your diesel fuel with natural gas, you are still going to be burning the same amount of BTU’s in the engine. You will very quickly burn through your stored CNG and be back on straight diesel fuel in a few hundred miles. With our kit you will substitute less gas in each piston stroke, but the gaseous fuel will take you farther. Our kits are much, much less expensive, and you can install our kits yourself.
Our kits are reliable, easy to install, safe for your engine, and cost effective. Go to the calculator below and run the numbers for yourself. If a C&E Clean Energy Solutions kit makes sense for you, we’re happy to help you however we can.
- Phone: 1-800-435-6810
- Email: info@cecleanenergy.net
In order to calculate your savings on a natural gas conversion kit for turbodiesels, you need to find the cost of four things:
- Your compressed natural gas (CNG)
- Your conversion kit (go to our Order Now page).
- The tanks to store the CNG on your truck.
- The percentage of diesel
- Finding CNG
The main factor to consider in how much our conversion kits will save you is whether or not you have a CNG filling station near you. Check right now by going here. The price you see is in Gasoline Gallon Equivalents (GGEs), which only contains 81% of the energy of a Diesel Gallon Equivalent (DGE). (Note: when you input the GGE price below, it will automatically recalculate the cost of a DGE).
If you do not have a CNG filling station, you will have to install a compressor at your home or business. The cheapest compressor is around $7,000 plus $1,600 in yearly maintenance. If you have several trucks, you will have to install a large compressor. That compressor will cost you from $26,500 and more to install. If you would like to purchase a compressor with your kit and tanks, please email us for a current price quote. info@cecleanenergy.net.
The calculations below assume that you have access to a CNG filling station.
- Your Conversion Kit
There are three types of conversion kits for turbodiesels. You can view them on our Order Now page. You will need to input the price of your conversion kit below.
- Your CNG Tanks
The cost of CNG tanks is fluctuating wildly because of demand. However, you should plan on spending at least $150 for every Diesel Gallon Equivalent (DGE) of CNG storage. You will be asked to input how many DGEs you want to store on board below.
Keep in mind that many tanks are around 70" long. These can contain from 9 to 15 GGEs. You can read more about the different types of tanks "F250 Powerstroke Natural Gas Conversion Project Pt. 2."
- Percentage of CNG substitution
There are a lot of factors that go into the rate of substitution, but to keep it simple, you can assume that heavy loads will get around 50% substitution and that lighter loads will get around 70% substitution (for further explanation, see the helpful article "Making a Stationary Diesel Run on Natural Gas").