Diesel/Natural Gas Conversions Offers Owners a Choice

Aftermarket systems give owners of older trucks some of the benefits of natural gas

September 2013, - Feature

by Deborah Lockridge, Editor-in-Chief - Also by this author

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A dual-fuel conversion system can offer some of the fuel- and emissions-saving benefits of a natural gas engine without going out and buying a brand-new truck.

Recent changes in Environmental Protection Agency rules that went into effect in 2011 made it easier for companies to certify conversions that allow diesel engines to burn a mixture of natural gas and diesel fuel. They may displace 50%, 60% or more of the diesel fuel with cleaner-burning, cheaper natural gas.

One of the key benefits of these systems is if a truck needs to run in an area where there is not a natural gas fueling infrastructure, the truck can run on straight diesel fuel.


Here are some of the companies offering these systems:

American Power Group

Before getting into the U.S. transportation market, APG offered dual-fuel systems for stationary power generation and for transportation uses in other countries. It has teamed up with the WheelTime network to help it market and install its Vehicular Turbocharged Natural Gas System. In addition, Ervin Equipment and Fitzgerald are providing glider kits with APG’s dual-fuel system. APG has EPA certification for more than 200 engine families.

Clean Air Power

Clean Air Power is a UK firm that is bringing its Genesis-EDGE Dual-Fuel conversion unit to the U.S. It’s working with UPS to put the system on 10 Mack MP8-powered tractors for fleet testing. Clean Air Power also has a Caterpillar C15 system that can be fitted to existing trucks or to new trucks using a glider kit.


The EcoDual MAX/SR system enables heavy-duty diesel trucks to displace an average of 60% to 70% of their diesel fuel use with natural gas. MAX/SR is available for Cummins ISX engines produced from 2004 to 2009. EcoDual is working on certification for other engines.

Converting to 100% natural gas:

Omnitek Engineering Corp. offers a diesel-to-100% natural gas system. “Diesel dual fuel is an exciting prospect, however, success and customer acceptance is limited,” the company says. “The promise of 50% to 60% diesel replacement is very attractive, but in reality savings in dollars will be more like 15% - 40% range.”

The system converts existing in-use diesel engines into compressed natural gas or liquefied natural gas – at a fraction of the cost of new engines, Omnitek says. It has more than 5,000 engine conversions worldwide but is still getting ramped up in the U.S. So far it has certification for the International DT-466 and says it will have approvals for several more engines by the end of this year and into 2014.

Omnitek is working with the Puget Sound Clean Air Agency for a pilot project to demonstrate its diesel-to-natural gas engine conversion technology for drayage trucks serving the Port of Seattle, Wash.

Learn more about alternative fuel conversions at


  1. 1. Ted Hazlewood [ February 02, 2014 @ 08:56AM ]

    I Ford F350 7.3 diesel. I would like to know if there is a system available to make my diesel operate on Natural Gas.

  2. 2. Tom Berg [ March 03, 2014 @ 07:35AM ]

    Ted, I just did an article on a dual-fuel system for heavy diesels, but the company (American Power Group) does not make one for light diesels. A contact at APG said that if there is a kit available, it’d probably cost way more money than you’d ever save in fuel. It might reduce smoke, but again, it’d be a very expensive way to do it.

    There might be a conversion out there but I can’t find one. I checked with NGV America’s website, which includes a link to a long list of NG kits ( Under Ford, only gasoline engines are listed.

  3. 3. Trey Rogers [ December 09, 2016 @ 12:39AM ]

    One of the major issues I find with The use of CNG is the diesel fuel acts as a lubricant as well as being burned as fuel CNG has much less lubricating properties than diesel, what is going to be the long range costs associated with shortened engine life and down time of equipment? What is the the effect on manufacturer's warranties? A dual fuel diesel engine would need more than an addition of CNG manifold, it also needs added engineering to the engine's lubrication, regeneration and likely other systems that were designed to operate within the specifications that were engineered to be efficient under the operating conditions for diesel not Compressed Natural Gas.


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