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EMD Natural Gas Engines

Direct Benefits of an ECI dual fuel system
  • Fuel cost savings
  • Significantly reduced emissions, in both diesel and gas modes
  • Fully rated horsepower
  • Retrofit system - expands capability and adds value to your present investment
  • Lower maintenance costs & improved longevity due to cleaner fuel
  • Retains diesel only versatility

Indirect Benefits

  • Reduces national dependence on foreign oil
  • Environmentally responsible technology
  • Shifts major fuel cost to a more price stable fuel medium

Related Topics:
Locomotive Tender Fuel Storage
Locomotive Emissions Page
Dual Fuel EMD Systems Specifications

How Do Operators Like It?

7149 in haul

The BN 7149, one of two natural gas locomotives developed for the Burlington Northern by Energy Conversions Inc. The successful demonstration locomotives operated on a commercial coal haul between Wyoming and Wisconsin from 1991-1996. The engines took the idea of natural gas rail out of the concept phase and into reality, proving the reliability, safety, and full-power capabilities of the clean burning ECI system.

For a detailed discussion on the economics and safety issues of using natural gas, please see the online version of The ECI Dual Fuel Sourcebook, an informational essay on the use of natural gas as a locomotive fuel.

Components of the ECI system

Energy Conversions Inc's dual fuel conversion systems are designed to retrofit a General Motors EMD 645 or 710 engine for natural gas operation. The ECI conversion system for EMD engines is similar for most applications, whether locomotive, power generation or marine. Designed with ease and economy of installation in mind, the kit may be installed by maintenance personnel over the course of a routine class overhaul. Systems consists of the following components:

  • ECI patented electronically controlled gas injectors
  • Specially designed pistons and cylinder heads
  • Electronic engine control and monitoring system
  • Supplementary diesel control hardware
  • Low Emission Idle (LEI)- ECI's patented bank idling system
  • Supplementary Aftercooling hardware

Auxiliary hardware (integral hardware not supplied by ECI )

  • Leak detection system
  • Engine water preheating kit

GIV installed

ECI dual fuel head with electronic gas injector installed

How it works

ECI Gas Injection Cycle

Low Pressure Direct Injection

The ECI dual fuel conversion is a low-pressure injection system designed for the EMD 645 and 710 model diesel engines. Natural gas is injected into the cylinder near the bottom of the stroke when cylinder pressures are low, thus requiring less injection pressure. Fuel and air mix during compression, then a small portion of diesel "pilot" fuel is dispersed into the cylinder at top of the stroke to facilitate combustion. The system achieves full horsepower in all throttle notches with only 120-150 psi of injection pressure.

ECI chose to use low pressure injection over a high pressure system for a number of reasons. Low pressure injection extends injector life, makes the fuel supply hardware within the locomotive engine's longhood safer and more cost effective, and improves the safety of the working environment on and around the locomotive. For more discussion on the aspects of low vs. high pressure systems, please see The ECI Dual Fuel Sourcebook .

Dual fuel pistons and heads

At the heart of the conversion are the specially designed ECI pistons and heads. The lower compression ratio and crown shape have been optimized to provide maximum power on either diesel fuel or natural gas. The power assemblies are applied using the standard diesel pack installation procedure.

gas piston

ECI's Dual Fuel piston on the right, next to a standard EMD piston. The ECI pistons provides optimum combustion in the dual fuel engine.

Electronic Controls

System operation is governed by ECI's patented electronic control unit, or ECU. The ECU uses industrially proven electronic technology together with custom software to monitor and manipulate critical engine functions through a variety of sensors. It controls fuel injection timing, engine speed and generator excitation, smoothly handling wheel slip and traction motor series-parallel transition. The ECU is able to detect cylinder temperature imbalances, gas leaks, and equipment failures. If a problem occurs on a dual fuel system, the ECU automatically switches the locomotive to full diesel operation, with no interruption of service.
The ECU allows a maintenance technician to communicate with the system using either a simple digital information screen or laptop computer. Gas engine functions can be viewed in real time, graphically display by custom ECI software. Modem transmission capabilities also allow data acquisition and fault history reviews from remote locations while the train remains in transit.


ECI's sophisticated engine control unit (ECU) performs a myriad of engine control functions, from injector valve sequencing to onboard diagnostics and logging performance histories.

Enhanced Cooling

In order to achieve full rated diesel power there are modifications done to the existing engine air cooling system. Additional radiators, more effective after coolers, some piping and the addition of water circulating pumps work to reduce the high temperature air the turbocharger produces. This equipment fits easily inside of the long hood, with the addition of contoured sheet metal necessary for the new radiators. Supplemental cooling is also claimed from the vaporization of the liquid natural gas on the fuel tender.

aftercoolersSpecial 6-pass aftercoolers enhance temperature control and maximize horsepower

Radiators installed

Flared radiators similar to SD45 style, enhance cooling of charge air for better dual fuel performance

Low Emission Idle (LEI)

An added advantage to the ECI Dual-Fuel EMD system regarding the reduction of emissions is the patented Low Emission Idle, or LEI. It's primary role is to curb excessive smoke which commonly occurs under low load conditions. LEI is an ECI patented component which employs an electronically controlled linkage that fuels left and right cylinder banks alternately while the engine runs in the lowest speeds. The system reduces fuel consumption by 15%, and brings down particulate emissions significantly.

LEI is also available as its own separate kit, and is compatible with any standard EMD diesel , as well as General Electric's FDL series engines. LEI is a very quick, practical, and economical way for you to reduce visible emissions in switch yards as well as in long haul service. See LEI page for more information.

LEI installed

The LEI electronic/ pneumatic control linkage helps reduce excessive smoke during low load conditions.

Durability and Reliability

Although locomotives have a young history with respect to natural gas use, ECI 's system is the first and only to operate successfully under the sustained rigors of commercial long haul locomotion. The Burlington Northern's successful demonstration of two ECI equipped dual fuel locomotives, 7890 and 7149, provided nearly five years of full time dual fuel service from 1991-1996. BNSF's corporate decision failed to renew the gas refuelling contract, which halted the use of gas on these locomotive thereafter. However, the locomotives continued to operate continuously in diesel-only mode with all the conversion equipment completely operational, until the locomotives' scheduled overhaul in late1998. Parts retained by ECI from the experimental locomotives show wear to be superior to that of standard diesel EMDs at the time of standard class overhaul. Apart from several minor component replacements made during the course of the demonstration, the ECI system remained intact and in excellent operating order. During the entire term, the locomotives proved very reliable, providing full power and returning shipments consistently and without incident.


A full discussion on the emissions benefits of ECI's system is included on the ECI Locomotive Emissions page. Included is an executive summary of the findings conducted on the ECI system by Southwest Research Institute, as well as data for the EPA Locomotive Emissions Standards.

Fuel Storage- LNG Locomotive Fuel Tender 

Go to page on LNG tender for a description of natural gas locomotive fuel storage.

Locomotive operation - How do the engineers like it?


The ECI conversion requires no special training for the locomotive operator. The converted locomotive behaves exactly like an ordinary diesel. An indicator light inside the locomotive cabin tells the engineer that the system is running on gas.
Transition between diesel and dual fuel modes is automatic and seamless.

Nearly every locomotive engineer who has had the opportunity to commandeer the gas locomotives have given them a resounding approval.


"It works great, plenty of power... no real difference from the regular diesels. Full speed ahead!"- S.J. Golubic, BLE

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