Energy Conversions - Home
Energy Conversions - Products
Energy Conversions - Applications
Energy Conversions - Performance Specs
Energy Conversions - News
Energy Conversions - Photos
Energy Conversions - Contact Us
Energy Conversions - Site Map

logo Economizer
Dual Fuel Conversion for Four Stroke Engines


The Economizer is a cost effective dual fuel conversion system for the industrial four stroke diesel engine market. It quickly enables the use of inexpensive natural gas without requiring the replacement of engines or significant engine components. Natural gas fuel replacement typically ranges from 40-70% of total engine fuel.

80% replacement on our Mitsubushi SN8PTA, very unusual.

The system is designed to be installed on new or existing diesel engines without modifying any internal engine components. Diesel-only operation remains unchanged with the Economizer system installed. Installation of the components is straightforward, with only reasonable mechanical expertise required. Final tuning and testing is typically performed by a trained service technician.

Dual fuel units allow the user the flexibility to run straight diesel or dual-fueled natural gas with diesel, an extremely important consideration for applications with a potentially interrupted gas supply.

The Economizer is engineered to be fail-safe; critical variables for dual fuel operation are monitored by the Economizer's ECU. In the event that gas operation is no longer warranted, full diesel operation is resumed instantly and seamlessly, with no interruption of engine service. This careful consideration given to protecting your engine and productivity is a distinct advantage of the Economizer dual-fuel system.


ECI's well-considered Economizer conversion system includes an electronic engine control unit (ECU) and industrial grade sensors. These components work together to protect critical engine parameters while mantaining the highest possible gas fuel replacement.

The ECU monitors various temperatures, pressures, and engine knock to determine when it is appropriate to operate with natural gas. When all parameters are within proper levels, dual-fuel operation is enabled and low pressure natural gas is delivered through an air/fuel diffuser to the intake air. Gas travels in the intake manifold to the combustion chambers, where it is compressed and ignited with a small amount of diesel “pilot fuel”.

An important consideration of running an engine on natural gas is the potential for the energy content of the gas to change. To stay one step ahead of this variable, The Economizer ECU utilizes closed-loop control to mantain maximum fuel replacement while protecting the engine from combustion knock or excessive temperatures. The ECI-developed Gas Flow Control Valve continually modulates the gas supply to the engine, making transitions between power levels smooth and stable.

The ECU can be connected to a laptop with optional software or to your facility's existing SCADA system for monitoring and data collection.


The ECI Economizer system can be adapted to virtually any four-stroke diesel, and is offered in three standard models with each model covering an approximate range of engine generator power.

System 1: 150 to 300 KW Single Turbo

System 2: 300 to 1000 KW Dual Turbo

System 3: 1000 to 2000 KW Dual and Quad Turbo

(Smaller and larger conversion systems are also available)

System Installation

Installation of the hardware usually takes a couple days:

The site needs a gas supply line with at least 2 PSI of available gas pressure. The supply needs to be routed to the engine area, and the ECI supplied regulator, filter, and control valves need to be plumbed in.

Sensors to measure critical engine functions like speed, load, knock level, boost pressure, water temperature, governor position and gas pressure all need to be properly mounted to the engine.

Wire harnesses can be provided pre-assembled for certain engines, whereas other engines will require a custom harness assembled on-site. The Engine Control Unit (ECU) needs to be mounted nearby the engine and supplied with power. Voltage for powering the control system is typically 24 volts DC.

The controller program is custom tailored to match the details of the engine/governor design. Fuel tables are developed for each engine family on site if necessary by performing a fairly simple load test. During the testing the fuel table numbers are generated and programmed into the control system. For engines already having been converted only testing and confirmation of proper operation is necessary.


An ECI conversion is a sound investment for power users who are looking to upgrade their current system to alternative fuel technology without revamping their entire system. As a retrofit technology, the ECI system provides an economically attractive alternative to buying costly new generators.

With the ability to operate both fuels, the engine will never be down due to a lack of adequate gas fuel supply. Another distinct advantage of dual fuel is the decreased engine wear that comes with the use of cleaner fuel. Due to a reduction of carbon soot buildup and cleaner lube oil, longer intervals between service maintenance can be expected. This means a longer economic life for the engine and a better overall return on your investment.

To determine approximate cost savings you will need to determine your present fuel cost, your projected fuel replacement percentage and replacement cost with natural gas. Be sure to apply any losses of efficiency and always estimate on the safe side. Ask an ECI representative to help you in determining your annual cost savings, including fuel and maintenance.

When considering the cost of natural gas and comparing options for using it as a fuel, discuss the contract options with your gas supplier. Many suppliers are willing to give better rates if they are able to interrupt your fuel supply. An interruptible rate is exactly why the Dual Fuel system is a desirable option.

Information about Knock:

Combustion knock is where the already ignited, burning air fuel mix in the combustion chamber starts to auto-ignite in adjacent areas from the increasing pressures and high temperatures. It causes high pressure spikes and can result in engine damage. Knock is the reason many engines can not run full power at a minimized pilot fuel setting. Each engine family has its own differences; different fuel timing, compression ratio and turbocharger configurations all have different effects on the tolerance an engine has for natural gas application.

The ambient temperature affects the combustion and so does the content of the gas. All of these factors come into play and make it somewhat difficult to predict exactly what power limit will be reached with minimized pilot fuel and what amount of pilot fuel will be required at full power. The Economizer system is designed to replace as much diesel fuel as is possible without running into the combustion knock limit. To accomplish this the controller is programmed to meter gas fuel into the engine based on its fuel map. The map is a curve fit to the capacity of the engine. Knock detection is used to protect the engine in case the fuel energy content changes and replacement levels need adjusting.


Quick Links:

PDF Sales Brochure

Economizer Pictures


Save money with cheaper fuel

Simple, high quality conversion is cost effective

Low pressure gas compatible

as much as 70% diesel to gas replacement

Maintains diesel-only capability for greater versatility

Achieves full rated horsepower in both diesel and dual fuel modes

>50% Reduction in NOx emissions

Fully automated operation

Cleaner fuel reduces engine wear and maintenance

Operation with Bio-Diesel is no problem


Standard Engine Conversion Packages:

CAT 3512 & 3516A

CAT 3406 & 3412

CAT C18 electronic engine

CAT 3608 2400kW

Cummins KTA50 G3

Cummins KTA50 G9

Cummins KTA 50 Locomotive

Cummins KTA 38

Cummins KTTA 19

GE 16 7FDL Locomotive

GE Dash 9 Locomotive

Mitsubishi SN8PTA

Mitsubishi S16RPTAA 2000kW

Wartsila 18V32 7.8 MW

The Economizer package can be adapted to these and many other engines.
Contact us for information about your specific application.


 Fuel curve of typical Economizer conversion, where knock limit is cause for measurable gas fuel limiting.



 Fuel curve on ECI Mitsubishi test engine. A Low BMEP rating reduces incidence of knock and provides higher replacement.

6411 Pacific Hwy. East, Tacoma, WA 98424-1587, USA
(253) 312-7888, FAX (253) 922-2258
© all rights reserved