Biodiesel Tax Credit Opens the Door for Mainstream Adoption
Flex Fuel Zooms in Brazil

Update: Westport/Isuzu CNG-DI Cleaner than Diesel, More Efficient than CNG

Just last month, Isuzu and Westport entered into a new joint venture agreement through which Isuzu will provide to Westport approximately CDN$1.5 million for the design and construction of two next-generation CNG-DI ELF trucks to be delivered in 2005 (earlier post).

A technical analysis presented by Isuzu this week at the 9th International Association for Natural Gas Vehicles (IANGV) Conference shows that the mono-fuel CNG-DI engines can be 75% cleaner than today’s diesel engines and 25%–30% more energy-efficient than today’s natural gas engines.

The conventional use of CNG as fuel makes it possible to achieve virtually zero PM emissions, with a significant reduction in NOx emissions as well. When it comes to the thermal efficiency, however, conventional CNG-powered engines are on par with gasoline-powered engines and slightly less efficient than conventional diesels.

Isuzu and Westport wanted to improve thermal efficiency by 25% or more over the conventional approach and to achieve at least 75% lower emissions than the current ultra-low-emission vehicles. It sounds like they achieved their emissions goal and slightly exceeded the goal on efficiency.

The CNG-DI system promises to be simple, lightweight, low-cost, reliable and durable. It also has lower noise and less vibration. Isuzu has concluded that there is good potential for commercial application of this technology.

—Masaki Okada, Senior Specialist, Engine Design and Development for Isuzu

Isuzu and Westport first showed the CNG-DI technology in a 2-ton ELF prototype truck brought to last year’s Challenge Bibendum. The truck won 2 Gold and 1 Silver awards there.

The CNG-DI engine in the ELF prototype used a 4.5-liter, in-line four-cylinder engine as the base. Isuzu developed the turbocharger, EGR (Exhaust Gas Recirculation), oxidizing catalytic converter and urea SCR catalyst for NOx reduction. Westport and Isuzu jointly developed the electronically controlled common rail injection system and hot-surface ignition system.

Isuzu/Westport CNG-DI ELF
Displacement4.5 liter
Engine configurationIn-line, 4-cylinder
Power100 kW (134 hp)
Torque500 Nm (369 lb-ft)
Fuel storage2-bottle CNG cylinders (Dynetek)
Storage pressure250 bar (3,675 psi)
Maximum speed130 km/h (81 mph)
Operational range300 km (186 miles)

Funding from the New Energy and Industrial Technology Development Organization (NEDO of Japan) and the Japan Gas Association supported the Isuzu/Westport research.



The "technical analysis" link goes to a press release with negligible technical content.  Neither does the press release indicate which of the product lines it is about.

All in all, a confusing and useless "news" item.


Hmm, yes. Bad choice of a text anchor for the press release on my part. Sorry about that. I don’t have access to that paper—let me see if I can get it from Isuzu.


Here is a link to the full paper. Development of CNG Direct Injection Diesel-Cycle Engine (1.23MB PDF).

U Khin Aung

Dear Sir,
I am NTU MSc student and doing research for CNG and NGV for Diesel and Gasoline engine.
Kindly let me know if you have any Technical information if available.

Thanking you.

Khin Aung
Petrol & Mechanical Engineer

Account Deleted

Dear Sir/Madam,
I am very interested in CNG fueled engines with direct injection. Could you tell me that the maximum lambda can be obtained? and how much Torque of this lambda?

Thank you so much

Tran Dang Quoc

The comments to this entry are closed.