envirifit

EnviroFit Retrofit Kit

Treehugger Kimberley D. Mok1 reports that the “ubiquitous two- and three-wheelers of South and Southeast Asia – which contribute massive amounts of pollution in the region – could be on the way to getting a green makeover.”

In June, Dr. Bryan Willson of Envirofit accepted an award for the retrofit kit. In the area of clean transport and mobility the World Clean Energy Awards gave recognition to the project in a ceremony in New York City. Envirofit hopes that the kudos from Basel, Switzerland will give the retrofit kits a boost in credibility to use when they pitch this innovative and efficient renewable energy strategy in Bangladesh, Sri Lanka, Pakistan, and India later this year.

While this blog has featured direct injection, it typically would avoid endorsement of more polluting two-stroke technologies. In first world countries, there is a transition underway from two-stroke to four-stroke engines to reduce pollution. Yet the EnviroFit strategy is recognition of how an incremental change in widely dispersed, lost cost, transportation could reduce fuel use and emissions. “According to Envirofit,” writes the trehugger in Auroville, India, “the kits could cut fuel consumption from 35 to 50 percent and decrease the emissions of a two-stroke engine by 90 percent.”

And, in those countries, where micro-financing has succeeded, EnviroFit hopes to make use of this financial strategy to overcome the increased cost of the technology that could inhibit adoption. As with other transportation initiatives, the way to cleaner, cheaper requires more upfront cost.


Direct injection allows for a locally rich region around the spark plug, eliminating the need for enrichment of the entire cylinder to achieve stable combustion. Elimination of rich air / fuel ratios significantly reduces carbon monoxide emissions.

Direct in-cylinder fuel injection is a technology that has shown the ability to greatly reduce emissions from two-stroke engines. In a DI (Direct Injection) system the carburetor is eliminated, and the fuel is introduced into the combustion chamber via an injector mounted in the top of the chamber’s cylinder head.

Exhaust products are then scavenged from the cylinder using air only. Fuel is injected into the cylinder later in the cycle, greatly reducing the amount of unburned fuel that is allowed to escape during scavenging.



Working with local partners and smaller, sustainable start-ups in the Philippine cities of Vigan and Puerto Princesa to install and service a projected 2 million kits.

Envirofit is a non-profit company established at Colorado State University in 2003, now working to develop and distribute retrofit kits. Commercial operations in the Phillipine cities of Vigan and Puerto Princesa have begun. These retrofit kit projects are currently underway. Envirofit is actively engaged with the Local Government Units of these cities to ensure successful implementation.

If these projects prove successful, then the hope is that such kits can improve the fuel efficiency of two-stroke engines, commonly used in many of the two-wheeler taxis and three-wheeler auto-rickshaws throughout the Philippines, India, Bangladesh, Sri Lanka, Pakistan and other parts of South Asia. Asian Development Bank estimate of 100 million two-stroke vehicles in Southeast Asia.

Applicable to 4-stroke and 2-stroke engines, the DI system creates a precisely-controlled, finely atomised fuel cloud allowing engines to run with greater fuel efficiently and with reduced emissions output. Orbital reports that such kits are in production and have been installed on engines as small as 50cc and as large as 500cc per cylinder.

1Retrofit Engine Kits To Reduce Southeast Asia's Pollution