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Greaves and Pinnacle partner to launch opposed-piston gasoline/CNG lean burn engine for 3-wheelers

Greaves Cotton Limited, one of the leading engineering companies in India with core competencies in diesel and gasoline engines, farm equipment and gensets, and Pinnacle Engines, the developer of a high compression ratio, four-stroke, spark-ignited (SI), opposed-piston, sleeve-valve architecture engine (earlier post), announced a technology partnership for the launch of a novel opposed-piston gasoline/CNG lean burn BSVI-compliant engine for 3-wheelers in India. This will make India one of the lead markets to adopt this technology.

The Pinnacle engine architecture features low heat loss and low surface-area-to-volume in the combustion chamber, resulting in less energy loss, contributing to greater fuel efficiency. The Variable Compression Ratio (VCR) allows for reduced pumping work (PMEP) from de-throttling (increased air flow), reducing heat loss and knock resistance.

In a 2012 SAE paper, Pinnacle engineers reported that, with the most basic configuration, the engine can realize light-load indicated efficiency improvements of 15-30% over conventional poppet-valve technology.

Greaves sees this move as an important milestone in establishing itself as a leading fuel-agnostic powertrain solutions & services company. This also allows Greaves access to export markets with large 3-wheeler population. With this advanced horizontal opposed piston design engines, Greaves aims to offer BS VI compliant high power and fuel efficiency engines with lower maintenance cost that results in higher savings to the end customer.

This partnership enables Greaves, currently the market leader in the 3-wheeler diesel engine space, to enter the larger 3-wheeler gasoline/CNG market, with a powerful customer value proposition.

The partnership leverages strengths on both sides, provides opportunities to enter new markets and customer segments.

Utilizing a proprietary hardware design and electronic control, Pinnacle’s unique lean-burn four stroke engine is protected by more than 170 patents. The technology is now ready to be taken into the Indian 3-wheeler market, providing a highly differentiated customer value proposition.


  • Willcox, M., Cleeves, J., Jackson, S., Hawkes, M. et al. (2012) “Indicated Cycle Efficiency Improvements of a 4-Stroke, High Compression Ratio, S.I., Opposed-Piston, Sleeve-Valve Engine Using Highly Delayed Spark Timing for Knock Mitigation,” SAE Technical Paper 2012-01-0378 doi: 10.4271/2012-01-0378.



For the record, a typical 3 wheeler engine is 150 - 200 cc, 5-6Kw power output for a petrol engine, 440 cc, 5.5Kw for a diesel.



Design from the past.


"sleeve-valve... Design from the past."

What isn't? In 2005 I would've called space vector control of an induction motor a "design from the past". And yet Tesla managed to apply the much-improved processing (and, subsequently, software) of the late-00's and make a much more efficient and responsive drive train based on that core concept.

Numerous ICE concepts get revived because improvements in economically practical fine-tolerance machining, materials (especially treatment/coating and joining methods), tribology, sensors and processing power made them practical. The oil consumption issues and limitations to variable timing of sleeve valve concepts aren't impossibilities anymore.

Afforable mass-manufacture of engines like this for last-mile mobility in India will make a real impact on transport pollution much sooner than the fantasies of shanty-dwelling tuk tuk operators recharging Li batteries from a 2 sq meter PV panel or a grid that doesn't exist. I'm not saying don't electrify these vehicles. I'm personally involved with a Delhi-based business that builds motors for just that purpose, and they sell a few hundred a month. But customers are boutique buyers who are far outnumbered by the smoky masses of impoverished operators who buy high-sulfur diesel from roadside sellers and have no reliable access to electricity.

There is no social cohort of people more willing to aspire endlessly (and unsuccessfully) to the Perfect while allowing the many opportunties for the Better to slip away than EV dreamers.


We have gone beyond sleeve valve in 1910 to poppet valves.


Poppet valves are flow-limited by their "curtain area", which is grossly inferior to sleeve valves'.  High efficiency demands that pressure drops (throttling losses) in an engine be strictly limited.  Sleeve valves are far less area-limited than poppet valves and can achieve lower pressure drops and higher efficiency.

Sleeve valves are largely impractical with single-piston designs.  They become far more practical with opposed-piston designs.  Sometimes it takes more than one major design change to get where you want to go.

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