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Pinnacle Engines introduces new opposed-piston engine with a promise of 30-50% better fuel economy

Illustration of a three-cylinder configuration of the Pinnacle opposed-piston engine. Click to enlarge.

Startup Pinnacle Engines unveiled plans to commercialize a new, more efficient combustion engine by 2013. The company says the new engine design enables significant reductions in fuel consumption and greenhouse gas emissions without increasing vehicle cost. Pinnacle has raised $13.5 million in venture funding from NEA, Bessemer Venture Partners and Infield Capital.

The Pinnacle engine is based on a four-stroke, spark-ignited (SI), opposed-piston, sleeve-valve architecture. Pinnacle says the engine achieves 30-50% better fuel economy in various drive cycle comparisons without the large cost penalty that can be associated with significant fuel economy improvement. The performance of the Pinnacle Engines design has been independently verified by FEV, Inc., a Pinnacle Engines development partner.

Engines that can deliver significant efficiencies within 5 - 10 years are critical as the global demand for vehicles places a strain on both natural resources and the environment. We believe Pinnacle Engines is in a unique position to have a major impact in that timeframe, by delivering exceptional efficiency gains at the lowest possible cost.

—Rohini Chakravarthy, Pinnacle Board member and a Partner at NEA

The core of Pinnacle’s technology resides in its engine architecture and the new “Cleeves Cycle”. (James Montague (Monty) Cleeves is the Founder, President, and CTO of Pinnacle.) The Cleeves Cycle operates on the Otto cycle (constant volume combustion) or Diesel cycle (constant pressure combustion) depending on operating conditions. Additional efficiency improvements will be realized through incorporation of variable valve timing, direct injection, turbocharging, and Pinnacle’s own low-cost variable compression ratio mechanism.

The result, says Pinnacle, is a more fuel efficient and scalable engine design, and one that is compatible with most fuels including gasoline, diesel, natural gas, propane and their biofuel replacements.

The company is in the process of commercializing its technology through a joint development and licensing agreement with an Asian vehicle OEM. Production is slated to commence in Q1 2013. Further developments, including plans for expansion into the global automotive market, will be revealed later this year.



This is exciting if they have a functional prototype running. Until then its a pretty drawing that reminds me of the circular piston engine


Some weaknesses of the Pinnacle engine are:
the sealing, the lubrication and the wear of the sleeve valves;
the cooling of the cylinder;
the lubricant control (the same problem with the two stroke port engines).

The question is:
does the Pinnacle combine the advantages of the four-stroke engines with the advantages of the two-stroke opposed-piston engines, or does it combine their disadvantages?

The four-stroke opposed-piston single-crankshaft full-balanced PatFour engine (at the bottom of the http://www.pattakon.com/pattakonPatPOC.htm page)
uses four conventional poppet valves.

Do you see any advantage of the Pinnacle engine over the PatFour?

Manousos Pattakos


@Henry Gibson:

"Single piston automobiles would be more efficient and can be used in hydraulic hybrid designs if only efficiency is wanted. The NOAX free piston hydraulic pump was used in a demonstration hydraulic machine and has be neglected for too long, even by INNAS. It is too bad that INNAS did go find the funding to demonstrate the NOAX in the two commercial PARRY People MOVERS."

While I was charmed too by the INNAS design, I became less supportive when I read some of their papers. Power to weight ratio seems to be 0.1 kW/kg, about 10 times lower than conventional engines. I know it's an engine in development and they already improved the power to weight ration significantly, but I don't know how much further they can go.


@Manousos Pattakos:

I am very interested in your design and you seem someone who can actually build an engine by himself, which deserves my utmost respect. Do you have a team behind you or any interest of car makers? It is probably quite expensive if it is still all self funded.


For SimonDM:

Thanks. It is self funded.

Even having the car ready for test drives (take a look at the pattakon VVA roller Civic B16A2 prototype having 330 rpm idling and flat torque curve from below 900 rpm to above 9000 rpm, at http://www.pattakon.com ) nobody is willing to try it.
You will not believe how much I have pressed them to take the car and compare it to theirs (Honda, Daimler, BMW, VW, Fiat etc).
As big companies, their snobbery is justified.

In this forum the Pinnacle engine and their bold claims are presented.
Why Pinnacle is not responding to the questions set by the forum members?
Shouldn't the small innovative companies like Pinnacle, EcoMotors, Achates, mce-5 etc be more open to the public questions?

If you like to make a copy of the PatOP or OPRE prototypes, just e-mail me to send you the blueprints.

Manousos Pattakos

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