Piston Engines Not Out Yet

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Piston Engines Not Out Yet

By John McElroy
WardsAuto.com, May 18, 2009 8:00 AM

Powertrain engineers tell me they wish they could spend the same kind of money on their existing gasoline-fueled piston engines. They say, “Let me add just $1,000 worth of technology to my (piston) engine and let me show you what I can do.”

They make a great point. A couple years ago, I interviewed Hans List, the head of AVL List, a major independent powertrain design and engineering company. He told me he expected to see a 70% improvement in fuel economy from gasoline-fueled piston engines by the middle of next decade. He said small-displacement engines with aggressive turbocharging strategies would be the key.

Then there is Homogeneous Charge Compression Ignition technology, which makes a gasoline piston engine operate much like a diesel. It promises to offer diesel-like fuel efficiency but at a fraction of the cost. We may be only three to four years away from seeing a production-ready HCCI engine.

But I think there could be another breakthrough on the way. Eliminating conventional camshafts has been the dream of engine designers for over half a century. Using solenoids to operate the valves, instead of cams, could eliminate mass and parasitic losses. And solenoid technology keeps getting better all the time.

Even more exciting would be doing away with the poppet valves we use in today’s engines. There was some very exciting development work that took place during World War II using rotating valves. These new valves resembled cylinders rotating inside the cylinder head, in the same place an overhead cam would be, with slots cut into the cylinder to function as the intake and exhaust valves.

This concept got rid of the reciprocating mass in the cylinder head, allowing the engine to rev much higher. But back in the 1940s, they had problems sealing these rotating valves.

The industry seems to think pouring more money into the engines it already has merely increases cost. And yet it is eager to invest in sexy new technology such as hybrid-electric vehicles. There seems to be a bias against the tried-and-true in favor of the technology “du jour.”

But with virtually every auto maker now losing massive amounts of money, low-cost solutions deserve a second look. Even though some of the technologies I mention could add quite a bit of cost to an engine, they could prove to be far more cost-effective than the glitzy technologies that are getting all the attention.

Plus, if cellulosic ethanol or fuel derived from algae really start to catch on, watch out! Piston engines suddenly will look like a low-cost alternative. And that’s why I keep saying the internal-combustion piston engine could be around for a lot longer than many imagine.

John McElroy is editorial director of Blue Sky Productions and producer of “Autoline” for WTVS-Channel 56, Detroit “Autoline Daily” the online video newscast.