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The Chrysler Neon and Two-Stroke Engines

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The Chrysler Neon and Two-Stroke Engines

When the Neon was first being designed, Chrysler said it would have a two-stroke engine with direct injection; the engine was to have no head gasket, with the head and cylinder block cast in a single piece. That was just about the last mention of the engine.

Joe Goulart directed the 20-person engine team, a joint venture with Mercury Marine, from its creation in 1989 until he died in early 1995.

Dr. Benjamin Sheaffer, Mercury Marine Advanced Engineering Manager at that time, wrote, "We investigated new two-stroke engine designs from other manufacturers,. However, after working with Chrysler engineers and seeing first-hand their current two-stroke design and emissions control technology, we concluded that an alliance with Chrysler would serve both parties well."

Both companies agreed to independently fund their own development, with the work coordinated by a program committee. Chrysler tested its 1.2 liter Phase 2 engines for 100,000 miles, then started to test 1.5-liter Phase 3 engines. These larger engines had a balance shaft rotating at the speed of the crankshaft, external exhaust gas recirculation (EGR), and two spark plugs per cylinder. The direct fuel injection system worked at 1,000 psi.

The direct injection engine would have been very advanced, at the time. The company claimed that the supercharged 1.5 liter three-cylinder produced 95 horsepower and 128 lb-ft of torque at just 2,400 rpm, and was about 80 pounds lighter than the 132 horsepower 2.0; it would have been more powerful than the engines used in export Neons, while gas mileage was estimated to be 10% higher than a conventional engine of similar power.

Automotive Industries test drove a 1.5-liter-equipped Dodge Shadow, reporting strong performance and smooth, quiet running. Internal tests verified the engine's durability.

It was supposed to be used in the 1997 Neon - but it clearly was not! The goal of selling 25,000 North American two-stroke Neons per year never resulted in a single sale.
A major problem was the oxides of nitrogen - NOx - which were fairly high, due to the extremely lean-burning nature of the engine. The EPA demanded on-board diagnostics which were not relevant to this engine, and oxygen sensors which were also not needed, but these demands could have been overcome.

In the end, executives concluded that other technologies applied to four-stroke engines would have the same effects as using a two-stroke; and gas mileage was not a major issue at the time, regardless. Chrysler's limited resources, customers' priorities, Bob Eaton's penny-pinching, and the takeover by Daimler all doomed the program, probably even more than regulatory issues.

The advances made by Chrysler and Mercury have been used, though, in both automotive and boating. For conventional car engines, these advances include better fuel injectors, a high pressure fuel pump, and direct injection.

Back to the 1940s

Way back in the 1940s, Chrysler had developed a direct-injection two-stroke concept engine witih opposed pistons, which operated for several years with various fuels on the Texaco, Diesel, and Otto cycles. It never went beyond the experimental stage, but an intriguing outgrowth of this program was a two-stroke diesel engine that reportedly had outstanding fuel efficiency. What happened to that?

Press Release

After seven years of researching two-stroke engine technology used in motorcycles, small boats and lawn mowers, Chrysler engineers have gained valuable experience in technologies associated with injecting fuel directly into the combustion chamber, according to Floyd Allen, executive engineer, core powertrain.

"We think we've shaved 18 months, maybe two years, off the development time for four-stroke direct injection engines," Allen said. "We've learned a lot about stratified charge, lean burn combustion, direct injection, highly-efficient, high-pressure injectors and high-pressure gasoline fuel pumps."

Four-stroke DI gas engines are believed to have the potential of one day achieving more than 45 miles per gallon, which is comparable to advanced, small displacement direct injected diesel engines of the future.

"We've also taken two-stroke technology as far as it can go without a lean burn catalyst, a device that might enable the two-stroke engine to meet the strictest, future emission standards in the United States," Allen said. "When that development comes, and I wouldn't be surprised if that happens in the next five years, Chrysler now has the potential to be ready with a marketable, two-stroke engine."

Two-stroke engines have long been promising because of better fuel economy, fewer parts, better efficiency and a smaller engine package (about two-thirds the size and weight of conventional engines) that would allow for more design flexibility and lower hood lines.

Chrysler first began looking at two-stroke engines in the 1940s when it applied a process developed by Texaco -- a uniflow, opposed-piston, ported engine. Chrysler revisited the subject more earnestly in 1989.

"We purposely kept it small, about 20 young engineers, working in a focused, frenzied environment of creativity, much as a racing team operates," Allen said. "In fact, the culture created here was, in many ways, a forerunner of the platform approach to building cars that Chrysler has instituted."

Many people, including some within the company, thought the technology didn't have a chance. Tom Lawrence, engine development supervisor, was aware of those skeptics from the time he signed up for the two-stroke team in 1989.

"As good as the technology sounded, there were potholes along the way," Lawrence said. "People within and outside the company were saying it couldn't be done.

"For example, it was said we couldn't make the engine idle because it would violate the second law of thermodynamics. We couldn't come close to the Tier 1 NOx standards because the invention of a lean burn catalyst didn't seem possible. Some people thought we were wasting company funds at a time when they were scarce. I don't recall if we took those statements as challenges, just ignored them or really didn't know any better. We just carried on."

On the contrary, it may turn out to be one of the best research investments Chrysler has ever made.

"It was a great investment," Allen said. "Seven years ago, two-strokes were an unknown quantity to us. Now, it's one more piece of the technology puzzle we understand. Would we do it again? In a New York minute!

"This is very similar to the infusion our Patriot program gave the hybrid electric vehicle development team. We took both technologies as far as we could and are now concentrating our efforts on those areas that appear to be most promising in the very near future."

The results from the two-stroke program include:

  • a direct injection fuel system that has promise for four-stroke applications.
  • a high-pressure fuel pump (capable of producing 2,000 pounds per square inch) that could survive the demanding environment of an automobile engine.
  • a mechanically-driven, centrifugal compressor, capable of spinning a compressor wheel at speeds of up to 1,400 revolutions per second, that could be used as a super-charger in four-stroke applications.
  • a roughly 10 percent improvement in city fuel economy over comparable four-stroke engines that delivers performance (128 lb-ft of torque).

Chrysler 1904-2018

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