The Internal Combustion Engine Is Here For The Long Run

Reprinted by permission of Engine Builder magazine.

For more than 100 years, the internal combustion (IC) engine has dominated the automobile industry with its power and convenience. It has provided this country and the world a reliable and economical source for transportation and has given enjoyment to scores of hot rod, classic car and restoration enthusiasts, as well as endless excitement in amateur and professional racing. It has also provided automotive technicians, repairers and installers continuous opportunities in business and employment.

The IC engine has been a part of nearly everyone's lifestyle for more than a century. The question, however, has been raised — how much life is left in the IC engine?

The environmental impact of the automobile today is a hotter issue than ever, as new emission regulations become law in not just the United States, but Europe and Asia as well. It's been estimated that by 2015, the pollution emitted from passenger cars will be less than one-twentieth of today's values.

The U.S. EPA in December 1999 signed the final Tier 2 emission regulations that were proposed in May of last year. The rule sets new, more stringent exhaust emission standards for passenger cars and light-duty trucks, and will be phased in beginning in 2004. The goal is to reduce tailpipe emissions of passenger vehicles by up to 77%.

The program focuses on reducing emissions of ozone-forming gases, including nitrogen oxides (NOx), non-methane organic gas (NMOG) and particulate matter (PM) from these vehicles. The same set of federal standards, expressed in grams of pollutants emitted per mile (g/mi), will apply to all passenger cars, light trucks and medium-duty passenger vehicles regardless of the vehicle or engine size.

The Tier 2 requirements also will reduce the average sulfur levels in the United States. In some parts of the country, these reductions have already begun to be phased in. Full compliance for most refiners will be completed by 2006. The new sulfur level limit of 30 parts per million (ppm) is roughly 90% less than the current national average of 340 ppm. This lower sulfur gasoline will aid in the improved emission technology for vehicles. In fact, the lower sulfur gasoline will help gasoline vehicles currently on the road reduce emissions through less degradation of their catalytic converters.

These environmental mandates have stimulated intensive industry research to develop alternative fuel vehicles. In recent years, the automakers have made great strides forward in converting the IC engine to run on alternative fuels such as natural gas, propane and alcohol.

Compressed Natural Gas (CNG), primarily methane, is being used in some applications because of its low cost and higher octane rating, which allows it to burn more efficiently. But CNG vehicles are limited at this time to trucks, vans and minivans because of the size and costs for the CNG tanks. Another drawback is limited public fueling stations. It's safe to say that for now and the near future, the electric battery-powered vehicle for consumers is not the answer. For 100 years, there have been failed attempts to develop a reliable electric vehicle. Many industry experts say the technology for a convenient, affordable and reliable battery-powered car is years, if not decades away. Limited technology of electric vehicles today is accompanied with a myriad of complaints: "they run out of juice too quickly," "take too long to recharge" and "the energy packs are too expensive."

Car manufacturers also are studying fuel cell technology. Although fuel cells are a cleaner form of energy that generate electricity from hydrogen and only emit water and heat, the technology is still in its infancy with little agreement on the type of fuel to be used or the type of infrastructure to deliver it.

Leading the fuel cell vehicle technology drive appears to be Daimler-Benz's NECAR 3 (New Electric Car). Unlike its predecessors, NECAR 3 fills up with methanol and with the aid of a reformer located in the rear of the vehicle, this liquid fuel is converted into hydrogen by water- vapor reformation. The hydrogen gas is then fed into the fuel cells where it reacts with atmospheric oxygen to produce electrical energy, which is used to power the vehicle.

Many industry experts agree that although fuel cell vehicles could have a huge impact as a future transportation source, manufacturers are still a long way from offering a commercially viable, lightweight and marketable alternative to today's car.

We have seen that other power plants in this country haven't prospered as the IC engine has. U.S. drivers have historically been anti-diesel. The same seems to hold true for the rotary engine, which, though discontinued here since the mid-1990s, is still used elsewhere in the world.

The rotary engine, with its fewer moving parts and flatter high-end torque curve than an IC engine, was considered an advanced motor system when it was first introduced. However, rotary (or Wankel) engines have in the past experienced sealing problems, poor fuel economy and higher emissions.

But the main reason rotary engines were abandoned in the U.S. was low sales. The motoring public seemed uneasy about buying a vehicle powered without pistons. Instead, the engine has a rotor with three corners that rotates inside an oval housing that provides three separate combustion chambers.

Some experts say that because automotive engineers have concentrated on improving the IC engine over recent years, the advantages of the rotary engine do not seem as great as they once were when Felix Wankel introduced them nearly 50 years ago. But that doesn't mean that the rotary engine is totally extinct. It's plausible that in the future the rotary engine could be reintroduced in this country with some design modifications on a limited scale.

Which brings us back to the gasoline IC engine. Blamed for contaminating the air, the IC engine has, over the years, been redesigned to curtail pollution. According to the EPA, engine and exhaust improvements have helped today's cars produce 60% to 80% less pollution than the cars produced in the '60s. Fuel economy also has reduced pollutants. One consumer and environmental advocacy organization reports that the nearly doubling of the miles per gallon output from cars in the mid-1960s, (14 mpg) to the federally required average of 27.5 mpg for models beginning in 1998, has saved hundreds of millions of tons of air pollutants.

So don't expect to see the IC engine on life support anytime soon.

OE manufacturers maintain there are plenty of design modifications still available to make the internal combustion engine of the present into a viable, efficient powerplant of the future. And it should be noted that this quest of reaching beyond new emission standards isn't just for the small-sized, four-cylinder engines, but for the powerplants used to power luxury cars, light trucks and SUVs, too.

Emerging technology

One of the more refined designs for improving efficiency of the IC engine is gasoline direct injection or GDI technology. Currently, nearly all of the major OEs have some type of GDI program underway, and one Japanese manufacturer has already implemented a GDI system.

After more than 15 years of research, Mitsubishi, in 1998, introduced the Carisma, the world's first mass-produced GDI-powered vehicle for the European market. Mitsubishi's 4G93 GDI engine combines the performance of a gasoline engine with the fuel economy of a diesel, while significantly reducing CO2 emissions. Following an agreement between Mitsubishi and Volvo, the Swedish automaker began using these unique Japanese-designed 1.8L Gasoline Direct Injection engines in the Volvo S/V 40.

The GDI concept is considered a large step beyond conventional fuel injection engines, where fuel and air are mixed outside the cylinder. This allows for waste between the mixing point and the cylinder, as well as imperfect injection timing. However, in Mitsubishi's GDI engine, fuel is injected directly into the cylinder with precise timing, eliminating waste and inefficiency. By operating in two modes, Ultra-Lean Combustion Mode and Superior Output Mode, the manufacturer claims its GDI engine delivers both unsurpassed fuel efficiency and superior power and torque.

The direct injection concept ensures that each fuel molecule to be used to maximum efficiency, which results in greater horsepower and improved gas mileage. It's estimated that the Mitsubishi GDI engine uses 15-20% less fuel than its conventionally injected counterpart. The GDI system also allows for a complete fuel charge burn, thereby offering reduced emissions and cleaner air.

Mitsubishi believes that just as carburetors were replaced by multi-port fuel injection (MPI) in the 1980s, gasoline direct injection will become the industry standard for the future.

So why aren't there more GDI systems being used today? The main reason is the cost. The development of electronically controlled GDI engines is an extremely expensive enterprise, which some industry experts have concluded has cost the auto industry hundreds of millions of dollars, which is probably why Volvo chose to adopt the Mitsubishi engine in its S/V 40 vehicle rather than developing its own system. Another giant step in reducing fuel use and emissions can be seen with Saab Automobile's latest concept — the Saab Variable Compression (SVC) engine. This design enables fuel consumption to be radically cut while increasing engine performance per liter of engine displacement.

The combination of reduced engine displacement, high supercharging pressure and a unique system for varying the compression ratio, allows the SVC engine to reduce fuel consumption of a conventional naturally aspirated engine by up to 30%.

Saab reports that the five-cylinder SVC engine has a displacement of 1.6L, though it can deliver power comparable to a highly tuned 3.0L engine when needed.

The unique feature of the SVC engine is its variable compression ratio capabilities. The SVC engine has a cylinder head with integrated cylinders (referred to as a monohead). The compression ratio is varied by adjusting the slope of the monohead in relation to the engine block and internal reciprocating components. This alters the volume of the combustion chamber with the piston at top-dead center, which in turn, changes the compression ratio.

The SVC concept and the 1.6L five-cylinder engine represent a leap forward in engine technology and provide a completely new platform for further engine development. The fact that the compression ratio parameter can now be controlled enables more accurate engine operation, and therefore, higher efficiency. The SVC can be combined with other engine technologies to further improve performance, lower fuel consumption and reduce exhaust emissions.

Hybrids

The marriage between a gasoline IC engine with an electric motor is yet another opportunity that breathes life into the internal combustion engine.

Unlike purely electric-powered vehicles, hybrids do not need to be plugged into an outside electricity source, and automakers are wagering that greater environmental and energy consciousness, as well as stricter emission rules, will boost demand for such cars. But how strong this demand will be remains to be seen.

Looking Ahead

As we peer down the road, the future for the IC engine appears to be secure. Honda, Ford and Volvo all have production engines now in some models that are actually cleaner than California's ultra low emission requirements.

And the introduction of hybrids on the highways is seen by many as a sign that fuel-cell-powered cars will not make significant advances into the vehicle market for at least 20 years.

The consensus is that new engine management systems, designs and materials are expected to keep the IC engine breathing healthy (and much cleaner) for quite some time.