A look back, a look forward

Aug. 5, 2015
The quest for further gains in fuel economy continue, mandated by a little thing called CAFE, short for Corporate Average Fuel Economy, a series of regulations enacted by Congress passed in reaction to the OPEC embargo of the ’70s.

My very first job was pumping gas at the service station where my dad filled up his work van and got the family station wagon’s oil changed. I was just under 16 years old, and the year was 1974. Gas had risen to a shocking $0.55 a gallon in response to the Organization of Petroleum Exporting Countries (OPEC) oil embargo that started the year before and all of a sudden, those little clown-size cars that were coming out of Japan and boasting double-digit fuel economy didn’t appear all that silly anymore. Once a nation that feasted on the world’s resources, Americans got a quick lesson on just how dependent we’d become.

Today, that double-digit fuel economy foreign compacts were offering wouldn’t even come close to the average fuel economy being achieved by modern mid-sized sedans. And the quest for further gains in fuel economy continue, mandated by a little thing called CAFE, short for Corporate Average Fuel Economy, a series of regulations enacted by Congress passed in reaction to the OPEC embargo of the ’70s.

The good old days

I drove to work in a 1966 Dodge Dart 4-door equipped with a 318 cid (Editor’s note:  That’s cubic inch displacement for you young techs. We didn’t list engine sizes in liters back then!) V8 mated to an automatic three-speed transmission. I don’t remember the fuel mileage that old beast was capable of, but at the time no one really cared. Before the embargo, gas only cost $0.20-0.25 a gallon! I do know that, like most cars of that era, mileage was a single-digit calculation unless you really kept a light foot on the pedal and never drove in the city.

About the time the embargo was in full swing, the average Joe was taking his frustration out on anyone and anything he could. One popular story that floated around was the guy that had just bought a new (Chevy, Ford, Dodge – it varied depending on who was telling the story) and was getting 100 miles to the gallon. When he took the new car in for service, he bragged about this impossible number to his service writer. Later that day, the owner returned for his car only to be told that the carburetor installed was a “special prototype” that should never have made it past the last line check and they (the dealer) had been instructed to replace it with another and return the magic carb back to the factory. The end of this story also varied quite a bit depending on the storyteller and covered everything from getting his magic part back by force to being escorted off the property by Federal agents who were pledged to guard the prototype with their very lives.

Any truth to that story? I doubt it, especially if you look at the designs of the time. Carbureted engines, mechanical points ignition systems, and (by today’s standards) sloppy mechanical fit. Couple that with a thirst for BIG engines, meaning a lot of air being sucked in and a lot of gasoline being consumed. As a comparison for you out there used to only liter displacements, consider that the Dodge 440 cid V8 would roughly be the equivalent of a 7.2 liter in today’s vernacular and you get the idea.

But the embargo changed all that. Families were turning in their big gas guzzling sedans and wagons for smaller, lighter cars with tiny little 4 cylinder engines. These early cars had doors less than half the thickness of the steel battle wagons we were trading in and engines that were anemic in performance compared to what most of us were used to. And even they were grossly inefficient compared to what is available today on any dealer lot.

What’s driving the change?

In 1975, Congress passed the Energy Policy and Conservation Act (EPCA) in response to the OPEC embargo. Part A of Title III of the EPCA established the Corporate Average Fuel Economy (CAFE) standards for automobiles under the direction of the Department of Transportation (DOT). Without going into a whole lot of detail, the gist is the Fed requires the automakers to meet a fuel economy goal based on a calculated average of the models they sell. Back in 1978, that mark was 18 miles per gallon (mpg). Today, the mark the OEMs are challenged to meet is 54.5 mpg by the model year 2025 – only a few short years away by engineering and development standards

But what is the driving force today? The embargo is a reference in a history book for most and America is no longer dependent on foreign oil according to many sources. Yet fluctuations in oil production and instability in the futures market still impacts us as a nation. It wasn’t all that long ago when we all saw gasoline prices double and triple in cost, and if you have a long commute (as I did), that extra cost placed a heck of a strain on the family budget.

Other factors are also now in play; environmental factors like the concerns over pollution, global warming, and diminishing resources. Argue the reality of any of these topics to your heart’s content, but it’s hard to argue with the idea of cleaner air and renewable energy sources.

(Courtesy Audi) Who says you can't turn water into fuel? Audi's "blue crude" is diesel made from water and CO2. (Courtesy Audi) Military interest in the manmade diesel goes beyond the fuel's cost per gallon. This plant can be built anywhere, cutting the costs of getting the fuel to the field. (Courtesy Audi) Not long after Audi's partner's sucess in creating diesel fuel, another succeeded in making an alternative to gasoline called "e-benzine."

Getting to the goal line

Coincidence or luck, the mid-70s was also the time computer technology was beginning to grow. Engineers knew how to make internal combustion engines more efficient and have for decades, but the technology needed to make those engineering dreams hadn’t been invented yet. As a result, most of the initial changes were more like Band-Aids applied to existing powerplants. If you can remember the late ‘70s – early ‘80s, you’ll know what I’m talking about. Electronic ignition was soon supplemented by computer controlled fuel injection – but the injection was fed through a throttle body not that too far removed from the carburetor we were used to.

It takes a long time to develop an engine design, and in defense of the OEMs they were suddenly put into a position of trying to meet standards that weren’t even on their radar a few years earlier. Soon, though, we began seeing the first fuel sequential fuel injection systems, with single injectors feeding single cylinders and the throttle body now only used to regulate the air flow into the motor. New terminology and acronyms were being introduced just as fast and all of a sudden we needed something called a “scan tool” to repair performance concerns we started calling “driveability” problems.

Over the last three decades, engineers have taken the available technology and applied it to the same internal combustion engine that I started learning on, with one major exception. Today’s engines are high performance powerplants in every way, producing more power per liter than the hot rods of the ‘60s and ‘70s and doing it while sipping fuel at rates unheard of back then.

Onward and upward

An internal combustion engine can be tuned to run very efficiently at any single rpm/load combination. Engineers can play with ignition timing, valve timing and opening/closing rates, and even the engine’s compression ratio to achieve that efficiency.

The challenge is to make it run efficiently at ALL rpm/load conditions.

You’ve seen the technology that is allowing just that. Let’s take a look at some of the highlights and maybe take a peak at what may be just down the road.

Variable Valve Timing

The idea for variable valve timing is not a modern one, and patents can be traced back to the 1920s. Even then, engineers were seeking ways to alter the valve opening duration to match the engine’s rotational speed. After all, air has mass and that impacts the time needed to completely fill the cylinder. As speed increases time available decreases, so it would be nice to get that fill started sooner – similar to the need for advancing the ignition timing.

Depending on the source, it seems that Fiat deserves credit for the first functional variable valve timing system. Developed by Giovanni Torazza in the late 1960s, this design used hydraulic pressure to vary the fulcrum of the cam followers and provided for both variable timing and valve lift. The pressure changed according to engine speed and intake pressure and the typical opening variation was 37%.

While Fiat may have credit for the first functional design, it appears Alfa Romeo was the first to use a variable valve timing system in production cars. The 1980 Spider 2000 used a mechanical system developed by Giampoalo Garcea. Nissan and Honda both introduced electronically controlled systems in the late ‘80s. The Nissan system altered cam phasing to improve idle quality and low-end torque while the Honda VTEC actually switches to a separate cam profile at higher engine speeds to improve peak power.

Once a unique design feature, the impact these systems can make on achieving fuel economy goals has made them almost a standard for current engine designs.

(Courtesy Fiat) The Fiat Multiair system is a simpler alternative to BMW's Valvetronic system. Both eliminate the pumping losses caused by the throttle plate restriction, using the intake valves to regulate incoming air.  (Courtesy FEV) The FEV-designed connecting rod allows nearly instant compression ratio changed without costly and complicated mecahnical linkages. (Courtesy FEV) Piston poistion relative to the connecting rod changes in relation to cylinder pressure and intake vacuum. 

Valvetronic and Multiair

BMW was the first to actually find a way to overcome the “pumping losses” caused by the restriction posed by the throttle plate in the throttle body assembly. Rather than use the plate to regulate the amount of air into the engine (to control engine speed), the Valvetronic system instead uses the intake valves for the job by varying the amount of lift and opening duration. But it’s a complex system, using an additional electronically actuated cam to vary the lift.

The Fiat system is much simpler. It essentially achieves what the BMW (and Nissan) system does by using hydraulic fluid running through narrow passages connecting the intake valves and the camshaft so the two can be decoupled. This system is modulated by an electronically controlled solenoid, and there are effectively two modes. When the solenoid is closed, the incompressible hydraulic fluid transmits the intake cam lobe’s motion to the valve, as in a traditional engine. When the solenoid is open, the oil bypasses the passage, decoupling the valve, which then closes conventionally via spring pressure. For example, to shut the valves early, as in a part-load situation, the solenoid would be closed initially and then open partway through the intake cycle. Modern solenoid design, along with a carefully structured control program, makes the system possible. Aside from the fuel economy and emissions benefits, Fiat claims Multiair also results in a 10% horsepower boost. 

And engineers are working on the next step, “camless” valve trains that will be able to alter valve opening/closing in response not only to engine rpm/load but also the needs of each individual cylinder.

Variable Compression Ratio

Another “not new” idea is varying the engine’s compression ratio to match need. At higher loads, a low compression ratio is desired to minimize maximum pressures and strain on the engine components. Higher compression at part load can help reduce emissions. And these engines already exist, but primarily in labs used for research. The complexity and cost are still prohibitive to apply the technology to production cars.

But that may change. FEV, an international engineering group with roots in Germany, offers a design that could be implemented in both diesel and gasoline engine designs. The FEV design uses a connecting rod with an eccentric located at the small end, where the piston pin mounts the piston to the rod. Combustion forces and inertia are all that is needed to move the piston from one end of motion to the other, effectively providing a compression range that can be engineered to whatever specification the automaker desires. The force of compression or intake vacuum actually moves the eccentric, and engine oil pressure supplied by the normal big-end lubrication circuit simply locks the device in one position or the other. A spool valve at the bottom of the connecting rod end cap slides from side to side to vary the position, by way of a control device mounted in the oil pan. According to the company, the reaction time from high to low is 0.2 – 0.6 seconds.

Synthetic fuels

Not really an engine related topic, but I thought it would be of interest when considering all the claims you see on the Internet about running your car on water. Well, Audi has done just that – created diesel fuel using water and CO2.

The base fuel is referred to as "blue crude," and begins by taking electricity from renewable sources like wind, solar or hydropower and using it to produce hydrogen from water via reversible electrolysis. The hydrogen is then mixed with CO2 that has been converted into CO in two chemical processes and the resulting reactions produce a liquid made from long-chain hydrocarbons – this is blue crude, which is then refined to create the end product, the synthetic e-diesel.

Audi says that the carbon dioxide used in the process is currently supplied by a biogas facility but, further adding to the green impacts of the process, some of the CO2 is captured directly from the ambient air, taking the greenhouse gas out of the atmosphere.

Just weeks after producing its first batch of synthetic diesel fuel made from carbon dioxide and water, Audi has laid claim to another synthetic, clean-burning and petroleum-free fuel called "e-benzin." Audi’s project partner Global Bioenergies created the fuel. In late 2014, Global Bioenergies started up the fermentation unit for a pilot program to produce gaseous isobutane from renewable biomass sugars such as corn-derived glucose. Gaseous isobutane is a sort of raw material for the petrochemical industry that can then be refined into a variety of plastics, fuels and other applications.

(Courtesy U.S. Patent Office) Old designs are new again. This is a variable valve timing design patent drawing from the 1920s. (Courtesy American Honda) Both Nissan and Honda introduced variable valce timing systems in the late 1980s but used different approaches and focused on opposite ends of the engine load spectrum.  (Courtesy BMW) BMW was the first to design a variable valve timing system that was used on both the intake and exhaust cams. 

The next step in the process was to run the material through a conditioning and purification process, allowing it to be collected and stored in liquid form under pressure. Some of it was then sent to Germany to be converted into isooctane fuel, creating a pure, 100-octane gasoline. Isooctane is currently used as an additive to improve fuel quality, but could also be used a stand-alone fuel. Audi calls the final, refined form of the fuel "e-benzin" and claims that it burns clean due to its lack of sulfur and benzene. Also, its high grade enables it to power engines using high compression ratios for more efficiency. Audi will test the fuel composition and conduct engine tests to see how it performs before eventually trying it out in vehicle fleets and says it could see the fuel being used in consumer cars on a large scale "very soon."

Both allow fuel to be made anywhere, making it a very interesting proposition to the military. While the cost of the synthetic diesel, for example, may be higher than conventional diesel fuel, the costs to get that fuel to the battlefield makes it much higher - both in terms of dollars spent and human lives placed at risk.

Yes, if the past few decades have taught us anything it’s that things change. Expect the same going forward, but at a much faster pace.

Sponsored Recommendations

Best Body Shop and the 360-Degree-Concept

Spanesi ‘360-Degree-Concept’ Enables Kansas Body Shop to Complete High-Quality Repairs

How Fender Bender Operator of the Year, Morrow Collision Center, Achieves Their Spot-On Measurements

Learn how Fender Bender Operator of the Year, Morrison Collision Center, equipped their new collision facility with “sleek and modern” equipment and tools from Spanesi Americas...

ADAS Applications: What They Are & What They Do

Learn how ADAS utilizes sensors such as radar, sonar, lidar and cameras to perceive the world around the vehicle, and either provide critical information to the driver or take...

Coach Works implements the Spanesi Touch system

Coach Works Uses Spanesi Equipment to Ensure a Safe and Proper Repair for Customers