Powertrains: global collaborations ... hybrids ... V-blocks ... & even spark plugs!

Looking @ DCX's Global Engine

"We wanted to bring premium technical features to the entry level," says Eric Ridenour, executive vice president Product Development, Chrysler Group as he describes the GEMA (Global Engine Manufacturing Alliance) world engine. Available in 1.8-, 2.0-, and 2.4-liter displacements, the design will be shared with Hyundai and Mitsubishi and built in five plants around the globe with a total capacity of two million units. "It's the largest engine program in the history of the auto industry," says GEMA president Bruce Coventry. One that DCX claims will return $100-million in savings when it fully replaces the current four-cylinder engine family. Two of the engine plants are in Korea, one in Japan, and the remainder are in Dundee, Michigan. Each of the U.S. plants measures 450,000 [ft.sup.2], and is capable of producing 420,000 engines annually. "Lots of effort went into making this engine easy-to-assemble," says Coventry, "and toward maintaining a common base engine design throughout the design and development process." Not only can any of the GEMA plants produce any version of the engine under this plan, any technology developed by the joint venture's members can be adopted by the others without a costly redesign of "their" engine.

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AROUND THE BLOCK

Hyundai handled the initial block and cylinder head design and was the short-block lead, but JL French (www.jlfrench.com) will deliver the high-pressure die-cast aluminum block from its Sheboygan, WI, facility in fully machined form to the Dundee plants. The block is stout, has cast-in iron liners, and has been designed to support the naturally aspirated, turbo-charged, and supercharged performance variants that inevitably will supplement the base engines. Ridenour says it has a 300 Hz natural frequency, is 30 lb lighter than it would be if made of cast iron, and boasts a 360[degrees] bell housing attachment flange to more tightly tie the transmission to the engine.

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Ample water jackets surround each siamesed cylinder and leave enough structure to help the block take high boost pressures, resist twisting, and provide a stable sealing surface around the wedge-shape combustion chamber. Displacement is altered by fitting thicker liners or altering the stroke, and the pistons have short skirts and wear graphite patches to reduce friction. They connect to a forged steel crankshaft that sits above the balance shaft/oil pump module. It is delivered to the assembly plant as a complete unit, attaches to the bottom of the block, and draws oil from the composite (steel-plastic-steel) oil pan through its integrated single-stage oil pump. Each block is automatically measured and its pistons, main bearings and connecting rod bearings are matched to ensure the tightest tolerances. This eliminates a number of machining operations, and also contributes to a claimed low noise signature.

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INSIDE THE HEAD

The most talked-about feature of this engine is bound to be the electrohydraulic dual variable valve timing system borrowed from the latest Mercedes E-Class V6. These units use pressurized oil to adjust the intake and exhaust cam phasing on a continuously variable basis, and sit at the end of each cam. "The timing is variable throughout the rev range," says Ridenour, "with little overlap at idle and more at speed. It gives us the flexibility to use more 'natural' EGR"--through altered exhaust valve timing--"in order to reduce pumping losses." The intake cam phaser has a 40 range of motion, while the exhaust cam unit has a 35[degrees] range of motion.

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The composite intake manifold has equal-length runners, and electrically triggered flow control valves. When closed, they block just over half of the intake port below 3,200 rpm in order to increase tumble by forcing air to curl back toward the intake as it fills the cylinder. The intake manifold is delivered to the line complete with the flow control valve unit and throttle body attached.

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The cams ride on direct-acting steel bucket tappets that come in 47 thicknesses. The differences are measured in microns, say engineers, and the tappets are automatically measured and matched to each head. This eliminates the need for lash adjustment, and parallels the thought process that has the 4-3-4 cam-drive link chain ride on composite ramps within the front cover. Eliminating the need for external adjusters saved weight, cost and complexity, and helped the three automakers easily surpass their durability bogeys. The head is topped by a composite valve cover with elastomeric seals, isolated grommets, and rubber bumpers. It comes to the line with the seals, oil cap, EGR valve, and bolts in place. Coil-on-plug ignition is used across-the-board. Nemak (www.nemak.com) supplies the head castings from its facility in Monterrey, Mexico.

Looking @ BMW's V10

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Look under the hood of BMW's M5 sedan or M6 coupe and you'll find a decade of cylinders, just like the company's current F1 race engine. Here are the highlights:

* A 5.0-liter 90[degrees] V10 producing 507 hp @ 7,750 rpm, 383 lb-ft @ 6,100 rpm, and with 80% of the maximum torque available in a 5,500 rpm band.

* Bore and stroke are 92.0 mm X 75.2 mm, making this a very oversquare engine.

* The crankcase is low-pressure die-cast using an over-eutectic aluminum-silicon alloy with a minimum 17% silicon. The silicon is exposed by machining the cylinders, and the iron-coated pistons (481.7 grams, including rings) run on the uncoated bores.

* Like BMW's F1 engine, the road V10 uses a bedplate structure crankcase. Made from aluminum with a gray cast-iron inset that reduces the thermal expansion of the aluminum housing, it keeps a check on main bearing tolerances and noise.

* The high-strength forged steel crankshaft runs in six main bearings and weighs 48.1 lb.

* Valves are operated by 1.1-in. ball-shaped cup tappets weighing 31 grams. The valves measure 1.38-in. for intake, and 1.20-in, for exhaust. BMW's Double VANOS variable valve timing is fitted.

* Four pumps make sure the engine is never starved of oil. Starting at 0.6g, one of two electrically driven pumps pulls oil out of the cylinder head and pumps it back to the sump. The M6 can generate 1.0g in cornering, 1.3g under braking.

* The spark plug electrode is electrically insulated from the cylinder head and connected to a control unit that measures the ionic current flow between the electrodes. This is used to determine when to adjust ignition timing to control knock.--CAS

Looking @ E3 Spark Plugs

Norman Garrett, director of Engineering, E3 Spark Plugs (www.e3sparkplugs.com) is used to the incredulous looks he gets when he talks about the company's DiamondFIRE spark plugs. All he has to do is mention how a change in electrode design--from a single J-shaped piece with rounded corners to a three-legged unit topped by an open diamond-shaped end piece with square corners--can boost power and fuel economy in any spark-ignition engine, forces air-gap discharges, and creates the preferred edge-to-edge spark path. Then he hits you with this one: "The EPA has written the E3 into its emission rulemaking for engines at or below 19 kW under the company's original 'Pyrotek' name." (It's true.) Although the spark plug is only available in the aftermarket, Garrett and his colleagues are willing to speak to any OEM about fitting the E3 to its vehicles. Here's what else you'll want to know:

* Test results showed the plug measurably increased combustion pressure at each cycle, produced the fastest flame speed and combustion rise of any spark plug, improved power output by an average of 6% in typical engine operating ranges, and--dependent on engine class--reduced fuel consumption by anywhere from 3% to 13%.

* During testing at Michigan State, the E3 plug demonstrated a reduction in both hydrocarbon and nitrous oxide emissions across all loads and speeds when tested in a 1998 Ford Escort MPFI four-cylinder engine.

* Despite being made of conventional materials, the E3 completed 20 million firing cycles with no performance degradation.

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PERFORMANCE TARGETS

Displacement         1.8L/1,798 cc    2.0L/1,998 cc    2.4L/2,360 cc
Output (hp/lb-ft)  140/125          150/140          170/165

RELATED ARTICLE: Hybrid Powertrains: The Two-Mode Approach

While GM seems to have been inactive in the hybrid arena compared with some of its competitors, it has been slowly gaining experience with a different type of hybrid setup--on city buses. And in the not-too-distant future, this system will be available in SUVs from GM and Chrysler, and even in Mercedes luxury cars.

When it comes to hybrid powertrain technology, Toyota seems to garner the lion's share of credit given its Prius and forthcoming Lexus 400h and Toyota Highlander HV models. Honda is certainly in the game, having brought out the Insight in 1999 (http://www.autofieldguide.com/driven/1101dri03.html), followed up by the '03 Civic Hybrid (http://www.autofieldguide.com/articles/050201.html), and most recently by the Accord Hybrid (http://www.autofieldguide.com/articles/110405.html). Ford has the Escape Hybrid. But General Motors seemingly has little in the way of hybrid technology, with the exception, it seems, of its full-size Silverado and Sierra pickups with the 14-kW electric induction motor (a.k.a., "starter generator") system that shuts off the engine when you come to a stop and which feature four 120-volt/20-amp electrical auxiliary power outlets, so contractors and the like can run electrical tools. Is that all there is at GM?

Hardly. In fact, while much public attention has been focused on passenger cars with hybrid systems, GM announced in the fall of 2003 that it was equipping city buses in the Seattle area with a parallel hybrid system. Generally, that response was met with indifference. Which is rather unfortunate. After all, if you think about buses, they have the ideal starting-stopping driving cycle for hybrid systems. (The reason why there has been criticism of some of the estimated city/highway MPG numbers for hybrid passenger cars is because they don't drive that sort of stop/start, stop/start.) And consider if you have responsibility for maintaining civic equipment like buses. All of that stopping can be troublesome for brakes. But as Tom Stephens, GM group vice president, Powertrain, points out, the GM/Allison hybrid system that is being used on what has been expanded to 18 U.S. cities (for a total 335 buses) has a regenerative braking system, which means that the energy generated during stopping is put into the 600-v NiMH battery pack for the next acceleration and, importantly, the base brakes aren't activated until the bus reaches about 3 mph, so there's less wear of the foundation brakes. There are two 100-kW electric motors used and an electronically variable hybrid transmission that provides an infinite range of gear ratios to the wheels, which permit the sizing of the diesel engine used in the buses to be reduced from a typical 11 liters to 8.9 liters or even, Stephens says, 5.7 liters. All that and a diesel particulate filter result in an emissions reduction, Stephens says, of 90%. Not only is air pollution reduced, but so is noise pollution: the hybrid system results in sound levels analogous to those of a passenger car. Stephens says that based on the typical drive cycle, there is up to a 60% improvement in fuel economy. "If we replaced the 13,000 buses in the nine largest U.S. cities, we would save 40 million gallons of fuel a year," he points out. In late October 2004, GM and Shanghai Automotive Industry Corp. Group (SAIC) announced that the two companies are collaborating on a hybrid bus system for China (as well as on fuel cell development). "What is our hybrid strategy?" Stephens rhetorically asks. "We're trying to target the high-fuel consuming vehicles first. That's why we went after buses and full-size trucks."

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But there is more to come from GM in hybrids. The work done on the bus system is going to be parlayed to high volume vehicles, first the Tahoe and Yukon SUVs in the late '07 model year to be followed sometime in '08 by new versions of the Sierra and Silverado pickups. The EP 40/50 hybrid systems from the buses are becoming the AHS2, about which Stephens claims, "it combines the best capabilities of a full hybrid with proven automatic transmission technology to deliver the world's first two-mode hybrid system."

"Full hybrid" means that the vehicle so equipped can operate with electric power only, the internal combustion engine (ICE) shut off; with the ICE only; or with a combination of the two. The "two-mode" portion is the key differentiator between what GM is doing and what Toyota has done. Stephens says that the "typical" hybrid system is a "single mode" unit. There are the same full hybrid capabilities as those that the system GM has developed provide, but they're achieved in a different manner. The fundamental difference is that the AHS2 uses a more conventional transmission than the ones used in a single mode system. Stephens explains that in the GM system they are using the gearing in the transmission to amplify the torque generated by the engine and the motors. "Think of it this way," he says. "When I took my driver's test, you had to do it with a manual transmission. What do you do when you get a little nervous? You start out in third or fourth gear rather than first, and there was sluggish acceleration. The same engine would go pretty good when you put it back in first. You had a transmission to amplify the torque." And that's what they're doing with the AHS2 system: using gearing to amplify the torque. Stephens says that a mechanical path for power transmission is more efficient than an electrical path: anywhere from about 80 to 97% versus 50 to 75%. This has plenty of ramifications. For example, the size of the electric motors can be reduced, as can the size of the inverter and the batteries. There are reduced mass, reduced cost, and reduced packaging requirements. With regard to packaging, the system not only makes use of automatic transmission technology, but it is being housed in the envelope of a newly developed six-speed automatic transmission. Inside that housing there are, in addition to traditional transmission gears, two hybrid motors coupled to the gears.

Note what GM is doing here. The fundamental parallel architecture used for the buses is being deployed for AHS2, as are the control algorithms. The control hardware, Stephens says, could be taken right out of one of the six-speed transmissions they'll be producing (he estimates that GM will be annually producing nearly one million six-speeds by '08). A phrase that's often heard around GM related to all activities is "run common, run lean." Which is something that is being played out in the hybrid arena.

DaimlerChrysler is in agreement that the two-mode approach is the way to go. That corporation has joined with GM in a cooperative effort. Observes Eric Ridenour, executive vice president of Product Development-Chrysler Group, "This will reduce independent development costs and rapidly advance hybrid technology." Just as GM plans to put the first consumer two-mode hybrid systems in trucks, Chrysler will have them in the Dodge Durango shortly thereafter, in late '07 or early '08. But these systems are not limited to trucks by any means. Dr. Thomas Weber, DaimlerChrysler board of management member with responsibility for Research and Technology and Development, Mercedes Car Group, says, "We will have the design lead for rear-wheel-drive luxury cars." Weber goes on to note that this cooperation will lead to economies of scale that would not be attainable on an individual basis, which will lead, he says, to "cost reductions in favor of our customers." Weber notes that the hybrid powertrain will be tuned specifically to the "brand values" of the vehicles they are applied to, so a Mercedes car with a two-mode system will "feel" like a Mercedes.

Apparently, representatives from GM and DCX were both participating in a conference on the subject of advanced powertrain and, Ridenour explains, they saw a lot of commonality in what they were doing, which led to this agreement. Ridenour goes on to say that they think this allows them to "leap frog" the competition.

From buses to luxury cars, and perhaps someday everything in between. While the end game for the ICE replacement still seems to be the fuel-cell-powered vehicle, the road to that leads straight through hybrids. But the question that comes up, in light of the penetration that Toyota has made in the consumer mindset as regards its leadership position with hybrids, is whether GM isn't late to the game. Stephens first notes that the total market at present is on the order of 0.2 to 0.3% of the entire market, then points out, "All of these technologies are going to be with us for a good, long time." Time--and technology--will tell.

GM's TWO-MODE HYBRID SYSTEM

The two-mode hybrid system can operate on electric power only, with the internal combustion engine (gas or diesel) only, or via a combination. The key differential between this system and others is that it makes use of "conventional" automatic transmission technology, which mechanically amplifies torque so that the two-mode system has comparatively smaller, lighter motors, batteries, etc. than a single-mode system.

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By Gary S. Vasilash, Editor-In-Chief

RELATED ARTICLE: Volvo Squeezes V8 Power Into a V6 Space

Volvo's first V8 raises the bar for compact, low-emission engines.

In 1999, Jorgen Svensson, the Volvo XC90's chief program engineer, went shopping for a V8. Volvo's first SUV was in early development and though it was slated to get both inline five- and six-cylinder engines, the automaker knew it would miss out on a lucrative slice of the American luxury SUV-buying demographic if it didn't offer V8 power. The problem was that Volvo had never made any V8s, and incurring the immense investment necessary to tool up for manufacturing a whole new engine was out of the question. So Svensson was tasked with looking for an off-the-shelf unit. At first he confined his search within Ford's operations, but Volvo's unwavering requirements for the amount of crush space between the engine and the passenger compartment dictated that the V8 had to be roughly the same depth as a compact V6. Ford didn't have anything that small, but executives pointed Svensson toward Yamaha, which had everything that Volvo lacked: expertise in building compact V8s, an existing manufacturing line, and spare capacity.

The result of the collaboration between Volvo and Yamaha is a study in how to squeeze a lot of engine in a little space. Measuring just 29.7 in. long and 25 in. wide, the XC90's V8 is compact, yet produces 311 hp@5.850rpm and 325 lb.-ft.@3,900rpm. "The packaging was the most demanding part of the project," says Svensson. He says the V8 had to fit entirely between the front frame rails in order to meet Volvo's front- and side-impact standards, and it had to be transverse-mounted to allow for enough crush space. On the most basic engine architecture level that meant that the angle between the cylinder banks had to be 60[degrees] instead of the standard 90[degrees]. They went further. To buy a few millimeters in width to accommodate the structural beam network, the left cylinder bank is offset half a cylinder ahead of the right bank. All accessory components (e.g., the alternator and A/C compressor) are bolted directly onto the engine itself without brackets. To save additional space, the exhaust camshafts are driven by secondary chains attached to the intake camshafts, and the starter motor is mounted directly above the transmission.

Shrinking the V8 came with a lot of headaches, which helps to explain why more automakers don't attempt to reduce the size of their engines even though under hood packaging space is at a premium. For example, a 60[degrees] configuration is prone to generate more vibration than a 90[degrees] unit, so Volvo had to add a counterbalance shaft to help tame the NVH. Also, while going bracketless saves space, it means the positions of accessory components have to be fixed very early in the design process, leaving designers little room to make adjustments later on. And generating over 300 hp in a very confined space produces a lot of heat, so Volvo has had to double-insulate the exhaust manifold and add heat shields.

VOLVO's XC90 V8

In addition to being one of the smallest V8s in the world, the XC90's latest engine may be the greenest as well. Thanks in part to four catalytic converters (two close-coupled, two mounted under the vehicle's floor) it is the first gasoline V8 to meet ULEV II emissions standards. Since the majority of harmful emissions are produced in the first 20 seconds after engine ignition, the XC90 V8 has an increased initial idling speed of 1,250 rpm to help quickly warm the cats, and a lean air/fuel mixture to keep emissions down.

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By Kermit Whitfield. Senior Associate Editor

By Christopher A. Sawyer, Executive Editor