Category Archives: New Technology

Cadillac Next-Gen V-6 Engines Led by 3.0L Twin Turbo

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DETROIT – Cadillac today announced a new generation of V-6 engines, led by an exclusive Twin Turbo V-6 that will be one of the industry’s most advanced six-cylinder gasoline engines. It leverages the latest technology to balance efficiency, performance and refinement in the upcoming, top-of-the-range CT6 luxury performance sedan.

The all-new Cadillac 3.0L Twin Turbo is designed to achieve new thresholds of refinement and specific output for the brand’s new prestige luxury sedan, which makes its world premiere March 31, at the New York International Auto Show. Production begins late this year at General Motors’ Detroit-Hamtramck Assembly Plant.

Peak output is estimated at 400 horsepower (298 kW) and 400 lb-ft of torque (543 Nm), making it one of the most power-dense V-6 DOHC engines in the world, developing 133 horsepower (99 kW) per liter.

The 3.0L Twin Turbo is the only six-cylinder engine to combine turbocharging with cylinder deactivation and stop/start technologies to conserve fuel. Cadillac expects the combination to enhance fuel economy by up to an estimated 6 percent. Cylinder deactivation temporarily deactivates two of the cylinders in light-load driving conditions to enhance efficiency and seamlessly reactivates them when the driver demands full power.

With the stop/start system, the 3.0L Twin Turbo is shut down in certain driving conditions such as stop-and-go city driving to reduce fuel consumption, automatically restarting when the driver takes his or her foot off the brake pedal.

“Cadillac’s elevation on the world stage is driven in great part by its advanced powertrain technology and the all-new 3.0L Twin Turbo powers past the traditional segment leaders with higher degrees of the performance and refinement their reputations were built on,” said Rich Bartlett, assistant chief engineer.

The highly-acclaimed Hydra-Matic 8L90 eight-speed automatic transmission transfers the 3.0L Twin Turbo’s power to the CT6.

Similar to the turbo system in the track-capable Cadillac ATS-V, the new 3.0L Twin Turbo features turbochargers with lightweight, low-inertia titanium-aluminide turbine wheels and an efficient, patented low-volume charge-air cooler, which contribute to optimal boost production and more immediate power delivery.

The advanced, low-inertia turbochargers enable the engine to sustain peak torque from 2,500 rpm to 5,000 rpm, giving it a broad torque curve that is conveyed to the driver through a feeling of responsive, sustained power across the entire rpm band.

“Torque is the pulling power of an engine and the new 3.0L Twin Turbo delivers it with confidence-inspiring smoothness and progression,” said Bartlett. “In fact, the potency of the torque across the rpm band is matched only by the satisfaction of the horsepower created as those revs climb quickly to 6,500 rpm.”

The 3.0L Twin Turbo’s estimated 400 horsepower and 133 hp per liter is 27 percent greater than the BMW 740Li’s 3.0L turbocharged I-6 (315 hp and 105 hp/L) and 29 percent more than the Audi A7’s 3.0L supercharged V-6 (310 hp and 103 hp/L).

All-new architecture

Cadillac’s new 3.0L Twin Turbo is part of a new generation of technologically advanced V-6 engines, which includes a new version of the award-winning 3.6L naturally aspirated engine employed for years across the brand’s model range. Each features all-new structural and combustion elements designed to complement higher performance and greater efficiency with exceptional quietness and smoothness.

The 3.0L Twin Turbo is up to 5 dB quieter than the Audi 3.0L TFSI engine, while the 3.6L is up to 4 dB quieter than the Infiniti 3.7L V-6.

Features shared by the 3.0L Twin Turbo and 3.6L include:

  • Stronger, stiffer aluminum block with increased structure in the bulkheads for superior rigidity
  • Tough, refined rotating assembly with a stiff forged-steel crankshaft, friction-reducing polymer-coated pistons and strong high-copper-content, sinter-forged connecting rods
  • New four-cam phasing system with intermediate park technology that enhances efficiency by enabling late inlet valve closing in certain conditions
  • All-new, patented “targeted” cooling system that provides strategic cooling of the engine’s hottest areas while simultaneously fostering faster warm-up, which enhances efficiency
  • New cylinder heads that enhance combustion performance and include direct injection and feature integrated exhaust manifolds
  • Revised, simplified timing drive system with cushioned chain sprockets contributing to quieter engine operation
  • All-new oiling system moves the pump inside the block for quieter operation. The two-stage oil pump also enhances efficiency.

“This new architecture leverages the best of Cadillac’s proven, awarded V-6 engine technology and takes it farther with a finer focus on refinement and durability to match its benchmark output and efficiency,” said Bartlett.

A more complete look at the architecture, features and attributes of the new V-6 family is available in the 3.6L release.

Unique foundation

While the 3.0L Twin Turbo is based on the same, all-new architecture as the naturally aspirated 3.6L V-6, it incorporates specific components and features to support the load and cylinder pressure characteristics unique to a forced-induction engine.

Its 86mm bore specification is about 10 percent smaller than the 3.6L, while both engines share an 85.8mm stroke. The smaller bore reduces the size and consequentially the weight of the pistons in the 3.0L Twin Turbo, making the most of the rotating assembly’s geometry to match the quicker rev capability enabled by the low-inertia turbochargers’ quick spool-up.

“With nearly zero turbo lag and a commensurately low-inertia rotating assembly, this engine climbs the rpm ladder and produces power on demand,” said Bartlett. “Its performance is more than just the maximum output – it’s how it is delivered and the new 3.0L Twin Turbo delivers it with smoothness and precision.”

The smaller bores also allow larger water jackets between the cylinders, which helps maintain optimal combustion temperatures across the rpm band and during sustained high-load, max-boost performance.

Additional features unique to the 3.0L Twin Turbo include:

  • Lower 9.8:1 compression ratio vs. 11.5:1 on the naturally aspirated 3.6L
  • Extreme duty 44MnSiV6 steel crankshaft forging
  • The pistons incorporate a specific steel insert in the top ring land to support the turbocharged engine’s higher cylinder pressures
  • Large, 36mm intake valves and 29mm sodium-filled exhaust valves enable the engine to process tremendous airflow
  • The valves are held at 19 degrees on the intake side and 16 degrees on the exhaust side vs. the 3.6L’s 18 degrees for the intake and 15 degrees for the exhaust
  • Valve spring pre-load tension is increased to manage the greater exhaust pressure during peak load performance
  • Hardened AR20 valve seat material on the exhaust side is used for its temperature robustness, while the heads are sealed to the block with multilayer-steel gaskets designed for the pressure of the turbocharging system
  • Tuned air inlet and outlet resonators, aluminum cam covers and other features contribute to exceptional quietness and smoothness.

Low-inertia turbochargers and vacuum-actuated wastegates

The twin, low-inertia turbochargers’ featherweight titanium-aluminide turbines are used with vacuum-actuated wastegate control for precise, responsive torque production. The titanium-aluminide turbines reduce rotating inertial load by more than 50 percent, compared with conventional Inconel turbine wheels. That means less exhaust energy – which spins the turbines – is wasted in stored inertial loads.

In practical terms, that means the relatively small size of the turbochargers and their lightweight turbines foster more immediate “spooling,” which practically eliminates lag, for an immediate feeling of power delivery. They produce up to 18 pounds of boost (125 kPa).

A single, centrally located throttle body atop the engine controls the air charge from both turbochargers after the temperature is reduced in the intercooler. This efficient design also contributes to more immediate torque response, while reducing complexity by eliminating the need for a pair of throttle bodies.

Unique vacuum-actuated wastegates – one per turbocharger – are used with the Twin Turbo for better management of the engine’s boost pressure and subsequent torque response for smoother, more consistent performance. They are independently controlled on each engine bank to balance the compressors’ output to achieve more precise boost pressure response.

The wastegates also work in concert with vacuum-actuated recirculation valves to eliminate co-surge from the turbos – a condition that can result in dynamic flow reversal, such as the moment immediately after the throttle closes. This overall system integration contributes to the engine’s smoother, more consistent feeling of performance.

Patented low-volume charge-air cooling

Cadillac’s patented, manifold-integrated water-to-air charge cooling system also contributes to more immediate torque response, because the compressors blow through very short pipes up to the intercooler.

With no circuitous heat-exchanger tubing, there is essentially no lag with the response of the turbochargers. Airflow routing volume is reduced by 60 percent when compared with a conventional design that features a remotely mounted heat exchanger.

“It is a very short path from the compressors to the intake ports,” said Bartlett. “The compressors draw their air directly from the inlet box and send their pressurized air through the intercooler immediately for a tremendous feeling of power on demand.”

The charge-cooling heat exchangers lower the air charge temperature by more than 200 degrees F (94 C), packing the combustion chambers with cooler, denser air for greater power. Also, the air cooler system achieves more than 80 percent cooling efficiency with only about 1 psi (7 kPa) flow restriction at peak power, which contributes to fast torque production.

Manufacturing

Both of Cadillac’s new V-6 engines will be produced at GM’s Romulus Powertrain Operations assembly facility, near Detroit, which received a $540-million investment to build the next-generation V-6 engines.

FAST FACT: In 1903, the first production Cadillac motor cars were equipped with a single-cylinder engine rated at 10 hp.

All-New, Advanced 3.6L V-6 to Drive Cadillac CT6

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DETROIT – An all-new 3.6L V-6 engine debuts in the 2016 Cadillac CT6, setting benchmarks for efficiency, refinement and durability in the brand’s range-topping large luxury performance sedan.


The clean-sheet engine design is the fourth generation of GM’s acclaimed DOHC V-6 engine family and incorporates new features, including Active Fuel Management (cylinder deactivation) and stop/start technology to enhance fuel economy up to a General Motors’-estimated 9 percent when compared to the previous engine.

Noise-reducing features, including an all-new cam drive system, contribute to the new 3.6L being up to 4 dB quieter at idle and under low load driving conditions than the benchmark Infiniti 3.7L V-6.

It also advances performance and fuel economy-optimizing technologies introduced on previous generations, including direct injection and continuously variable valve timing. Output is SAE certified at 335 horsepower (250 kW) and 284 lb-ft of torque (385 Nm).

“This new 3.6L V-6 raises the bar for all naturally aspirated V-6 engines in the industry and perfectly augments the CT6’s new standard for sophistication,” said Ameer Haider, assistant chief engineer for V-6 engines. “It builds on the established strengths of previous Cadillac engines, pushing the technologies to new heights and introducing new ones that take performance, refinement and efficiency to benchmark levels.”

GM’s Active Fuel Management system temporarily deactivates two of the 3.6L’s cylinders in light-load driving conditions to enhance fuel efficiency and seamlessly reactivates them when the driver demands full power.

With an efficiency-enhancing stop/start system, the engine is shut down in certain driving conditions such as stop-and-go city driving to reduce fuel consumption, automatically restarting when the driver takes his or her foot off the brake pedal.

Additional engine highlights include:

  • Stronger, stiffer aluminum block with increased structure in the bulkheads for superior rigidity
  • Tough, refined rotating assembly with a stiff forged-steel crankshaft, friction-reducing polymer-coated pistons and strong high-copper-content, sinter-forged connecting rods
  • New four-cam phasing system with intermediate park technology that enhances efficiency by enabling late inlet valve closing in certain conditions
  • All-new, patented “targeted” cooling system that provides strategic cooling of the engine’s hottest areas while simultaneously fostering faster warm-up to enhance efficiency
  • New, higher-flow cylinder heads that enhance direct injection performance and feature integrated exhaust manifolds
  • Revised, simplified timing drive system with cushioned chain sprockets contributing to quieter engine operation
  • All-new lubrication system with a variable-displacement, two-stage oil pump that enhances efficiency. It is located inside the oil pan, which contributes to greater noise abatement

“The new 3.6L is designed to deliver peak performance, efficiency and refinement with maximum durability – and minimal maintenance,” said Haider. “Those attributes put it at the forefront of naturally aspirated V-6 engine offered in any luxury car around the world.”

An all-new Hydra-Matic 8L45 paddle-shift eight-speed automatic transmission is paired with the new 3.6L V-6 in the CT6, elevating the CT6’s driving experience with one of the luxury market’s smoothest, quietest and most efficient powertrain combinations.

In addition to the CT6, the 2016 Cadillac ATS and CTS will offer the all-new 3.6L, where they are expected to lead their respective segments in fuel economy and non-boosted V-6 power. Also, a new 3.0L twin-turbocharged engine based on the same architecture will be offered on the CT6.

Stronger, quieter foundation

Structurally, the all-new 3.6L V-6 is similar to the proven, award-winning design of the previous V-6 engines, including an aluminum, deep-skirt cylinder block.

The optimal 60-degree cylinder angle is retained, with the bore size enlarged from 94mm to 95mm and the bore centers stretched from 103mm to 106mm. The cylinder block features six-bolt main bearing caps and inter-bay breather vents that enhance power and oil flow management.

A larger crankshaft bore diameter and wider bearing cap bulkheads in the block provide higher main bearing load-carrying capability. The block also accommodates larger, 12mm cylinder head bolts to provide greater clamping strength for the engine’s higher output.

The crankshaft is forged from 1538MV steel and inherently stiffer than a conventional cast-iron crankshaft, contributing significantly to the engine’s smoothness, quietness and durability.

Attached to the crankshaft are high-strength connecting rods and pistons. The rods are sinter-forged and composed of a high-copper alloy that stands up to high heat and resists bending, while the polymer-coated hypereutectic pistons are designed to minimize friction, allowing for a tighter piston-to-bore clearance that results in quieter operation.

The new 3.6L V-6 also incorporates oil-spray piston cooling, which helps reduce noise, lower combustion temperatures and enhance durability by drenching the underside of each piston and the surrounding cylinder wall in an extra layer of cooling, friction-reducing engine oil.

Continuously variable valve timing with intermediate park feature

Camshaft phasing allows the greatest variances in valve timing to make the most of power and efficiency. The new 3.6L V-6 engine takes that technology to the next level with intermediate park technology for the intake camshaft phasers.

Because optimal part-load efficiency requires retarding the intake cams to reduce pumping losses, the effect also reduces the effective compression ratio, which affects the engine’s cold-start performance. Conventional cam phasing system authority is limited by how far the intake cams can be retarded in the parked position without affecting cold starting.

Intermediate park technology, which incorporates an intermediate-lock intake variable valve timing cam phaser, allows the cams to be parked at the most favorable position for cold starting, while expanding the amount of intake cam retard for other conditions by adding another 20 degrees of intake phaser authority. This enhances fuel efficiency and reduces emissions.

Targeted cooling system

Unlike conventional systems, which force coolant flow from the front of the block to the back, the new 3.6L’s patented targeted cooling system sends coolant simultaneously to each water jacket in the heads and block.

This new, parallel-flow design maximizes heat extraction in the area of the upper deck, intake and exhaust valve bridges in the heads and integrated exhaust manifold with a minimal amount of coolant. The result is more even and consistent cooling, which enhances performance, and faster engine warmup, which improves cold-start efficiency and reduces emissions.

Additionally, the strategic sizing of the coolant jackets in the head and the block reduces the cooling system thermal inertia, allowing the use of a smaller water pump, which requires about 50 percent less power to drive, enhancing fuel efficiency and even allowing a lower overall height of the cylinder block.

New cylinder head design

An all-new cylinder head design builds on the airflow attributes of the current V-6, supporting a broader power band that ensures excellent low-rpm torque, for strong power at take-off, and excellent airflow at high-rpm, for greater horsepower.

Engineers achieved that through increased in-cylinder mixture motion, a faster burn rate of the air-fuel mixture and attributes that took full advantage of the new intermediate park cam phasing system.

Highlights include:

  • The intake valves are 6 percent larger, resulting in a 5-percent increase in flow capacity and a significant 25 percent increase in in-cylinder mixture motion
  • The exhaust valves are also 6 percent larger, for a 10-percent increase in flow capacity
  • The injector angle was increased from 22 degrees to 24 degrees, which helps reduce emissions and oil dilution
  • The adoption of a smaller, 12mm spark plug (vs. the previous 14mm plug) allows it to be more centrally located in the cylinder for improved flame propagation and greater light-load efficiency
  • A combustion chamber design to promote in-cylinder mixture motion, achieve a faster burn rate and increase dilution tolerance to take full advantage of the intermediate park cam phasing system

The new head design also has improved combustion chamber cooling enabled by the patented targeted cooling system, which reduces the chance for knock and enhance high-load efficiency.

An integrated exhaust manifold rounds out the head’s features, saving weight over a conventional, separate head/manifold assembly.

Direct injection and Active Fuel Management

The all-new 3.6L V-6 continues to employ direct fuel injection to make the most of efficiency and performance. Along with the placement of the fuel injector in the combustion chamber, the piston top is carefully shaped to promote a through mix of the air and fuel, and direct the fuel spray to ensure a more complete combustion.

A higher-capacity engine-driven fuel pump supports the higher output of the new engine and contributes better fuel atomization, which enhances performance, and reduced emissions.

Active Fuel Management, also known as cylinder deactivation, imperceptibly shuts down the No. 2 and No. 5 cylinders in certain light-load driving conditions to save fuel.

Refinement and durability

A number of new and enhanced features are designed to make the all-new 3.6L V-6 one of the industry’s quietest, smoothest and most durable engines:

  • Oiling system – It’s all-new and features a dual-pressure-control and variable-displacement vane pump that enhances efficiency by optimizing oil pressure as a function of engine speed. The oil pump is relocated beneath the cylinder block, inside the oil pan, contributing to the engine’s smoother, quieter operation
  • Two-piece structural oil pan – For stiffness and strength, the oil pan features an aluminum structural upper section. A stamped steel lower section provides optimal noise-absorption characteristics, for quieter performance.
  • Two-stage PCV system – This revolutionary system maintains low oil consumption. If features a pre-separator between the block and the engine’s rear cover and a high-efficiency separator in the center of the block’s “V.”
  • Camshaft drive – It is all-new, with a simpler design – two chains and six sprockets vs. the previous three chains and nine sprockets – with lower chain loads, which enhances durability. The lower tension of the chain drive, along with cushioned ring sprockets, also reduces noise and vibration.
  • High-flow intake manifold and acoustic cover – The lightweight composite intake manifold offers greater airflow capability than the current 3.6L engine, which matches with the higher-flow heads to support the new engine’s greater output. A one piece engine cover mounts atop the manifold for exceptional noise isolation.

Manufacturing

The new Cadillac 3.6L V-6 engine will be produced, along with the new 3.0L Twin Turbo engine, at GM’s Romulus Powertrain Operations assembly facility, near Detroit, which received a $540-million investment to build the next-generation V-6 engines.

FAST FACT: Cadillac’s legacy of innovative engine technologies includes the industry’s first electric engine starter (1912), the first regular-production water-cooled V-8 engine (1915) and even a V-16 engine renowned for its smoothness (1930).

Cadillac CT6 Elevates the Science of Mass Efficiency

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DETROIT – Cadillac will use an advanced mixed-material approach for the lightweight body structure of the upcoming CT6 range-topping sedan. The structure is aluminum intensive, but the new Cadillac also includes 13 different materials customized for each area of the car to simultaneously advance driving dynamics, fuel economy and cabin quietness.

CT6 Structure.1280.1280

The CT6 will debut March 31 at the New York International Auto Show and go into production late this year at General Motors’ Detroit-Hamtramck assembly plant.

“This is the rocket science of automobile construction and manufacturing today,” said Cadillac President Johan de Nysschen. “With the CT6, we used high-strength aluminum and high-strength steels; lightweight chassis components; we integrate aluminum and steel where it makes sense; we eliminate every gram of mass possible, while achieving world-class performance.”

Weight reduction helps improve fuel efficiency, contributes to desirable vehicle dynamics and aids in creating a more resilient passenger cell. Sixty-four percent of the CT6 body structure is aluminum, including all exterior body panels – and the mixed material approach saved 90 kg (198 pounds) compared to a predominately steel construction.

Thirteen complex high-pressure die cast components make up the lower structure of the CT6 body, along with aluminum sheets and extrusions. The vehicle underbody uses steel close-out panels on the lower structure to create a bank vault-quiet cabin without the added weight of extensive sound-deadening material, often used to compensate for aluminum panels in the occupant compartment.

“The structure of the CT6 is one of the most-advanced body systems we’ve ever produced,” said Travis Hester, Cadillac CT6 executive chief engineer. “The innovation surrounding our joining techniques have enabled us to create a vehicle structure with the highest torsional rigidity of any Cadillac while achieving one of the most mass-efficient vehicles in the segment.”

Cadillac in January revealed a series of high-technology material joining techniques that create a new methodology for assembling the CT6. These enabled engineers to design a completely new structure for which 21 patents are pending.

“This new construction approach has enabled us to produce a world-class vehicle that is larger in size and includes more standard equipment while achieving lower overall mass,” Hester said.

  • High-strength steel is used strategically to reinforce the body structure, and is also used in conjunction with high-strength aluminum to create a safety cage surrounding the occupants.
  • The structural portion of the B-pillar is constructed completely of high-strength steel, which was chosen to aid vehicle ingress, egress and visibility, in addition to mass savings and added cabin quietness.
  • A high-strength aluminum impact bar was added to the rear of the vehicle, and a combination of high-strength aluminum and steel was used for front and side impact zones to further increase passenger safety in the event of collisions.

A combination of aluminum spot welds, steel spot welds, flow drill screws, self-piercing rivets, laser welding, aluminum arc welding and hundreds of feet of structural adhesive are all used in assembling the body of the CT6.