Engine history bonus question for 100 points: What technology has been shared by the P-47 Thunderbolt fighter plane, Oldsmobile's 1962 Jetfire V8, the Saab 99 Turbo, and the 2016 BMW M4 GTS?
Answer: Water injection, a proven technique for raising the knock threshold, enabling a higher compression ratio for more power output over a wide operating range. Water injection is particularly effective in highly boosted engines, hence BMW's adoption of it in a limited-production run of M TwinPower 3.0-L Turbo inline six units powering the track-day-focused M4 GTS.
BMW's engineering logic says that in turbocharged engines, the intake air is heated in the turbo compressor to as much as 160°C (320°F). But the effectiveness of intercoolers in reducing the pressurized intake-air temperature is limited by system size, configuration, and vehicle aerodynamics. So simply increasing boost pressure to raise engine power is not viable, as it would exceed the knock threshold.
Enter water injection where, in the case of the M4 GTS application, a fine mist of H2O is injected at 145 psi (10 bar) by three dedicated injectors into the intake plenum. This reduces the intake air temperature by an additional 27°C (80°F) beyond the intercoolers' capability, allowing spark timing to be advanced and more efficient, lower-temperature combustion to be realized. The engine is calibrated for minimum 95 RON gasoline.
Water injection adds complexity and cost, as BMW realizes. In the M4, the water injection module consisting of a 1.3 gal plastic water tank, a pump, sensors and valves resides in a compartment under the trunk. Water supply lines connect to the engine's intake plenum. The quantity of water injected varies depending on load, rpm, and temperature; track-day flogging may require the water tank be topped off at each refueling, while normal street driving extends the interval to about every fifth refueling, according to BMW engineers.
The BMW M water injection system, developed in collaboration with Bosch, uses an expanded engine ECU and a unique self-diagnosis system. If the water tank runs dry, or the system malfunctions, boost pressure and spark timing are adjusted so the engine continues to operate safely. And in everyday use, each time the engine is switched off, the water supply line automatically drains into the tank to prevent icing in freezing temperatures. (The early H2O-injected aero engines used a mixture of water and glycol for anti-icing measures.)
Besides its knock-mitigation capabilities, the BMW M4 GTS engine brims with technology for reduced mass, greater throttle response, and low friction. Its closed-deck cylinder block is engineered for increased rigidity, enabling higher cylinder pressure. The cylinder bores feature a twin-wire arc-sprayed (“plasma”) coating that reduces weight versus a linered block. The twin turbochargers are single-scroll types, and the 24 valves are actuated by Valvetronic variable lift control and Double-VANOS continuously variable camshaft timing. The result is a claimed 493 hp (368 kW) at 6250 rpm, and 442 lb·ft (599 N·m) at 4000-5500 rpm.
Porsche's 3.0-L turbo Boxer rebellion
Porsche joins the downsized-and-boosted trend in 2016, with an all-new turbocharged 3.0-L horizontally-opposed “boxer” six replacing naturally-aspirated 3.4-L and 3.8-L engines in the 911 Carrera and Carrera S. Known internally as 9A2, this is an entirely new architecture targeting increased efficiency and lower CO2 emissions with added power.
The 3.0-L as fitted to the Carrera gets an extra 20 hp (15 kW), with peak output now at 365 hp (272 kW). The Carrera S engine also gains 20 hp, for 414 hp (309 kW) total. Peak torque also is increased by 44 lb·ft (60 N·m), to 331 and 368 lb·ft (450 and 500 N·m) on the respective models, available from 1700 to 5000 rpm.
The new boxer uses one BorgWarner turbocharger per cylinder bank. The hotter S version of the 3.0 L features modified turbine compressors, a specific exhaust system and tuned engine management. The mono-scroll, fixed-vane turbos use a vacuum-operated wastegate system to manage boost pressure, set at 13 psi (0.9 bar) in the Carrera and 16 psi (1.1 bar) in the Carrera S. Compression ratio on both variants was reduced 12.5:1 to 10.0:1, and both are rev-limited to 7500 rpm.
The Carrera and S will not carry “Turbo” badges; that will remain the province of the super-high-performance 911 GT, according to the company. Besides improved acceleration and top speed, the turbo engine enables the Carrera models to achieve lower fuel consumption and emissions: the S with PDK transmission has a combined figure of 7.7 L/100 km, an improvement of 1.0 L/100 km. Claimed CO2 emissions are 169 g/km for the regular Carrera, 174 g/km for the S.
The move to turbocharging required a new engine airflow system for combustion and intercooling in this industry-unique rear engine application, with combustion air entering the car body in the center of the rear spoiler and flowing through ducts to the induction manifold and twin intercoolers. The 3.0-L's Continental-supplied, centrally-located injectors are fed by two fuel pumps, one per cylinder bank, operating on a system pressure of up to 3626 psi (250 bar). Variable exhaust-camshaft timing facilitates precise control of the charge exchange process. On the intake side, Porsche's VarioCam Plus adjusts both valve lift and opening duration.
The 9A2 engine features plasma-coated cylinder bores, its iron content helping to reduce ring-to-bore friction, according to Porsche engineers. Overall mass reduction was a focus of the development program; the two turbochargers and their intercoolers and related plumbing added 77 lb (35 kg) to the 911's powertrain, requiring extensive use of FEA to then remove 33 lb (15 kg). The crankcase uses a new design with thin-wall coolant galleries and different aluminum alloy to save 3.3 lb (1.5 kg). A reinforced-plastic oil pan replaced the old aluminum pan, saving 4.4 lb (2 kg). A new-design oil pump cuts 2.6 lb (1.2 kg).
The biggest single mass reduction is in the 911's exhaust system: 15.4 lb (7 kg). Reduced parasitics are addressed by the clutched water pump, which allows complete decoupling from the engine; this also helps the engine reach operating temperature faster. The A/C is also clutched.
The new boxers' power flows through a new dual-mass flywheel and twin-disc clutch.
Hyundai-Kia's new Kappa turbo triple
Powertrain engineers at Hyundai's Namyang R&D complex developed the new 1.0-L T-GDi “Kappa” 3-cylinder engine to cover a broad range of products under both the Hyundai and Kia brands, in multiple global markets. The new triple debuted in late 2015 in the Europe-only Cee'd GT range, and is expected to power North American models (including Accent, Rio, Forte, Elantra, Soul and Veloster) over those vehicles' next product cycles, according to industry suppliers apprised of Hyundai-Kia's future product schedule.
Key development bogies were led by the need to deliver power and torque equivalent to the current G4FC 1.6-L GDI unit but at lower rpm and with 10 to 15% lower fuel consumption. Initially there will be two European market output ratings: 99 hp (74 kW) and 118 hp (88 kW). Both versions deliver a rated peak 127 lb·ft (172 N·m) from 1500 to 4000 rpm.
High-pressure die casting (HPDC) the aluminum cylinder block provided mass savings, even though it uses iron liners; the fully dressed engine and manual transmission weigh 182 lb (82.4 kg), Kia claims. The block's ladder-frame construction adds to its structural stiffness. Additional weight savings comes from integrating the timing drive cover with the engine support bracket, and reducing the piston compression height. For reduced-friction operation with improved durability, the new triple's piston skirts are embedded with molybdenum disulfide, and piston oil rings are chromium nitrided, applied using physical vapor deposition (PVD) developed for Hyundai's Tau series engines.
The Kappa cylinder head breathes via straight intake ports, rather than the slightly curved port in the incumbent G4FC engine. Engineers explain that the straight port terminates in a shrouded intake valve configuration for improved tumble for more rapid combustion, improved knock suppression and greater low-end torque. The engine is also fitted with an integrated exhaust manifold for faster catalyst light off.
A single-scroll turbo is used in conjuction with an electrically operated wastegate. Each fuel injector features six laser-bored holes arrayed in a pyramid configuration for optimum dispersion in the combustion chamber. The injection systems operates at up to 2900 psi (200 bar).
Two thermostats allow independent cooling of the block and head. The head's thermostat opens at 190°F (88°C) to avoid detonation, while the block's opens at 221°F (105°C) to reduce mechanical friction.
GM brings 2.8-L Duramax diesel to midsized trucks
The official EPA fuel economy estimates-31 mpg highway, 22 city, and 25 combined-make the 2016 Chevrolet Colorado and GMC Canyon powered by GM's 2.8-L Duramax 4-cylinder turbodiesel the most fuel-efficient pickups sold in North America. Automotive Engineering has put many road-test miles on the new midsized diesel trucks, in Michigan and California, and found it's easy to exceed 30 mpg on a highway trip sans load.
The new engine-part of the trucks' North American product plan since its inception-produces SAE-rated 181 hp (135 kW) and 369 lb·ft (500 N·m), giving the Colorado/Canyon towing capability of 7600 lb and 7700 lb (3447 and 3492 kg) in their respective 4WD and 2WD variants, topping a number of full-size spark-ignited competitors including the latest Ram 1500 V6 and naturally aspirated Ford F-150 3.5 L V6. The diesel is paired with GM's 6L-50 6-speed planetary automatic, with standard 3.42:1 final drive gearing that includes the G80 limited-slip/locking differential.
A descendant of GM's previous diesel-development relationship with Fiat, the Thailand-built “mini Duramax” carries DNA from VM Motori-it's a cousin to the VM-sourced diesel briefly available in the Jeep Liberty, and has a 2.5-L variant for global markets. “The team spent more than three years developing the new 2.8 for use in the midsize trucks,” explained Assistant Chief Engineer Scott Yackley. “There was a lot of detail work in not only making the engine emissions compliant, but also able to meet North American customer requirements for smooth and quiet operation.”
The four-cylinder Duramax was launched in 2011, its architecture combining a cast-iron cylinder block and aluminum head, the latter secured with 10 head bolts. A laminated steel-and-aluminum “acoustic” oil pan is part of a comprehensive NVH attenuation package-twin balance shafts; unique fuel injection timing map in the Continental ECU; a centrifugal pendulum absorber (CPA); hydraulic engine mounts; and strategic insulation including three acoustic absorbers on top of the engine-for North America that is quite effective in making the diesel almost invisible to ears inside the cabin.
Yackley noted that engineers relocated the oil pump so it is now driven off of a balance shaft, measurably smoothing the pump's vibration profile. A segment-first technology he's proud of is the CPA, integrated with the torque converter and supplied by Luk. The CPA, a type of tuned mass absorber, contains a secondary spring mass that, when energized, cancel the diesel's amplitude of torsional vibrations. CPAs are currently used on BMW and Mercedes automotive diesels, an area in which Luk (part of Schaeffler Group) has deep experience.
The Honeywell M12 EC-5 turbocharger is a variable-geometry machine operating at 35-40 psi boost pressures under peak loads. It features a new compressor wheel design optimized for performance and low noise, Yackley said. Exhaust exits through a long megaphone- shaped “venturi-cooled” tailpipe similar to those used on Duramax V8-equipped 2500/3500 trucks. There is no muffler on the diesel Colorado/Canyon, because the truck meets GM's pass-by noise standards. Yackley noted that sans muffler, the system produces less backpressure downstream of the DPF (diesel particulate filter).
Another segment first is the integrated, driver-selectable exhaust brake system, similar to that used on GM's HD diesel models. When the exhaust brake is engaged in Cruise mode, algorithms signal the cruise control system to maintain the desired downhill vehicle speed, keeping the driver from having to apply the brakes and exit cruise control to maintain speed. In non-cruise mode, the transmission and the exhaust brake deliver the correct amount of braking to assist in vehicle control, regardless of vehicle load.
A somewhat controversial design/engineering decision is the diesel's timing belt, rather than a chain, which Yackley claimed is suitably robust for a 150,000 mi (241,000 km) service life before replacement. The choice of a belt has GM diesel fans buzzing on various Internet blogs.
Cold-start was another focus for Yackley's team. The Duramax employs a ceramic-tip glow plug in each cylinder to pre-heat the combustion chamber, along with a larger output starter and bigger-amp-hours battery. A block heater kit is available for extreme-cold conditions.
Fully dressed, the Duramax weighs about 510 lb (231 kg), according to Yackley. With its full emissions suite including cooled EGR module, diesel oxidation cat, SCR, and particulate filter, the diesel option is 250 to 300-lb (113 to 136-kg) heavier than the GM 3.6-L all-aluminum gasoline V6 also available in the trucks, and about 430 lb (195 kg) heavier than the spark-ignited 2.5-L inline four base engine.
As an integrated package, the 2.8-L Duramax and Colorado/Canyon are impressive despite the diesel's $3700 option price. Broad torque delivery, a responsive throttle, minimal turbo lag at low rpm, and a nearly perfect match of transmission and final gearing make the trucks unique and desirable, and not just for diesel enthusiasts.
Nissan VR30DETT: new 3.0-L twin turbo
The first Nissan twin-turbo V6 to power an Infiniti-brand model debuts in the 2016 Q50 Red Sport 400, a special high-performance sedan aimed at BMW's M5.
Based on Nissan's VR-series V6 launched in 3.8-L form on the 2007 GT-R, the new direct-injected engine is designated VR30DETT. It will be available with two performance ratings: 400 hp (298 kW) and 350 lb·ft (475 N·m), and 300 hp (224 kW) and 295 lb·ft (400 N·m). Both engines make peak power at 6400 rpm, with peak torque available from 1600-5200 rpm.
The aluminum 60° cylinder block features “square” 86 × 86-mm (3.39-in) bore and stroke dimensions, with thermal-arc-sprayed bores. The technology, also known as “plasma coating,” is claimed to reduce ring-to-bore friction by 40% and saves 3.8 lb (1.7 kg) compared with the outgoing VQ-series V6, Kyle Vargason, Manager of Infiniti Product Planning, told Automotive Engineering.
The all-new aluminum cylinder heads were thoroughly redesigned for boosted DI duty. They incorporate integrated exhaust manifolds, with close-coupled catalytic converters and compact twin direct-mount IHI turbochargers with twin air-to-water intercoolers. The cast-in manifolds allow the cats to reach operating temp twice as fast as those of the old VQ engines. They also result in an 11.7-lb (5.3-kg) mass reduction versus separate manifolds.
An optical turbine speed sensor allows the twin-turbo system to perform up to 220,000 rpm at steady condition and up to 240,000 rpm at transient condition, said Vargason. He explained that the optical sensor, along with an electronically-controlled-and-actuated wastegate, provide a higher degree of boost control and improved response in transient conditions. Also helping to increase engine response time is a new electronic intake cam phaser.
To reduce weight, the lower oil pan, cam covers, and intake manifold are molded using an organic-derived reinforced plastic resin. As installed in the Q50, the new VR30DETT weighs in at 486.3 lb (220.6 kg) fully dressed. The turbocharger/intercooler system (which Nissan calls the CAC) accounts for 56.9 lb (25.8 kg). Sans CAC, the 3.0-L V6 weighs 39.1 lb (14.1 kg) less than the 3.7-L VQ-series V6 it replaces.
Moving to direct injection helps increase fuel economy by 6.7% versus the 3.7-L, Nissan engineers claimed. The VR30DETT is manufactured at the Iwaki, Japan, engine plant.
First production Turbo engine for Honda
It's remarkable that 2016 marks the first-ever appearance of a turbocharged engine in a Honda-badged production car. Prior to the 1.5-L DOHC I-4 in the all-new Civic, Honda offered turbo bikes with electronic port fuel injection (the CX500 and CX650 V-twins) in 1982-83, and a few years later was winning Formula 1 races (and the 1988 F-1 Constructor's title) with its dominant turbo V6.
But despite being a latecomer to the downsized/boosted trend for passenger vehicles, the new Civic engine brings proven technology and formidable performance. Equipped with direct injection and a low-inertia single-scroll Mitsubishi TD03 intercooled turbo machine with electric wastegate, the DOHC engine is SAE rated at 174 hp (130 kW) at 5500 rpm, and 162 lb·ft (220 N·m) available between 1800 and 5500 rpm. Honda is touting EPA fuel economy estimates of 31 city/42 highway/35 combined mpg.
The new Turbo engine's base architecture follows established Honda practice using a die-cast aluminum cylinder head and block, and undersquare (73.0 × 89.4 mm) bore/stroke dimensions. The block features cast-iron cylinder liner that are “plateau” honed using a two-stage machining process to help reduce piston-to-bore friction and improve long-term wear characteristics. The block houses a micropolished, forged-steel crankshaft and con rods. The rods use fracture-split “cracked” bearing caps, and drive a new-design lightweight piston that employs a moly-coated skirt and low-friction ion-plated rings.
Both piston crown and intake port geometries are designed to promote a high-tumble inlet charge that helps optimize combustion efficiency. Pumping losses are minimized, and torque is increased, by the engine's independent variable valve timing that has authority over both intake and exhaust camshafts. Note that the new Turbo engine does not employ Honda's i-VTEC system which also controls valve lift as well as timing. (The new Civic also is available with a 2.0-L naturally-aspirated, oversquare, port-injected I-4 featuring i-VTEC.)
To help manage the thermal challenges of the boosted engine (peak boost pressure: 16.5 psi/1.13 bar; 10.6:1 compression ratio), the cylinder head features “strategic” cooling with coolant jackets surrounding exhaust ports, and sodium-cooled exhaust valves. The underside of each piston crown is cooled by a pair of oil jets. The exhaust manifold is cast integrally with the head, following the industry trend toward faster catalyst light off.
To optimize space in the compact, 4-valve combustion chamber M12-type spark plugs rather than the larger M14 type are used.
A low-friction, silent-chain drives the two camshafts-both of them hollow for reduced reciprocating mass. And low-friction oil seals are used throughout.
Turbo Civic models offer a Honda-engineered CVT that was developed from the unit used in 4-cylinder Accord models, but with a final-drive ratio that is 4.7% higher, for reduced engine rpm during highway operation. Uniquely, Honda's CVT uses a twin-damper torque converter to help reduce turbocharger lag during acceleration. In a series of test drives of the 2016 Civic Turbo, Automotive Engineering found performance to be far superior to that of the 2.0-L model, and about on par with Honda's 2.4-L engine, with linear power delivery through the 5500-rpm torque peak.
FCA adds water-cooled EGR to Pentastar V6
FCA's “Pentastar” 3.6-L gasoline V6 receives significant upgrades for 2016 that enable the broadly-used engine to gain efficiency, while positioning it for a move to direct injection and advanced aftertreatment strategies at a future date.
The addition of new liquid-cooled EGR, a new two-step variable valve lift system on the intake side, and increased compression ratio to 11.3:1 (from 10.2), enable the V6 to deliver 6% greater fuel economy on the combined U.S. FTP along with a 5.0 hp/3.7 kW increase (to 295 hp/220 kW) and 15% more torque under 3000 rpm, according to Bob Lee, FCA North America Vice President of Engine, Powertrain and Electrified Propulsion.
The new water-cooled EGR, typically a feature of heavy diesels, reduces exhaust-gas temperature from 650°C to 130°C (1202°F to 266°F), Lee told Automotive Engineering. The reduced gas temperature helps enable the higher compression ratio by suppressing knock at higher loads. And the EGR in itself delivers a 0.8% improvement in fuel economy and low NOx emissions, he said. High-tumble intake ports and shrouded valves further enhance fuel, air, and exhaust mixing.
The new valvetrain (https://youtu.be/YZtqCq9TXZg) is situated in a new, lighter thin-wall cylinder head. It is activated by oil pressure under control by four solenoid valves-two for each cylinder head. Each roller cam follower incorporates a high-lift section held in place by a spring-loaded lockpin; the high-lift mode (10.3 mm/0.41 in) is the default.
On acceleration, a solenoid valve opens and oil pressure pushes the lockpin, releasing the high-lift follower section. It pivots down on a bushing, and the roller follower runs on low-valve-lift (5.75 mm/0.23 in) cam lobes, in which the engine stays through to the 2800-rpm switchover point.
The switchover reduces pumping work and contributes to improved combustion, which delivers both the modest increase in horsepower and boosts fuel economy by 2.7%, Lee explained. New eight-hole fuel injectors (vs. the previous four-hole), high-tumble intake ports and 100-mJ ignition coils combine for a claimed 1% fuel economy improvement. The 2016 engine's VVT authority has been increased to a range of 70°, vs. 50° previously. (VVT on the old Chrysler-designed engine was part of the control system that eliminated the need for EGR.) And the system expands the operating range of the carryover idle stop/restart system-a real-world fuel economy benefit that also gives FCA a CAFE credit.
These upgrades added 13 lb (6 kg) to the engine's overall mass, the EGR and variable lift system accounting for over 7.5 lb/3.4 kg. Along with the lighter head castings, weight reduction actions include a lighter (by almost 2 lb/0.9 kg) and stronger block; smaller oil pan; the new two-piece intake manifold, and even details like nodular cast-iron main bearing caps vs. the old powder cast iron-a 0.8-lb (0.4-kg) savings. On average the upgraded Pentastar V6 weighs 4 lb/1.8 kg less than its predecessor.
Various friction-reducing improvements, including slimmer crankshaft journals and crankpins, improve fuel economy 1%.