Η Chevrolet ανακοίνωσε τον νέο V8 6,2-λίτρων κινητήρα της ο οποίος θα τοποθετηθεί για πρώτη φορά στη νέα Corvette.

Η πέμπτη γενιά small block V8 κινητήρων της Chevrolet, είναι τεχνολογίας άμεσου ψεκασμού, διαθέτει συνεχώς μεταβαλλόμενο χρονισμό βαλβίδων και έχει αναλογία συμπίεσης 11,5:1. Διαθέτει επίσης μια “Runners in a Box” πολλαπλή εισαγωγής, μεταβλητή αντλία λαδιού και ένα ειδικά σχεδιασμένο σύστημα εξάτμισης.

Αποδίδει 450 άλογα με 610 Nm ροπής, με κόφτη 6.600 σ.α.λ, με την Corvette με αυτό τον κινητήρα, να κάνει τα 0-100 χλμ/ώρα σε περίπου 4 δευτερόλεπτα.

Ο κινητήρας είναι πιο αποδοτικός από τον LS3 V8 αφού διαθέτει και σύστημα απενεργοποίησης των μισών κυλίνδρων και σε χαμηλά φορτία, έχει μέση κατανάλωση 9,8 λίτρα/100 χλμ.

Περισσότερες λεπτομέρειες μπορείς να βρεις στο δελτίο τύπου που ακολουθεί.

[Πηγή: Chevrolet]

Δελτίο Τύπου

All-New 2014 Corvette LT1 V-8 a Technological Powerhouse

  • Advanced technologies including direct injection, active fuel management, continuously variable valve timing support advanced combustion system
  • Preliminary output of 450 horsepower (335 kW) and 450 lb.-ft. of torque (610 Nm)
  • Helps deliver estimated 0-60 performance in less than four seconds and best-ever fuel economy in the Corvette

DETROIT – When the all-new 2014 Chevrolet Corvette arrives late next year, it will be powered by a technologically advanced, racing-proven 6.2L V-8 delivering an estimated 450 horsepower and helping produce 0-60 times in less than four seconds.

The new Corvette LT1 engine, the first of the Gen 5 family of Small Block engines, combines several advanced technologies, including direct injection, Active Fuel Management and continuously variable valve timing to support an advanced combustion system.

“Our objective for the development of the all-new LT1 was to raise the bar for performance car engines,” said Mary Barra, senior vice president, global product development. “We feel that we have achieved that by delivering a true technological masterpiece that seamlessly integrates a suite of advanced technologies that can only be found on a handful of engines in the world.

“What makes this engine truly special is the advanced combustion system that extracts the full potential of these technologies. The art and science behind that combustion system make the Corvette LT1 one of the most advanced V-8 engines in the world,” said Barra.

Output, performance, and fuel economy numbers will not be finalized until early next year, but the new LT1 engine is expected to deliver:

  • The most powerful standard Corvette ever, with preliminary output of 450 horsepower (335 kW) and 450 lb.-ft. of torque (610 Nm)
  • The quickest standard Corvette ever, with estimated 0-60 performance of less than four seconds
  • The most fuel-efficient Corvette ever, exceeding the 2013 EPA-estimated 26 miles per gallon on the highway.

“The Holy Grail for developing a performance car is delivering greater performance and more power with greater fuel economy and that’s what we’ve achieved,” said Tadge Juechter, Corvette chief engineer. “By leveraging technology, we are able to get more out of every drop of gasoline and because of that we expect the new Corvette will be the most fuel-efficient 450 horsepower car on the market.”

Advanced combustion system optimized with 6 million hours of analysis

“The Corvette LT1 represents the most significant redesign in the Small Block’s nearly 60-year history – building on its legacy to make one of the world’s best engines even better,” said Sam Winegarden, vice president, Global Powertrain Engineering. “More than just great horsepower, the LT1 has been optimized to produce a broader power band. Below 4,000 rpm, the torque of the Corvette LT1 is comparable to that of the legendary, 7.0L LS7 out of the current Corvette Z06. The LT1 is a sweetheart of a power plant and drivers will feel its tremendous torque and power at every notch on the tachometer.”

Increased power and efficiency were made possible by an unprecedented level of analysis, including computational fluid dynamics, to optimize the combustion system, the direct injection fuel system, active fuel management and variable valve timing systems that support it. More than 10 million hours of computational analysis were conducted on the engine program, including 6 million hours (CPU time) dedicated to the advanced combustion system.

Direct injection is all-new to the engine architecture and is a primary contributor to its greater combustion efficiency by ensuring a more complete burn of the fuel in the air-fuel mixture. This is achieved by precisely controlling the mixture motion and fuel injection spray pattern. Direct injection also keeps the combustion chamber cooler, which allows for a higher compression ratio. Emissions are also reduced, particularly cold-start hydrocarbon emissions, which are cut by about 25 percent.

Active Fuel Management (AFM) – a first-ever application on Corvette – helps save fuel by imperceptibly shutting down half of the engine’s cylinders in light-load driving.

Continuously variable valve timing, which GM pioneered for overhead-valve engines, is refined to support the LT1 AFM and direct injection systems to further optimize performance, efficiency and emissions.

These technologies support the all-new, advanced combustion system, which incorporates a new cylinder-head design and a new, sculpted piston design that is an integral contributor to the high-compression, mixture motion parameters enabled by direct injection.

The LT1 head features smaller combustion chambers designed to complement the volume of the unique topography of the pistons’ heads. The smaller chamber size and sculpted pistons produce an 11.5:1 compression ratio, while the head features large, straight and rectangular intake ports with a slight twist to enhance mixture motion. This is complemented by a reversal of the intake and exhaust valve positions, as compared to the previous engine design. Also, the spark plug angle and depth have been revised to protrude farther into the chamber, placing the electrode closer to the center of the combustion to support optimal combustion.

The pistons feature unique sculpted topography that was optimized via extensive analysis to precisely direct the fuel spray for a more complete combustion. The contours of the piston heads are machined to ensure dimensional accuracy – essential for precise control of mixture motion and the compression ratio.

Race-proven legacy, state-of-the-art performance

The first Small Block V-8 debuted in the Corvette in 1955. It displaced 4.3L (265 cubic inches) and was rated at 195 horsepower, drawing air and fuel through a four-barrel carburetor. Five years later, V-8 power helped Corvette secure its first victory at the 24 Hours of Le Mans.

In 2012, the Small Block-powered Corvette Racing C6.R beat Ferrari, BMW and Porsche to sweep the drivers’, team, and manufacturer championships in production-based American Le Mans Series GT class. These championships make Corvette Racing the most successful team in ALMS history, with a total of 77 class wins, eight drivers’ championships, and nine manufacturer and team championships since 2001.

“The engine requirements for a production car and a race car are remarkably similar,” said Jordan Lee, Small Block chief engineer and program manager. “In both cases, you want an engine that is powerful and efficient, compact and lightweight, and durable. That combination is what made the original Small Block so successful. Today, the introduction of state-of-the-art technologies and engineering makes one of the best performance car engines in the world even better.”

As an example, the new LT1 engine is 40 pounds lighter than a competitor’s twin-turbo 4.4L, DOHC V-8 with similar output. That weight savings not only improves the Corvette’s power-to-weight ratio, but also contributes to a near-perfect 50/50 weight balance for enhanced steering response and handling.

The new LT1 is also four inches shorter in overall height than the competitive DOHC V-8. That also improves handling by lowering the center of gravity while enabling a low hood line – contributing to the Corvette’s iconic profile, as well as ensuring exceptional driver visibility.

The new LT1 is the third engine in the Corvette’s history to be so-named, with previous versions introduced in 1970 (Gen 1) and 1992 (Gen 2). All iterations of the LT1 – and all Small Block engines – have shared a compact design philosophy that fosters greater packaging flexibility in sleek vehicles such as the Corvette.

“The power and efficiency of the Small Block V-8 are hallmarks of Corvette performance,” said Lee. “But, the compact size and great power-to-weight are just as important for the overall driving experience. The all-new LT1 will play a huge role in making the all-new Corvette a world-class sports car, in terms of technology, performance, and refinement.”

Engine features and highlights

All-aluminum block and oil pan: The Gen 5 block was developed with math-based tools and data acquired in GM’s racing programs, providing a light, rigid foundation for an impressively smooth engine. Its deep-skirt design helps maximize strength and minimize vibration. As with the Gen 3 and Gen 4 Small Blocks, the bulkheads accommodate six-bolt, cross-bolted main-bearing caps that limit crank flex and stiffen the engine’s structure. A structural aluminum oil pan further stiffens the powertrain.

The block features nodular iron main bearing caps, which represent a significant upgrade over more conventional powdered metal bearing caps. They are stronger and can better absorb vibrations and other harmonics to help produce smoother, quieter performance.

Compared to the Gen 4 engine, the Gen 5’s cylinder block casting is all-new, but based on the same basic architecture. It was refined and modified to accommodate the mounting of the engine-driven direct injection high-pressure fuel pump. It also incorporates new engine mount attachments, new knock sensor locations, improved sealing and oil-spray piston cooling.

Advanced oiling system, with available dry-sump system: The LT1 oiling system – including oil-spray piston cooling – was also optimized for improved performance. It is driven by a new, variable-displacement oil pump that enables more efficient oil delivery, per the engine’s operating conditions. Its dual-pressure control enables operation at a very efficient oil pressure at lower rpm coordinated with AFM and delivers higher pressure at higher engine speeds to provide a more robust lube system for aggressive engine operation.

Standard oil-spray piston cooling sprays the underside of each piston and the surrounding cylinder wall with an extra layer of cooling oil, via small jets located at the bottom of the cylinders. For optimal efficiency, the oil jets are used only when they are needed the most: at start-up, giving the cylinders extra lubrication that reduces noise, and at higher engine speeds, when the engine load demands, for extra cooling and greater durability.

An available dry-sump oiling system promotes exceptional lubrication system performance during aggressive driving maneuvers and high cornering loads. It includes two stages: a pressure stage and a scavenge stage. The pressure stage includes the new, dual-pressure-control and variable-displacement vane pump.

Dexos semi-synthetic motor oil, with a 5W30 specification, helps reduce friction to further enhance the LT1’s efficiency.

New, tri-lobe camshaft: Compared to the Gen 4 Small Block, the camshaft remains in the same position relative to the crankshaft and is used with a new rear cam bearing, but it features an all-new “tri-lobe” designed lobe which exclusively drives the engine-mounted direct injection high-pressure fuel pump, which powers the direct-injection combustion system. The cam’s specifications include 14mm/13.3mm (0.551/0.524-inch) intake/exhaust lift, 200/207-crank angle degrees intake/exhaust duration at 0.050-inch tappet lift and a 116.5-degree cam angle lobe separation.

New, cam-driven fuel pump: The direct injection system features a very-high-pressure fuel pump, which delivers up to 15Mpa (150 bar). The high-pressure, engine-driven fuel pump is fed by a conventional fuel-tank-mounted pump. The direct injection pump is mounted in the “valley” between cylinder heads – beneath the intake manifold – and is driven by the camshaft at the rear of the engine. This location ensures any noise generated by the pump is muffled by the intake manifold and other insulation in the valley.

PCV-integrated rocker covers: One of the most distinctive features of the new engine is its domed rocker covers, which house the, patent-pending, integrated positive crankcase ventilation (PCV) system that enhances oil economy and oil life, while reducing oil consumption and contributing to low emissions. The rocker covers also hold the direct-mount ignition coils for the coil-near-plug ignition system. Between the individual coil packs, the domed sections of the covers contain baffles that separate oil and air from the crankcase gases – about three times the oil/air separation capability of previous engines.

Intake manifold and throttle body assembly: The LT1’s intake manifold features a “runners in a box” design, wherein individual runners inside the manifold feed a plenum box that allows for excellent, high-efficiency airflow packaged beneath the car’s low hood line.

Acoustic foam is sandwiched between the outside top of the intake manifold and an additional acoustic shell to reduce radiated engine noise, as well as fuel pump noise.

The manifold is paired with an electronically controlled throttle, featuring an 87mm bore diameter and a “contactless” throttle position sensor design that is more durable and enables greater control.

Four-into-one exhaust manifolds: The LT-1 uses a cast version of the “four-into-one” short-header exhaust manifold design used on the Gen 4 LS7 engine. The cast header passages enable consistent exhaust flow into the “wide mouth” collector at the converter.

Cooling system, humidity sensor and more: Additional features and technologies of the Gen 5 Small Block include:

  • A revised cooling system with an offset water pump and thermostat for more efficient performance
  • Air induction humidity sensor ensures optimal combustion efficiency, regardless of the surrounding air’s humidity
  • 58X ignition system with individual ignition coil modules and iridium-tip spark plugs
  • All-new “E92” engine controller.

General Motors’ investment in the Gen 5 Small Block will create or retain more than 1,600 jobs in five North American plants, including Tonawanda, New York, which recently received upgrades to support its production.

Gen 5 Small Block Combustion Driven by Advanced Analysis

Computational analysis on the Gen 5 Small Block that debuts in the next Chevrolet Corvette began five years ago and has consumed 0.1 quadrillion bytes of disk space on General Motors’ computers. That’s the equivalent of 18 billion typed pages or 23,000 DVD discs.

Much of the analysis was devoted to the engine’s all-new advanced combustion system, which supports a trio of Next-Gen technologies never before used together on the Corvette, including direct injection, Active Fuel Management and variable valve timing. They contribute to preliminary output of 450 horsepower (335 kW), making the new 6.2L LT1 the most powerful and efficient standard engine ever offered in the Corvette.

Thirty analysts worked on the Gen 5 on their computers – including the development of all-new software – for several years before the first physical test engine was built, creating a design that is more volumetrically efficient than the Gen 4 Small Block. In addition to the advanced combustion system, they designed and evaluated every component in the engine, from the connecting rods to the rocker covers. They used a variety of commercially available software and proprietary software developed by General Motors.

Designers had to start from scratch when it came to the design of the Gen 5’s new combustion system. The overhead valve arrangement and two-valves-per-cylinder arrangement was completely different than the DOHC design of GM’s other direct-injected engines. The flow field – the motion of the air/fuel mixture – is more complex with an overhead-valve design and direct injection requires more mixture swirling for optimal combustion.

To deliver on the horsepower, torque and efficiency goals for the engine, they had to determine:

  • The optimal placement of the injector in relationship to the spark plug within the combustion chamber
  • The optimal size of the intake and exhaust valves – and the angles at which they’d be held in the cylinder head
  • The size and volume of the combustion chamber
  • The configuration of the piston head, which is crucial in supporting direct injection combustion.

More than 75 iterations of combustion systems for the Gen 5 were developed and evaluated through computational analysis, before a final design was selected. The resulting cylinder head configuration for the Gen 5 is all-new, along with a new, dished piston design. They work cohesively to exploit the high-compression, mixture motion parameters enabled by direct injection. Smaller combustion chambers complement the dish volume of the pistons’ heads. The pistons also feature “risers” at the top to direct the fuel spray for a more complete combustion.

Another significant change is the reversal of the position of the intake and exhaust valves, compared to the Gen 4 Small Block. The change, which is supported by an all-new intake manifold design, enabled a straighter path for the air charge into the combustion chamber. The airflow enters the combustion chambers via large, 2.13-inch (54mm) hollow intake valves and exits through 1.59-inch (40.4mm) hollow sodium exhaust valves. The valves are held at new, 12.5-degree intake/12-degree exhaust angles, vs. the Gen 4’s 15-degree angle, and they are splayed slightly to reduce shrouding and enable greater airflow.

Additional analysis-driven engine design features include:

  • Knock performance was improved over the Gen 4 design, which enabled a higher compression ratio that supports greater power
  • The spark plug was also moved closer to the center of the combustion chamber, pushing the flame for the combustion process closer to the center of the cylinder – an essential enabler of the direct injection system’s efficiency
  • The configuration of the exhaust port supports a minute amount of exhaust gases to be drawn back into the cylinder during the next combustion cycle, for a more complete burn that enhances efficiency and reduces emissions
  • Displacement of the Corvette’s LT1 engine was optimized at 6.2L for sustaining fuel-saving cylinder deactivation with Active Fuel Management, based on the car’s weight and the engine’s torque output
  • Dozens of iterations of the wet- and available dry-sump oiling systems for the Corvette were evaluated to ensure optimal performance during the high loads of driving on a racetrack.

Computational analysis also drove mass optimization and noise-reducing initiatives with the Gen 5 Small Block, all of which supporting the implementation of the new combustion system. The direct injection system, for example, uses an engine-mounted, camshaft-driven high-pressure fuel pump. Because the feature had never been implemented on a Small Block, analysis drove the design of components such as the intake manifold, oil pan and more. The computer tests calculated the resonance of the components to predict their noise levels and “played” them against one another to determine probably noise and vibration sources. Component designs, including shape and sized, were refined until noise and vibration targets were achieved.

Inside the engine, the shapes and configurations of the rotating parts were evaluated for mass optimization, ensuring the highest quality and durability was achieved with the lightest, most efficient parts. When the need for a change was identified, it could often be implemented within a week, rather than several weeks or even months, when compared to evaluating physical components.

Gen 5 Small Block Lubrication System

The new Gen 5 Small Block’s lubrication system supports Next-Gen advanced technologies, including Corvette’s first applications of direct injection, Active Fuel Management and continuously variable valve timing. They help the completely reengineered 6.2L engine produce the greatest standard horsepower, torque and efficiency in the car’s 60-year history.

Highlights include:

  • Standard wet-sump lubrication or available high-performance dry-sump system
  • All-new variable-displacement, dual-pressure-control oil pump with increased flow capacity for optimal oiling efficiency
  • Pressure-activated oil-spray piston cooling for greater efficiency, durability and quietness
  • New windage tray design enhances oil flow control and crankcase breathing
  • Rocker covers with patent-pending positive crankcase ventilation system for greater oil life and lower oil consumption
  • Dexos semi-synthetic motor oil, including a 5W30 specification for the Corvette, that helps reduce friction to enhance the engine’s efficiency.

The available dry-sump oiling system promotes exceptional lubrication system performance during extended high-rpm use under high cornering loads. It includes two stages of oil pumping, including the new, dual-pressure-control and variable-displacement vane pump and a scavenge pump.

Efficient oiling

Variable displacement enables the Gen 5’s oil pump to efficiently deliver oil as demanded by the engine’s operating conditions. Its dual-pressure control enables operation at a very efficient oil pressure at lower rpm coordinated with the Active Fuel Management and operation at a higher pressure at higher engine speeds providing a more robust lube system with aggressive engine operation. As with Gen 3 and Gen 4 Small Block engines, the new vane-type oil pump is crankshaft-driven.

Oil-spray piston cooling, in which eight oil-spraying jets in the engine block drench the underside of each piston and the surrounding cylinder wall with an extra layer of cooling, friction-reducing oil, is standard on all Gen 5 engines – previously it was only a feature of the supercharged LS9 and LSA engines. The oil spray reduces piston temperature, promoting extreme output and long term durability. The extra layer of oil on the cylinder walls and wrist pins also dampens noise, for a quieter driving experience.

For optimal efficiency, the oil jets are used only when they’re needed the most: At start-up, giving the cylinders extra lubrication that enhances the engine’s durability, and at higher engine speeds, when the engine load demands it.

A redesigned windage tray is also used with the Gen 5, featuring a new oil scraper design. It enhances performance and efficiency by improving oil flow control and bay-to-bay crankcase breathing. The tray is mounted on the bottom of the engine, between the main bearing caps and oil pan.

Dry sump details

The dry sump system scavenges liquid oil and any resulting mixture of oil, air and crankcase gases from the bottom of the engine oil pan through an internal scavenge return tube. This oil mixture is pumped to the top of the dry sump tank (mounted in the engine compartment but external to the engine). Within the tank, the oil mixture is tangentially spilled out on a spiral-shaped internal baffle where the contact and flow about the internal surfaces of the tank promote separation of air and gasses that are entrained in the oil. These gasses are directed by the PCV system (see section below) through a series of baffles and tubes back to the combustion chamber to be burned.

The de-aerated oil is directed down the walls of the tank to collect in the 10.5-quart reservoir (wet-sump application feature a six-quart capacity), conditioned and ready for use. The second stage of the dual-stage gerotor pump then draws the conditioned oil from the tank and pressurizes it, feeding it to the engine via the oil filter and oil cooler. The routing of the engine oil to and from the dry sump reservoir also provides the benefit of passive oil cooling.

PCV-integrated rocker covers

One of the most distinctive features of the all-new Gen 5 engine is its domed rocker covers, which house a patent-pending integrated positive crankcase ventilation (PCV) system that enhances oil economy and oil life, while reducing oil consumption. It also contributes to low emissions for the Gen 5.

The rocker covers also hold the direct-mount ignition coils for the coil-near-plug ignition system. Between the individual coil packs, the domed sections of the covers contain baffles that separate oil and air from the crankcase gases – about three times the oil/air separation capability of previous engines. Each cover features and inlet and outlet path for the crankcase gases, with the separated oil dropping back onto the engine within the covers and the remaining air/gases circulated back into air intake stream for combustion. The system also prevents moisture from accumulating in the engine.

This integrated PCV system is an essential contributor of the Gen 5’s efficient performance and long-term durability – and the domes for it on the rocker covers make the Gen 5 engine instantly recognizable.

Gen 5 Small Block V-8 Durability and Validation

The Gen 5 Small Block was subjected to the toughest durability testing ever for a V-8 engine from General Motors. It included millions of hours of computational analysis that perfected the design of everything from the design of the combustion system to the shape of the connecting rods, to thousands of hours of physical testing.

Once the Gen 5’s basic design was refined on the computer, physical properties were constructed and tested on a variety of dynamometers – including a unique tilt-stand fixture that tilted the engine to simulate the load experienced in the Corvette during high-speed cornering on a racetrack. It can tilt up to 53 degrees and simulate lateral acceleration of up to 1.3g.

The toughest test session on the Corvette’s LT1 Gen 5 engine was a grueling, GM-proprietary performance durability procedure, where it was subjected to a high-speed/high-load torture session that simulated full-throttle blasts from the equivalent of 0 to 120 mph. With simulated transmission shift points inserted during the high-load test, the engine cycles non-stop between peak torque and peak horsepower for hundreds of hours – the equivalent of thousands of miles.

Testing on the Gen 5 Small Block began in late 2010. Additional procedures included:

  • Severe thermal cycle testing, which quickly cycles the engine between extreme cold and hot coolant temperatures to validate the durability of engine components such as the head gaskets, exhaust manifolds and more. The coolant temperatures ran up to 239 F (115 C).
  • The “hot scuff” test, in which a brand-new engine – or “green” engine to the engineers – was run at wide-open throttle with no break-in period, which helped test bearings, piston ring sealing, bore scuffing and more.
  • Active Fuel Management validation, which cycled the engine in and out of the cylinder-deactivating feature hundreds of thousands of times at a variety of engine speeds to ensure the performance and durability of its unique valve lifters.
  • 24-hour racetrack equivalency testing to validate the performance of the available dry-sump oiling system.

And while the computational analysis indeed provided engineers with test engines that were very close to the mark, the physical testing revealed real-world variances that the perfection of a computer model couldn’t anticipate. As a result, the specifications for some of the Gen 5’s bearings and intake valves were revised, along with the cam phasing of the continuously variable valve timing system.

All of the testing was performed at GM’s state-of-the-art Powertrain Engineering Center in Pontiac, Mich. The 450,000-square-foot facility is one of the industry’s largest and most advanced powertrain development centers. It contains 120 test cells and energy generated by the engines running on the dynamometers is recaptured and used to provide approximately 15 percent of the center’s electricity.

Corvette, the Small Block V-8 and LT1

When the next Corvette hits the street and racetrack, it will do so with an all-new, Gen 5 Small Block V-8 engine. Named LT1, it will be the most powerful and efficient standard engine ever in the car’s six-decade history, thanks to a trio of Next-Gen technologies – the first Corvette applications of direct injection, Active Fuel Management and continuously variable valve timing – for greater performance and efficiency.

The Corvette wasn’t born with a V-8 between its front wheels. It arrived in the fledging sports car’s third model year, 1955, where it was an option selected by 90 percent of customers. That first 4.3L (265 cu. in.) engine produced 195 horsepower (145 kW) with a four-barrel carburetor. The new Gen 5 LT1 – the third Small Block to carry the moniker – displaces 6.2L (376 cu.-in.) and delivers an estimated 450 horsepower (335 kW).

The Small Block V-8 engine was physically smaller, 50 pounds lighter and more powerful than the “Blue Flame” inline-six engine it replaced in the 1955 Corvette. Its 4.4-inch bore centers – the distance from the center of one cylinder to the next – would come to symbolize the compact, balanced performance of the engine’s architecture. Every generation of the Small Block – including the forthcoming Gen 5 – features 4.4-inch bore centers.

After only two years on the market, the Small Block began a steady march upward in displacement, power and technological advancement. In 1957, a version equipped with mechanical fuel injection was introduced, dubbed Ramjet. The only other high-volume manufacturer to offer fuel injection at the time was Mercedes-Benz.

Mechanical fuel injection was discontinued in the mid-Sixties, but the Small Block introduced electronically controlled fuel injection in the 1980s on the Corvette and established a benchmark with the 1985 launch of Tuned Port Injection on the C4 Corvette generation. This electronically controlled port fuel injection system was advanced in its day and its basic design is still used on most passenger cars and light-duty trucks more than a quarter-century later.

The introduction of the Gen 3 Small Block with the 1997 launch of the C5 Corvette ushered in a new era of technologically advanced performance. It was a clean-sheet redesign of the architecture – retaining, of course, the 4.4-inch bore centers and cam-in-block foundation – with features including an aluminum, long-skirt cylinder block with six main cap fasteners, high-flow cylinder heads that improved high-rpm horsepower and a lightweight composite intake manifold.

As the C6 Corvette enters its final year, it sends off the Gen 4 Small Block with a couple of notable distinctions: The 7.0L LS7 engine that powers the Corvette Z06 is the largest-displacement production Small Block ever, while the 638-horserpower 6.2L supercharged LS9 engine in the Corvette ZR1 is the most powerful production Small Block ever, helping power the car to a 205-mph top speed.

LT1 legacy

The first LT-1 (with a hyphen) engine was introduced in the Corvette in 1970 as an option. It was a raucous, racing-inspired engine with solid valve lifters, a high-lift camshaft and high-winding personality that redefined Small Block performance. Displacing 350 cubic inches (5.7L), with a compression ratio of 11:1, it was rated at 370 horsepower at 6,000 rpm and 380 lb.-ft. of torque at 4,000 rpm. It was enough to push the Corvette from 0 to 60 mph in less than six seconds.

Indeed, the LT-1 was a true high-performance powerhouse, featuring many heavy-duty components not found on the Corvette’s standard 350 engine, including a stronger cylinder block with four-bolt main caps, forged aluminum pistons, a high-rise aluminum intake manifold, a baffled oil pan for reduced windage, a transistorized ignition system and high-volume oil and fuel pumps.

Only 1,287 Corvette’s left the factory in 1970 with the LT-1 engine. It remained in production for another couple of years, but lower compression ratios and other regulations-conforming changes resulted in lower horsepower.

The LT1 (no hyphen) returned to the Corvette in 1992, launching the five-year lifespan of the Gen 2 Small Block. It built on the successful design of the L98-code Gen I Small Block that debuted in the 1985, featuring the port fuel injection design that most automotive engines still use today. Like the original LT-1, the Gen 2 version displaced 350 cubic inches and featured a four-bolt-main block.

The Gen 2 LT1’s most significant update over the Gen I Small Block was a reverse-flow cooling system, which cooled the cylinder heads first to achieve lower cylinder temperatures. That allowed a higher, 10.4:1 compression ratio that helped achieve greater power: 300 horsepower at 5,000 rpm and 330 lb.-ft. of torque at 4,000 rpm. It helped the Corvette achieve 0-60 acceleration comparable to the 1970 model, while also helping propel the 1992 model to a top speed of more than 160 mph.

To mark the final year for the C4 Corvette generation and the final year for the Gen 2 Small Block, a pair of special-edition models was offered in 1996 with a higher-power version of the engine, dubbed LT4. It was rated at 330 horsepower and is easily identified by its red cast-aluminum intake manifold.

After an 18-year hiatus, the LT1 returns to the Corvette for 2014, matching an all-new car with an all-new Gen 5 engine – one of the most technically advanced engines in the world and the most significant redesign of the Small Block ever. It will have the highest base horsepower and torque, as well as the greatest efficiency, of any Corvette in its 60-year history.

With preliminary output of 450 horsepower (335 kW), the new LT1 builds on a heritage of high-winding, power-dense Small Blocks that have become high-performance legends.

LT1 engines compared

1970 LT-1 (Gen 1)

1992 LT1 (Gen 2)

2014 LT1 (Gen 5)

Displacement

350 (5.7L)

350 (5.7L)

376 (6.2L)

Bore x Stroke (inches)

4.00 x 3.48

4.00 x 3.48

4.06 x 3.62

Cylinder block

cast iron

cast iron

cast aluminum

Main bearing cap fasteners

four

four

six

Cylinder heads

cast iron

cast aluminum

cast aluminum

Valve sizes (intake / exhaust)

2.02 / 1.60 inches

1.94 / 1.50 inches

2.13 / 1.59 inches

Compression ratio

11.0:1

10.4:1

11.5:1

Camshaft type

solid lifter

hydraulic

hydraulic

Fuel delivery

four-barrel carburetor

port fuel injection

direct injection

Ignition

transistorized with cam-driven distributor

“Optispark” optically triggered distributor

individual coil-on-plug

Horsepower

370 @ 6,000 rpm

300 @ 5,000 rpm

450 (estimated)

 

Corvette and Small Block Performance Milestones

1955: 265-cid V-8 debuts in the Corvette as an option, with 195 horsepower. Ninety percent of customers select it.

1957: 283-cid V-8 introduced; Rochester mechanical fuel injection helps the Small Block produce 283 horsepower – or one horsepower for every cubic inch.

1959: William Mitchell, vice-president of GM styling, races the original Sting Ray Corvette racing car concept, which features a 315-horsepower version of the fuel-injected 283 Small Block.

1964: 327-cid Small Block is rated at 375 horsepower with Rochester fuel injection; the first Holley four-barrel carburetor is used on a production Small Block engine.

 

1969: The 350-cid Small Block is introduced in the Corvette. The standard engine is rated at 300 horsepower and an available “L46” version is rated at 350 horsepower.

1970: The first LT-1 debuts in Corvette, rated at 370 horsepower and 380 lb.-ft. of torque.

1972: Final year for the Gen 1 LT-1.

 

1982: Cross Fire electronic fuel injection introduced, featuring a pair of diagonally opposed throttle bodies feeding a 350 engine and rated at 200 horsepower.

1985: Tuned Port Injection introduced on the Corvette, ushering in modern age of port fuel injection and increasing the Corvette’s horsepower rating 230.

1986: Aluminum cylinder heads introduced mid-year on the Corvette.

1987: Hydraulic roller lifters introduced on the “L98” Tuned Port Injection engine, reducing friction for greater efficiency and performance – the Corvette’s output jumps to 240 horsepower.

1992: Gen 2 LT1 introduced in the Corvette, featuring reverse-flow cooling system, all-new cylinder heads and computer-controlled ignition timing, pushing horsepower to 300 – a 20-percent jump over the ’91 Corvette’s L98 engine.

1996: High-output LT4 with 330 horsepower in limited-edition Corvette models is the finale for the Gen 2 engine.

1997: New Gen 3 Small Block debuts in the all-new C5 Corvette, carrying the LS1 name and featuring all-aluminum construction, deep-skirt block and 350 horsepower.

2001: Higher-performance LS6 engine with 385 horsepower powers the new, track-oriented Corvette Z06. Horsepower increases to 405 in 2002.

2005: The Corvette’s new, 6.0L LS2 engine with 400 horsepower introduces the Gen 4 Small Block.

2006: Racing-inspired 7.0L LS7 engine debuts in the Corvette Z06 with 505 horsepower features including forged titanium connecting rods, high-flow cylinder heads, titanium intake valves, dry-sump oiling system and more.

2008: The 6.2L Small Block debuts on the Corvette with 430 horsepower.

2009: New Corvette ZR1 receives 638-horsepower, supercharged LS9 Small Block – the most powerful production-car engine ever built by GM and enabling a 205 mph top speed.

2011: GM builds its 100 millionth Small Block on Nov. 29. It is an LS9 engine built at the Performance Build Center, in Wixom, Mich.

2012: Final year for the Gen 4 engine in the Corvette.

2013: New LT1 Gen 5 Small Block debuts in the seventh-generation, 2014 Corvette with preliminary output of 450 horsepower (335 kW) – 231 percent more power from only 42-percent larger displacement. It is the most significant redesign in the Small Block’s nearly 60-year history.

Gen 5 Small Block LT1 Specifications

Engine type: 90-degree V-8 with overhead valves; continuous VVT

Displacement: 6.2L (376 cubic inches)

Bore x Stroke (in / mm): 4.06 x 3.62 / 103.25 x 92

Cylinder block: cast aluminum with nodular main caps

Main bearing fasteners: six, including two cross-bolts per cap

Crankshaft: forged steel

Connecting rods: powder metal, 6.125 inches in length

Pistons: eutectic aluminum alloy

Compression ratio: 11.5:1

Cylinder heads: 319-T7 cast aluminum with 59.02cc combustion chambers

Valve angles (degrees): 12.5 intake, 12 exhaust

Intake valves: 2.13 inches (54mm) hollow

Exhaust valves: 1.59 inches (40.4mm) hollow sodium

Camshaft: Hydraulic-type with tri-lobe for fuel-pump drive

Camshaft lift: 0.551-inch (14mm) intake / 0.524-inch (13.3mm) exhaust

Camshaft duration: 200-degrees intake / 207-degrees exhaust (at 0.050-inch)

Lobe separation angle: 116.5 degrees

Fuel delivery: direct injection

Intake manifold: “runners in a box” design; composite construction

Throttle: 87mm electronically controlled throttle body

Ignition: 58X with individual coil-on-plug and iridium-tip spark plugs

Horsepower / kW: 450 / 335 (estimated)

Torque – lb.-ft. / Nm: 450 / 610 (estimated)

Max. engine speed 6,600 rpm (fuel cutoff)

General Motors Powertrain Development Center

The Gen 5 Small Block LT1 engine for the next-generation Corvette was tested and validated at General Motors’ Global Powertrain Engineering Development Center, in Pontiac, Michigan.

Engineers use the Powertrain Development Center’s dynamometer facilities to bring advanced, fuel-saving powertrains like the LT1 to market faster and at less cost by reducing development time by 10 weeks. The 450,000-square-foot facility is the largest and most technically advanced powertrain development center in the world.

The facility features two test wings with 120 flexible dynamometer test cells and more than 100 powertrain component test stands. Advanced test automation, environmental control and data analysis capabilities are expected to improve GM’s powertrain engineering efficiency by 50 percent on many lab procedures. For example, computer-controlled dynamometer tests and math modeling – including 68 new laboratory calibration procedures – allow GM to reduce the number of expensive vehicle road tests required to validate a system.

By shifting some road testing to the laboratory, along with using computer math simulation tools, engineers who previously developed calibrations with expensive vehicles can now perform this work with greater accuracy, repeatability and, ultimately, quality.

The efficiencies realized at the center build on GM Powertrain’s ongoing global Road-to-Lab-to-Math initiative that transitions testing historically conducted in a vehicle to advanced lab and computer-aided analysis. Engineers use computer-aided engineering software to run simulated and controlled laboratory tests of powertrains and components to optimize fuel economy, emissions and performance. This reduces the amount of physical vehicle tests. Vehicle testing is used later in development to confirm that designs meet the powertrain program targets.