But 11.5:1 compression? The last production engine to leave the factory with that much squeeze was the ZL-1 427 at 12:1. But while that fire breathing monster needed high-octane race juice so it didn't sound like a diesel, the new LT1 does it on 93-octane or less. That's right, if you feed the LT1 (we're gonna keep saying LT1 until you finally stop picturing the '90s mill) regular gas, it'll keep going without detonating a piston out the side of the block. It might not smoke the tires like when 93 is in the tank, but it'll still make the new C7 move like lightning. It's entirely possible that thanks to direct injection and the unique combustion chamber design, the compression could go up even higher in the future.
"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, 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 BMW'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 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."
The original LT-1 debuted in the '70 Corvette (370-hp) and Camaro Z28 (360hp), and was the most powerful carbureted small-block ever installed in a production car.
Engine Features and Highlights
All-Aluminum Block and Oil Pan
The Gen V 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 III and Gen IV 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 IV engine, the Gen V'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 lubrication 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 engine load demands extra cooling and greater durability.
An available dry-sump oiling system promotes exceptional lubrication 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
As with the Gen IV engine, the camshaft remains in the same position relative to the crankshaft and is used with a new rear cam bearing, but it now 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 intake/exhaust duration at 0.050-inch tappet lift, and a 116.5-degree lobe separation angle.
New Cam-Driven Direct Injection 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 the cylinder heads under the intake manifold, and is driven by the tri-lobe at the rear of the camshaft. 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 lower 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 body, 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 LT1 uses a cast version of the "four-into-one" short-header exhaust manifold design used on the Gen IV 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 V engine 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.
Rebirth of the Horsepower Factory
To produce the new LT1, GM invested millions of dollars in modernizing the Tonawanda Engine Plant, the birthplace of tens of thousands of high-performance engines during the muscle car era. Now in the 21st century, it will be reborn, just like the LT1 name, and crank out what should be millions of Gen V small-blocks. The LT1 is just the first in a new line of efficient, powerful, American V-8s that easily outclass their competition.
Tonawanda first opened in 1938, and will celebrate its 75th birthday in 2013.