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The LS7’s specifications include:
Unique cylinder block casting with large, 104.8-mm bores and pressed-in cylinder liners
Forged steel main bearing caps
Forged steel crankshaft
Titanium connecting rods with 101.6-mm stroke
Forged aluminum flat-top pistons
11.0:1 compression
Dry-sump oiling system
Camshaft with .591-inch lift
Racing-derived CNC-ported aluminum cylinder heads with titanium intake valves and sodium-filled exhaust valves
Titanium pushrods and valve springs
Low-restriction air intake system
Hydroformed exhaust headers with unique “quad flow” collector flanges.
“In many ways, the LS7 is a racing engine in a street car,” said Dave Muscaro, assistant chief engineer of small-block V-8 for passenger cars. “We’ve taken much of what we’ve learned over the years from the 7.0-liter C5-R racing program and instilled it here. There really has been nothing else like it offered in a GM production vehicle.”
One of the clearest examples of the LS7’s race-bred technology is its use of titanium connecting rods. They weigh just 480 grams apiece, almost 30 percent less than the rods in the LS2 V-8. Besides being lightweight, which enhances high-rpm performance and rpm range, titanium makes the rods extremely durable.
The LS7’s CNC-ported aluminum cylinder heads are all-new and designed to meet the high airflow demands of the engine’s 7.0-liter displacement, as it ingests approximately 100 cubic feet more air per minute than the Corvette’s 6.0-liter LS2 V-8 – an 18-percent increase in airflow. Consequently, a hydraulic roller camshaft with .591/.591-inch valve lift is used to allow plenty of air to circulate in and out of the engine.
To ensure optimal, uninterrupted airflow, the LS7’s heads have straight, tunnel-like intake runners. Very large by production-vehicle standards – even racing standards – they are designed to maintain fast airflow velocity, providing excellent torque at low rpm and exhilarating horsepower at high rpm. The heads feature 70-cc combustion chambers which are fed by huge, 56-mm-diameter titanium intake valves. The lightweight titanium valves weigh 21grams less than the stainless steel valves used in the LS2, despite the valve head having 22 percent more area. They are complemented by 41-mm sodium-filled exhaust valves, vs. 39.4-mm valves in the LS2. To accommodate the large valve face diameters, the heads’ valve seats are siamesed; and, taken from experience with the engines of C5-R racecars, the LS7’s valve angles are held at 12 degrees – versus 15 degrees for the LS2 – to enhance airflow through the ports.
All LS7 engines are assembled by hand at GM Powertrain’s new Performance Build Center in Wixom , Mich. The exacting standards to which they are built include deck-plate honing of the cylinders – a procedure normally associated with the building of racing engines and almost unheard of in a production-vehicle engine.
Dry sump oiling system
The LS7 has a dry-sump oiling system designed to keep the engine fully lubricated during the high cornering loads the Corvette Z06 is capable of producing. An engine compartment-mounted 8-quart reservoir delivers oil at a constant pressure to a conventional-style oil pump pick-up at the bottom of the engine. The pressurized oil feed keeps the oil pick-up continually immersed in oil at cornering loads exceeding 1 g.
Oil circulates through the engine and down to the oil pan, where it is sent back to the reservoir via a scavenge pump. The large-capacity reservoir, combined with a high efficiency air-to-oil cooler, provides necessary engine oil cooling under the demands of the engine’s power output. With the dry-sump system, oil is added to the engine via the reservoir tank – which includes the oil level dipstick.
The LS7’s dry-sump system was developed and tested on racetracks in the United States and Europe , including Germany ’s famed Nürburgring. And while common in racing cars, the Corvette Z06 is one of just a handful of production vehicles – and the only production Corvette – to ever incorporate such a high-performance oiling system.
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