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Why do Corvette fans call the C6 Z06's LS7 a 427?

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Why do Corvette fans call the C6 Z06's LS7 a 427?
What 427 usually means. In Corvette lore, 427 means the 1966–69 big-block cars, like the 435 hp L71 (by 1967) and the L88, built in just 216 cars. GM calls them some of the most-coveted Corvettes ever produced.

What 427 usually means

In Corvette lore, 427 means the 1966–69 big-block cars, like the 435 hp L71 (by 1967) and the L88, built in just 216 cars. GM calls them some of the most-coveted Corvettes ever produced.

Source: GM press release, Jan 12, 2012

Where 427 comes from. Each cylinder is a 4.125-inch circle (bore) by 4.00 inches deep (stroke): π/4 × 4.125² × 4.00 ≈ 53.5 cubic inches, × 8 cylinders ≈ 427.6. So 7.0 liters is about 427 cubic inches, the engine's displacement.

Where 427 comes from

Each cylinder is a 4.125-inch circle (bore) by 4.00 inches deep (stroke): π/4 × 4.125² × 4.00 ≈ 53.5 cubic inches, × 8 cylinders ≈ 427.6. So 7.0 liters is about 427 cubic inches, the engine's displacement.

Source: GM 2007 Corvette specifications

A 427 that isn't a big-block. GM said the previous 427 was a big-block design, while the LS7 is a small-block V-8. Pressed-in cylinder sleeves allow its 104.8 mm (4.125-inch) bore. Pictured: a 1967 Corvette 427 big-block.

A 427 that isn't a big-block

GM said the previous 427 was a big-block design, while the LS7 is a small-block V-8. Pressed-in cylinder sleeves allow its 104.8 mm (4.125-inch) bore. Pictured: a 1967 Corvette 427 big-block.

Source: GM 2006 Corvette Z06 press release, Jan 10, 2005

Making a pushrod V8 rev. A pushrod V8 works its valves with rods from the camshaft. Redline is 7,000 rpm (fuel cut 7,100), against a 6,600 rpm limit for the 6.0 L LS2. Titanium connecting rods, almost 30 percent lighter than the LS2's, helped.

Making a pushrod V8 rev

A pushrod V8 works its valves with rods from the camshaft. Redline is 7,000 rpm (fuel cut 7,100), against a 6,600 rpm limit for the 6.0 L LS2. Titanium connecting rods, almost 30 percent lighter than the LS2's, helped.

Source: GM press release, Feb 8, 2005

Oil that stays where it's needed. In a hard corner, oil in a normal sump can slosh away from the pickup. For cornering above 1 g, GM fitted a dry sump with an 8-quart tank.

Oil that stays where it's needed

In a hard corner, oil in a normal sump can slosh away from the pickup. For cornering above 1 g, GM fitted a dry sump with an 8-quart tank.

What you'd notice: You add oil at the reservoir tank, not the usual engine fill.

Source: GM LS7 press release, Jan 10, 2005

The payoff: 505 hp, built by hand. The C6 Z06 LS7 makes 505 hp at 6,300 rpm and 470 lb-ft at 4,800 rpm, SAE certified (measured to an industry standard). Each LS7 engine was assembled by hand by one builder in Wixom, Michigan.

The payoff: 505 hp, built by hand

The C6 Z06 LS7 makes 505 hp at 6,300 rpm and 470 lb-ft at 4,800 rpm, SAE certified (measured to an industry standard). Each LS7 engine was assembled by hand by one builder in Wixom, Michigan.

Source: GM 2007 Corvette specifications; US rating

The short answer. '427' on a C6 Z06 is a displacement figure with a deliberate callback, not a big-block. In 2013 Chevrolet put the name on the car: the 427 Convertible Collector Edition, with the same LS7. Pictured: a 2006 C6 Z06 coupe.

The short answer

'427' on a C6 Z06 is a displacement figure with a deliberate callback, not a big-block. In 2013 Chevrolet put the name on the car: the 427 Convertible Collector Edition, with the same LS7. Pictured: a 2006 C6 Z06 coupe.

Source: GM press release, Jan 12, 2012

Sources and assumptions

Assumptions:

Photos:

The short version

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