From a recent issue of Vette magazine

Written and Illustrated by Vette Columnist, K. Scott Teeters

Illustrated Corvette Series No. 154
The C6 LS3 Small-Block Chevy Engine “The Mighty LS3”

I believe that one day, we will look back at the first six years of the C6 and call them “The Golden Years of High-Performance Corvettes.” For those of us who have been following Corvettes for a very long time, we tend to think of the ‘60s and early ’70s as “The Golden Years”—and for a long time, they were. While fuel-injection has been available in Corvettes since 1957, those early mechanical fuelies were often difficult to live with. By the time the big-block Chevy engine arrived in ’65, it was easier to produce more power with more cubic inches. Perhaps if the auto industry hadn’t been so preoccupied with emissions standards in the ‘70s, it could have brought fuel-injection back before the ‘85 L98. The giant leap forward happened in ’97 with the all-aluminum LS1. From there, things just kept getting better.

An all-aluminum Corvette engine had been on the Corvette’s wish list since 1957. The ’69 ZL1 was a great start, but when performance went on hold in the early ‘70s, that engine was relegated to crate status. The arrival of the first C5 in 1997 was revelatory. Not only were the shape and structure all new, but the engine was also a fresh design. Although we often refer to the LS engine as a small-block Chevy, there’s nothing left from the old mouse motor.

The LS1 served the Corvette well in its eight-year tour of duty. It helped bring home the gold from Le Mans in 2001 and was the foundation for the LS6 that powered the ’01-’04 Z06. When the C6 debuted in 2005, it was powered by the much-improved LS2. The new base engine was slightly larger, up 18 cubic inches to 364 ci. Engineers improved everything from the air intake to the exhaust system, picking up an additional 50 hp over the LS1. The base-model Corvette now had 400 horsepower.

You have to hand it to the Corvette engineers: like Duntov, they always want more. The C6 Z06 was powered by the 505hp, 427ci LS6, an engine that silenced any remaining chatter about the Vette needing more power. If the base LS2 didn’t have enough grunt for buyers, that’s what the Z06 was for. When the ’08 Corvette was released, customers were greeted with yet another new engine: the 430hp LS3.

Before we dig into the juicy details of the LS3, let’s put some perspective on this amazing base Corvette engine. In 1968 the base engine was a cast-iron 327 with 300 hp. That was “gross” power, measured without any engine accessories and quite unrealistic. Starting in 1972, ratings were “net” to account for the power loss of an air cleaner, accessories, and exhaust systems. This is how engines are still measured today. So what was the net output of the base ‘68 327? A reasonable guess would be around 250 hp. The LS3’s 430hp net rating would be at least 525 gross horses when you consider that the newer engine is also much more efficient. This is why a base-model ‘08 Vette can run the quarter-mile in 12.4 seconds at 116 mph with a top speed of around 185 mph. Plus, the car can get nearly 30 mpg on a 55-mph turnpike. Corvettes from the original “Golden Years” were never this fast or quick. You had to go to Joel Rosen and buy a Phase III car to beat those times. And Phase III cars equipped with a Hone Overdrive transmission never saw mileage figures like the ’08.

Let’s look at what makes the LS3 such a mighty mouse. Although they look similar, the LS3 is not a tweaked-to-the-max LS2. The aluminum-alloy block is from the L92 high-performance truck engine. Casting and machining revisions were made to enhance strength and improve bay breathing. The cast-in-place iron cylinder  sleeves are mated with new flat-top aluminum/silicone alloy pistons designed for high-rpm performance. Compression is 10.7:1, and the LS3 redlines at 6,600 rpm. Head bolts thread deep into the main-bearing webs, and the crankshaft is held in place with 6-bolt, steel main-bearing caps. The main-bearing webs are 20 percent stronger. Crankshaft stroke is unchanged, but the cylinder bores have grown from 101.6mm to 103.6mm.

GM’s LS engines have some interchangeability surprises. The cylinder-head design was borrowed from the LS7 Z06 and received some modifications. The intake valves are 9 percent larger than the LS2’s, and the camshaft has 5 percent more lift. Pushrod location was modified to allow larger ports with fewer turns and bosses in the way. The combustion chambers are slightly larger, resulting in a slight loss of compression.

The refinement that goes into new Corvettes is a far cry from the old big-blocks with their booming side pipes. The LS3 uses the Nylon-6 glass-reinforced intake manifold and injectors from the LS7 Z06 engine. However, the LS3 manifold has been “acoustically tuned” to reduce engine noise. Acoustic foam is sandwiched between the top of the manifold and an additional “skull cap” acoustic shell. The ECM (Engine Control Module) allows the LS3 to produce more power, run cleaner, and get better fuel mileage. New beauty covers with “LS3” branding also help reduce engine noise and protect the rocker covers and coils.

LG Motorsports dyno-tested a manual-transmission ‘08 LS3 with just 30 miles on the odometer. The results showed 389.5 hp and 377.4 lb-ft of torque at the rear wheels. If you factor in a conservative drive-train loss of 17 to 18 percent, the engine was pushing 450 hp.

In another time, the LS3 would have been “the” performance engine for Corvettes. But the Z06’s 505hp 427 LS7 and the ZR1’s 638hp LS9 cast very long shadows, and hardly anyone pays attention to the base power-plant. Fast-forward two years to the ‘10 Grand Sport with the manual transmission. The manual Grand Sports receive the same dry-sump oil system used on the Z06 and the ZR1. These engines are hand-assembled at the Wixom, Michigan engine assembly facility by a single technician that signs his work. The extra TLC enables the ’10 Grand Sport to run the quarter-mile in 12.1-seconds at 117-mph – astonishing!

LG Motorsports also hot-rodded an LS3 just to see how much more power was left in the engine. Using long-tube headers, a performance cam, ported heads, a cold-air intake, an under-drive pulley, and a custom ECM tune, the LG crew pushed output to 506.7 horses and 457.1 ft-lb of torque. Yes, this is one base engine that truly deserves the name “The Mighty LS3.”

Save the Wave,

Scott

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RELATED LINKS:

K. Scott Teeters’ 11 X 17 print of this article as seen in Vette can be purchased at the link below.

Illustrated Corvette Series No. 154
The C6 LS3 Small-Block Chevy Engine “The Mighty LS3”

More Corvette Engine Art By Scott

Free Corvette Engine E-Book

QUESTIONS:

Did you like this article?

Is the LS3 your favorite Corvette Engine?

If not, which Is?

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