|Illustrated Corvette Series No. 154 - 2008 LS3 Engine
"The Mighty LS3" Here's the Story...
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 drivetrain 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 powerplant. 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 underdrive 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.” - KST
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Illustrated Corvette Series No. 138 - 2008 427 Limited Edition Z06 Corvette
"Past & Present"
The next time you’re admiring one of those ’66-’69 427 Corvette beauties, give a big thank-you to NASCAR. “What?” you ask. “Corvettes never raced in NASCAR.” True enough, but the top-secret “Mark II” 427 was Chevy’s answer to the big-block engines that powered the dominant Fords, Mopars, and Pontiacs in the NASCAR races of the early ‘60s.
When it became clear that its small-block Impalas could no longer keep up with the competition, Chevy responded with the Z11 427 - essentially a 409 truck engine with a longer stroke. What is more commonly known as the Chevy big-block began in July ‘62 as a project helmed by Chevy engineer Dick Keinath. The engine was known internally as the Mark II, but the auto press called it “Chevy’s Mystery Motor.” The bottom end of the block was similar to that of the 409, but it was the cylinder heads that made the mojo. The new free-flowing heads had staggered valves that looked as if they were pointing in all directions, earning the motor the additional nickname, “The Porcupine.” The Mark II produced over 500 horsepower, more than enough for Smokey Yunick’s Impala at the ‘63 Daytona 500. The car had problems but shattered several speed records and garnered a lot of attention in the process.
All this made for great magazine copy until GM proclaimed, “We don’t race” and canceled the Mark II project. Still, the new big-block was a runner, and Corvette product planners were looking for a way to make power than could be squeezed from the fuel-injected 327. Chief of Corvette Engineering Zora Arkus-Duntov didn’t like the new engine, as it ran counter to his lightweight philosophy for sports cars and racing. The total big-block package added 150 pounds to the car, mostly to the front end. Duntov lost this battle, but buyers won a big boost under the hood.
Creating a production big-block Corvette involved a lot more than just dropping in a new engine. Here’s a list of the basic parts that needed to be modified or added: a new hood for engine clearance, a wider radiator, a larger fan and radiator shroud, a revised crossmember, stiffer front springs and a larger sway bar, a stronger clutch, heavy-duty rear axle shafts and universal joints, an improved Positraction differential, a new rear anti-sway bar, and host of smaller details. Print ads announced the new big-block this way: “You have heard the rumors, now hear this...There is a Turbo-Jet 396 from Chevrolet.”
The production big-block had arrived, though not as a 427. In order to comply with GM’s policy of not offering cars with engines over 400 cubic inches, the first version displaced 396 ci. Conservatively rated at 425-horsepower (450 was closer to the real figure), the $292 L78 option had 50 more horses than the $538 fuel-injected 327. Obviously, it was the end of the line for the famous fuelie. With the new off-road sidepipes, the ’65 big-block Vette had lots of bark and bite.
The following year, GM dropped all pretense and boosted the big-block’s displacement to a more appropriate 427 ci. And to prove that the engine could be civilized, the hydraulic-lifter L36 provided 390 hp without the solid-lifter hassle.
Then, in ’67, Chevy created another Corvette legend—the 435hp L71, topped with three 2-barrel carburetors and a large, triangular air cleaner. In addition to the iron L71, Chevy would develop three other variations on the 427 theme. These included the aluminum-headed L88 and L89, as well as the ultra-exotic, all-aluminum ZL1.
Now let’s fast-forward 40 years from the first 427 Corvette to the ‘06 LS7-powered Z06. Although considered a small-block engine, the high-tech LS7 shares nothing with its SBC predecessors. Packing 505 net hp (at least 600 horses by the old “gross” rating system) the C6 Z06 can click off high 11s in the quarter-mile all day long, with the air conditioning and CD player running.
The ‘08 Corvette 427 Special Edition Z06 is a trim-only package that uses the same hardware as a regular Z06. The $12,920 option comes with Crystal Red Tintcoat paint, “stinger” hood graphics and 427 badge, exclusive 10-spoke chrome wheels, a body-colored rear spoiler and door handles, “427” embroidery on the seats and floormats, and Z06 door plates. Additionally, every car is signed and numbered by recently retired Corvette plant manager Wil Cooksey. The production run is limited to 427 units domestically and 78 imports, for a total of 505—the same as the LS7’s output rating. Corvettes have a long history of being bold, fast, and uniquely American. The 427 Special Edition Z06 fits right into that tradition. - K. Scott Teeters
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Illustrated Corvette Series No. 137 - 2008 Corvette Pace Cars
"Twins Pace the '08 Indy 500"
In 1978, Vette Magazine was a bi-monthly publication and I was a contributing artist and writer. I was talking with then editor, Marty Schorr about my next illustrated article when he asked, “Did you hear the good news?” Corvettes were in the performance doldrums those days, so we were all hungry for some juicy performance news. “A Vette is going to pace the Indy 500 and they’re going to offer replicas!” In the fourteen years I had been following Corvettes I never once heard the mention of a Corvette pacing the Indy 500. Even though many muscle cars had paced the 500, being a sports car, the Corvette just seemed like a disconnect for the Indy 500. But it was a gorgeous car that made speculators delirious with possibility of quick financial gain. For many years, the only ones that gained financially were a few dealers that were charging up to $10,000 over the $13,653 Pace Car Special price tag.
Initially, Chevy was only going to make 300 Pace Car Specials to commemorate the production run of the ‘53 Corvette. But dealers and buyers howled, so Chevrolet just let the orders come in. By the end of ’78, 6,502 Pace Car Specials were built. Let’s fast forward to ‘86 when General Chuck Yeager drove a yellow pace car Corvette convertible. To avoid the mess of the ’78 Pace Car Special, Chevrolet decided that all ‘86 Corvette convertibles were considered “Pace Car Specials,” which really let the air out of the speculator bubble because there were 7,315 - each with a set of Indy 500 Pace Car decals the customer or dealer could apply. Very few decal sets adorned the sides of ’86 roadsters.
2008 marks a very interesting milestone for the Corvette and its relationship with “the greatest spectacle in motorsports.” Not only is it the 30th anniversary of the first Indy 500 Pace Car Corvette, it is the 10th time a Corvette has paced the 500. That’s a record, Corvette fans, for the entire history of the Indy 500 pace cars. A Corvette has paced the 500 in ‘78, 86, 95, 98, 02, 04, 05, 06, 07, and ’08. Replicas of the pace car Vettes were offered in ‘78, 86, 95, 98, 07, and 08, and have proven to be some of the most valued of the special edition Corvettes. And if all that isn’t enough for you, for ‘08 Chevy had TWO Corvette pace cars on hand. The black and silver car is the version available to the public and the “is it green or gold” E85 Ethanol Z06 that is not available to the public.
The “for public consumption” pace car is available in either coupe or convertible and was priced at $59,090 for the coupe and $68,160 for the convertible. This is your base, 436-horsepower Corvette with either 6-speed manual or the $1,250 optional paddle-shift automatic transmission and the new 5-spoke aluminum wheels. The package includes the special black and titanium paint scheme, Indy 500 logos on the front fenders, a Z06 rear spoiler, and the interior has Indy 500 logos embroidered on the seats. The car is equipped with the 3LT option package that includes the heads up display, power telescoping steering column, auto-dimming mirrors, memory package, heated seats, US9 radio, compass, and the homelink garage door opener. Convertibles get the power roof option. For a little extra grunt, the dual mode Z06 exhaust is included and the Z51 suspension package provides extra grip. The only other extra cost options were the $1,750 Bose Navigation system, the $750 glass roof, and the $1,400 dual removable roof panels. Emmerson Fittipaldi drove the actual E85 pace car and to finish off the entire package, Emmo signed all 500 ’08 Pace Car Specials.
The E85 Ethanol Z06 pace car is a one-of-a-kind experimental Corvette that shows that high-performance can be green. Decoration aside, the car is a stock Z06 with modifications to the fuel system and powertrain controller. E85 Ethanol fuel is 85-percent ethanol and 15-percent gasoline. Indy Car race cars run on 100-percent ethanol. This is the same system currently being sold as GM’s “Flex Fuel” option for SUVs and trucks. GM has built over 2.5 million E85-capable vehicles and Chevrolet offers 7 E85 vehicles. The Gold Rush Green paint is stunning with color that fluxuates between metallic gold to metallic green depending on the light level and the angle of light. Just think of green as in “cash,” and gold as in “Kugarand coins.” The subtle checker pattern on the sides is similar to the production pace car. Emmo said that the E85 will do around 200-mph!
There’s an interesting connection between the E85 Pace Car and Emmerson Fittipaldi. The two-time Indy 500 winner (’89 and ‘93) is in the ethanol refining business in his native Brazil, which is the global leader for ethanol usage in cars.
2008 represents the fifth year in a row that a Corvette has paced the Indy 500 and the second year in a row that Chevrolet has dished up two special edition Corvettes. In ‘07 we saw the Ron Fellows Special Edition Z06 and another Pace Car Special. This year we have the Special Edition 427 Z06 and the Pace Car Special. I think that Chevy is liking this “special edition” thing. Will we see an ’09 ZR1 or an E85 ZR1 Pace Car Special? Now there’s something to ponder. - K. Scott Teeters
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Illustrated Corvette Series No. 130 - 2008 Production Corvette
"The Mid-Cycle Refresh"
While it might seem like the C6 Corvette was just released, the ‘08 model is actually the fourth edition of the car. “Mid-cycle refresh” is the term Corvette engineers used when introducing the press to the new-and-improved ’08 model. “Mid-cycle” suggests to us that the current platform may be halfway through its production run.
If you follow the Internet Corvette rumor mill, it’s obvious the gossipers have added a third shift. The ‘net is practically afire with spy photos and speculation as to what the next Z06 might be like, including the possibility of the car having something “over the top” under the hood and lots of carbon fiber. There’s even the rumor that the C7 will fulfill Duntov’s dream of a mid-engine Corvette. Regardless of how the next Vette turns out, one thing is very clear: The days of 10-plus-year production runs are over. Chevy sold 40,561 Vettes in ‘07. That’s 4,794 more units than the best C5 sales year, 2002. You’d have to go all the way back to the late ‘70s and early ’80s to find better sales figures. All this makes GM’s bean-counters happy enough that they leave the Corvette engineers alone to improve the car.
What’s notable about how the Corvette development team works is that its members take a systematic, incremental approach to making improvements. They examine everything from the moment air enters the intake manifold to the moment the exhaust leaves the tailpipes. Every facet—from where the rubber touches the road to the feeling of the steering wheel—is carefully tweaked. When Dave Hill was Chief of Corvette Engineering, he brought with him his Cadillac quality background and applied it to the Corvette. Heck, the Cadillac XLR is built at the Bowling Green Corvette plant. When customers talk, Corvette planners and engineers listen.
Spotting an ‘08 Vette is easy—just look for the new split-spoke wheels. But the big news is under the hood. The new LS3 packs 30 more horsepower more than the LS2, giving it 430 horses and 424 lb-ft of torque. The optional Dual Mode Exhaust, using technology borrowed from the Z06, adds 6 more ponies and a delicious exhaust growl over 3,500 rpm.
Zero-to-60 mph acceleration comes up in 4.1 seconds for the manual car and 4.3 seconds for the automatic. Top speed is 190 mph. This performance bump starts with a new acoustically tuned intake manifold and Z06 injectors. High-flow heads are based on the LS7’s and have 9 percent–larger intake valves. The camshaft boasts revised timing. The strengthened block received a .06-inch overbore, increasing displacement to 376 ci. The new pistons were designed for high-rpm performance. Pop the hood, and you’ll notice the LS3’s new engine cover shields the rocker covers and has a noise-reducing insert for a more refined sound.
The drivetrain has an improved manual-shifter linkage for quicker shifts and better feel. As for the paddle-shift automatic, it was also improved for quicker shifts, and there’s an optional 2.73 performance axle (included with the Z51 option). Finally, the rack-and-pinion unit was modified for increased road feel at all speeds.
Bowing to customer complaints about the car’s interior, designers added brushed-aluminum trim, new doorsill plates, and an optional leather package that adds two-tone hides to the dash, instrument panel, and doors. XM Satellite Radio and OnStar are both standard, plus there’s a jack for your iPod.
Don’t want to make the stretch to the Z06? The Z51 option has an enhanced suspension, Goodyear Eagle F1 tires, and larger brakes in a package you can live with every day. Could things get any better? They could: Just wait till you see the ‘09 ZR1! - K. Scott Teeters