Last month, VETTE took you behind the scenes to GM's state-of-the-art Performance Build Center for the creation of the 100-millionth Chevrolet small-block. The milestone mill--a 6.2L LS9 rated at 638 hp--was assembled by Skilled Engine Builders who build Corvette's LS3 dry-sump, LS7, and LS9 engines. They were assisted by special guests, including retired Chevrolet executives and engine engineers, and media journalists.
This month, we'll continue the small-block celebration by asking GM's official illustrator, David Kimble, to help us pick 10 of the most significant Chevy small-blocks that were (and are) factory-issue in America's Favorite Sports Car.
To date, Kimble has illustrated nearly every Chevrolet production small-block engine, and he's working on detailed, cutaway illustrations of the Gen V small-block, which will power the Corvette line beginning in '14.
Kimble is contractually obligated to not divulge details of the fifth-generation small-block until General Motors gives the nod, but Tom Read, GM Powertrain Communications, let us tear loose some non-classified tidbits from him.
"The fifth-generation small-block is under development and moving forward as planned," Read says. "The engineering center and development lab in Pontiac, Michigan, is working full-throttle to bring the best-ever engines online soon. The new small-blocks will feature an entirely new, direct-injection combustion system that will really help improve efficiency over the current-generation engine. We're investing more than $1 billion in manufacturing facilities associated with producing Gen V small-blocks, including Tonawanda, St. Catharines, and various locations in Mexico. Additional good news is that [the investment] will result in 1,711 jobs [being] created or retained. We can confirm that Defiance Casting Operations of Defiance, Ohio, has signed on to manufacture the Gen V engine blocks and cranks, and Bedford Powertrain of Bedford, Indiana, is on board to manufacture the cylinder-head castings."
Read also intimated that the LS nomenclature can't and will not carry over to fifth-gen small-block V-8s. That means you shouldn't expect the engine order codes LS10 or LS11 moving forward. Instead GM will use a new three-digit alphanumeric sequence for Gen V, though exact details are still top secret.
While you're waiting for Chevrolet's fifth-generation small-blocks to find their way into Corvettes of the not-so-distant future, come along with us and enjoy an insider's look (literally) at 10 of the most-significant Chevy small-blocks to power production Corvettes in the last 60 years.
Note: Kimble states that he considers the '70 LT1 and the '85 L98 among Chevrolet's/Corvette's most significant small-blocks, but he hasn't had the opportunity yet to illustrate them.
(Note: Alphanumeric engine-order codes do not begin until '63)
Bore x Stroke 3.75- x 3.00-in
Fuel System Carter Wrought Cast Four Barrel (WCFB) carburetor
Horsepower/Torque (lb-ft) 195/260
Cam Solid-lifter, 264/266-deg duration, 0.404/0.413-in lift
Did you know? Model-year 1955 Corvettes optioned with the Chevy V-8 small-block featured an enlarged, gold "V" in the Corvette script on the front fenders. The Corvette's powerplant was rated 15 hp higher than the V-8/four-barrel slated for Chevrolet passenger cars, thanks to a more-aggressive-lift cam. Unlike the large-domed oil-bath filter used with other Chevy V-8s that year, Corvette's powerplant featured a stylish, louvered, less-restrictive, air cleaner with an element that consisted of oiled lathe chips. The firing order was 1-8-4-3-6-5-7-2 and stayed that way through '96.
Bore x Stroke 3.75- x 3.00-in
Fuel System Carter Wrought Cast Four Barrel (WCFB) carburetor (standard); two Carter Wrought Cast Four Barrel (WCFB) carburetors (optional)
Horsepower/Torque (lb-ft) 210/268 (standard), 225/270 (optional)
Cam Solid-lifter, 264/266-deg duration, 0.404/0.413-in lift (standard); solid-lifter "high-lift," 287/266-deg duration, 0.404/0.413-in lift (optional)
Did you know? Corvette's base engine increased in horsepower due to added compression and new ram's-horn exhaust manifolds, which were less restrictive than the previous model year's log-style manifolds.
Adding RPO 469 to a Corvette sales order upped the V-8's ante to 225 hp. It included Chevy's first V-8 aluminum intake manifold, which housed two Carter four-barrels.
A special "high-lift" camshaft (RPO 449) became available late in the year, with a "for competition use only" warning. Oddly, the cam's duration--not its lift--was higher, according to some Corvette historians. A total of 111 of these bumpsticks were factory installed, and an unknown number were sold over-the-counter, despite the fact that Chevrolet never published an official horsepower rating for engines so equipped.
The Corvette small-block's nine-finned aluminum rocker-arm covers were die cast by the Hoover vacuum company.
Compression 9.5:1 (standard), 10.5:1 (optional)
Bore x Stroke 3.87- x 3.00-in
Fuel System Carter Wrought Cast Four Barrel (WCFB) carburetor (standard); two Carter Wrought Cast Four Barrel (WCFB) carburetors or fuel injection (optional)
Horsepower/Torque (lb-ft) 245/300 (standard); 250/285, 270/305, or 283/290 (optional)
Cam Hydraulic-lifter, 300/300-deg duration, 0.398/0.398-in lift (standard); "Duntov" solid-lifter, 287/287-deg duration, 0.394/0.400-in lift (optional)
Did you know? There were six factory speed options for Corvettes in '57: RPO 469A and 469C featured the 2x4 carburetion from the previous model year ("A" designated a hydraulic cam, and "C" specified a solid-lifter cam) and were rated at 250 hp and 270 hp, respectively. RPOs 579A, B, C, and D featured fuel-injection ("A" and "C" had hydraulic lifters and were rated at 250 hp; "B" and "D" had solid lifters and were rated at 283 hp.)
Late in the year, Hoover introduced the seven-fin rocker-arm cover, which cleared the air meter on the fuel-injected Corvettes, unlike the earlier-style covers.
Engine order codes L75, L76, L78, L79, L84 (shown)
Bore x Stroke 4.00- x 3.25-in
Fuel System Carter AFB four-barrel (standard); Holley four-barrel or Rochester fuel injection (optional)
Horsepower/Torque (lb-ft) 250/350 (standard); 300/360 (L75), 365/350 (L76), 375/352 (L84) (all optional)
Cam Solid-lifter, 300/300-deg duration, 0.398/0.398-in lift (standard); solid-lifter, 342/342-deg duration, 0.447/0.447-in lift, or solid-lifter, 346/346-deg duration, 0.485/0.485-in lift (optional "Duntov 0.030/0.030")
Did you know? Model-year 1965 was the fourth year of the 327 and the second year of both the larger-valve (2.02/1.60) heads and the Duntov 0.030/0.030 camshaft, which earned its nickname from the recommended valve lash adjustment. It was the fourth and final year of the second-generation Rochester mechanical fuel injection. The L76 once again received a high-rise aluminum intake manifold.
Bore x Stroke 4.00- x 3.48-in
Fuel System Electronic sequential-port fuel injection
Horsepower/Torque (lb-ft) 300/340
Cam Hydraulic roller, 279-/276-deg duration, 0.447/0.459-in lift
Did you know? The LT1 was the first architectural redesign of the Chevy small-block engine. It featured reverse-flow cooling with a gear-driven water pump, in which the heads were cooled before the block; a fully solid-state distributor (the Optispark), which was relocated from behind the intake manifold to the front of the timing cover and was driven by the camshaft; and aluminum cylinder heads. All LT1s installed in Corvettes left the factory with Mobil 1 synthetic oil, which eliminated the need for a separate oil cooler.
Bore x Stroke 3.90- x 3.62-in
Fuel System Electronic sequential-port fuel injection
Horsepower/Torque (lb-ft) 345/350
Cam Hydraulic roller, 198-/209-deg duration (at 0.050), 0.500/0.500-in lift
Did you know? The LS1 heralded the Chevy small-block's third generation, though its only noticeable resemblances to the '55 edition were its shared 4.40-inch bore spacing and two-valve pushrod design. The "Gen III" engine's clean-sheet redesign relied heavily upon computational fluid dynamics (CFD) and finite- element analysis (FEA) electronic engineering tools. It featured the Chevy small-block's first use of a deep-skirt block, cross-bolted main-bearing caps, forged powdered-metal connecting rods, investment-cast-steel needle-bearing rocker arms, beehive valvesprings, equal-length intake ports, a composite- material intake manifold, and electronic throttle control. The firing order changed to 1-8-7-2-6-5-4-3.
Bore x Stroke 3.90- x 3.62-in
Fuel System Electronic sequential-port fuel injection
Horsepower/Torque (lb-ft) 405/400
Cam Hydraulic roller, 204-/211-deg duration (at 0.050), 0.525 /0.525-in lift
Did you know? The 385hp LS6 was considered a work in progress when it was released in '01. For the next model year, GM engineers fitted the LS6 with a higher-lift cam and a larger outlet for the air-cleaner housing. They also eliminated the mass airflow sensor's honeycomb diffuser, helping push the powerplant's horsepower rating to 405 in '02-'04.
Bore x Stroke 4.125- x 4.00-in
Fuel System Electronic sequential-port fuel injection
Horsepower/Torque (lb-ft) 505/470
Cam Hydraulic roller, 211-/230-deg duration (at 0.050), 0.588-/0.593-in lift
Did you know? The LS7--the first production 427ci powerplant under a Corvette hood in 37 years--is the first Chevy production small-block to feature a 7,000-rpm redline, titanium connecting rods and intake valves, and hand-built assembly. A three-valve-per-cylinder design was planned, which would have been another first for the Chevy small-block, but was cancelled.
Bore x Stroke 4.06- x 3.62-in
Fuel System Electronic sequential-port fuel injection
Horsepower/Torque (lb-ft) 430/424
Cam Hydraulic roller, 204-/211-deg duration (at 0.050), 0.551-/0.552-in lift
Did you know? The LS3 block and heads are based upon the parts introduced on the L92 high-performance truck engine. The LS3 uses the Nylon-6 glass-reinforced intake manifold and 5 g/s fuel injectors from the LS7.
Displacement 364 ci (supercharged)
Bore x Stroke 4.06- x 3.62-in
Fuel System Electronic sequential-port fuel injection
Horsepower/Torque (lb-ft) 638/604
Cam Hydraulic roller, 211-/230-deg duration (at 0.050), 0.562-/0.558-in lift
Did you know? The LS9 is the first supercharged Corvette production small-block in the marque's 60-year history. Before this 6.4L powerplant was released to the public, GM engineers put it through more than 6,800 hours of dyno testing, including a simulated 24 Hours of Le Mans race. When installed in the Corvette ZR1, it yields a power-to-weight ratio of 5.2 lbs/hp, compared with the Z06's 6.2 lbs/hp.
Growing up in L.A., the son of an aerospace-industry middle manager and midget racer, David Kimble formed an affection for all things automotive at an early age. This obsession, combined with a skill in drawing, led him to study drafting and technical illustration at the Academy of Technical Arts.
Word of his artistic talent and love of racing spread quickly through southern California race shops and eventually reached Jerry Titus, then technical editor of Sports Car Graphic magazine. Although Kimble was working as a contractor at North American Aviation, assigned to the Apollo space program, his career as an automotive illustrator was effectively born.
Requests for his art from Road & Track led Kimble to establish his own business in 1976, David Kimble Illustration. Since then, his works have been featured in a wide variety of major magazines, and his style has attracted a dedicated following.
Upon the request of Chevrolet Deputy Director of Communications Thomas D. Hoxie, Kimble began illustrating Chevrolet small-block engines in 1991, beginning with the LT1.
Kimble uses a technique similar to animation-cel painting: First he creates a detailed pencil drawing. After GM approves the drawing, he overlays drafting film onto it and makes a fine-line inking using technical pens. The next steps begin on a film positive of the inked drawing. Using watercolor paints, which he sprays through airbrushes, he applies the color detail primarily onto the back of the positive, and adds shadows, highlights, and value adjustments to the front. His last step in each cutaway illustration's creation is to have the original art digitally scanned. Using this method, he's illustrated dozens of small-block cutaways, and he says he won't stop until he's transformed every Chevy small-block ever manufactured into a two-dimensional work of art.
"David Kimble is an icon at GM," says Tom Read of GM Powertrain Communications. "Those who know his work appreciate it as a true art form. David is an artist-engineer--a perfect combination for someone to put the three-dimensional mechanical art that is the GM small-block onto canvas.
"Over the years we've contracted David to perform his magic and bring out the technical highlights of our engines as no one else can. The warmth of his colors and feeling in his lines still can't be matched by the somewhat sterile computer-aided-design (CAD) images. David's perspectives are dead-on. His art serves multiple uses, from internal engineering reference to using them to accompany press releases, to becoming the prized framed print on a customer's garage wall."