LS3 Engine Engineers - Inside Information

In a VETTE exclusive, we introduce you to the engineers in charge of the Corvette's LS3 engine components. Part 1: Cylinder block, rotating assembly, and oiling system

Christopher R. Phillip Apr 1, 2011 0 Comment(s)
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Despite the exotic allure of the ZR1's blown LS9 and the low-end grunt of the Z06's 427-cube LS7, the engine most commonly found in today's Corvettes is the "Gen IV" 6.2L LS3, which is standard equipment in all base and Grand Sport models.

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More than 38,000 LS3s have been factory installed in Corvettes since the powerplant's introduction for model year 2008. It's easy to imagine that today's sophisticated technology has put computers and robots in charge of these engines—from design and development through assembly and validation—but that's simply not the case. Behind every component in your Corvette's engine—including the block, rotating assembly, heads, lubrication system, and even the bolts and fasteners—is a highly trained GM Design Responsible Engineer.

"DREs are the core product engineers for engines," GM Technology Communications, Powertrain spokesperson Tom Read says. "They are the ones ultimately responsible for the design, development, validation, and continuous improvement of the individual components that make up the engine.

"Their expertise on their component is simply unmatched in the company, and, in many cases, in the field," Read continues. "Not only do they know their part, they influence future design direction. Our DREs assure parts can be manufactured and assembled properly at the suppliers and/or engine plants and follow up on any issues with the design. When they bring a new part to life, they make sure it fits within established best-design practices and use design secrets GM has developed over the years. The DREs work hand-in-hand with computer-aided designers, simulation experts, and development engineers. If that weren't enough, they also talk constantly with integration engineers to make sure their parts work harmoniously with the entire vehicle system and listen to feedback coming from the field—the Corvette customer."

For the most part, these engineers shy away from the limelight. Their passion is in assuring the components that go into your Corvette's engine are perfect every time, and that future Corvette engine parts take full advantage of the latest in emerging design and manufacturing materials and technologies. Though you may not instantly recognize their names, these men are critical to ensuring that you can enjoy your Corvette with absolute confidence, whether you drive it on the street or on the racetrack.

We asked eight of them to tell us about the roles they play in the Corvette's design and manufacturing process. This month you'll meet four of them—the men responsible for the LS3 block, rotating assembly, and oiling system. Next month, you'll meet the Design Responsible Engineers for the LS3's heads, intake, cam, head bolts, and fasteners.

Cylinder Block
Name: Jason Murphy
Title: Design Responsible Engineer
Years with GM: 11

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Other experience: Designer: block design; Designing Engineer: Gen III block casting and machining; Designing Engineer: dyno validation testing; Component Test Engineer: component testing, Wixom Test Lab

What LS3 part(s) are you responsible for? Cylinder block, bearing caps, cam bearings

What LS7 and LS9 parts are you responsible for? Same

What other Corvette parts have you been involved with in the past? LS1, LS6 cylinder blocks

Why do you think your LS3 part is the most important part on the engine? The power output of the LS3 requires that the block can hold up to severe operating conditions. A superior design is required in order to package the big bores for max displacement and crankcase bay-to-bay breathing features inside to reduce pumping losses. The LS3 block interfaces with basically everything—cooling, lubrication, power development, and cylinder-head joints. If you have an LS3 block, you have the same strength in virtually all areas as in the LS9. As a matter of fact, LS9 block-strengthening features have gone into all 6.2L small-block blocks since the release of the ZR1.

What is a focus area you watch when designing the LS3 part, especially knowing it is for a Corvette engine? Lower-end construction to reduce mean and alternating stresses—in other words, stresses that could potentially create a fracture-initiation site. We really watch cylinder bore features that have a maximum effect on minimizing bore distortion. These areas are critical in any block, but especially the LS3 because of its high output.

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What are the current trends with your LS3 part? Where is it going? Lighter weight, bore stability, increased lower-end strength, and tighter tolerances. All of these features have been hallmarks of our small-block engines from the beginning. Our design and manufacturing systems make the LS3 one of the best in the industry in these areas. Our quest in these areas will continue as we forge ahead to be even better.

Compare your part with aftermarket parts of the same item. What makes yours better? Our blocks go through a much more thorough and stringent development and validation schedule than typical aftermarket blocks. Thankfully, many of the aftermarket blocks follow very closely some of the key changes we make based on the global resources and technical expertise we have at our disposal. Our designs are pretty strong—aluminum Gen III and Gen IV blocks in the boneyards are becoming premium commodities for street rods and various other projects.

Do you own a Corvette, a classic car, or have a related hobby? One of my favorite cars of my past was my Impala SS with an LT1, to which I added a performance engine calibration and "hot" cam. I enjoy designing systems that meet end-of-test requirements at time of teardown; it's direct feedback that we did a good job. I enjoy following various types of racing, mainly to follow technology improvements for internal-combustion engines. Although it isn't in production yet, I have a patent for a cylinder-block casting bulkhead-window formation.

Crankshaft
Name: Paul Gelazin
Title: Design Responsible Engineer
Years with GM: 26

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Other experience: 18 years as an Engine Structural Analysis Engineer

What LS3 part(s) are you responsible for? Crank, bearings, damper, flexplate, engine balancer

What LS7 and LS9 parts are you responsible for? Same

What other Corvette parts have you been involved with in the past? All Gen III and IV rotating cranktrain components (crank, bearings, damper, flexplate, and flywheel).

Why do you think your LS3 part is the most important part on the engine? The crank is the main component that takes the unnatural reciprocating events and transfers them into rotational power. The design has to be robust enough to handle all the punishment that eight power cells (piston, pin, and rod), working to create 430 hp, can throw at it under a multitude of speeds and conditions.

What is a focus area you watch when designing the LS3 part, especially knowing it is for a Corvette engine? Crank structural integrity is foremost. There was an additional focus on fatigue strength enhancements to meet durability requirements, since the LS3 is the most demanding application for the iron crank. This strength is created by inducing compressive residual stresses in the undercuts (the area where the journals meet the side of the crank throws) with rolling loads in the range of 6,000-7,000 newtons. This process significantly improves the fatigue strength in the critical sections of the main and rod journals.

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For the LS3 dry-sump application, a steel crank is used and is actually machined from the LS9 forging. It is also an undercut and rolled design, and can handle anything you can throw at it in the Grand Sport.

What are the current trends with your LS3 part? Where is it going? The latest focus has been on robustness enhancements in the journal-bearing system. We're always looking at improved bearing materials and coatings to provide an added level of protection against extreme operating conditions.

Compare your part to aftermarket parts of the same item. What makes yours better? The LS3 cranktrain has a significant amount of analytical input guiding the design. We have many requirements with regards to torsional response, bearing loads, oil-film thickness, bending deflections, mass, and strength. While the aftermarket may enhance a certain aspect, we use the analytical tools to design a crank that meets all the requirements for a better overall engine package.

Do you own a Corvette, a classic car, or have a related hobby? My interest has been airplanes since I was a kid, so I have more wrench time on airplane engines than car engines. I have a TCM IO-520L, which is a 520ci Opposed Six that produces 300 hp at 2,850 rpm. It's in a six-place Cessna 210M that we use like the family Suburban.

Piston-and-Rod Assembly
Name: Tom Halka
Title: Design Responsible Engineer
Years with GM: 35

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Other experience: DRE for 3800 V-6 piston and rods, calibrator, emissions-test engineer, power-development engineer

What LS3 part(s) are you responsible for? Piston, connecting rods, pins, rings

What LS7 and LS9 parts are you responsible for? Same

What other Corvette parts have you been involved with in the past? All Gen III and Gen IV pistons and rods, including LS1, LS6, and LS2

Why do you think your LS3 part is the most important part on the engine? Everything about the LS3 flat-top piston is the latest and greatest in terms of performance and refinement. It has a full-floating pin for strength and quiet running, an asymmetrical skirt profile and polymer coating for close fit, and the top groove is anodized for strength and durability.

What is a focus area you watch when designing the LS3 part, especially knowing it is for a Corvette engine? One of my main priorities is making sure that the piston bosses live through high-speed inertia testing. This area has to be absolutely bulletproof. They cannot fail, period. We use structural computer analysis and high-speed dyno testing to prove out the parts. Not only that, I've personally reviewed LS3 pistons run at Virginia International Raceway and the Nürburg-ring as part of the development.

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What are the current trends with your LS3 part? Where is it going? We're always looking at more specific power capability. We want to make it as light as possible for high speed but not sacrifice a nickel's worth of durability. One future trend we're watching closely is diamond light coating for rings.

Compare your part to aftermarket parts of the same item. What makes yours better? Our piston design has more analytical backing than any original-equipment Corvette piston in history. Aftermarket piston manufacturers typically don't have the capability to develop skirt profiles for good noise and scuff characteristics with given material properties.

Do you own a Corvette, a classic car, or have a related hobby? I have a rare '79 Buick Century Turbo Coupe with the 3.8L V-6, which was the prerunner to the Grand National [engine]. I rebuilt the engine with many "tweaks," including stock GN pistons. It's faster than a stock GN, while still running the carbureted turbo system. I used to crew for a friend who ran in Formula Ford. I also enjoy NASCAR and go to Michigan International Speedway when I can.

Oil Pump
Name: Tom Bishop
Title: Design Responsible Engineer, Engine Lubrication and Ventilation
Years with GM: 14

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Other experience: Lube and vent systems development engineer and engine calibrator for Gen IV small-block truck applications, including the 4.8L, 5.3L, 6.0L, and 6.2L

What LS3 part(s) are you responsible for? The complete LS3 lubrication system. This includes the oil pump, oil pan, oil pickup tube, crankshaft oil deflector, oil filter, and oil

What LS7 and LS9 parts are you responsible for? Same

What other Corvette parts have you been involved with in the past? Oil pump, oil pan, oil-pickup tube, crankshaft oil deflector, valley covers, rocker covers, PCV systems (hoses and restrictors), PCV air/oil separators, front covers, oil filter, oil-fill cap, oil-fill tubes for LS2, LS3, LS7, and LS9 engines

Why do you think your LS3 part is the most important part on the engine? The most important part of any engine is the lubrication system. If it doesn't work properly, you're walking home. The oil pump is at the heart of the system and must be optimized to efficiently and effectively feed oil to the engine under all operating conditions, ranging from oil temps of -40 degrees (C) to more than 150 degrees. Corvettes are "track ready" right off the assembly line, and the lube system's performance has the ultimate say on if an engine is ready to race. The LS3 oil pump works in concert with the oil-pickup tube, the crankshaft oil deflector, and the oil-pan design (on which I hold a patent) to deliver oil to the engine at the right pressures and flows. A less-than-optimal oil pump and lube system would result in an engine that would not support the design requirements or meet customer expectations.

What is a focus area you watch when designing the LS3 part, especially knowing it is for a Corvette engine? The porting on the inside of the oil pump received a lot of attention when the LS3 pump was designed. The inlet and discharge-port geometry determine how well the pump delivers oil to the engine. Special focus was placed on port development at high engine speeds to ensure that pump performance meets the high engine-operating requirements associated with the Corvette platform. Port timing, width and depth, and port entry/exit geometry were extensively studied, analyzed, and tested to be sure that the pump's performance was optimized for all operating conditions.

What are the current trends with your LS3 part? Where is it going? Mass reductions are constantly being evaluated and implemented where feasible. Clearances between internal pump components are studied to see where internal drags and frictions can be reduced without sacrificing pump performance. More and more engine devices are hydraulically controlled, and this puts constant pressure on the oil pump to meet the ever-increasing system demands for flow and pressure.

Compare your part to aftermarket parts of the same item. What makes yours better? The LS3 oil pump is better than any aftermarket oil pump out there and backed up with extensive design work and validation testing. Before a pump leaves the GM design floor, computerized analytical tools, like Computational Fluid Dynamics (CFD), are used to ensure that all features are optimized for performance. Pumps are then built and extensively tested on component bench tests, as well as on firing engine-dyno tests. Finally, the pumps are installed on engines destined for test vehicles and tested on racetracks around the country—like Grattan, Virginia International Raceway, and Road America—to verify that they are track ready from the factory. Some aftermarket pumps are simply reverse-engineered versions of the GM design with cosmetic changes. Some aftermarket pump manufacturers remove or change key features without any technical understanding of the impact.

Do you own a Corvette, a classic car, or have a related hobby? My favorite work activity is riding shotgun in a Corvette on a racetrack during a development-test session, while monitoring lube-system performance. It's like riding a rollercoaster in a rocket ship. My favorite ride is my father-in-law's '79 Light Blue Corvette on an empty country road.

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