The New Three-Six, Vee-Six
All About Camaro's New Base Engine
by Hib Halverson, Content Director

The changes to the 2012 Camaro's 3.6-liter V-6 represent greater refinement to an already well-balanced package. The base engine in Chevrolet's sporty coupe is a key factor in customer satisfaction as V6 Camaros are 60% of the market. The new V6, called the "LFX", uses new, lightweight components and has engineering enhancements designed to improve performance, efficiency and durability. Not only its it more powerful and has a wider rpm range than the current, LLT V6, Chevrolet estimates the '12 Camaro, equipped with the 2LS trim package, an LFX V6 and an automatic transmission will deliver an 30 mpg, one mile-per-gallon more than its predecessor.

“This is great engine architecture and our engineers have never stopped working to make it even better,” said Ameer Haider, GM Powertrain's Assistant Chief Engineer for V-6 Engines. “The enhancements for 2012 will deliver reduced engine weight, better fuel economy and lower emissions, along with the greater power that Camaro drivers will certainly appreciate.”

The revised three-six still has a 60° bank angle, aluminum block and heads and a forged steel crankshaft. What's new in the bottom end is a stronger and lighter connecting rod. The new rod's raw material is powdered metal–steel to be exact, the same material as the PM rods used in the ZL1's supercharged LSA V8. The powder is first pressed into shape or "briquetted" under extremely high pressure. Then it is heated or "sintered" such that the steel particles bond. After that, the rod undergoes the traditional forging process. This type of manufacturing results in a stronger part and one that is of "net shape," meaning it requires no machining for profile or balance.

 This PM steel has 3% copper rather than the 2% of the LLT rod. The greater copper content results in about 10% more fatigue strength and allows a slight mass reduction. More weight savings come with the rod's "net shape" which makes the design more consistent in mass than rods of traditional manufacture

Like most modern GM connecting rods, the new LFX forging is a "cracked rod." During manufacturing, to split the big-end, a stress riser is cut into its inside diameter. The rod is then stressed such that it fractures, or cracks, at that riser. The jagged surface left on both pieces precisely locates and locks the rod cap in place once the rod is assembled. The new rod increases bottom end reliability/durability such that other changes could be made to increase power and raise the engine's rev limit.

 The new engine's cylinder heads retain a dual-overhead camshaft, four-valve-per cylinder layout. The head castings are new and have an improved intake port along with larger intake valves having 7% greater area.

Complimenting the enhancements to the intake side, the LFX head castings have integral exhaust manifolds. More power, better fuel economy and fewer emissions rarely appear together, but the new V6 achieves all three by eliminating cast iron exhaust manifolds, heat shields, gaskets and 18 bolts and integrating the exhaust manifold into the head casting. With no joint between head and manifold, the potential for a gasket failure is eliminated. The change reduces engine weight by 13-lbs. per engine.

“Reducing engine mass of this magnitude doesn’t happen often,” Ameer Haider continued. “Engineering usually looks for reduction in terms of grams not pounds. It’s just like removing a set of golf clubs from your car when you don’t need them–ultimately it saves fuel. When combined with other mass reductions, the customer will see better fuel economy over time with better performance.”

Extensive computational fluid dynamics (CFD) analysis and flow bench testing was performed to optimize intake and exhaust flow. Because of the larger intake valves and better intake ports, intake airflow improves by 7 percent which is a key enabler of the new engine's 11 more horsepower. Exhaust flow through the integral manifold is 10 percent better than that of the previous, LLT V6. 

The new cylinder heads decrease the overall width of the engine by 4.6 inches for more packaging space in the engine bay and easier service access. Due to less surface area, the new head design contributes to a reduction in engine noise at idle.

“The new, patented design benefits the customer in all the key areas without any tradeoffs," Haider said. “Emissions, performance, fuel economy, and noise all improve with the integrated exhaust manifold.”

The LFX heads retain the direct fuel injection introduced on the LLT, but the injector design has been updated with better spray characteristics. Direct injection delivers fuel directly into the combustion chamber whereas older, port fuel injection systems deliver it upstream of the intake valve. Direct injection allows increased compression ratio for more efficient combustion and that leads to increased fuel efficiency at part- or wide-open throttle.

The intake camshafts have more duration and, for improved reliability at the new engine's higher rpm range, both cams are now held in place by saddle-type bearing caps. Intake duration determines how long the intake valves are open. By using larger valves and holding them open longer, more air flows into the combustion chambers and given more fuel, the result is more power. Normally, the tradeoff in that is greater fuel consumption, however, new fuel injector design is better matched to the engine’s combustion dynamics. Plus, the variable-valve-timing used on the LLT carries over to the LFX.

The result is more power without sacrificing fuel economy and, in fact, the LFX Team gets to have their cake and eat it too, because not only is there no gas mileage sacrifice, fuel efficiency actually increases slightly over that of the LLT.

The LFX's integral exhaust manifolds allow the engine's catalytic converters to be closer to the engine. As a result, "cat light-off" occurs sooner, resulting in lower exhaust emissions. Further emissions reductions come from the LFX's more efficient combustion.

A weight saving, glass-reinforced nylon intake manifold, such has been used on the Gen 3 and 4 V8s since 1997, replaces the previous aluminum part. Along with its weight reduction, the composite intake manifold has a smaller radiated surface area to help it maintain noise and vibration characteristics comparable to the previous aluminum unit. Finally, the throttle body is updated with a new, digital throttle position feature that eliminates a previous mechanical contact for more trouble-free operation.

To improve durability and reduce engine noise and vibration, the engine's front cover was strengthened with additional support ribs and an additional cover-to-block bolt. The cylinder block is modified slightly to accommodate that extra fastener. More noise reduction comes with a new fuel pump for the direct injection system, along with a new, isolated fuel rail. The new fuel pump is quieter, while the isolated fuel rail decreases fuel system noise.

The LFX is lighter than the current 3.6L V-6. Integrating the exhaust manifolds with the cylinder heads saves approximately 13 pounds and the new composite intake manifold saves approximately 5.5 pounds. Additionally, the lighter front cover and lighter connecting rods bring the total weight savings to 20.5-pounds which helps fuel efficiency and takes weight off the Fifth-Gen's front end.

“It isn’t often we get the opportunity to take more than 20 pounds off an engine. We met some aggressive targets while retaining great strength and reliability,” ACE Ameer Haider said. “The engine is as durable as ever but now with improved performance and efficiency.”