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Originally from GM Powertrain...
PONTIAC, Mich. – In auto production, more power, better fuel economy and fewer emissions rarely appear together. But the 2012 Camaro 3.6L direct injection V6 engine achieves all three by combining the exhaust manifold with the cylinder head into a single aluminum casting.
Each integrated exhaust manifold cylinder head – a V6 has two -- replaces a cast iron exhaust manifold, six bolts, a gasket and a heat shield and three bolts. By eliminating this joint, the potential for a gasket failure is eliminated. And the change reduces engine weight by 13 lbs. or 6 kg per engine. Reducing mass helps improve fuel economy and the 2012 Camaro 2LS model is EPA estimated at 30 mpg highway.
“Reducing engine mass of this magnitude doesn’t happen often,” said Ameer Haider, GM assistant chief engineer for V6 engines. “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 simulation and bench testing was performed to perfect cylinder-head airflow. Intake airflow is improved 7 percent with the use of larger intake valves (38.3 mm v. 36.9 mm), which are primarily responsible for an increase of 11 horsepower. Exhaust flow is 10 percent better than the previous V6.
Lower emissions, narrower engine size and noise reduction round out the list of benefits for the new head design. With the catalytic converter closer to the engine exhaust point, the emissions reduction process begins sooner, resulting in lower emissions. The new cylinder heads decrease the overall width of the engine by 4.6 inches (117 mm) for significantly more packaging space in the engine bay making underhood work easier. Due to less surface area, the new design contributes to a 1 decibel reduction in engine noise at idle.
“The new, patented design benefits the customer in all the key areas without any tradeoffs, said Haider. “Emissions, performance, fuel economy, and noise all improve with the integrated exhaust manifold.”
Each integrated exhaust manifold cylinder head – a V6 has two -- replaces a cast iron exhaust manifold, six bolts, a gasket and a heat shield and three bolts. By eliminating this joint, the potential for a gasket failure is eliminated. And the change reduces engine weight by 13 lbs. or 6 kg per engine. Reducing mass helps improve fuel economy and the 2012 Camaro 2LS model is EPA estimated at 30 mpg highway.
“Reducing engine mass of this magnitude doesn’t happen often,” said Ameer Haider, GM assistant chief engineer for V6 engines. “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 simulation and bench testing was performed to perfect cylinder-head airflow. Intake airflow is improved 7 percent with the use of larger intake valves (38.3 mm v. 36.9 mm), which are primarily responsible for an increase of 11 horsepower. Exhaust flow is 10 percent better than the previous V6.
Lower emissions, narrower engine size and noise reduction round out the list of benefits for the new head design. With the catalytic converter closer to the engine exhaust point, the emissions reduction process begins sooner, resulting in lower emissions. The new cylinder heads decrease the overall width of the engine by 4.6 inches (117 mm) for significantly more packaging space in the engine bay making underhood work easier. Due to less surface area, the new design contributes to a 1 decibel reduction in engine noise at idle.
“The new, patented design benefits the customer in all the key areas without any tradeoffs, said Haider. “Emissions, performance, fuel economy, and noise all improve with the integrated exhaust manifold.”
This is mostly a lie.
The manifolds were integrated to save the cost of the manifolds. It probably saves GM about $35 or $40 bucks and engine. No manifolds and fewer holes to drill and tap. Of course the heads are going to run hotter and may crack but GM will probably get most heads to last well past the warranty period.
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