GM develops integrated exhaust manifold cylinder head for 3.6L V6 direct injection engine; improvement in performance, fuel economy, emissions and noise
|The reduced complexity of the design of the new integrated exhaust manifold cylinder head (bottom) compared to the old (top). Click to enlarge.|
GM has combined the exhaust manifold with the cylinder head into a single aluminum casting in the 2012 Camaro 3.6L direction injection V6, achieving both better fuel economy while reducing emissions.
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. The change reduces engine weight by 13 lbs. or 6 kg per engine. Reducing mass helps improve fuel economy; the 2012 Camaro 2LS model is EPA-estimated at 30 mpg US (7.8 L/100km) highway.
Extensive simulation and bench testing was performed to perfect cylinder-head airflow. Intake airflow is improved 7% with the use of larger intake valves (38.3 mm v. 36.9 mm), which are primarily responsible for an increase of 11 hp. Exhaust flow is 10% better than the previous V6.
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.
Reducing engine mass of this magnitude doesn’t happen often. 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.
The new, patented design benefits the customer in all the key areas without any tradeoffs. Emissions, performance, fuel economy, and noise all improve with the integrated exhaust manifold.—Ameer Haider, GM assistant chief engineer for V6 engines
|Tom Sutter, Chief Engineer for GM V6 engines, describes the cylinder head design change and the integrated exhaust manifold.|