I did not want to overwhelm the site with truck news yesterday but here we go again. [fimg=right]http://www.cleanmpg.com/photos/data/501/2014_Silverado_4_3L_V6_-_2.jpg[/fimg]Wayne Gerdes - CleanMPG - Dec. 14, 2012 Meet the 2014 Silverado and Sierra’s Ecotec lineup. Following up on the 2014 Chevrolet Silverado and GMC Sierra Pickup Preview, a new engine family is being introduced from familiar displacements that have been produced for decades. Namely the 4.3L V6, 5.3L V8 and a 6.2L V8. Saying that, while most manufacturers would have moved the bar, with some advanced tech thrown their way, maybe these old dogs have learned some new tricks? I am just not sure they learned enough just yet. All of these engines incorporate direct injection, cylinder deactivation (this has been less than optimized in the past) and continuously variable valve timing (which has been used for decades by other in far less important automotive lines) to make the a reasonable amount of power, torque and efficiency. The new 4.3L V6 will offer budget-conscious customers what GM is calling a “state-of-the art” truck engine, with ample torque to power a crew cab and tow a trailer. I am not so sure about the “state-of-the art” statement but hopefully it will be a much improved upon V6 as it is competing with some pretty hearty competitors in this segment. The 2013 RAM 1500 with its 3.6L Pentastar and 8-speed AT come to mind. The new 5.3L V8 is engineered for more horsepower, more torque and better fuel economy than the current 5.3L V8. Again it needed it as it was not only inefficient but not power or efficiency competitive with something like Ford’s 3.5L EcoBoost released over 2 years ago. The new 6.2L V-8 is expected to be the most capable engine offered in any light-duty pickup truck. Combustion According to the company more than 100 iterations of the combustion systems were evaluated through computer modeling before a final design was selected for each engine displacement. For example, truck engines often need to provide maximum power under heavy load for long periods of time, such as towing a trailer up a mountain grade. You do not want to know what I removed from this release “here” but it was fluff The new engines run at an 11.0:1 compression ratio to simultaneously increases both power and thermodynamic efficiency. To reduce pre-ignition (knocking) on a warm day, the Silverado and Sierra’s combustion system reduces the need to trim back spark advance to control detonation, helping maintain both performance and real-world fuel efficiency. Due to direct injection alone, cold starts emissions are reduced by about 25 percent. The engines also feature a new cylinder-head design and a new, sculpted piston to optimize the mixing of air and fuel in the engine and the burning of the mixture to create power. The heads features smaller combustion chambers shaped to complement the unique topography of the piston heads. The smaller chamber size and sculpted pistons produce a compression ratio of 11.0:1 or higher, depending on the engine, while the heads features large, rectangular intake ports with a slight twist to enhance mixture motion. To further enhance combustion, the intake and exhaust valve positions have been switched from previous versions, and the valves are now slightly canted toward the cylinder centerline. Also, the spark plug angle has been revised and the electrode is now closer to the center of the chamber to support optimal combustion. The pistons feature unique sculpted topography that was optimized via extensive computer analysis to precisely direct the fuel spray for better mixing and more complete combustion. The contours of the piston heads are machined after casting to ensure dimensional accuracy – essential for precise control of mixture motion and the compression ratio. Cylinder Deactivation Cylinder deactivation is now standard on all three engines. The new trucks make the most out of cylinder deactivation, with improved engine mounts, electronic throttle control, adaptive exhaust systems, improved aerodynamics, low-rolling resistance tires, and other technologies that help the engines operate in four-cylinder mode for longer periods of time, further increasing efficiency. The system uses oil pressure, controlled by the powertrain control module, to deactivate the lifters on selected cylinders, closing the valves for those cylinders. It deactivates four of the cylinders on the V8 engines and two cylinders on the V6 under light load conditions – operating the engines as a V-4 – and seamlessly reactivates the cylinders when the driver demands greater power. The transition takes less than 20 milliseconds and is virtually imperceptible. The one problem with this system in the past is GM was so gun shy about allowing I4 operation that it was essentially a 60 mph or below system and rarely could you ever launch with it even though you were never into the pedal. Even though past engines had the ponies to drive under cylinder deactivation, the solution was extremely touchy at best. I have much higher hopes for it today given the CAFE and competitive pressures GM is enduring within both the truck and car segments today. Engines features and highlights Weight-saving aluminum engine blocks: For 2014, all three engines for the Silverado and Sierra use lightweight aluminum blocks with cast-in iron cylinder liners. The blocks were developed with math-based tools and data acquired in GM’s racing programs, providing a light, rigid foundation for a smooth and strong engine. A deep-skirt block design helps maximize strength and minimize vibration at the expense of friction in some cases. Cross-bolted main bearing caps are secured to the block with four main bolts and two cross bolts each. A structural aluminum oil pan further stiffens the bottom of the block. The result is an engine that is quieter, smoother and more dependable. The oiling system incorporates a new variable-displacement oil pump that enables more efficient oil delivery, based the engine’s operating conditions. Its dual-pressure control enables operation at a very efficient oil pressure at lower rpm, and then delivers higher pressure at higher engine speeds to provide a more robust lubrication. I like this feature! Oil capacity has been increased to six quarts for the 4.3L and eight quarts for the V8 engines. I am not sure why however as it adds more expense to the maintenance routine. All engines use GM’s Dexos oil for increased fuel efficiency and longer oil life, and V8s are engineered to use 0W20 oil to improve lubrication and reduce friction. How about that! At higher engine speeds, small jets spray oil on the underside of each piston. This helps reduce piston temperature, enabling the engine to maintain maximum horsepower and torque without detonation and ignition timing cutback. PCV-integrated rocker covers: New domed rocker covers house a patent-pending integrated positive crankcase ventilation system that enhances oil life, reduces oil consumption and reduces exhaust emissions. The domed sections of the covers contain baffles that separate oil and air from the crankcase gases, with about three times the oil/air separation capability of previous engines. The exhaust manifolds were developed to improve durability and sealing and reduce operating noise. The cast iron manifolds feature saw cuts along their cylinder head mounting flange, which split the flange into three separate sections on the V6 and four separate sections on the V8s, allowing each section to move under extreme hot-cold temperature fluctuations to virtually eliminate movement of the exhaust manifold gaskets. That helps ensure proper sealing for the life of the engine and reduces the chance of gasket failure. The exhaust manifolds also feature triple-layer stainless steel heat shields, which limit heat transfer to the engine bay and help further reduce noise. Additional features and technologies of new Silverado and Sierra engines include: A revised cooling system with an offset water pump and thermostat for more efficient performance An air induction humidity sensor ensures optimal combustion efficiency Individual ignition coil modules and iridium-tip spark plugs All in, there is nothing ground breaking about any of this but it will improve both performance and efficiency for an engine lineup that needs it most. While the HP, Torque and fuel economy ratings will not be released until late winter/early spring of next year, an improvement is an improvement and I have high hopes that the newer old 4.3L in particular is finally able to rise to the occasion and compete with both Ford and RAM as both of those companies have moved forward leaving the current GM truck engine lineup and in particular the V6 engine in their dust.