Follow up on the 2014 Silverado/Sierra Preview - The Engine(s)

Discussion in 'In the News' started by xcel, Dec 14, 2012.

  1. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    [​IMG]I did not want to overwhelm the site with truck news yesterday but here we go again.

    [fimg=right][/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.


    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.
  2. Jay

    Jay Well-Known Member

    Aluminum block to save weight. Cast iron (!) manifolds to add weight? :confused:
  3. herm

    herm Well-Known Member

    That improved oil/air separation is to prevent deposits on the valves that come with direct injection. Is the humidity sensor something new in the industry?

    What compression ratio does the competition use?
  4. phoebeisis

    phoebeisis Well-Known Member

    11/1 -my 98 has 9.4/1 guessing the 5.3's are just under 10/1?

    So maybe the 5.3 will match the 22mpg hy of the Ford 3.5?
    Maybe the 4.3 will match the 23mph of the Ford 3.7?
    Zero chance they will match the 3.6 Ram 25mph

    GM doesn't have the $$ for R&D to develope completely new truck motors-and they also might see some marketing advantage o keeping the SBC
    I wonder how much developing the 2 mode cost-which was tooooo expensive-and only matches the Ram in combined mpg ?
    The Volt-expensive

    Now GM was betting on $5-$6 gas maybe-Volt would sell a lot better with $6 gas-folks might have bought 2 modes with $6 gas?
    The guessed wrong.
  5. RedylC94

    RedylC94 Well-Known Member

    Hint: Exhaust gases are hot.
  6. herm

    herm Well-Known Member

    Three new engines is pretty risky, I dont like it too much but you know how conservative I am.

    The advantage of the small block chevy architecture is no timing belt or chain driving four overhead cams?
  7. phoebeisis

    phoebeisis Well-Known Member

    Yes it is compact-and perhaps at low RPMs it has an inherent friction advantage??
    Not sure on the friction advantage-but twice as maybe valves sliding up and down- dual cams
    VS- kinda long rods sittimg on those Hyd lifters-not sure how much friction that entails?

    Any proof the pushrod SBC have a friction advantage at lower RPMs?
    But V6 VS V8 hard to overcome the V-6 friction and heat loss advantages
  8. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    I was under the impression that these three engines are "all new" , albeit with identical displacement to the old ones. It does seem a little suspicious..............

    If the 4.3 is "all new" , then why so much displacment ? Do they NOT want to compete with Ford and RAM for 6-cylinder FE ? I can see why they might want the same bore-to-bore spacing. I haven't checked bore and stroke compared to the ancient 4.3 , but I imagine the new one is (more) undersquare , as most engines are.
  9. phoebeisis

    phoebeisis Well-Known Member

    All new but with exactly the same displacement-configuration-
    and much more displacement than their competitions "base models"

    Well lets see how they deliver.
    Yes they might have all new different parts-but all new ??
    Guess for packaging reasons-fitting trans motor mounts- makes sense to keep them essentially the same size-
    I bet the bore stroke is all but the same as last year's models
  10. RedylC94

    RedylC94 Well-Known Member

    With the pushrods, they may need the displacement to get near the power of competing OHC engines. (Power=torque×speed, which tends not to be the forte of pushrod engines)
  11. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi All:

    Because these are "state of the art" ancient pushrod engines, RPM limitations rear their ugly heads rather quickly. I am not sure but I think GM is making a big mistake with ancient "State of the art" with DI instead of all-new state of the art with DI unless these things really perform some magic.

    Place the average driver or journalist behind the wheel and cylinder deactivation is gone. DI has so far proven not to add any highway fuel economy as well. What does that leave??? I am even more worried now that I have had a look at the tech.

    James, what are the Duramax guys speculating about the old - new “state of the art” drivetrains?

  12. Not a whole lot on the 2 dmax forums I'm on a lot. Most are waiting for the 2500/3500 to be released. Some are disappointed no 4.5 dmax in the 1500. Maybe a bigger concern on the gm gas forums.

    A few quotes:

    "Will be curious to see how they stack up against the twin turbo Ecoboost."

    "since the EPA is cracking down and putting the companies that make dpf deletes out of business, I'd buy one if these and put a lift and a charger on it.".

    "Only the displacements are the same...

    Pretty fascinating technology at work in those engines. I hope they're putting out some serious power now! Direct injection, 11:1 compression, infinitely variable valve timing, all new better flowing heads, these out to be some badass motors. Can't wait to see the mileage and power numbers."

    "interested to see what the new V6 is. Yes, its a 4.3, but it shares nothing with the "traditional" 4.3 that we've known for the past 30 (??) years.

    My guess is the new 4.3 will basically beanLS1with 2 cylinderslopped off. (because if you cut 2 cylinders off of a 5.7 liter displacement V8 engine, you're left with a 4.3 liter V6)"
    Last edited: Dec 16, 2012
  13. phoebeisis

    phoebeisis Well-Known Member

    Other than being more compact-
    do 2 valve pushrod engines have ANY inherent efficiency advantage over modern OHC 4 valve engines?
    Do they have a slight friction advantage-at lower RPMs maybe?
    I'm trying to read GMs mind on the "why" of 2 valves and pushrods in a 4valve OHC world?
    Of course it is cheaper to rework old- but something other than CHEAP?
    It is the question GM has been asked for 25 years-
    They built a 4 valve V-8-Northstar- but had problems-and the straight 6 in the trailblazer-let it sorta die on the vine?
    Just can't be that hard to do?
    Why? Other than cheaper and compact?
  14. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    I always thought the 4.2 straight six in the TrailBlazer was a sweet engine with cutting-edge tech for its time. It would have been a good engine for a "sensible" Camaro , in other words , a smaller and lighter Camaro , if it could be attached to a good manual trans. But maybe SUV and truck buyers (especially GM) don't want technology , they want cheap. I don't know.

    I'm really not qualified to comment on trucks and SUV's anyway.
  15. phoebeisis

    phoebeisis Well-Known Member

    Hey I'm not qualified either-
    BUT it never stopped me from commenting on things I know almost nothing about!

    Yeah I liked that straight six-nice modern engine-shouldn't have needed balance shafts(guess it didn't have them)
    Should have had PLENTY of developement potential.
    Did GM discontinue it?
    They almost immediately undercut it buy offering the Trailblazer with the 5.3 in premium performance trim-made no sense.
    Should be able to make nearly the same hp with a 4 valve 4.2 as a 2 valve 5.3?
    Yeah-made no sense!
  16. We had a 6 cyl trailblazer. I rarely drove it but what I remember was the Agent would avg 17-18 mpgs. The few times I drove it a full tank I could get 22-23 mpgs. It 'could' pull our 4100 lb camper, but worked it and would only get 11-12 mpgs going easy on it. My work van at the time would get better mpgs pulling the camper so we always took it instead.
  17. phoebeisis

    phoebeisis Well-Known Member

    A buddy of mine has a 6 cyl trailblazer. He says he gets 24-25mpg in pure hy driving.
    I point out I get 21mpg(98 suburban) with a "real truck" not a 3/4 scale truck.
    He is a gun show reloader Texas La-so he loads it up really heavy-and he doesn't have all the room I have
    and he is a GM nut-so I never tire of pointing out he doesn't have a "real" SBC.
    Kidding of course-but GM never bothering developing that 6-
    immediately undercut it by offering the 5.3.
    What motors does Cadillac use in their cars-do they still have a 4 valve V-8 in their lineup?
    I know the Escalades use the pushrod motor
    all that $$ for an Escalade-and you get pushrods
    Of course-same story Corvette-2 valve pushrod-works pretty well-big HP- goodish FE

    So is there ANY efficiency advantage to the 2 valve pushrod motors??
    or are they just cheaper-and "good enough" for GM?
    Northstar sour them on 4 valve OHC V-8's?
  18. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi All:

    Here is one of the quotes from the PR:

    Jordan Lee, Small Block Chief Engineer and Program Manager
    Maybe GM has found something in the small block program we do not know about but after driving the 4.3L and 5.3L V8 against the 3.5L EcoBoost in a drag race and the latter in a 7,500 pound tow off, they were literally 10 and 5 truck lengths behind in a 600’ drag race respectively. The 5.3L struggled with the tow by comparison as well.

    F-150 with the 3.5L EcoBoost vs. Silverado with the 5.3L V8 in a 600' drag.... Completed tens to hundreds of times.​

    The 4.3L in particular was way behind the power curve and felt really doggy by compassion to anything I have driven recently.

    Of course this was 2011 but DI, an increase in CR and variable valve timing do not usually make an ugly engine pretty again. Not in this day and age that I know of anyway?

    All told, I really hope GM pulled one out of the hat because this sounds like a recipe for disaster. And a celebration at both Ford and RAM at the same time.

  19. southerncannuck

    southerncannuck Well-Known Member

    I think these engines are being marketed to buyers who are more interested in seemingly more reliable technology than those looking for the absolute best fuel mileage. I bet they sell a ton of them.
  20. herm

    herm Well-Known Member

    Do we really care about high rpms or drag races?.. the important thing for trucks is low end torque, I think..

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