By on September 16, 2015

GM Ventures Sees Potential in Fuel Saving Technology

General Motors may use an advanced cylinder deactivation technology, co-developed with Delphi and Silicon Valley startup Tula Technologies, in its SUVs and V-8 cars to shut down up to six cylinders to maximize fuel economy, Automotive News reported.

According to the automaker, GM in 2012 invested in Tula, which specializes in automotive engineering. The automaker announced in January that it would pursue the advanced cylinder deactivation technology for some of its SUVs, which could improve fuel economy by 15 percent in cars with engines with more than four cylinders.

The system, dubbed Dynamic Skip Fire, keeps the throttle open during operation and controls cylinder firing through a special valve that cuts off oil to the deactivated cylinders’ valve lifters. According to the company, the engine computer changes the deactivated cylinders to avoid vibration or noise.

According to the report, a GMC Yukon Denali with a 6.2-liter V-8 was fitted with DSF to shut down all but two cylinders on a highway drive. The Yukon’s fuel economy improved by 21 percent, according to Automotive News.

“This technology holds the potential to improve fuel economy on select GM vehicles without degrading power capability when it’s required,” Jon Lauckner, GM chief technology officer, vice president of Global R&D and president of GM Ventures, said in a statement.

The cost could be between $300 and $600 depending on the engine for the technology.

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88 Comments on “Cylinder Deactivation Could Drop a Corvette Down to 2 Cylinders...”


  • avatar
    CoreyDL

    Perhaps Dynamic Miss Fire would have been more appropriate. Though that kind of sounds like a drag queen.

  • avatar
    BDT

    21 percent is nothing to sneeze at.

  • avatar

    heresy!

  • avatar
    DeadWeight

    What could possibly go wrong?* It sounds like all plus and no minus.

    *Based on Guangzhou Motors engine history.

    • 0 avatar
      DeadWeight

      “The system, dubbed Dynamic Skip Fire…”

      GM has had this technology for a long time, I assure.

    • 0 avatar
      tresmonos

      Say what you want about their vehicles, but GM is possibly the best powertrain development and manufacturer there is. I’d say that after 30 plus years of messing with cylinder deactivation tech, this will *probably* work very well.

      • 0 avatar
        DeadWeight

        Whaaaaaaaaaaat?

        I wouldn’t bother to respond if this wasn’t you, but aside from transmissions (even I as much as I detest GM can’t deny GM makes durable and smooth transmissions), Toyota (including Lexus), Honda…?

        As someone once said, brilliantly, GM does powertrain development by Excel Spreadsheet, hence why a 1990s era Oldsmobile Cutlass Cierra could match a 1990s era Toyota Camry in terms of NVH on paper.

        • 0 avatar
          bball40dtw

          LS/LT V8 > just about everything else

          For example, I don’t really like the Silverado. The look isn’t offensive, but I don’t care for the interior layout, driving position, or center stack/IP. However, the 6.2L V8 is goodness. It just is.

          • 0 avatar
            DC Bruce

            AS the owner of a ’15 Sierra with this engine and after 11,000 miles, I have to agree whole-heartedly. The only downside is the requirement for 94 octane fuel. The IP shows when the engine shifts to 4 cylinders. The instantaneous fuel economy readout jumps immediately. 24 mpg at 60-65; 21 mpg at 75-80, driving east from Denver. The shift back to 8 cylinder mode is not quite imperceptible; but if you didn’t learn to recognize it by watching the IP, it would be undetectable.
            I’m a little curious as to how shutting off two more cylinders is going to produce a 21% FE increase. That’s pretty dramatic.

        • 0 avatar
          APaGttH

          Even in the darkest days of GM and the Farago days of TTAC it was LS swap FTW.

          LS engines are reliable, efficient, light weight (relatively), uncomplicated, easy to work on, have a bevy of cheap parts, and countless bolt on providers.

          Don’t like how the particular engine was configured out of the factory? It is stupid easy to swap out parts from this LS engine to put in that LS engine to get X improvement (sacrificing maybe mileage, or NVH, or, altering the torque curve, or…).

          There isn’t a high performance or truck family of engines available today that are better when you check off all the boxes.

          [INSERT RANT ABOUT HEAT SOAKING C7 HERE]

          • 0 avatar
            bball40dtw

            I like to think that during the GM bankruptcy, Alan Mullaly, Bill Ford Jr, and Mark Fields were trying to figure out how to buy GM’s Powertrain division without having to deal with the rest.

          • 0 avatar
            CJinSD

            The LS may be an excellent design, but it is hardly an example of quality manufacture. Was piston slap even a term before the LS reached the market?

          • 0 avatar
            WhiskeyRiver

            I can already see an aftermarket run on the Corvette 8-6-4-2. Can’t wait to stuff one in my ’70 GTO Judge.

        • 0 avatar
          MrGreenMan

          You must not have driven GM products…lately.

          GM can make durable and smooth RWD transmissions. The FWD transmission baffles them.

          The 6-speed GM/Ford FWD transmission is a far better experience in Ford products.

          Edit: lately

          • 0 avatar
            APaGttH

            The biggest problem with GM transmissions is not the transmissions, it is the programming. They are generally programmed to be super biased to fuel economy. Loooooooooooooooooooooooong slllllllllllllooooooooooooow shifts. Loooooooooooooooooooooong waits to kick down when the gas pedal is planted.

            I get it, you shouldn’t have to do this but the fastest, easiest, and best cure for this is a $250 to $300 programmer and retune of the transmission.

            Hey, got to keep the CAFE monster happy.

          • 0 avatar
            bball40dtw

            I can’t stand the transmission programing on the GM V8 trucks. It makes me angry. It’s like the V8 has to overcome the transmission programming. The 5.3L is especially horrendous.

        • 0 avatar
          Maymar

          GM’s been at the cylinder deactivation thing for 8-9 years now – has it presented any real problems?

        • 0 avatar
          DeadWeight

          “I wouldn’t bother to respond if this wasn’t you…”

          For the record, that was a poor choice of words.

          There are many here that I WOULD have responded to had they made the same remarks, but a notable few I’d probably ignore (true GM fanboys, blind to objectivity regarding any matter GM related).

          p.s. X2 – I realize now, also, that your comment was entirely in jest per your /sarc tag below.

      • 0 avatar
        Pch101

        “Say what you want about their vehicles, but GM is possibly the best powertrain development and manufacturer there is”

        You can’t be serious.

        • 0 avatar
          APaGttH

          They further qualified the statement to be around LS/LT engines, which would then also imply strongly RWD drive lines (yes the LS4 was put in the W-Body, an outlier).

          I think it isn’t a terribly unfair assessment to say the GM LS/LT engine family in RWD applications are darn good – some of the best in the industry.

          I don’t think (I would hope not) saying that a GM 2.4 with a 6-speed FWD auto is better than the equivalent Toyota – that would be blasphemy.

          • 0 avatar
            golden2husky

            The LS/LT engines are superb, period. GM owes a lot of folks an apology for many missteps, but this engine family is not one of them. Regarding AFM I just don’t get the hate. If long term durability is caused by half the engine being unpowered for long periods of time (as asserted by the B&B) the mixing of the unpowered cylinders makes that a non-issue, if it ever was one.

      • 0 avatar
        bullnuke

        Got to agree with tresmonos on this one. Relays mysteriously rattle things on and off, interior light randomly turn on and drain the battery, the tin worm hits weird spots to the point of nothing but chassis-engine-seats remain but GM powertrains will still move what’s left through the gates of the junkyard. Just “ask the man who owns one”…

      • 0 avatar
        tresmonos

        It’s getting easier to troll this site.

      • 0 avatar
        wmba

        @ tresmonos

        Only decent reply here.

        This Skipfire tech is licensed from Tula Technology which GM invested in at startup, and keeps the engine equally warm all over by using all 8 cylinders in a random manner. However, GM may not go the whole random route from what I’ve read, because that would be a few bucks more.

        This was announced back in January, BTW.

      • 0 avatar
        VolandoBajo

        Yeah, right, thirty years of tinkering, it still doesn’t work right, but by the law of averages, it should start working right soon.

        Cutting off lubrication to the valve guides of the inactive cylinders sounds like a formula for premature wear and premature failure.

        I’ll tell you what, let’s let someone else try that out on their almost $100K brand new sports car. I think I’d rather start out with a used sports car costing less than half that, and then refurbishing it.

        Let someone else do the field engineering on the reliability or lack thereof of this new system, same as the old system, GM path to fuel economy.

        I don’t know how they can publish stuff like this with a straight face, or where they can come up with enough suckers, er, buyers to buy into what has been a thirty year failed experiment, whose only new feature is cutting the number of active cylinders in half, when running at maximum economy. If it didn’t work for 2 or 4 out of 8 cylinders, what will make it different when this cockamamie scheme is tried on 6 out of 8 cylinders?

        But maybe this is the way forward for GM…next stop being eight single cylinder engines, all synchronized electronically, with two driving each wheel. That way they can just shut off the engines whose cylinders they don’t want running, instead of having those cylinders rotating but not firing.

        After all, if other manufacturers can synchronize an electric and a gas motor driving wheels, why not just extend GM’s scheme but eliminate the weak link…the inactive cylinder that continues to rotate.

        If I thought that idea was any good, I’d patent it. But I wouldn’t touch it with a ten foot pole.

        Oh, and GM could also capitalize on other thirty year old previous failures…let’s make those eight single cylinder engines diesel engines, but built on standard four stroke bottom ends, to reduce costs.

        That technology failed enough times for GM that they must have figured out a way for it to work by now, also.

        And by the way, if you send me a thousand dollar deposit for one of them, I will also give you an opportunity to buy in on the ground floor of a new bridge I am going to build from Brooklyn to Manhattan, one that will reap massive returns for early investors such as yourselves.

        But act now, before others buy into what could have been your part of the future.

    • 0 avatar
      dantes_inferno

      @ DeadWeight: What could possibly go wrong?

      > Cylinder Deactivation Could Drop a Corvette Down to 2 Cylinders

      And for those times when you need to accelerate out of the path of a speeding tractor-trailer, GM has a solution for that – “engine deactivation”.

  • avatar
    28-Cars-Later

    I think this kind of tech is the way to go. Stop forcing turbocharged garbage on us and give us this.

    • 0 avatar
      Aquineas

      Agreed, but I want it on a car for at least 5 years of production before I’ll spring for it.

    • 0 avatar
      Sigivald

      I want both; a 6 or 8 with a low-pressure turbo *and* deactivation.

    • 0 avatar
      EAF

      Although I’ve never come across it first-hand, I have read owner complaints (& a GM TSB) concerning excessive oil consumption in AFM equipped vehicles.

      I cannot remember the exact details but it involves oil deposit formation in the piston ring grooves. The build up occurs only on the deactivated cylinders. I have also read of collapsed lifters, again on the deactivated cylinders. DW is right, this isn’t new tech.

      I’m with you 28, despite more moving parts I too prefer a V8 to a turbo 4 but I don’t want my V8 equipped with cylinder deactivation.

      • 0 avatar
        Carlson Fan

        Yep your right about what happens with the AFM engines. I’ve watched oil consumption increase on our ’07 Tahoe due to AFM. We’ve owned it since new. As we speak I’m waiting for a device to come in the mail that plugs into the Tahoe’s OPD port and disables the AFM. We’ll see if that cures it.

      • 0 avatar
        87 Morgan

        You are correct, the 5.3 in 07 – 08′ have oil consumption issues. The oil control ring seizes after prolonged use of AFM and you get consumption. Collapsed lifters follow.

        I had my 5.3 in suburban rebuilt (kinda, new pistons and rings) under warranty. I have not used a drop of oil since.
        @Carlson Fan. Their really is no solve other than new Pistons. The TSB has them running some de carbon junk through etc to hopefully free them, doesn’t work. Turning off the AFM will help in the future, but in your case as was mine, as they say, once the toothpaste is out of the tube….

        All that said, the LS/Vortec engines are the most universal and easy to use. Stuffing one in my 57′ this winter with a 4L60. Plenty of tunes available to download that address the shift point as well as cams available that get you darn near 400hp out of a 5.3 from a junkyard.

        • 0 avatar
          Carlson Fan

          @87 Morgan – Yes I’m afraid w/115K your correct about the toothpaste. But we’ll see if it at least stabilizes the oil consumption which is about a quart every 1000 miles. The Tahoe will shortly become a back-up/tow/road trip vehicle so at that point i can live with the excessive oil consumption.

          • 0 avatar
            87 Morgan

            If you are going to be towing be sure to check at every fill of the gas tank. I was burning a quart or better per tank when driving in the mountains. The heavier the load read RPMS the more she consumed.

          • 0 avatar
            Carlson Fan

            Yep I’ll be sure to monitor it during towing. No matter what I tow I always run it in “3” because it runs so slow in OD. So it’s always turning around 2700 to 3K RPM on the highway/interstate.

            Got my Range device in the mail yesterday. Taking it out to the Black hills, SD from Minneapolis in October so we’ll see how much oil it burns during that trip. I’ve noticed as the oil gets older and dirty the oil consumption goes up. Not as bad after a fresh oil change.

    • 0 avatar
      WhiskeyRiver

      I’m sure they will solve the oil filter adapter metal burr issue with this new engine. Then it will be perfect.

  • avatar
    gasser

    Will these new engines also be available with factory casting/maching debris?

  • avatar
    Chocolatedeath

    Does anyone make a diesel with cylinder deactivation? Or start stop?

    • 0 avatar
      bball40dtw

      Mazda makes a diesel with start/stop. It also has a brake energy recovery system called i-ELOOP.

      • 0 avatar
        Chocolatedeath

        Would it be to complicated to apply both too one engine? The reason I ask is simple. I want a six cylinder diesel/hybrid with those two techs thrown in. I want this in a large CUV for about 50 grand. Whom ever creates this would have my money for at least two redesigns.

    • 0 avatar
      pragmatic

      Diesels have no throttle, why would you need cylinder deactivation?

      • 0 avatar
        Sigivald

        To reduce pumping losses [sucking in, compressing, and expelling air takes energy!], when you don’t need N cylinders worth of power.

        • 0 avatar
          Sigivald

          (Actually, looking at your post below, maybe it’s a no-op, if they’re minimizing pumping losses in another way.

          Might explain *why* nobody does it, then.

          If it was of value, I’d expect to see it in every heavy-duty truck engine, and I’ve never heard of it, so… we can infer it’s either of no benefit or so marginal as to not be worth it.)

  • avatar
    APaGttH

    On paper this makes sense. Cylinder deactivation is definitely mainstream at this point with a number of makers using the technology.

    This is not the GM 8-6-4 which suffered from a Rube-Goldberg design and technology not being available to meet the concept.

    Once you’re moving it takes very little engine effort to keep you moving at highway speed.

    On the other hand i see this really appealing more to compliance testing. The reality of American highways for 50% of the population is there is no smooth, rolling along at 65-70 MPH without being on and off the brakes due to congestion. Obviously if you’re rolling on two cylinders any input from the gas pedal at all will move you to 4 or all 8.

    I know that the L76 in the G8 suffers from two issues. Early production 9L1 2009 cars got bad lifters from Eaton. GM has been reading on the forums pretty solid on swapping them out, and they tend to rear their ugly heads well before the 5/100 warranty expired (got mine done at 4/34K). The other issue is really more in the programming. The G8 almost never goes to cylinder deactivation and even the slightest touch of the gas pedal turns it off.

    Another issue that owners wrestle with on cylinder deactivation is after market exhaust systems. The exhaust has to be tuned to deal with the different configurations the engine can run – without it the drone into the cabin can be horrific at certain speeds and RPMs.

    • 0 avatar
      ClutchCarGo

      I think it could work as advertised anytime you can effectively use cruise control. Admittedly, this is not during most commutes, but it could well work on road trips.

  • avatar
    Austin Greene

    I wonder about thermal efficiency declining precipitously in winter driving.

    • 0 avatar
      RideHeight

      I wonder about coolant temperature and cabin heat during a long sub-zero highway drive.

      Or did I just say the same thing as you but in liberal arts terms?

      • 0 avatar
        Sigivald

        Yes.

        And it wouldn’t be hard to detect low coolant temperature and reactivate cylinders to maintain operating temperature.

        Ditto for the cabin, or take a hint from the hybrids and diesels and add an electric heater to take up the slack.

        • 0 avatar
          golden2husky

          Should be no problem at all. My hybrid will start its cold engine with a twist of the heater knob even if propelling the car was on battery.

        • 0 avatar
          redav

          I support grille shutters in all cars to keep more thermal energy in the engine when the weather/engine is cold.

          • 0 avatar
            gasser

            My Dad used to “winterize” our ’51 Ford by putting a large piece of cardboard between the grill and the front of the radiator from Thanksgiving to Easter. Thus the engine stayed warm enough to actually work the heater.

    • 0 avatar
      pragmatic

      I wonder how the cat stays hot and how they reduce NOx if there is O2 in the exhaust from the shut off cylinders. Unless they are killing the valves too, but they seem to be killing the DI and keeping the throttle more open so pumping losses are gone.

  • avatar
    sgeffe

    Did I read the article correctly that the ECU would vary which physical cylinders are shut down? (IOW, when a V8 goes to 4 cylinders, it’s not the same four that shut down every time.) That would stop the oil-burning and other issues.

    NVH is still going to be a problem, but I can deal with a little growl when I can go at Vmax with A/C blowing ice cubes and 2 pax aboard, and still pull mid-30s on an N/A SOHC V6!

    • 0 avatar
      EAF

      Good point, I misread the article.

      On a V8, if any 2cyl can be strategically activated, it would make sense that issues with oil consumption could be eliminated. It would also follow that NVH levels, when compared to AFM, would benefit greatly as well.

      No more turbos in 2017? Lol

  • avatar
    Synchromesh

    Tula is actually a large city in Russia which houses a major armament complex. Considering Corvette designer’s Russian roots I suppose it makes sense.

  • avatar
    Master Baiter

    Here’s an idea: use the de-activted cylinders as an air compressor. On deceleration and braking, store the compressed air in a tank. Release the air in the tank back into the cylinders on acceleration to supplement gasoline power.

    • 0 avatar
      EAF

      True. Or if GM could harness the power contained in a bolt of lightening, and somehow channel this power into the flex capacitor. The problem is you can never accurately predict when or where such a strike will occur. :-)

    • 0 avatar
      redav

      Or, it when full engine load isn’t needed, it could run a generator and store electricity, then when more power is needed, that generator is a motor to provide extra torque.

      • 0 avatar
        KixStart

        “Or, it when full engine load isn’t needed, it could run a generator and store electricity, then when more power is needed, that generator is a motor to provide extra torque.”

        Do you know you’re describing a hyrbrid or are you being unintentionally ironic?

  • avatar
    DenverMike

    This is just more proof what a stup!d concept the Eco Boost V6 was, as far as replacing V8s. Here’s a V8 that’s more fuel efficient than the EB, more powerful, more compact, and weighs at least 100 lbs less.

    I’m baffled as to why we’re so obsessed with cylinder count and displacement.

    • 0 avatar
      Rudolph

      Cylinder count & displacement
      Decades ago the GMC I6 truck engine (302 cu in) was used in oval dirt track races – unbelievable torque for the time ‼

    • 0 avatar
      redav

      I get the idea behind govts taxing displacement, but with forced induction, those govts look like a special kind of dumb. (Want a 5L engine making 300+ hp? Get prepared to take it up the tailpipe in taxes. Want a 2L turbo making 300+ hp and getting the same mpg? Great!)

      Cylinder count is a more logical issue. The more cylinders, the more internal engine drag, so fewer cylinders should mean more efficiency. But when “should” doesn’t overlap “does,” it’s time to stop talking about it.

    • 0 avatar
      KixStart

      “Here’s a V8 that’s more fuel efficient than the EB, more powerful, more compact, and weighs at least 100 lbs less.”

      According to the GM Press Release. Similar documents have also described other GM wonders that didn’t quite work out in the real world.

      • 0 avatar
        Sigivald

        Well, I think we can trust them on power and packaging [after all, we know how bit their engines are, and adding deactivation shouldn’t change the size or significantly affect weight].

        The only qualm will be on the fuel economy.

        • 0 avatar
          DC Bruce

          A site called “the fast lane truck” ran a Ford Ecoboost pickup pulling 10,000 lbs. of trailer up the I-70 grade from Silverton to the tunnel at the top and also ran a Chevy 6.2 8-speed pulling the same load. IIRC, the Chevy did a little better than the Ford in fuel consumption and basically the same speed (the 65 mph speed limit). Pickup trucks.com ran a more carefully controlled test over a 100 mile loop in Michigan; and the 6.2-powered trucks were several mpg better than the 3.5 liter Ecoboost — and this was running empty. As is well known by now, the Ecoboost engines generally seem to have disappointing fuel economy in owners’ hands, as compared to their EPA ratings.


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