By on August 23, 2010

GM’s decision to use its off-the-shelf 1.4 L four as the range-extender power source was a compromise born of necessity. The originally conceived 1.0 L turbocharged three cylinder engine didn’t exist (in the US), and GM’s pre-bankruptcy budget was a little constrained to spend the bucks for the tooling. The 1.4, in a different state of tune, is shared with the Cruze, as is as much of the rest of the car as possible. GM has made it pretty clear that the gen1 Volt is a bundle of compromises, given the time, technology and budget constraints it faced. But the gen2 is apparently another story. In an echo of GM past, Volt Vehicle Director Tony Posowatz tells Automotive Engineering that the engine options are wide open; way way wide open:

“That may be a Stirling cycle engine, perhaps it’s a Wankel, a gas turbine, a small displacement motorcycle engine– you can extend the possibilities to a lot of different alternatives.”

Aw come on Tony, this isn’t Popular Science of the sixties anymore. Unless the gen2 Volt is a lot longer off than the usual model cycle, isn’t it a bit late to be dusting off the Stirling cycle programs from back then? Or is this just the same old GM routine of seeding mid-engine Corvette rumors for the last five decades? I’m betting on the Wankel, because the tooling for GM’s Wankel engine is probably still in a warehouse somewhere.

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48 Comments on “Volt gen2 Range Extender: The Field Of Infinite Engine Possibilities...”


  • avatar
    1996MEdition

    “That may be a Stirling cycle engine, perhaps it’s a Wankel, a gas turbine, a small displacement motorcycle engine– you can extend the possibilities to a lot of different alternatives.”

    or this…..
    internetsiao.com/pink-hamster-wheel-car/

  • avatar
    brettc

    So the one to buy will be the next version? It’s almost like we’ve heard this before or something. I’ll keep it in mind when I’m shopping for my next vehicle at a non-GM dealership.

  • avatar
    TokyoPlumber

    When NGMCO, Inc. bought assets and operations from General Motors Corporation on July 10, 2009 the clever, string-pullers thought they’d kept all the old liabilities out of the new GM. Unfortunately, such was not the case. The business culture so deeply ingrained within the old GM (now Motors Liquidation Company) still pervades the new GM (General Motors Company). A change in ownership structure did not alter the hue or texture of the 100+ year old fabric that is this company.

    GM has never been short of interesting ideas and concepts. Execution, deployment, making-it-metal is their failing. For decades GM has consistently fallen short when it comes to bringing new ideas to market as fully developed and competent products. “Almost, but not quite” is the mantra of GM’s senior managers. What’s most important is talking up the next concept. Determining why some newly introduced vehicle didn’t measure up to expectation are bones to be chewed by those outside GM.

  • avatar
    Tstag

    JLR already have a Jet engined series hybrid prototype. Personally I think Jet engines are the way to go in such designs as they are much more efficients than IC’s or rotary’s.

    • 0 avatar

      For a host of complicated reasons, a small turbine is not as efficient as a big one. Williams had a lot of trouble with FJ22 even, but even for an engine that small I estimate a turboshaft version would easily put out 800 hp. It’s about 10 times as big as Volt needs. And slapping together an engine from old Garrett components would probably produce the fuel economy a Chevy Silverado, and an engine overhaul every 20,000 miles.

    • 0 avatar
      L'avventura

      Back at the 1998 Detroit Auto Show, GM also built a turbine version of their EV1 in a serial-hybrid configuration.

      Either way, any bespoke engine wouldn’t be ideal for the Volt. It doesn’t make economic sense to design and build an engine that can only be fitted into a single model.

      My guess will be the Volt Gen2 will have an small displacement HCCI-engine. The greatest challenge for an HCCI engine has been to keep the engine in HCCI mode throughout the rev range. An extender engine wouldn’t have this problem as it will always be running at a constant speed.

    • 0 avatar
      niky

      An HCCI that’s in charge compression all the time…

      …you mean: diesel? :)

  • avatar

    This is very exciting, and would be a great payoff for the flexibility that Volt’s engine-generator architecture affords. But I suspect Tony is lying. It will not happen.

  • avatar
    James2

    GM could save itself a lot of time and trouble by licensing *current* Wankel technology from Mazda.

    • 0 avatar
      Robert Schwartz

      After all, they are not using it anymore.

    • 0 avatar
      gslippy

      Except that Mazda’s rotary is going to finally bite the dust after 2011 due to its inability to keep up with emissions regulations.

      http://green.autoblog.com/2010/05/06/emissions-regulations-to-kill-mazda-rx-8-after-2011-model-year/

      Anyway, licensing the Wankel technology would be counterproductive for the green virtues of the Volt, not to mention cost.

    • 0 avatar

      They can also talk to Revolution Engines, although being as big as GM they probably won’t.
      http://www.revrotaryinc.com/index.html

    • 0 avatar
      L'avventura

      Mazda is expected to update their Rotary engine sometime in the near future. They’ve already showed the direct-injected 16X which should meet global emissions regulations. The problem hiterto has been that the Wankel engine wasn’t able to maintain ideal air-fuel mixture under low-load conditions. Direct injection should go a long way in addressing Wankel’s greatest faults.

      However, outside of Mazda we are unlikely to see its use as an extender engine. Its still a fairly expensive engine to build, and the goal of these PHEVs is to get the price down to affordable levels. Hence, spending money on an exotic extender engine is not ideal.

      Suzuki has shown off a 660cc 3-cylinder extender engine in their PHEV Swift. This may be the ideal extender engine, its mass-produced for the kei-car market, cheap, and incredibly light.

  • avatar
    gslippy

    It they went Diesel, then it would be even more like a locomotive.

    Seriously, they need to get costs in line before a gen-2 Volt is a viable development project. Some of the cost reduction must come from the battery.

    The Cruze-ish 1.4L is probably very cost-effective. All those other options mentioned are either cost killers or market killers. Does anyone seriously think GM is going to put a small motorcycle engine in a Volt, let alone be able to sell it?

    Somebody at Nissan is laughing at GM right now; even with its limited range, the Leaf’s controls, cost, and complexity aren’t hampered by this issue.

    • 0 avatar
      KixStart

      If the Cruze-ish 1.4L is “probably very cost effective,” why does the Volt cost so darned much? After all, it only has 2/3 the battery (the most spendy part) that the Leaf has.

      And estimates suggest it’s going to be very heavy, which will hurt both performance and range (with both fuels).

      Something must be done to lighten it up and bring down the cost.

    • 0 avatar

      I wasn’t aware that R&D on a new concept in automotive powertrains was so cheap.

    • 0 avatar
      gslippy

      @KixStart: The Volt’s costs are driven up by:

      1. It has two propulsion units, even though only one drives the wheels.
      2. It has a huge lithium battery – very expensive.
      3. Engine, drivetrain, & cooling management controls are necessarily complex.
      4. Labor costs will be higher for such a vehicle.

      One reason gasoline-powered cars are so plentiful is they’re cheap to build. A 1.4L Cruze engine is about as low cost as Chevy can go for this application. All those other options are pie-in-the-sky technology, and higher cost.

  • avatar
    Syke

    This is going to sound like an incredibly dumb question, but think about it for a minute: If all the gasoline engine has to do is to power the generator/alternator/whatever-electricity-producer, why can’t they just hook up a two cylinder Briggs and Stratton engine? Or something like it? Granted, it’s going to have to be worked over for smoothness, emissions, etc., but why can’t an off the shelf industrial motor do the job? After all, it’s only powering a generator, like the one you hook into the transfer switch on the house when a summer storm takes the distribution lines out.

    If anything surprised me when the Volt was announced, it was that they were using a 4 cylinder, 1.4 liter engine. For the needed purpose, that sounded like extreme overkill.

    • 0 avatar
      Russycle

      I had the same reaction to the engine choice. I’d love to give GM the benefit of the doubt, I mean it took Toyota a few tries to get the Prius right, but they’ve screwed the pooch way too many times.

    • 0 avatar

      They wanted a car-like performance in the limp-home mode, that’s why. With a lawnmower engine, a depleted Volt would not be legally allowed on freeways in some locales, for example.

    • 0 avatar
      LectroByte

      1.4 is probably not overkill, it sounds about right to me. Once the battery is discharged, then all the energy to move the car and its contents is coming from the gasoline engine. You are losing something in the conversion from gasoline to electricity, but I’d expect that a gas engine optimized to a certain RPM to drive the generator could have some efficiencies over the engine in your average car though.

    • 0 avatar
      Disaster

      The engine is wayyyy overkill and GM knows it…hence the search for a different engine. They only need about 10-20hp to scoot down the freeway. A 30hp motor would have enough extra power to keep the batteries boosted enough for those short acceleration boosts. Ideally, you want an engine optimized for steady state efficiency…a typical IC engine is completely wrong for this application.

    • 0 avatar
      John Horner

      Pete has it right. Imagine you are driving your Volt cross country on Interstate 80 through Colorado. There are some very, very long uphill grades to be pulled through, and the engine-generator is going to have to provide all of the power for doing so once the battery pack has been drained.

      Just watch how slowly a vintage VW bus climbs that grade to see what happens when you only have 50 horsepower or so available. I don’t think the new Volt owner would be happy not being able to drive at the speed limit through Colorado. A tiny little 20-30 hp engine would be completely unsuitable.

    • 0 avatar
      JonKessler

      I-80 doesn’t go through Colorado. But I’m not sure 30hp would get you over the mountains of Nebraska either.

  • avatar
    Andy D

    wha happened to the 3 cyl Geo Metro Aka Suzuki Swift?

  • avatar
    newfdawg

    The research and development people at General Motors always seem to
    be devising interesting ideas, unfortunately their execution is always troubled; they never reach the potential that GM originally promised.

  • avatar
    Da Coyote

    Hmmm, from my extensive wastage of $$ to GM through the years I can confidently predict that any new engine will be poorly designed (thanx to MBAs – engineers know what they’re doing, but MBAs are engineering flunkouts), and poorly constructed (thanx to UAW) of poor quality materials (thax to MBAs, UAW, and now the most incompetent class of idiots in existence, the US Govt).

  • avatar
    pgcooldad

    GM is a day late dollar short on the use of a Wankel. FEV Motorentechnik — an engine and powertrain systems R&D company based in Aachen, Germany already uses a small 26 HP Wankel rotary engine that turns on and sends a current to the batteries to provide an extra 190 miles of range on a small amount of fuel for a Fiat 500— and it only has a 3.17 gallon tank!
    The LiiON can go 50 miles on a charge before the Wankel kicks in. It can go from 0-37 mph in less than 6 seconds, and has a top speed of more than 75 mph.

  • avatar
    carve

    A Stirling would be a TERRIBLE idea in this car for two reasons.

    1) This engine won’t be USED AT ALL during daily commutes
    2) They have bad power to weight ratios.

    Since the gas engine will seldom be used, the priorities are different than in normal cars. Things like reliability and efficiency are far less important in this application than weight, size, cheapness, and low-maintenance. Air-cooled, for instance, might be beneficial to reduce weight and the requirement to change coolant.

    They should put in an engine that can sustain the car at 85 mph on level ground, or maybe 55 up a 5% grade, and nothing more. Maybe 40 hp, to take a WAG. We’re talking small motorcycle engine.

    The reduced size and weight of the engine can be replaced with battery, extending the EV range, reducing the liklihood the engine will be needed even further.

    The detrements of the small engine could be mitigated in two ways.
    1) Use the bigger battery to buffer the power more. Right now, I think under gas power the volt only uses about 5% of battery capacity as a buffer…between 25 and 30 % I think. Why not 20-40%? Run that engine at full-tilt until you hit 40, and throttle down, that way you’re ready for the next call for acceleration.
    2) Use GPS to predict engine demand. If you’re within a few miles of home, and headed in that direction, no need to use the engine to pump the battery up to 40%. If the GPS think you can make it home before you hit 20%, then let that happen. Likewise, if the GPS knows you’re on a freeway, and are approaching a hill in a few miles, kick the motor in far enough in advance to have enough energy to make it to the top without losing any power. GPS could make more accurate predictions by remembering where you’re probably going when you’re on a particular route at a particular time, or by having a few hot keys for common destinations (e.g. home, work, beach, Costco, parent’s house).

    Eventually, hopefully they’ll be able to shrink the engine and tank down enough to attach to a receiver hitch, or maybe have it as a removable module in a bay that can fit either a motor & tank, or an additional battery. You’d only swap in the motor if you’re going on a road trip. Maybe a longitudinal flat-2 with an 4-5 gallon tank. The tank doesn’t need to be any bigger than a typical person’s bladder can handle on a road trip- maybe 200 mile range, + 40-60 miles on the battery, and small will be good to help ensure the gas doesn’t get too old. Such a system could be further cheapened by replacing the generator with a CVT and 5th wheel, with battery charging occurring by putting the electric-driven wheels in regen while the 5th wheel is pushing.

    All that said, I could think of a good use of a Stirling: in a car that sort of splits the difference between a Volt and a Prius. A non-plug-in hybrid with a relatively small battery. You could have a ~20 hp Stirling that runs continuously as soon as you start the car, and a ~165 hp electric motor to handle the actual motivation of the car. That’d probably get pretty killer mileage.

    • 0 avatar
      Lokki

      After reading all this, I am more firmly grounded in my fundamental belief about electric/hybrid vehicles. They’re all Rube Goldberg machines whose best performance doesn’t ultimately improve substantially upon the performance of the currently available versions of Rudolf Diesel’s engine in real world use.

      “Eventually, hopefully they’ll be able to shrink the engine and tank down enough to attach to a receiver hitch, or maybe have it as a removable module in a bay that can fit either a motor & tank, or an additional battery. .

      All this complexity for cars that won’t really save any -significant- amount of the world’s oil useage. Ships and power plants, plastics, and industrial uses use up a far higher percentage of oil than automobile fuel.

      Additionally, there really isn’t a carbon-based fuel shortage.
      America has a 600 year supply of natural gas. I spent Sunday evening with a friend who is currently finalizing the design of a plant that cracks natural gas into JP4 and diesel. They’re already being used on a smaller scale on some oil rigs at sea where the gas had previously just been burned off into the atmosphere.

      There’s there’s gasoline from coal.

      Finally, the whole “C02″ is evil thing is another story… but even if you accept that, cars aren’t the major source of it, and even if you think they are, cutting American production of it won’t do anything when the dung fires of India and Pakistan et al are considered along with the industrial outputs of China and the thirld world.

      /rant off.

      Electric/hybrid cars really are fun as intellectual exercises. Sort of like back in the 60′s when the fashion was to have the most elaborate possible chronometer on your wrist.

  • avatar

    GM had a license to build the Wankel in the 70′s.I have a bunch of Popular Science magazines from the 70′s with articles about GM production plans for the engine. I think they could not get the emissions/reliability to meet their standards. AMC was going to buy them for the Pacer then had to do an emergency re design when GM cancelled production . I wonder if the license was time limited or they lost it in the “government takeover”.

  • avatar
    GS650G

    With a spanky new engine the new price should climb well over 50K. Perfect for a supposed economy car. Not. You can’t call it eco friendly since it still burns gasoline.

    The next time our Deal Leaders decide to bail out a car company can we have a referendum on it instead?

  • avatar
    niky

    They need the extra power to allow the Volt to limp home at highway speeds.

    This is where the argument for a wheel-driving gasoline engine comes into play, because it’s extremely wasteful to have the engine driving the generator that charges the batteries that drive the motors (whew… it’s even harder to say it!) when you could have a 1 liter engine that just drives the wheels through a simple CVT.

    If you need the make the onboard generator powerful enough to run the car, it compromises the package. Extra weight. Extra complexity… you’re never going to leave it running overnight to charge it… are you?

    But then… the Volt has to sell itself on convenience, much like the Prius did. The original Insight was technically a better car than the Prius, but it demanded too many sacrifices from the client. If the Volt demands that the client put up with a 40 mph speed limit with the battery drained, the client is going to look elsewhere.

    • 0 avatar
      niky

      Ah… yes… it doesn’t charge… but that’s still engine-generator-electric motors… you need to push out a lot of hp to overcome the conversion losses in that system and still maintain highway speed.

      54 hp would be more than enough if the engine was driving the wheel directly… but this isn’t the case.

  • avatar
    esldude

    Folks keep forgetting, the engine does not recharge the batteries in a Volt. Only plugging it in does that. It is a serial hybrid after all. Engine turns gen to drive the car if batteries aren’t doing the job.

    As for what engine you need, well it would take about 54 hp to push the volt up a 6% grade at 55 mph. More than enough for highway speeds on the flat of course. That would be rather sluggish response nonetheless. My guess would be an overall effective improvement that won’t break the bank will be something rather conventional like a small 2 or 3 cylinder turbo motor running at higher than usual speed. Should be lightweight, can be efficient, small, and since it only turns a generator making it drive right isn’t much of a problem.

  • avatar
    GS650G

    The volt’s purpose is political, it’s here to make a statement of some kind. Except that Nissan already made it for less money. And Toyota found ways to express that statement a myriad of different ways from increasing performance to creating a car that already is being converted to PHEV by it’s owners.

    Ford could build a better EV with the platforms they have and experience gained through mild hybrid tinkering but they are playing with real money, not 60 billion tax dollars. And their stock price shows it.

    We will look back on this debacle one day and wonder just what the hell these people were thinking. We are supposed to buy this car with all these issues for the price of a decent BMW?

    Tell me again what the demographic is for this thing, the cost benefit equation, or even how it saves icebergs and rain forests?

    Does anyone trust their transportation in this science project masquerading as a car?

  • avatar
    John Horner

    The mid-engine Corvette idea actually got pretty far along through the development process. We ended up getting the Fiero instead :(.

  • avatar
    PeriSoft

    Ahh, the gas turbine, fated to always be happening next year, like Linux on the desktop, the video phone, set top boxes as computer replacements, and the end of rotating media.

    I read a great Popular Mechanics article from 1983 or so on Google Books: It was announcing the (at long last) final arrival of the practical electric car: 0-60 in 12 seconds, 300 mile range, 30 minute recharge. If you search, you can find one of those articles every two or three years since then, like clockwork, each the same as the last.

    • 0 avatar

      Funny you should mention that, because I use Linux on my desktop exclusively (well actually a laptop). And the video phone is heavily used these days: it’s called “Skype”. Can a gas turbine be far behind?

    • 0 avatar
      niky

      Two of my five computers are Linux-based… thinking of installing Android OS on one, actually, and checking it out.

      A gas turbine is probably not going to be practical for at least a half-decade or a decade more. Microturbines are still way too expensive and complex for use in mass-market vehicles.

  • avatar
    GarbageMotorsCo.

    So we should expect this gen II Volt to cost about 80 grand (before added dealer markups) then?

  • avatar
    snabster

    this is a stupid question, and a bit off topic, but perhaps somebody can take me to school. Why can’t someone take regular engine, but instead of a turbocharger, use a small turbine from the exhaust gas to produce electricity? I understand that wouldn’t work with the Volt, serial hybrid blah blah, but as a mild hybrid you could take off the accessory belt and run the power steering, alternator, AC and everything else off electricity.

    Or add a second turbine behind the turbocharger if you really need the increase in air density.

    • 0 avatar
      psarhjinian

      Interesting idea.

      Possibly it’s an issue of efficiency: you’d lose energy to heat twice (the motor/generator and the turbo) and to state changes three times (turbo>generator, generator>battery, battery>motor). It’s more efficient to just force more air into the engine.

      That said, it could be switchable: boost on acceleration and generation on cruise. I don’t know enough to say if backpressure would cause more loss than power generation would.

    • 0 avatar
      carve

      No reason at all other than added cost and complexity. They’re called turbo-alternators, and have been talked about for a long time, but never produced. I think one of BMW’s recent “Efficient Dynamics” concept cars might use one.

    • 0 avatar

      I think the BMW ED actually uses an intermediate heat transfer agent in order to avoid running the exhaust itself through the turbine. I don’t know to what end though. Turbocharged motors are common these days, surely it’s not because of reliability concerns.

  • avatar
    snabster

    @carve; thanks — I knew somebody here would point me in the right direction.

  • avatar
    Mr Carpenter

    How about this?

    A small (and I mean small) high speed three cylinder diesel of about 1 litre running at “best efficiency” RPM – or cycling off; powering a hydraulic pump; attached by high pressure lines to a 5 or 6 gallon globe; in which there is a diaphragm separating nitrogen from hydraulic fluid; computer controls to run it, and hydraulic pump/motors on each wheel.

    You therefore have a super-efficient all-wheel drive diesel-hydraulic-hybrid of (relatively) low cost using virtually no to very few “rare earth minerals” which can be run on bio-diesel (see http://www.changingworldtechnologies.com), diesel from oil, peanut oil, diesel from coal, etc.

    Not to mention the fact that the fuelling infrastructure is already in place and mechanics already have a clue about working on diesel engines.

    Just a thought….


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