Follow Slashdot stories on Twitter

 


Forgot your password?
Close
typodupeerror
×
Hardware Hacking Power Build Technology

A New Lease On Internal Combustion 431

Posted by kdawson from the more-power-to-ya dept.
Somnus suggests we check out the latest issue of MIT's Technology Review, where researchers describe how they can dramatically boost engine output and efficiency by preventing pre-ignition, or "knock." How they do it: "Both turbocharging and direct injection are preexisting technologies, and neither looks particularly impressive... by combining them, and augmenting them with a novel way to use a small amount of ethanol, Cohn and his colleagues have created a design that they believe could triple the power of a test engine."
This discussion has been archived. No new comments can be posted.

A New Lease On Internal Combustion More

A New Lease On Internal Combustion

Comments Filter:

  • I find many of life's problems... (Score:5, Funny)

    by 26199 ( 577806 ) * on Tuesday March 13, 2007 @05:35PM (#18338957) Homepage

    ...become simpler with the addition of a small amount of ethanol.

    In a large glass.

    • "Ethanol would be stored in its own tank or compartment and would be introduced by a separate direct-injection system."

      This does tend to give new meaning to the term "fuel siphoning". Imagine the fun...

      *grin*
    • What would you say to some nice ethanol?

      I'd say, "Don't get too comfortable in that glass!"


  • Old (Score:2, Interesting)

    by jevring ( 618916 )
    Wow, this is yesterdays news. People in the tuning industry have been controlling "knock" in various ways for a long time. Either by raising the octane number on your ful (add ethanol or booster), so that you can had move advanced ignition timing, or simply retarding your timing and using the same octane rating fuel as you normally use

    • Re: (Score:3, Insightful)

      by AP2k ( 991160 )
      Even still, water and alcohol injection used to cool the charge is not new, and has been around since the 30's.

      Whoever wrote the article doesnt understand why SUVs and trucks have big engines. Its not because they are powerful, its because they need lots of torque. You can pull a trailor up a hill in an S2000 just like you can a road tractor, but the tractor will use much less fuel and less wearing of the engine doing it.B enignes arent going anywhere in SUVs any time soon, despite this seemingly "revolutio

      • Re: (Score:3, Insightful)

        by Original Replica ( 908688 )
        If the main reason for big engines is high torque, how does Hybrid tech change our engine needs? If we can continue to tweek combustion for a set load (generator) we just need the electric motors and batteries to catch up to the demands of heavy hauling to make mileage improvements in SUVs and Big Rigs. Sure this might be the reapplication of old tech, but every step towards efficency helps. If an ethanol injected engine becomes "cool" with the SUV crowd, then we all win. Many if not most SUVs are status sy

    • Re:Old (Score:5, Informative)

      by iamhassi ( 659463 ) on Tuesday March 13, 2007 @05:53PM (#18339251) Journal
      "People in the tuning industry have been controlling "knock" in various ways for a long time."

      Exactly. This sounds a lot like water injection, which has been around forever and does increase mpg by about 10% in turbo cars and allows lower octane fuel.

      Here's what's going to kill the technology from TFA:
      "Ethanol would be stored in its own tank or compartment and would be introduced by a separate direct-injection system. The ethanol would have to be replenished only once every few months, roughly as often as the oil is changed. A vehicle that used this approach would operate around 25 percent more efficiently than a vehicle with a conventional engine."

      This is exactly like water-injection [wikipedia.org] and it's why we don't see water-injection in vehicles. No one wants to have a separate tank that we need to remember to fill-up, and the 10% increase provided by water just isn't enough. This is the same story except it's ethanol, not as easy to find as water, and it's 25% better mpg instead of 10%.

      We will never see a production ethanol injection vehicle. Vaporware with a capital V

      • Re:Old (Score:5, Insightful)

        by drinkypoo ( 153816 ) <drink@hyperlogos.org> on Tuesday March 13, 2007 @06:01PM (#18339393) Homepage Journal

        This is exactly like water-injection and it's why we don't see water-injection in vehicles. No one wants to have a separate tank that we need to remember to fill-up, and the 10% increase provided by water just isn't enough. This is the same story except it's ethanol, not as easy to find as water, and it's 25% better mpg instead of 10%.

        But the story is different because the system will know what to do when it runs out of ethanol, which is to say retard timing and reduce mileage and power output until you add more ethanol. Water injection is aftermarket and usually not compensated for automatically.

        The mileage improvement is pretty compelling and I think we'll see it implemented if fuel prices rise much more.

        • This link was posted by someone else responding to the original post.

          http://en.wikipedia.org/wiki/Oldsmobile_V8_engine# Turbo_Jetfire [wikipedia.org]

          If you read the section, you'll notice that, even without fancy computer controls, they had designed the engine to retard timing when the reservoir was empty. The reason they discontinued the engine really was that people just didn't bother keeping the thing filled.

          Unfortunately, people are lazy. Unless the system is designed to kill the engine when the ethanol tank runs dry

          • Unfortunately, people are lazy. Unless the system is designed to kill the engine when the ethanol tank runs dry they won't bother keeping it full. If you did kill the engine that way they would, simply, refuse to buy the car (as was the case in the 60's).

            The difference is that gas was pennies in the sixties and is over three dollars a gallon right now (at least in NoCal) and is probably going to continue to rise over the years ahead.

      • Re: (Score:2)

        by misleb ( 129952 )

        No one wants to have a separate tank that we need to remember to fill-up, and the 10% increase provided by water just isn't enough.


        10% is borderline, but 25% is pretty significant. I'd definitly give this serious consideration. Maybe we won't see it in "production" but certainly there'd be a market for retrofits or special orders. I'd love it if I could retrofit my Hyndai with this.

        -matthew

    • Re:Old (Score:5, Informative)

      by MightyYar ( 622222 ) on Tuesday March 13, 2007 @05:54PM (#18339261)


      From TFA (and this goes for the reply above mine as well as the parent):
      "Similar approaches, some of which used water to cool the cylinder, had been tried before. But the combination of direct injection and ethanol, Cohn says, had much more dramatic results."

      Show me someone in the tuning industry using directly injected ethanol along with a turbocharger and regular gas. I've never heard of this approach.
      • Regardless, dual fuel will be the catch. Aside from convenience issues of filling up two tanks, E85 isn't even available everywhere in the US, and it's practically nonexistant outside of the US, Brazil, and Sweden. That means you can't take road trips, but more importantly it means the market is probably too small to be worth the effort.

    • Re:Old (Score:5, Informative)

      by dr_wheel ( 671305 ) on Tuesday March 13, 2007 @05:57PM (#18339313)
      I was thinking the same thing when I started reading the article. A quick search at any of the major car enthusiast websites will lead you to dozens of threads on direct injection and forced induction (turbocharging). This isn't news. There are already direct injection, turboed factory motors out there. The 2007 Saturn Sky Red Line, for example, is powered by a 2.0-liter direct injection turbo engine. You may have heard of another auto manufacturer using this same technology in it's diesel engines... VW's TDI (Turbo Direct Injection).

      The "new" part comes where they are using ethanol direct injection. It's a new twist on an old idea. See also water-methanol injection:
      http://en.wikipedia.org/wiki/Water_injection_(engi nes) [wikipedia.org]

      Sure, it's not anything evolutionary. And the article might read like 1st Grade literature for anyone who is familiar with cars and tuning... but it's still interesting stuff.

    • Re: (Score:3, Informative)

      by Loualbano2 ( 98133 )
      This actually is somewhat new.

      What they are doing is different from old alcohol injection that merely mixed the injected fuel with ethanol before it went past the intake valve.

      This method is using directly injecting ethanol similar to a diesel motor. The advantage seems to be the same effect but with way less ethanol. The article quoted having the ethanol refilled on the order of months.

      While the effects of alcohol injection are well known and are not new, this method seems to make it way more practical,

  • Rudolph Diesel (Score:5, Insightful)

    by LiENUS ( 207736 ) <slashdot&vetmanage,com> on Tuesday March 13, 2007 @05:39PM (#18339027) Homepage
    Congratulations You've discovered the same thing as Rudolph Diesel except that you don't quite have it right. You don't need to use ethanol or port injection ditch both of those and use good ol fashioned vegetable oil. 0 preignition and you can turn the boost way up on a tiny engine.
    • Why is this rated "funny"? Mythbusters did this:

      "Although there's no word on damage to the engine from using used cooking oil, a diesel-fueled car did run on it. However, the MythBusters speculate that once this alternative fuel achieves a significant interest level among the public, used cooking oil will be hoarded as a saleable commodity. The used cooking oil also did not quite fit the requirement of improved fuel efficiency, as it yielded approximately 10% less distance for an equivalent amount of dies

      • Re: (Score:3, Informative)

        by LiENUS ( 207736 )
        the beauty of a diesel is it runs on any oil, used cooking oil, cod liver oil, diesel fuel oil, motor oil. Properly setup itl'l run on used motor oil, used transmission fluid, used any oil.

    • Re: (Score:3, Insightful)

      by JesseL ( 107722 )

      0 preignition and you can turn the boost way up on a tiny engine.
      It's actually more like 100% preignition in a diesel, but they're built to withstand it without grenading.

      • Re: (Score:3, Interesting)

        by LiENUS ( 207736 )
        It's actually more like 100% preignition in a diesel, but they're built to withstand it without grenading. By design its impossible for diesel to have pre-ignition unless somethings wrong. so its 0% preignition, there is however 100% detonation which is a completely different thing. Pre-ignition is where your intake charge and fuel mixture ignite before your spark plug fires. Since diesels have no spark plug there is no spark plug firing event however intake charge also lacks fuel. So it can't ignite before

  • Internal Combusiton? (Score:3, Funny)

    by Reverend528 ( 585549 ) on Tuesday March 13, 2007 @05:39PM (#18339033) Homepage
    This headline made my brain spontaneously combusit.
  • Just with a spark plug instead. This is similar to water injection and water/methanol injection on a turbo gasoline engine.

    • Re: (Score:3, Informative)

      by drinkypoo ( 153816 )
      You can already do alcohol/nitrous injection into a diesel engine for power, and water injection has been fairly common for diesel performance for quite some time now. But because diesels don't have knock (they OPERATE by compression/hotspot ignition) this technology is utterly inapplicable there.

  • Not the final solution (Score:4, Insightful)

    by dal20402 ( 895630 ) * <dal20402&mac,com> on Tuesday March 13, 2007 @05:40PM (#18339049) Journal

    I suppose my first question is, when the owner inevitably lets the ethanol run out, what happens? Can the engine computer dial down the boost enough to prevent detonation? Or does the engine just have to shut down?

    That aside, it's always great to improve internal-combustion efficiency, but the real solutions will have a more dramatic effect than this. My own view is that the solution should be a plug-in series hybrid with about 60 miles of electric-only range and the ability to run maybe 400 more with the engine providing generator power. This would not seriously compromise the essential attributes of modern cars, while *dramatically* (think 80% or more) improving their fuel economy in many real-world usage patterns.

    Then we should have nuclear power behind all those 220v outlets... and 90% of cars should be much smaller, with people able to obtain bigger trucks for big jobs on demand from time-share or rental companies... a guy can dream, can't he...

    • When the Ethano runs out, the engine begins to "knock". It ignites before the right time. This decreases fuel efficiancy quite a bit, and could theoretically damage the engine if you did it long enough.

      But as you pointed out, a smart engine should be able to recognize that Knock is occuring. While the computer can not change the size of the cylinders, it could change the amount of fuel/air injected. This would reduce the chance of damage, but severly impair engine performance.

      The rest of your ideas a

    • I suppose my first question is, when the owner inevitably lets the ethanol run out, what happens?

      The engine will not be able to run at high boost (power).

      Can the engine computer dial down the boost enough to prevent detonation? Or does the engine just have to shut down?

      That depends on the static compression ratio of the engine, but if it's kept down to a reasonable value the engine should be able to run but the controller will open the turbo wastegate. If the static compression ratio is high enough to

    • Yes it is called a knock sensor and they have been in use for years. In most cases the knock lets the computer know it is happening and it will then retard the timing to eliminate the knock. In this case the computer only has to retard the timing and adjust the waste gate to drop the boost pressure to eliminate the knock.

    • Re: (Score:2)

      by Xiph ( 723935 )
      if you'd bother reading TFA you'd realized they did answer that question. You'll need to add more alcohol about as often as you change oil, the lack of oxygen to peoples brains is a much bigger problem

      • If you'd bother reading my comment, you'd see I was asking about neglectful owners, not anything in TFA. How many of the people you know actually change their oil on time?

        If these were in large-scale use the ethanol *would* run out. Often. My question was whether, when that happens, you get reduced power or your car stops running.

    • Then we should have nuclear power behind all those 220v outlets... and 90% of cars should be much smaller,

      Exactly. During the summer when the grids are already at full capacity it would be a very bad idea to have hundreds of thousands of electric cars charging at the same time. Then you won't pay your hard earned $$$ to BP or Exxon but instead to power companies like Enron. We actually need two things - 1) more energy and 2) a good way to store it (this implies a safe and economical way to distribute it as

    • I suppose my first question is, when the owner inevitably lets the ethanol run out, what happens? Can the engine computer dial down the boost enough to prevent detonation? Or does the engine just have to shut down?

      Not to worry; for decades now, we've known that water injection can similarly increase the power output (but not the overall efficiency) of an engine.

    • Re: (Score:2)

      by jez9999 ( 618189 )
      If you're gonna dream, at least dream of something [steorn.com] more idealistic, panacea-like, and less complex. :-)

    • Re:Not the final solution (Score:5, Interesting)

      by Rei ( 128717 ) on Tuesday March 13, 2007 @06:28PM (#18339805) Homepage
      and 90% of cars should be much smaller,

      Americans would never accept that. You might as well just say "and fairy princesses should fly down from candyland and give us all ponies to ride."

      I think a more realistic possibility is that vehicles will just get much lighter. As an example, if Boeing can make the Dreamliner out of carbon fibre, perhaps it's not that long before we start seing reasonably priced, mass-produced carbon fibre car bodies. There's also reasonably good odds of significant price reduction in titanium and titanium alloys, and aluminium use is becoming more widespread in the automotive industry.

      My ideal "dream" situation? A "grid" transportation system, in which vehicles are networked together without any humans behind the wheel (except "offroad"). electric vehicles which get their power from the road (standing wave transmission, perhaps). Autoconvoying and optimized speeds to greatly reduce traffic, increase road capacity, and reduce wind resistance. With vehicles much lighter from being pure-electric without need for even carrying the power source, high speed "bulletways" with coils of wire embedded in them, so that vehicles with halbach arrays (magnetic arrays with highly lopsided fields -- near double-strength on one side, near zero on the other) can employ "Inductrac" style maglev, eliminating rolling losses and having very little maglev losses at high speeds.

        * Greatly reduced wind resistance and no rolling losses.
        * Still your own, personal vehicle (the profiles would likely be a bit different from present day for optimal convoying, though)
        * Never having to drive. Play, sleep, work, chat, whatever during the trip.
        * Less need for roads eating up cityspace
        * Less traffic
        * Much faster travel, to the degree that airlines would be needed much less often.
        * Much less energy use
        * Independent of oil.
        * No need to even be in your vehicle while it's moving -- automated delivery, automated pickup of your kids or groceries (if the store will load for you), etc.
        * The great economic benefits of travel being automated and fast.
        * Much less space used up downtown for parking, as vehicles can drive themselves to and from less convenient parking without you.
        * No speeding tickets
        * Very few accidents (no human error, no drunk driving, etc)

      The benefits go on, and on, and on. Unfortunately, we have all of our existing infrastructure to deal with. Thankfully, it can be moved towards in stages. First hybrids, then plugin hybrids, then electrics, then grid-power electrics. First radar-assisted braking (like we have now), then wireless transponders to assist traffic, then increasing wireless information exchange and planning. Once vehicles are light enough, all-electric, and are designed for high-speeds with automated operation, inductrac-style maglev becomes realistic for long stretches.

      • Re:Not the final solution (Score:4, Interesting)

        by Osty ( 16825 ) on Tuesday March 13, 2007 @06:52PM (#18340097)

        * Never having to drive. Play, sleep, work, chat, whatever during the trip.

        I'm not sure I'd put that in the "benefit" column. I enjoy driving. What I fear most when people start talking about future transportation technology is that almost everybody assumes that driving is a chore and nobody should have to do it anymore. While it would be great to get the people who don't like driving off the road (the people who eat, read, do their makeup, change clothes, etc all while driving), if the solution involves removing my own ability to drive then I'm against it.

        Note that I didn't say anything about what I would drive. Electric, hybrid, magnetic, petrol, whatever, I'm fine with it as long as I'm allowed to stay in control of my personal vehicle.

      • Re: (Score:3, Insightful)

        by ThousandStars ( 556222 )
        Americans would never accept that. You might as well just say "and fairy princesses should fly down from candyland and give us all ponies to ride."

        Americans would and eventually will accept smaller cars, at least as soon as gas prices rise high enough. This could happen through any number of methods, including declining oil production, wars in oil states, or Pigouvian taxes [blogspot.com]. The latter makes a lot of sense because it would help prevent the first two in a feasible time horizon and with few negative external

  • Why stick with petrol? (Score:5, Interesting)

    by shplorb ( 24647 ) on Tuesday March 13, 2007 @05:42PM (#18339067) Homepage Journal
    This sounds an awful lot like a modern diesel engine. Modern diesels are turbocharged and use common-rail injection to achieve insane pressures at the injector heads (for really fine atomisation of the fuel), which directly inject into the cylinder. I believe the newer engines even stagger the injection during the compression and combustion cycles too to achieve more power and cleaner burning.

    (NB: I'm not a revhead so I might be talking shit)

    • Re:Why stick with petrol? (Score:5, Informative)

      by drinkypoo ( 153816 ) <drink@hyperlogos.org> on Tuesday March 13, 2007 @05:59PM (#18339341) Homepage Journal
      You're correct about all that, but the insanely high pressure is probably as much about getting the fuel into the chamber as it is about proper atomization. See, in a gasoline engine the fuel is [typically] drawn in with the intake air charge, although they are using direct injection sometimes as well. But in a diesel the ignition timing is controlled by injection timing. Diesels are typically over 17:1 compression - my Mercedes (currently defunct) is 22:1, PLUS an 11 PSI turbocharger. So you need considerable pressure just to get the fuel into the chamber. My Mercedes is old-school, it uses indirect injection (think CVCC, it's got a prechamber) but it also uses a mechanical injection pump that basically consists of a cam that runs five cylinder-type pumps (think hydraulics) and is driven by a connection to the crankshaft.
  • I'm not an eco guy by any stretch of the imagination, e.g. I still have an open mind about the cause of global warming. But I definitely believe what they said in Who killed The Electric Car [sonyclassics.com]: With at least $1 Trillion worth of oil in the ground, the oil industry will do ANYTHING to prevent people from finding an alternative source of energy.

    Even promoting more efficient cars.

  • There really isn't a shortage of power in modern car engines. What we need is efficiency, and not mere volumetric efficiency at that. The article implies that a smaller engine would be more efficient since it could be lighter, but even if knock is controlled, it will have to be a very stout block with either heavy components (rpm limiting) or expensive titanium components. Knock isn't the only thing that wears/damages a high performance engine. Heat (and heat cycling), friction, and lubrication all hav
    • It doesn't have to have heavy components. They could be forged aluminum :) That's significantly more expensive than steel, but a lot cheaper than Ti. And in quantity they wouldn't be nearly as expensive as the aftermarket performance parts typically available. Modern engines are already specifying higher grades of oil and coolant than have been common.

  • I don't get it (Score:4, Interesting)

    by roman_mir ( 125474 ) on Tuesday March 13, 2007 @05:46PM (#18339127) Homepage Journal
    How do we go from this:

    A vehicle that used this approach would operate around 25 percent more efficiently than a vehicle with a conventional engine.

    to this: ...Cohn and his colleagues have created a design that they believe could triple the power of a test engine, an advance that could allow automakers to convert small engines designed for economy cars into muscular engines with more than enough power for SUVs or sports cars.

    does a 25% increase in efficiency translate into tripling the power output?
    • 'cause it has ethanol in it. It is the latest eco-buzzword! It will cure all our problems!

    • Re:I don't get it (Score:4, Informative)

      by dal20402 ( 895630 ) * <dal20402&mac,com> on Tuesday March 13, 2007 @05:52PM (#18339215) Journal

      Yes. Note that I don't actually believe the claim about tripling power, at least not with a whole lot of *very heavy* reinforcement of the block and heads.

      For example: (Note: Numbers strictly pulled out of ass.)

      2.4l conventional engine: 150 hp, 30 mpg

      2.4l Super-Mega-Monster-Gas-TDI-Ethanol engine: 450 hp, 12.5 mpg

      Your engine is 25% more efficient per hp and is generating 3x as much power.

      Of course, the real application they have in mind is to create reinforced motorcycle-size engines that can power sedans, or small car motors that can power SUVs. If your 2.0l engine can create 360 hp, big torque, and get 17-18 mpg, you've reinvented a turbodiesel, except that your engine is (even with reinforcements) way smaller and lighter.

      • 2.4l conventional engine: 150 hp, 30 mpg

        2.4l Super-Mega-Monster-Gas-TDI-Ethanol engine: 450 hp, 12.5 mpg         - that's the part I don't get. Is there a dependency between efficiency and power output? I don't see it. They are saying that by increasing efficiency by 25% they are tripling the power output.

        and by the way I don't think it's 150hp, 30mpg to 450hp, 12.5 mpg. It sounds more like 150hp 30mpg to 450hp 22.5mpg, but this can't be right, when the power tripples, the mpg has to be calculated from that tr
    • The efficiency gain is obrained by using the exhaust heat energy to compress the incoming air and thereby get more air into the engine, which increases power output. The increased power output requires added fuel (as well as the added air) but essentially, more of the available energy is extracted from the fuel before the exhaust is dumped overboard.

      Typical gasoline engines are about 30% efficient from a heat standpoint: 30% of the chemical energy in the fuel is converted to torque at the flywheel. The re

  • Um, we figured this out decades ago. Race engines types of higher octane solutions to raise boost and compression. Methanol, Ethanol, Alcohol, Race fuel. It's simple chemistry. Pure gasoline packs more energy but is unstable, additives like Ethanol raise octane ratings making the fuel more stable but packing less punch (energy per volume of fuel). E85 is equivalent to 108-116 octane, good stuff, but not for a Buick. Throw it into a regular car and you need to suck down more fuel to get the same output

    • Re: (Score:2)

      by spun ( 1352 )
      Yeah, we've been keeping ethanol in a separate tank from gasoline and injecting it separately and directly into the cylinders to cool them and prevent knock forever. Riiiiight.

      You should really read the article before making snide comments meant to demonstrate your superior knowledge of a topic.

    • Re: (Score:3, Insightful)

      by Andy_R ( 114137 )
      The difference between this idea and simply mixing ethanol into the petrol is that the ethanol is injected first, so it vapourises, cooling the compression chamber down, in a similar way to a water injection intercooler. Quite how they arrive at a huge power gain from this isn't adequately explained though, and they do seem to ignore the difficulties of strengthening an engine enough to cope with triple the power, and a few thousand freeze/thaw cycles per second, and the extra weight that's going to add.

      Get

      • Re: (Score:3, Insightful)

        by tygt ( 792974 )

        give me about 60 mpg (and thats using our smaller british gallons!)
        You mean the little ones that are only about 120% the size of the US gallons?
  • Wow these guys should sell this technology to the drag racing community...oh wait they have been burning alcohol for years to give them the ability to, reduce intake charge temperatures, reduce pre-ignition in high compression and large boost scenarios.

    Yes we should be burning more ethanol and it is a outstanding engine fuel however pre-blending by the oil companies is a crappy idea. How about blending the fuel at the pump so I can buy pure ethanol and or blended. If one could buy pure ethanol at the pump t
  • Aside from the ethanol bit, BMW already uses direct injection and turbocharging to get 300hp, 300ft-lb and 30 MPG (highway) out of a 3 liter I6. N54 engine from the 2007 335: http://www.bimmerfest.com/forums/showthread.php?t= 144546 [bimmerfest.com]

  • Kids and car enthusiasts did this decades ago (Score:3, Interesting)

    by Oz0ne ( 13272 ) on Tuesday March 13, 2007 @05:56PM (#18339293) Homepage
    Seriously. Direct injection, fine tuned control of timing, and turbo charging all put together is what you see in a large number of hobbiest race cars. Drag, autocross, whatever. A lot of times they'll skimp on tolerances thus reducing the reliability of the engine, but it's not at all uncommon to take a solid normally aspirated engine and triple it's output with some good planning and bit of machine work.

    I've personally never added a turbo where there wasn't one before, but I HAVE done machine work, timing work, and injector work. I've taken a car from 220 hp to 290 hp with no detriment to the mileage, just better fuel/air mixtures and precise timing. It doesn't surprise me at all that people who've actually studied combustion instead of working on it for fun have been able to triple the output.

    What's surprising is how inneficiently tuned a lot of engines come from the factory.

    • Re: (Score:2)

      by thsths ( 31372 )
      > What's surprising is how inneficiently tuned a lot of engines come from the factory.

      For American cars, I absolutely agree. Those engine sizes are just massive, and the power is not usually what you could expect. Of course the upside is that the engine will last forever.

      European cars (especially the engines designed in Germany) and Toyota engines are much smaller, but develop an astonishing amount of power. This does benefit the efficiency, but it is possible to ruin such an engine if you abuse it (revv
  • Please drop your internal combustion research. This is a dead-end technology that relies on us burning stuff that we buy from terrorists. Please focus your efforts on a fusion engine that uses garbage like in the movies. The flying car part can wait though. Just get the fusion engine going. Thanks.
  • Do you really think that the Big Three will adopt new engine technology?

    You can still find push-rod engines being built today...
    • I know it's /. but...

      if you rtfa, you'd see that Ford is testing it.

    • Re: (Score:3, Insightful)

      by couchslug ( 175151 )
      "You can still find push-rod engines being built today..."

      Within the right rpm range, they are perfectly suitable for many installations.
      OHC engines are nice for high rpm use, and a dandy martketing feature, but pushrod engines can do the job from industrial equipment to Top Fuel drag racing.

  • Turbo lag, premature combustion (Score:3, Informative)

    by hcdejong ( 561314 ) <hobbes@@@xmsnet...nl> on Tuesday March 13, 2007 @06:06PM (#18339469)
    If they use this to increase turbocharger pressure, I'd expect turbo lag [1] to become a problem again. It'd be better to increase the compression ratio instead. Or maybe combine ethanol injection with some of the variable-compression designs that have been surfacing lately.

    Also: why would premature combustion still be a problem in a direct-injection engine? It should be possible to inject the fuel when it is needed, and not before. Or would that lead to timing problems?

    1: turbo lag is the delay between pressing the accelerator and power output rising. It's affected by the size of the turbocharger, boost pressure and a few less important factors.

  • Audi RS4 (Score:4, Informative)

    by mihalis ( 28146 ) on Tuesday March 13, 2007 @06:17PM (#18339611) Homepage
    Audi already uses direct injection and uses a compression ratio of 12.5:1 in its 4.2 liter v8 achieving 100 horsepower/liter without a turbocharger, see 2007 Audi RS4 review at Edmunds.COM [edmunds.com]

    I'm intrigued to imagine what they could do if this ethanol based charge cooling works out. I'm already forced to put 15% ethanol in my Audi V8 (sadly NOT an RS4), living in NYC, but if this works out maybe I can support the farmers AND have a powerful car for the weekends (I commute on the subway).

  • Buy a direct injection turbo charged car today! (Score:4, Insightful)

    by Spoke ( 6112 ) on Tuesday March 13, 2007 @06:22PM (#18339691)
    People have long known that ethanol fuels have high octane ratings (the measure of how knock resistant a fuel is).

    People have also long known that turbo charging an engine is a great way to extract more power out of a small engine.

    People have also known that direct injection allows you to reduce the tendency to knock since it lets you inject fuel into the hot engine at the very last second - reducing the amount of time the air/fuel mixture has to heat up.

    And guess what? Mazda produces cars today that has both direct injection and is turbo charged. For example, the MazdaSpeed 3 [mazdausa.com].

    It's 2.3 liter engine produces 263hp and 280lb/ft of torque and has an EPA fuel economy rating of 20/28mpg. So yes, while it does provide good power and decent gas mileage, it's nothing earth shattering compared to turbocharged cars without direct injection.

    The engine has a very high compression ratio for a turbo charged gasoline engine (9.5:1), especially one that pushes over 15psi of boost into the cylinders. That is direct injection working for you.

    For example, the slightly bigger turbo charged 2.5 liter Subaru WRX engine has a compression ratio of 8.4:1 and maximum boost of 11.6psi is rated at 230hp/235lb/ft of torque (though it is admittedly underrated) with similar fuel economy as the Mazdaspeed 3 considering that it is all-wheel-drive (20/26mpg EPA). The more powerful WRX STi has the same 2.5l displacement, 8.2:1 compression ratio and a bigger turbo pushing 14.5 psi is rated at 293hp/290lb/ft of torque but less fuel economy, 18/24mpg.

    Unless there is a lot of potential still to be found by combining these 2 technologies, I see it as more of an evolution rather than a revolution. Perhaps a 1.0 liter engine would be able to muster 120+ hp/torque but I find it hard to believe that it could achieve mileage ratings significantly higher than a hybrid. And you still can't turn the engine off when idling or coasting down hill.

    So how about a direct-injection, turbo-charged, atkinson cycle hybrid and combine the best of all technologies?
  • You can go buy an engine right now that uses turbocharging, high static compression, and direct injection. The Audi 2.0T FSI engine, featured in the A3, A4, VW Jetta, and VW Passat feature this.

    Ethanol is an octane enhancer (which prevents pre-ignition), and lets you run either higher boost, higher static compression, or more ignition advance.. all of which make more power (or more efficiency), and none of which, even in combination, will triple the output OR fuel economy. Many auto enthusiasts are discov

  • This is not news, or a discovery. (Score:3, Insightful)

    by a4r6 ( 978521 ) on Tuesday March 13, 2007 @06:26PM (#18339751)
    For anyone that knows their stuff about car engines, this article is a joke.

    Both turbocharging and direct injection are preexisting technologies, and neither looks particularly impressive. Indeed, used separately, they would lead to only marginal improvements in the performance of an internal-combustion engine.
    Really? So there aren't people slapping large turbochargers on little 3 liter supra engines and increasing the engine output 5-fold? Or is that only marginal?

    That aside, the problem with this is that a turbocharged engine at full output is very inefficient. A larger naturally aspirated engine will always be more efficient than the small turbocharged engine of the same maximum output. That's because a lot of energy is wasted compressing the intake charge, more than can be made up for with the displacement decrease, even with the newest fanciest garrett turbos. The only merit efficiency-wise of turbo engines is engine efficiency at low loads (when the engine is not under boost) relative to the maximum output. There is obviously a balance to be struck here, and that's why 18 wheelers have big v8's with turbo chargers, rather than even bigger engines or smaller engines running under high pressure. Designing a motor vehicle is always a balancing act, and in most cases a turbo is not helpful because of the cost, reliability and other shortcomings versus the benefits.

    Recently, car makers have started using direct injection to combat preignition that can damage an engine. It allows them to run leaner fuel mixtures, higher compression and more aggressive spark timing, improving the power/efficiency of engines. Direct injection has the exact same benefit with turbocharging. There are no compounded benefits from mixing the two technologies.

  • Equivalent (but inferior) to WATER injection. (Score:3, Insightful)

    by Ungrounded Lightning ( 62228 ) on Tuesday March 13, 2007 @06:33PM (#18339865) Journal
    Turbocharging already gives about a 2-to-1 boost while avoiding the knock limits - and it doesn't require a second tank, just higher-octane gas (which, at current price levels, doesn't command all that high a cost premium over regular). So the claimed 3-to-1 boost, while a significant further improvement worth going after, isn't as big a jolt as the standalone description would make you think.

    (My commuting vehicle is a 4-cylinder turbo - and 15 years old. It has 100k miles on it and I'm rebuilding the vehicle around it at a cost of about 8 grand - suspension, tranny, major engine service - because I can't get an equivalently performing vehicle on the current new market at any reasonable price. That's apparently because adding a turbo to a small passenger car has enough downsides that the public isn't interested. (Or perhaps because the auto companies' marketing departments are totally clueless.))

    Direct WATER injection of a high-compression ALSO gets this 3-to-1 or better boost. It has the same advantages as the alcohol injection at less cost: Higher power, reduced preignition, etc. But you can go even farther, since water won't, itself, combust.

    You also get more efficient transfer of heat to mechanical advantage by using the vaporization of the water powered by the heat of the regular fuel.

    And water is easier to find and cheaper than ethanol when it comes time to refil the second tank.

    This has been well known for a long time.

    The reason it hasn't been built into production engines so far: It requires two tanks of consumables. Run out of one and the engine has to stop, or run in a degraded mode. Auto makers haven't wanted to add that sort of operational complexity due to liability and consumer satisfaction issues.

    This "new" idea has the same drawback, only moreso, since the second consumable liquid is less generally available and already highly regulated.

    = = = =

    On the other hand, we've now got much more flexible computerized control of the engine. With the compression boost provided by a turbo (which can be disabled by software control if the alcohol or water runs out), a car with an empty second-fuel tank can still run while meeting emission requirements and without self-damage. You'd lose 2/3 of your peak power and your MPG would drop. But the car would remain legal, street-legal, and unharmed.

    So perhaps it's time to revisit direct cooling-fluid injection, dual-consumable, internal combustion engines.

    But if so, unless research shows that ethanol has some BIG advantage over water, using water would have the advantage that you don't need to modify the support infrastructure.

  • by combining them, and augmenting them with a novel way to use a small amount of ethanol, Cohn and his colleagues have created a design that they believe could triple the power of a test engine

    What did someone overturn Carnot cycle efficiency?

    You can always detect hype when they completely disregard the second law of thermo.

    Some brilliant scholar once said "In this house, we obey the laws of thermodynamics!"

  • Preignition is NOT knock (Score:4, Informative)

    by Alizarin Erythrosin ( 457981 ) on Tuesday March 13, 2007 @07:07PM (#18340295)
    Preignition is when the fuel/air charge ignites at the point of lowest compression, and then the engine has to compress this hot, expanded gas. This is how holes get burned in pistons. Knock is detonation, where the fuel/air charge does not burn in a controlled flame front, i.e. it suddenly detonates. It requires that timing advance be backed down a bit.

  • Power vs Efficiency (Score:3, Insightful)

    by Doc Ruby ( 173196 ) on Tuesday March 13, 2007 @07:48PM (#18340889) Homepage Journal

    Cohn and his colleagues have created a design that they believe could triple the power of a test engine.
    [...]
    A vehicle that used this approach would operate around 25 percent more efficiently than a vehicle with a conventional engine.


    Triple the power doesn't mean triple the efficiency, if "antiknock" means more fuel is burned. 25% more efficient is more like it. Fuelcells are typically 50% fuel efficient, compared with 40% maximum (to date) internal combustion. That's about a 25% efficiency increase, it's already here, and it's just getting started. Plus the drastically reduced pollution (especially Greenhouse pollution) means huge energy efficiency at the end of the cycle, when climate disasters are avoided. Meanwhile fuelcell efficiency is just getting started, racing towards 80% (over triple typical internal combustion efficiency) and beyond.

    So while this advance might be good for the market that's not ready for fuelcells, the fuelcells still look better. But at least we've got scientists and engineers working on fuel efficiency, and not just ways to squander the remaining fuel for combustion engines. That's a big change in efficiency in itself.

Slashdot Top Deals

E = MC ** 2 +- 3db

Close