Downsizing with Direct Injection and Turbocharging Is the Future of Gasoline Engines

Discussion in 'In the News' started by xcel, Apr 29, 2012.

  1. xcel

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

    [​IMG]Hyundai’s direct injected and turbocharged 1.6L is but one example.

    [fimg=right]http://www.cleanmpg.com/photos/data/501/Hyundai_1_6L_GDI.jpg[/fimg]Wayne Gerdes - CleanMPG - April 29, 2012

    Hyundai’s 1.6L GDI-T – Powerful and efficient far beyond what its ratings indicate.

    Hyundai’s award winning Gamma 1.6L I4 is the smallest Hyundai engine to use Gasoline Direct Injection (GDI) with turbocharging to provide a highway fuel economy rating of 38 mpg with lower emissions.

    GDI + Twin-Scroll = Fast and Efficient

    The 1.6-liter turbocharged GDI I4 engine scheduled to be inside the upcoming 2013 Veloster Turbo produces 201 HP at 6000 rpm and 195 lb-ft of torque from 1750 – 4500 rpm. And it does so on regular unleaded.

    The Veloster Turbos 1.6L GDI-T is currently estimated to deliver a 27/38 mpgUS city/highway when mated to Hyundai slick shifting 6-speed. The engine features a twin-scroll turbocharger that when combined with the GDI system, results in almost instantaneous power delivery. Hyundai has brought this technology down its line-up from the award winning Sonata 2.0T.

    Hyundai’s twin-scroll turbo in explicit detail

    Twin-scroll turbochargers designs have two exhaust gas inlets divided by split walls inside the turbine housing, with both gas passages controlled by a waste-gate. A twin-scroll turbo recovers even more energy from the exhaust than a single-scroll turbocharger, thanks to a divided manifold. The twin-scroll design separates the cylinders whose exhaust gas pulses interfere with each other, resulting in improved pressure distribution in the exhaust ports and a more efficient delivery of exhaust gas energy to the turbocharger’s turbine.

    At the start of the intake stroke of cylinder one and when both the intake and exhaust valves of cylinder one are open (valve overlap period), cylinder three already starts its exhaust stroke with the exhaust valve open. If the exhaust passages of cylinder one and three were connected, the exhaust gas pulse from cylinder three would increase the back pressure of cylinder one. This would reduce the induction of the fresh air and increase the amount of hot residual gases inside the cylinder. With the twin-scroll turbocharger setup, the interference is minimized.

    The result of this superior scavenging effect from a twin-scroll design leads to better pressure distribution in the exhaust ports and a more efficient delivery of exhaust gas energy to the turbocharger's turbine. This in turn allows greater valve overlap, resulting in an improved quality and quantity of the air charge entering each cylinder. In fact, with more valve overlap, the scavenging effect of the exhaust flow can literally draw more air in on the intake side. At the same time, drawing out the last of the low-pressure exhaust gases help pack each cylinder with a denser and purer air charge. Maximum boost from the turbocharger is 18 psi.

    The twin-scroll turbocharger design has several other advantages over traditional, single-scroll turbocharging systems, including:
    • Improved combustion efficiency
    • Low engine-speed efficiency
    • Kinetic exhaust gas energy is not wasted or trapped
    • Cooler cylinder temperatures
    • Lower exhaust temperatures
    • Leaner air/fuel ratio
    • Better pressure distribution in the exhaust ports and more efficient delivery of exhaust gas energy to the turbocharger's turbine
    GDI

    The GDI fuel delivery system contributes to improved fuel efficiency and lower emissions. This shorter, more direct path of fuel delivery allows for greater control of the fuel mixture at the optimum moment, thus improving efficiency. The fuel is injected by a camshaft-driven, high pressure pump that operates at pressures up to 2175 psi. Direct injection also utilizes a higher-than-normal compression ratio, while achieving a best-in-class 125.6 horsepower-per-liter in the Veloster Turbo.

    Hyundai American Technical Center Inc. (HATCI) Powertrain Director, John Juriga:
    Along with GDI-T, the turbocharged Gamma engine also features Dual Continuously Variable Valve Timing, an electronic throttle control, a roller timing chain, variable induction and innovative anti-friction coatings such as CrN Physical Vapor Deposition (PVD) coating and Diamond Like Carbon (DLC) coating.

    Looking Forward - Direct Injection Improves Fuel Economy, Reduces Emissions

    By 2016, the number of hyper-efficient gasoline fueled I4s will increase by 20 percent to more than 20 million units globally. Based on this trend, most every automaker will offer a turbocharged gasoline engine.

    With 2025 CAFE standards of 54.5 mpg looming, high-precision direct injection technology allows vehicles to consume less fuel and produce fewer emissions without sacrificing output. Using Bosch technology including direct injection, turbocharging and variable valve timing, engines can achieve upwards of 18 percent reduction in fuel consumption and emissions. In combination with extreme downsizing, Bosch aims to achieve a 30 percent reduction in fuel consumption for gasoline engines equipped with their technologies.
     
  2. Ophbalance

    Ophbalance Administrator Staff Member

    Re: Downsizing with Direct Injection and Turbocharging Is the Future of Gasoline Engi

    Oh my... I'd LOVE to take this one for a drive;). Now make a convertible version for my mid-life crisis mobile please!
     
  3. herm

    herm Well-Known Member

    Re: Downsizing with Direct Injection and Turbocharging Is the Future of Gasoline Engi

    a bit of ethanol will really boost the cooling effect of direct injection, allowing the engine to do full timing advance and perhaps best the gas economy of regular gasoline!

    In any case the atkinson engine / HSD transmission combo gives you even more efficiency without using a turbo or direct injection.. and the best part is that the Paice patent runs out this year.
     
  4. RichXKU

    RichXKU Mr. Forced Regen

    Re: Downsizing with Direct Injection and Turbocharging Is the Future of Gasoline Engi

    If DI and turbo are really the answer, then the examples on the road today must be poorly tuned.

    The Honda CR-V is leading class FE with 2.4L non-turbo, non-DI, 5-speed transmission.
    The competition offers worse FE despite possessing one or both of these technologies, and a 6-speed auto. (Chevy Equinox: 2.4L DI; 2013 Ford Escape: 2.0L Turbo+DI).

    The same goes for the Civic HF which also has no DI, no Turbo, and 1 less gear but still beats:
    Mazda 3 SkyActiv
    Hyundai Elantra
    Chevy Cruze Eco
    Ford Focus SFE

    So what gives? It sounds like Honda has been spending a lot of late nights in the lab, while the other guys are just throwing random tech into the engine bay so management stops hassling them.
     
  5. worthywads

    worthywads Don't Feel Like Satan, I am to AAA

    Re: Downsizing with Direct Injection and Turbocharging Is the Future of Gasoline Engi

    Do they all have the same HP and performance for comparison? What about price?
     
  6. ItsNotAboutTheMoney

    ItsNotAboutTheMoney Super Moderator Staff Member

    Re: Downsizing with Direct Injection and Turbocharging Is the Future of Gasoline Engi

    Well, I'm sure that the following helps a bit:
    Focus: 2,907
    Chevy Cruze Eco: 3,102
    Civic HF: 2,698

    But, yes, Honda simply has some very good engineering. Presumably if they added DI it'd give another bump.
     
  7. RichXKU

    RichXKU Mr. Forced Regen

    Re: Downsizing with Direct Injection and Turbocharging Is the Future of Gasoline Engi

    I know the CRV starts lower than the other two. The civic HF should be very close as well.

    Here's some HP/Torques:
    Civic HF: 140/128
    Mazda 3 SkyActiv: 155/148
    Hyundai Elantra: 148/131 (apparently the Elantra does not have DI, my mistake)
    Chevy Cruze Eco: 138/148 (Turbo, but not DI)
    Ford Focus SFE: 160/146

    Power to weight ratio is about the same. (Thanks I.N.A.T.M.)

    Honda CRV: 185/163
    Ford Escape: 173/177; 237/250 (more with premium fuel)
    Chevy Equinox: 182/172
     
  8. worthywads

    worthywads Don't Feel Like Satan, I am to AAA

    Re: Downsizing with Direct Injection and Turbocharging Is the Future of Gasoline Engi

    Sorry, that was sort of a rhetorical queston, but thanks.

    At 201 HP the GDI is significantly above the Civic HF and most of the others. If Hyundai chose to make a 1.2L with 140/128 hp/torque it may well beat the Civic HF. Hyundai may be betting on more sales to people wanting power and good economy. Sorta like diesels where people pay a big premium not expecting a payback, but power with economy. No doubt not all engine design groups are getting equal results, but Turbo and DI seems to have promise.
     
  9. waltermlee

    waltermlee Well-Known Member

    Re: Downsizing with Direct Injection and Turbocharging Is the Future of Gasoline Engi

    It looks like the Honda design traded off torque for higher fuel efficiency.
    Torque is nice when towing or going uphill on an extended steep incline.
     
  10. Jay

    Jay Well-Known Member

    Re: Downsizing with Direct Injection and Turbocharging Is the Future of Gasoline Engi

    Wayne, thanks for going into some detail about how twin-scroll turbos work. I had never heard of them before. Maybe I can find an animation somewhere that shows the operation.
     
  11. Kurz

    Kurz Well-Known Member

  12. worthywads

    worthywads Don't Feel Like Satan, I am to AAA

    Re: Downsizing with Direct Injection and Turbocharging Is the Future of Gasoline Engi

    ^

    Nice find.
     
  13. Jay

    Jay Well-Known Member

    Re: Downsizing with Direct Injection and Turbocharging Is the Future of Gasoline Engi

    Very cool link, Kurtz. Thanks. It shows the GDI also. Looks like it's a mechanical injection system driven off the cam rather than EFI.
     
  14. herm

    herm Well-Known Member

    Re: Downsizing with Direct Injection and Turbocharging Is the Future of Gasoline Engi

    That serpentine belt is at least 10ft long :)
     
  15. brick

    brick Answers to "that guy."

    Re: Downsizing with Direct Injection and Turbocharging Is the Future of Gasoline Engi

    Turbocharging and direct injection are absolutely the future of ICE technology. DI turbo engines allow less displacement and fewer cylinders to produce a given level of peak power and torque. Kilowatt-for-kilowatt, that means less power spent on overhead (friction, loss to reciprocating mass, etc.) as well as more efficiency at typical continuous power levels, which are often just a fraction of an engine's maximum capability. I agree that there are other technologies which are just as effective or more, such as the downsized and atkinsonized engines (with port fuel injection and no forced induction) that Toyota, Ford, and others use in their hybrids. But I think those are special cases because they would not produce the same level of efficiency and driveability in the absence of a HSD-type hybrid system.

    Looking to the future, there is more to be gained from the DI-turbo combination. DI allows control of the combustion process that you can't even dream of with port fuel injection. Today, manufacturers are using it to run much higher compression engines on regular 87 octane gas. Down the road, we could see the return of lean-burn engines that meet today's stringent emissions goals. A stratified charge spark ignition (SCSI) uses a stream, rather than a fog, of gasoline. When lightly loaded (cruising), these engines can inject less fuel without the high combustion temperatures that cause such high NOx emissions. At high load they can go back to a fog and run stoichiometric for higher power.

    It's neat stuff. I look at today's DI-T engines as not only great technology for present needs, but a foundation for even better things to come.
     
  16. Chuck

    Chuck just the messenger

    Re: Downsizing with Direct Injection and Turbocharging Is the Future of Gasoline Engi

    It would be interesting to compare engine sizes and horsepower thru the years.

    I did a skim and concluded over the past 50 years, engines are about three times as powerful for a given displacement.
     
  17. herm

    herm Well-Known Member

    Re: Downsizing with Direct Injection and Turbocharging Is the Future of Gasoline Engi

    I'm not sure of the long term durability of direct injection and turbocharging.. maybe in 10 years I will change my mind.

    HSD and its variations are the future.
     
  18. xcel

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

    Re: Downsizing with Direct Injection and Turbocharging Is the Future of Gasoline Engi

    Hi Herm:

    HSD is great as is DI and Turbocharging but I still like Honda's use of simple and far less expensive MPFI while atkinsonized off the low power cam lobes (< 3,500 RPM or so) as the current best method for low cost big highway FE while providing a very respectable 140 HP when on the hot cam for those that think they need to win the race into their garage.

    Tim, DI can be used in an atkinsonized engine but turbo-charging is not, right? And what happens to a leanburner in an atkinsonized engine? Torque goes to ½ or less?

    Wayne
     
  19. MaxxMPG

    MaxxMPG Hasta Lavista AAA-Vee Von't Be Bach

    Re: Downsizing with Direct Injection and Turbocharging Is the Future of Gasoline Engi

    I did some digging for the Spark Vs Barge comparison. My 2011 Hyundai Elantra GLS has a 1.8L four cylinder that delivers 145hp in the PZEV version I have. The car weighs about 2800 pounds. A 1973 Chevrolet Impala, weighing about 4300 pounds, offered a 350 cubic inch (5.7L) pushrod V8 with 2 barrel carburetor and a net hp rating of 145. Same horsepower, less than 1/3 the engine size.

    Much of the lofty horsepower numbers in today's small engines are actually due to advances in engine manufacturing and design that allow higher engine speeds. Horsepower is "torque over time", so doubling the rpm doubles the horsepower for a given amount of twist (work) the engine offers. That's the reason today's engines are "upside down" on the numbers - HP is higher than torque. The old iron big blocks were the opposite - under 200hp but torque was close to 500 lbs-ft at 2000rpm or less. And ditto for diesels, where "HP" doesn't tell the story because the mountain-o-torque peak is at a low rpm and the bulky diesel engine components usually don't want to rev much past 4000.

    In HP, a Chevy small block of 40 years ago matches today's Cruze/Elantra/Focus C-class cars, even as these cars are 2/3 the weight, and have first gear ratios nearly double that of the 3AT in the 40 year old Chevy. In torque, today's small V8s and turbo V6s offer as much power as the 440-500 cubic inch V8s of the past, and close to double the horsepower. How did they almost double the horsepower? Today's engines breathe easier, so peak torque is available at higher rpm. More rpm for a given torque number means more horsepower.

    With all the talk about power, we can't forget about the difference in fuel economy and emissions between a pre-catalyst V8 and today's high-volume I-4. Emissions on the old car: Literally hundreds of times higher. And fuel consumption on an old small block V8 is about three times greater.
     
  20. brick

    brick Answers to "that guy."

    Re: Downsizing with Direct Injection and Turbocharging Is the Future of Gasoline Engi

    You can certainly add a turbocharger to an atkinsonized engine, at which point it becomes a Miller cycle engine. Mazda did it in the Millennia (but with PFI I believe). It's not a bad way to go since forced induction compensates for the loss of torque. I'm honestly not sure why more manufacturers haven't tried it.

    I'm not sure about lean-burning on top of atkinsonization. Torque would definitely decrease. Whether or not that capability improves efficiency probably depends on whether or not atkinsonization puts the engine at high enough loading while at a cruise. As I think about it more, the benefits of running lean diminish whet you could just pair it with a CVT and cut down on cruising RPM's (running the engine with a wider throttle) instead.
     

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