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testing Hyundai's Theta II DGI engine - Click above for high-res image gallery

When the swoopy new 2011 Sonata goes into production at Hyundai's plant in Alabama early next year, it won't offer a V6 engine anymore, but it will get the company's first ever direct-injected engine. This week in South Korea, Hyundai took the wraps off its 2.4-liter Theta II GDI four-cylinder. Like similar engines from other automakers, Hyundai's engineers have taken advantage of the charge cooling effect of direct injection by boosting the compression ratio to 11.3:1. As a result the engine produces 198 hp and 184 pound-feet of torque at 4,250 rpm in Korean spec.

The direct injection system is setup to use a two-pulse strategy similar to modern common rail diesels. The initial smaller pulse is ignited by the spark plug and then followed by a second larger pulse as the piston begins its downward stroke. GM uses a similar strategy for its 2.4-liter DI Ecotec because it helps warm the engine faster, heating the catalytic converter and reducing emissions. The GDI Theta II produces from 7-12 percent more torque across its rev range than the port-injected version of the same engine. Efficiency should also improve by about 10 percent although the final certification figures aren't complete yet. The Theta II also gets continuously variable valve timing on both camshafts to round out its high tech upgrades. In addition to the regular Sonata sedan, this engine will likely also be used for the new Sonata hybrid when it debuts late in 2010.

[Source: Hyundai]

press release


- GDI lowers emissions while improving fuel economy & torque

- 2.4 Theta II GDI generates 201ps@6300rpm and 25.5kg.m@4250rpm

- First application in 2010 1H on new Sonata

- GDI to be first in mid-size sedan segment, beating competitors to market

- Unveiling coincides with 9thHyundai-Kia Int'l Powertrain Conference

(Namyang, Korea) To help meet its goals of environmental leadership, Hyundai Motor Company today unveiled the 2.4 Theta II GDI, its first Gasoline Direct Injection engine before an audience of engineers attending the Ninth Annual Hyundai-Kia International Powertrain Conference.

Representing the biggest advancement in fuel injection, an '80s technology that replaced the carburetor, GDI puts Hyundai at the cutting edge of engine design and management by achieving three seemly incompatible goals: GDI lowers emissions while raising power output and improving fuel economy. Prior to GDI, a gain in one area came at the expense of the other two.

With a compression ratio of 11.3:1, the 2.4 Theta II GDI delivers 201ps@6300rpm and 25.5kg.m@4250rpm in its Korean domestic market specification.

"The Theta II GDI convincingly demonstrates Hyundai's advanced powertrain engineering capabilities," said Dr. Lee Hyun-Soon, Vice Chairman and Chief Technology Officer.

Developed with a budget of 170 billion won over a 46 month-long research period, the new 2.4 Theta II GDI engine will make its debut in the first half of 2010 starting with the recently launched Sonata, beating the mid-size sedan competition to market with this exciting new technology. GDI application will subsequently be expanded across the gasoline engine family and applied to other Hyundai models.

One serious limitation of conventional fuel injection is that as engine revolutions increase, the valve opening and closing times get progressively shorter, thus reducing the time available to inject fuel. GDI avoids this problem altogether by positioning the fuel injector in the most optimal location, directly inside the combustion chamber to offer unparalleled precision. With this shorter and more direct path, far greater control is attained over the combustion process: A high pressure fuel pump injects the fuel at pressures of up to 150 bar, in precise amounts and intervals.

The injection is split into two phases to achieve optimum combustion: in the first phase, the pilot injection and ignition trigger the pistons downward power stroke. Then, in the main injection phase, during the pistons descent, more fuel is injected and is ignited. This split-injection technique reduces loading on the catalytic converter and helps lower emissions. This is particularly beneficial during cold starts when emissions are highest because the catalyst has not reached its optimal operating temperature. Split-injection enables the catalytic converter to reach the optimal operating temperature faster thus reducing emissions by 25 percent during cold starts and meet's California Air Resources Board's ULEV-2 and PZEV standards

GDI's other benefits include improved dynamic performance and better gas mileage. Compared to a conventional engine of the same displacement, GDI delivers 7 percent more torque at low revolutions and 12 percent more torque at the high-end for better take-off and overtaking performance. And perhaps best of all, a vehicle equipped with a GDI engine will get about 10 percent better mileage than a vehicle equipped with a conventional multi-point fuel injected engine. Precise mileage figures will be announced when retail sales begin.

GDI has been applied to the second generation of Theta: Theta II features numerous design enhancements over its predecessor starting with the application of a three-stage variable induction system (VIS) which improves engine "breathing," automatically adjusting the volume of the air sucked into the combustion chamber to create the "optimal" air-to-fuel mix under different engine load conditions.

Further performance gains were made possible by incorporating Dual Continuously Variable Valve Timing (DCVVT) which improves engine breathing on the intake and exhaust sides for better fuel economy and lower emissions. Depending on engine load and speed, DCVVT can extend or shorten the duration of the valve opening and closing for more power and lower emissions. And the DCVVT system is governed by a new steel chain with an innovative roller and tooth designed for silent operation and durability.

While DCVVT and VIS improve power output, engineers have also come up with several important weight saving innovations. Special attention was focused on the bulkhead, the area of the aluminium cylinder block accumulating the highest stresses: Reinforcement yielded a stiffer block without incurring a weight penalty. A redesign of the crankshaft (semi-eight-balance type) led to an equally important weight reduction. The catalytic converter is also lighter thanks to a new canning process which allows for the use of thinner gauge stainless steel and requiring far less welding.

Another major engineering challenge was to reduce internal friction to attain better fuel economy. Friction reduction measures include a revision of the piston pin from a fixed-type to a full-floating design which cuts down on friction between the piston and cylinder wall. And under the piston crown, engineers have added a cooling jet which sprays oil over the piston walls reducing friction and contributing to an improvement in fuel economy.

The Conference's plenary session open today under the banner "Creative Sustainable Powertrain Evolution for Green Growth." Wednesday will see a large number of technical presentations delivered in various sessions covering the future of gasoline engines, new developments in exhaust emission after-treatment, fuel efficiency improvement and transmissions. Some 600 specialists from Europe, Japan, the United States and Korea are attending this years event.

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    • 1 Second Ago
      • 5 Years Ago
      Great job,Hyundai.
      • 5 Years Ago
      I think they should drop the v6 and offer the hybrid w/ 2.4 Theta II GD as their top engine choice...as long as there are some noticeable performance advantages.
      • 5 Years Ago
      Hyundai is a big development partner with Mitsubishi, and it was Mitsubishi who made great strides in making GDI mainstream back in the mid 90's.
      • 5 Years Ago
      2011 Sonata will have a V6.

      KDM Sonata never had a V6 model so it's not offered with new Sonata.

      The US Sonata always had a V6 model and Hyundai has a V6 engine plant in Alabama that they cannot idle by not offering a V6.
        • 5 Years Ago
        @ Other Man:

        It's not a turbo. It makes 198hp from the DI 2.4L. If they turbo'd that DI 2.4L, they could easily make the hp of the V6 with better gas mileage.
        • 5 Years Ago
        The HMMA engine plant will be making the engines for the Kia plant as well.

        As an owner of a Lambda V6-equipped Sonata, I am very upset about this change. The Lambda is a fantastic engine. Just awesome. And Hyundai sort of abandoning it and apparently not making the V6 an option on the new Sonata. So far, all press says no V6. One person on Autoblog says there will be a V6 option. I dunno which is right but I lean toward the press. And it makes me mad.

        Damn fine engine. Shame if they leave it totally behind like it seems they are. :(
        • 5 Years Ago
        That's something I didn't know. It makes sense because I don't see how they'd replace a 249 hp V-6 with a turbo-4 making just under 200 hp.

        I suspect it will have the new 3.5 from the Sorrento with 273 horsies.
      • 5 Years Ago
      Its easy to keep rolling along when all of your recent successes are growth, not 'maintenance.'

      GM or Toyota have to sell more cars just to keep the lights on due to their massively inflated overhead costs.

      Being the up-and-comer has proved a benefit to both Hyundai and Subaru. Lower overhead, smaller management, fewer union constrictions means more customer dollars go directly towards keeping the ball rolling in design, engineering, and marketing.
      • 5 Years Ago
      @ RayJ

      > how is it that Hyundai is developing for fast.

      Time in Korea is running roughly at twice the pace in the US. They work until late night, and work on Saturdays too. What takes 20 years in the US takes only 10 years in Korea, for something like nuclear reactor, brand new fighter jets, etc. Cars are developed in two years or less.

      Consider, Daewoo started developing Lacetti in 2006 and launched it by 2008. However, it's taking GM more than two years to take Daewoo's finished drawings and set up US production of Lacetti as Chevrolet Cruze.
      • 5 Years Ago
      That is just awesome! A direct injection engine that makes 198hp..maybe even more if Hyundai tweaks it is just awesome! Good job Hyundai!
      • 5 Years Ago
      I'm curious to see this charted against both Honda's K24 (in the Accord Coupe or TSX, not the sedan) and the previous Hyundai 4-cyl. I honestly can't say I'm impressed, until I physically see the "7-12% increase in torque across the range".

      So far GM's DI 4-cyl has really impressed me, particularly in the FWD crossovers. Not the fastest off the line, but for those concerned about stretching every drop of gasoline in the tank, it beats the pants off many-a-contender.

      Disclaimer: I'm not a GM fan. But I always acknowledge a good product when I drive one.
        • 5 Years Ago
        What would be the purpose of comparing it to the coupe's engine, other than to try to make Honda look better? The sedan is what is going to compete with this engine and it's going to be a problem for Honda. The current, heavier, boxier Sonata, without GDI or a 6AT, already gets better mileage than the Accord. CR got 26 overall and 40 on the highway with the current version. Presumably this will do even better. Also, either version of the Honda engine only makes 162 ft/lbs of torque and that max 190HP is at 7,000 RPMs. Doubt many family sedan buyers would be really comfortable revving their engine that high to get to all the power that's there. Even the 6,300 for the Hyundai seems a tad high; 300 more than the current engine.

        Also, Hyundai isn't really quoting PS figures; they're just using that because Koreans are familiar with it. They're really quoting HP so 201 is the correct number, not the converted figure Autoblog is saying. That 200 mark will be a big emotional barrier to cross if the US version hits that and still gets the best mileage ratings in the class.
      • 5 Years Ago
      GM's own 2.4L DI 4-banger is making about the same power (180hp) as this Hyundai engine, so they have obviously caught up to other automakers in that respect, but I am curious what kind of mileage this engine will get - GM's engine gets about 30 MPG Highway (depending upon application of course).
        • 5 Years Ago
        Well to be more accurate, GM's engine makes more than 180. It all depends on tune and application (power versus efficiency) - which is why I was wonder what kind of mileage this Hyundai engine gets.

        Still though, Hyundai is obviously in the ballpark of automakers.
        • 5 Years Ago
        Given how many ways there are to measure HP, and not just units, but even look at how Honda/Acura had to re-rate their engines a few years back because they were using methods that produced optimistic numbers, I consider this engine and GM's 186HP engine to be in the same ballpark. We could perhaps measure them both with SAE standard setups to be more sure though.
        • 5 Years Ago
        I would not call a 20% improvement "about the same".
        • 5 Years Ago
        The NON-DI engined 2.4 Theta II already get 32mpg on the highway (EPA).

        The more powerful DI engined 2.4 Theta II will only improve on that.
        • 5 Years Ago
        @ Hazdaz

        > GM's own 2.4L DI 4-banger is making about the same power (180hp) as this Hyundai engine,

        This new Hyundai Theta-II engine is rated at 198 HP, so obviously not the same power.
        • 5 Years Ago
        Apparently I need to refresh the page more often.
      • 5 Years Ago
      Strap on a turbo and put it in the 2012 Genesis Coupe and lose 300 pounds. Sounds like fun.
        • 5 Years Ago
        What the hell are you talking about. In todays society of ultra advance computers it is rare sight to spot a forced induction engine without Direct Injection. Turbo/Supercharged DI is becoming fairly common and is already in numerous engines: Audi/VWs 2.0T SIDI and 3.0T supercharged, BMWs 3.0 TT and 4.4 TT, Chevys 2.0t DI, the upcoming Cruze 1.4T DI, the upcoming Regal, Ford/Lincoln 3.5TT Eco-boost, Mazdaspeed 3 2.3 DI and numerous other makes.
        • 5 Years Ago
        or just put a bigger turbo on the coupe. still it's nice to see other automakers hopping on the DI bandwagen. With GM, Hyundai and everyone else following VAG it's only a matter of time before everything's DI.
        • 5 Years Ago
        Most turbocharged engines aren't direct injected since it just makes it more complex/expensive/unreliable. The reason you get more power is because you're running higher compression, but if you're putting turbos on it you'd be running lower compression ratios anyway-totally negating the extra power DI would have given.
        That's not to say that someday they won't have turbo DI engines when DI is more common and cheaper to implement, but as it is it makes little sense for automakers to boost DI engines. Which is why most boosted engines, even ones where their non-boosted siblings have DI, don't use direct injection.
        • 5 Years Ago

        Direct injection increases the pressure of the fuel spray, better atomizing the fuel for better, more efficient combustion. It doesn't have much to do with compression. Turbo charging and direct injection is a two-fold expense which is why we haven't seen it much in the past. Both are not particularly cheap, so why not use a bigger DI engine or a smaller port injected turbo? The reason for it now is simple... CAFE. Fuel mandates require more fuel efficient cars.
        • 5 Years Ago
        Glad to see more manufacturers are using DI these days.

        Also, the non-DI 2.4 they already used in the Sonata was fairly torquey for a four.
      • 5 Years Ago
      Unlike toyota, Hyundai going powerful & fuel efficiency way by non-hybrid method.

      I don't know which side is a winner.
        • 5 Years Ago
        Can't go by fuel efficiency car company.

        Otherwise.. MINI should be considered a Car company.

        Lotus could be considered a car company.

        These companies don't have

        1. PICKUP TRUCKS - either small OR full size.
        2. They don't have full size SUV line either. (Hyundai does have a 7 passenger I believe now). But non of them have the ROLLING TRAILERS like Excursions/Escalades etc.

        3rd most fuel efficient company... I dont look at companies.. I look at Model VS Model to compare APPLES AND APPLES.
        • 5 Years Ago
        They have no hybrid model.
        But, 3rd most fuel efficient car comapany in US.(behind toyota and honda)
      • 5 Years Ago
      I'm glad to see this news, as the 2011 Sonata is on my short list for a new sedan (the G35 Coupe wouldn't work if we start a family).

      200HP is fine for a family sedan, even if C&D says it lacks the power of a V6. If the weight is kept down, the weight distribution is closer to 50/50, etc. there may be dynamic benefits to the 4 vs. the 6.

      I read somewhere that only 10% of the Sonata buyers opted for the V6, so I could see them dropping it. It will help keep the cost advantage vs. the Accord even when Hyundai does a fancy technology package.
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