The injection is split into two phases to achieve optimum combustion during the catalyst heating operation right after the cold start. First, the pilot injection is applied during the piston's descent in the intake stroke and then, in the second, at the end of the compression stroke, the rest of the fuel is injected and then ignited after some delay. This split-injection technique reduces loading on the catalytic converter and helps lower emissions.
When an engine is cold, so is the catalyst. Traditional engines run high rpm's for a few seconds upon startup to "fire" the catalysts. The GDI's split-injection strategy enables the catalyst to reach operating temperature faster. This helps reduce emissions by 30 percent during cold starts meeting California Air Resources Board's ULEV-2 and PZEV standards.
Dynamic Performance and Fuel Economy Improved
Compared to a conventional engine of the same displacement, GDI delivers 7 percent more torque at low engine rpm's and 12 percent more torque at the high-end for better take-off and overtaking performance. Best of all, GDI boosts gas mileage by up to 10 percent compared to a conventional engine.
Variable Induction System (VIS)
Design modifications in the Theta-II 2.4L GDI engine continue with a 2-stage variable induction system which improves engine breathing by automatically adjusting the volume of the air drawn into the combustion chamber to create the optimal air-to-fuel mix under different engine load conditions.
Continuously Variable Valve Timing (CVVT)
Depending on engine load and speed, CVVT can modulate the phasing of the valve opening and closing for more power and lower emissions. The new Continuously Variable Valve Timing System improves engine breathing on the intake and exhaust sides for better fuel economy and lower emissions. And the CVVT system is run by a new steel chain with an innovative roller and a retuned chain tensioner for the improved fuel efficiency and robust durability.
Weight and Friction Reduction
A critical engineering challenge is to find ways to reduce engine weight and internal friction to attain better fuel economy. Friction reduction measures in the Theta II 2.4L GDI include a revision of the piston pin from a fixed-type to a full-floating design which helps reduce friction between piston and cylinder wall. This further improves long-term durability.
And under the piston crown, engineers have added a piston cooling jet which sprays a fine oil mist to the bottom of the piston reducing heat and contributing to the durability.
Weight reduction measures include a new lighter-weight aluminum cylinder block and a lighter weight crankshaft. Hyundai engineers looked for weight savings throughout the engine, inside and out. In the end, the Theta-II 2.4L GDI is more than 10 pounds lighter than its predecessor.
Next Steps?
Hyundai has stated aggressive goals aiming at fuel economy leadership. The benefits of GDI technology will be expanded over time to the entire family of Hyundai gasoline engines. GDI is one technology out of several that will help deliver superior efficiency, durability, quality and value to Hyundai customers.
photo:Hyundai
When an engine is cold, so is the catalyst. Traditional engines run high rpm's for a few seconds upon startup to "fire" the catalysts. The GDI's split-injection strategy enables the catalyst to reach operating temperature faster. This helps reduce emissions by 30 percent during cold starts meeting California Air Resources Board's ULEV-2 and PZEV standards.
Dynamic Performance and Fuel Economy Improved
Compared to a conventional engine of the same displacement, GDI delivers 7 percent more torque at low engine rpm's and 12 percent more torque at the high-end for better take-off and overtaking performance. Best of all, GDI boosts gas mileage by up to 10 percent compared to a conventional engine.
Variable Induction System (VIS)
Design modifications in the Theta-II 2.4L GDI engine continue with a 2-stage variable induction system which improves engine breathing by automatically adjusting the volume of the air drawn into the combustion chamber to create the optimal air-to-fuel mix under different engine load conditions.
Continuously Variable Valve Timing (CVVT)
Depending on engine load and speed, CVVT can modulate the phasing of the valve opening and closing for more power and lower emissions. The new Continuously Variable Valve Timing System improves engine breathing on the intake and exhaust sides for better fuel economy and lower emissions. And the CVVT system is run by a new steel chain with an innovative roller and a retuned chain tensioner for the improved fuel efficiency and robust durability.
Weight and Friction Reduction
A critical engineering challenge is to find ways to reduce engine weight and internal friction to attain better fuel economy. Friction reduction measures in the Theta II 2.4L GDI include a revision of the piston pin from a fixed-type to a full-floating design which helps reduce friction between piston and cylinder wall. This further improves long-term durability.
And under the piston crown, engineers have added a piston cooling jet which sprays a fine oil mist to the bottom of the piston reducing heat and contributing to the durability.
Weight reduction measures include a new lighter-weight aluminum cylinder block and a lighter weight crankshaft. Hyundai engineers looked for weight savings throughout the engine, inside and out. In the end, the Theta-II 2.4L GDI is more than 10 pounds lighter than its predecessor.
Next Steps?
Hyundai has stated aggressive goals aiming at fuel economy leadership. The benefits of GDI technology will be expanded over time to the entire family of Hyundai gasoline engines. GDI is one technology out of several that will help deliver superior efficiency, durability, quality and value to Hyundai customers.
photo:Hyundai