Jeep has introduced its Hurricane four-cylinder engine, a turbocharged 2.0-liter unit producing 325 horsepower. This engine incorporates advanced technologies for power output and fuel efficiency, setting a new standard for performance in its class.
Turbulent Jet Ignition (TJI)
The Hurricane 4 engine features Turbulent Jet Ignition (TJI), a pre-chamber combustion technology adapted from Formula 1 and Maserati's Nettuno V6. This sophisticated system uses a small chamber within the main combustion chamber to significantly improve the fuel-air mixture before ignition. The pre-chamber includes an insert specifically designed to distribute pre-mixed air efficiently to the main combustion chamber. The engine further optimizes fuel delivery by utilizing both direct and port fuel injection.
TJI integrates twin-spark ignition, a crucial element for maximizing combustion efficiency. One spark plug is located in the pre-chamber for initial ignition, while a second spark plug resides in the main chamber, providing additional combustion support, particularly under higher loads. This dual-spark design aims to extract the maximum possible energy from the fuel-air mixture.
Pre-chamber combustion is a key contributor to the engine's impressive power output and enhanced fuel economy.
In the Grand Cherokee, the Hurricane 4 achieves an EPA-estimated 27 miles per gallon highway.
Variable Geometry Turbo (VGT)
The Hurricane 4 includes a variable-geometry turbocharger (VGT), a technology that offers precise control over turbo performance. This system uses an actuator to adjust vanes within the turbocharger’s exhaust housing, which effectively controls the speed and volume of exhaust gas entering the turbo. This dynamic adjustment directly impacts power output and responsiveness.
The turbocharger itself is robust, featuring a 55-millimeter compressor wheel and a 50-millimeter turbine wheel. It is capable of supplying a substantial 35 psi of boost. Stellantis appears to manufacture some components for the system, including a Pierburg compressor wheel speed sensor, indicating integrated engineering.
The VGT's ability to regulate turbo speed significantly enhances responsiveness during throttle input. It also meticulously manages exhaust gas velocity for improved efficiency during cruising and transient situations. Beyond performance, VGTs contribute to emissions control by facilitating quicker catalytic converter warm-up during cold starts and managing overall exhaust energy. This technology is notably uncommon in gasoline engines, found in select high-performance models like the 997-generation Porsche 911 GT2RS and the 718 Cayman S.
Additional Optimizations
The intake camshaft utilizes an electric phaser, allowing the ECU to adjust camshaft position independently of actual engine operation. This enables camshaft adjustment even when the engine is off, which facilitates smoother start/stop transitions by decompressing cylinders. It also provides a broader range of intake cam adjustment, significantly enhancing combustion efficiency across various operating conditions. The Hurricane engine operates on the Miller cycle, which extends intake valve opening for improved fuel-air mixing and overall efficiency.
Pressurized air from the turbocharger is effectively cooled by a water-to-air intercooler, which is primarily supported by a front-mounted heat exchanger. This ensures denser, cooler air enters the engine, optimizing performance.
The engine block is constructed from aluminum with extensive webbing and deep skirts, suggesting robust bottom-end strength and durability. Despite its strength, the design employs minimal material, contributing to overall engine lightness.