Deep Dive: Jeep's New 500-Horsepower "Hurricane" 3.0L Inline Six


Deep Dive: Jeep's New 500-Horsepower "Hurricane" 3.0L Inline Six


It’s the ultimate conundrum: the world appears to be moving away from internal combustion engines, but it’s also difficult to walk away from something that works so well. Gasoline as a liquid fuel offers excellent power density, which means an engine can extract lots of power from a single gallon of this liquid energy. But burning fossil fuels creates carbon dioxide and other gases that – admittedly – aren’t the best for the planet.

One answer is to build a smaller displacement engine that feels and performs like a larger one. That’s what Stellantis has accomplished. The company recently introduced a spinoff of their 2.0L gasoline, direct-injected, and turbocharged inline four-cylinder by adding two more cylinders and calling it the Hurricane. Technically, the original turbo four was also dubbed the Hurricane, so perhaps this is the original Hurricane - version 3.0.

This dual overhead camshaft (DOHC) inline six-cylinder should not be judged on size alone. Despite its diminutive displacement at 3.0L, the Hurricane has a significant punch for an engine of it's size. The standard engine produces 420 horsepower and 468 ft-lb of torque, while the high-output variety is good for 510 horsepower and 500 ft-lb of torque.

Jeep "Hurricane" 2.0L turbo four cylinder

The new Hurricane six-cylinder is based upon the same architecture as the 2.0L "Hurricane" turbo-four already found in Jeep vehicles.

While peak numbers are impressive, a crucial point is that the High Output engine is responsive enough to generate 90 percent of peak torque from 2,350 RPM to redline. Those are V8 numbers.

Veteran Chrysler readers are probably channeling the anvil-like Chrysler Slant Six right about now, but this new engine reaches far beyond those cast iron Eisenhower days in favor of an all-aluminum engine with direct gasoline injection, twin turbocharging, independent dual overhead camshafts with variable valve timing, forged crankshafts, forged pistons (in the high-output version), and a host of other features that would have been race engine fare a scant few years ago.

Let’s take a quick look at the features of this new engine, starting with the foundation and working our way outward. As we alluded in the intro, this new 3.0L inline six is merely an extension of the inline four cylinder turbo 2.0L engine using the same bore and stroke and bore spacing and an aluminum block. The casting employs the extended or deep skirt design that adds additional strength with splayed, four-bolt main caps fitted with cross-bolted hardware.

Instead of using conventional pressed-in iron cylinder liners, Stellantis chose a relatively new process called Plasma Transfer Wire Arc (PTWA) that sprays a molten steel mixture on the cylinder wall that not only creates a surface that is ten times harder than a conventional liner, but is also incredibly thin, saving weight.

The spray process creates its own deep pockets for holding oil while offering a much greater load-bearing surface. This reduces wear, allowing the finish to retain is original shape much longer. To take full advantage of the combination of a PTWA bore material and aluminum block, each cylinder is torque plate finish honed.

This PTWA process has already been used in Ford’s 5.2L Voodoo engine with apparent great success. According to Ford, they’ve seen PTWA coated engines with only minor wear after the equivalent of 200,000 miles of testing. One drawback is that because the coating is very thin – roughly 0.002-inch - if the cylinder wall is damaged by a piston, for example, an over-bore is not possible and will thus require a new block. Other features include piston squirters to keep the underside of the pistons cool during high output use.

Stellantis 3.0L Hurricane six

At 3.0L displacement (that's 183 cubic inches), the Hurricane six cranks out horsepower on-par with a V8. What's more impressive, is that about 90% of that power is available throughout the powerband.

The Hurricane six will also benefit from the strength of a forged steel crankshaft and connecting rods. The standard six will push hypereutectic pistons but its high-output counterpart will be fitted with forged aluminum pistons for additional strength. The forged pistons are further bolstered with an anodized top ring land and a diamond-like coating (DLC) on the wrist pins. The compression ratio for the direct-injected high-output engine will be at 9.5:1 which may seem conservative but that’s to accommodate the 26-psi boost levels that we’ll detail in a moment. The standard output engine uses a higher static compression ratio of 10.4:1 with its focus on optimizing fuel mileage rather than peak power.

The engine will also sport a cast aluminum oil pan to further increase strength around the rotating assembly and engine oil is supplied with a continuously variable output pump with a single stage scavenge system to ensure the oil does not stack up inside the turbochargers.

The 16-valve DOHC head will feature pentroof combustion chambers with a centrally located direct injector. The fuel system will operate at 350 bar which is 5,075 psi of pressure using a pair of mechanical fuel pumps to generate these extremely high pressures. Each camshaft will be electro-hydraulically controlled as separate units, which means that not only can the cams be advanced for low-speed torque and retarded for high-speed use but the lobe separation angle can be continuously varied as well with wider separation at low speeds to minimize valve overlap while tightened to increase overlap at peak engine speeds.

Clearly the key to this entire system is the cylinder pressure this engine can generate using a pair of small, responsive turbochargers. Engineers have configured the engine to pair the turbochargers with alternate firing cylinders. Using the inline 6’s classic 1-5-3-6-2-4 firing order, alternate cylinders fire in a front-half / back half of the engine orientation.

Think of the twin turbo layout in these terms:

  • Turbo A feeds cylinders 1, 2, and 3
  • Turbo B feeds cylinders 4, 5, and 6

This shortens the exhaust plumbing between the exhaust ports and the hot side inlet to the turbo. The engine is essentially divided vertically in half (front to rear) with each turbo receiving an exhaust pulse every 120 degrees of engine rotation. To accomplish this, the exhaust manifolds are water-jacketed and integrated into the cylinder head. In operation, cylinder 1 directs an exhaust pulse to Turbo A. Next, cylinder 5 fires 120 degrees later and shoots an exhaust pulse into Turbo B located nearest the rear half of the engine.

This configuration sends even exhaust pulses every 120 degrees to each of the turbochargers, producing a smoother distribution of exhaust pressure pushing the turbos to spool up more quickly. This combines with the latest turbo impeller technology that reduces back-pressure into a fast reacting combination that is the main reason for the 90 percent of maximum torque number we touched on earlier.

2022 Jeep Grand Cherokee 4xe

Delivery of vehicles equipped with the new Hurricane six are expected to start in the second half of 2022.

Once boost is created, inlet discharge temperature is reduced by a charge air intercooler and then directed to the cylinders. The intercooler circuit uses an electric pump to circulate the coolant. The standard engine’s slightly higher static compression ratio manages detonation by limiting boost to 22.4 psi while the high output engine’s lower compression allows an increase in boost up to 26 psi. With barometric pressure at 14.7 psi at sea level, 26 psi of boost is theoretically equivalent to a 1.77:1 increase in cylinder pressure (ignoring pumping and other losses for this discussion). If we use this number to multiply the displacement, this theoretically creates the equivalent of a 324ci engine (183ci x 1.77 = 324ci).

This impressive cylinder pressure is complemented with direct gasoline injection. Fuel pressure is created with a pair of high pressure mechanical pump that generate an impressive 5,075 pi of peak fuel pressure that vaporizes most of the fuel as it is injected.

With this introduction of the engine before production, there are a multitude of unanswered details about the 3.0L Hurricane. But this basic outline still points to impressive power numbers from a small displacement engine. Generally, small displacement engines suffer from weak torque right off idle requiring heavier throttle input to compensate. But with an engine delivering 90 percent of peak torque as low as 2,350 rpm, that might offer some impressive drivability. The Hurricane’s horsepower numbers are equal to the larger Ford EcoBoost 3.5L 60-degree V6 numbers at 500 horsepower but appear to exceed the Ford’s 400 lb-ft of torque. Perhaps the horsepower race is not quite dead.

There’s little argument that it’s hard to beat an inline six for smoothness. Packaging this longer inline six engine is always a concern but overall it appears this new Hurricane may stir up some interesting winds in the continuing debate over whether there’s life out there for internal combustion engines.

Jeep "Hurricane" 3.0L six

The Hurricane six is designed for potential electric integration for future applications as well. That potentially could lead to interesting setups, like a low-range electrical crawler gear that uses the engine as a generator...we hope!

Stellantis 3.0L "Hurricane" Inline-Six Specifications

Engine LayoutGasoline direct-injection, dual overhead cam, 24-valve
Cylinder LayoutInline six cylinder
Horsepower420 (standard output), 510(high output)
Torque468 (standard output), 500 (high output)
Firing Order1-5-3-6-2-4
Bore3.31 inches (84mm)
Stroke3.54 inches (90mm)
Displacement 183 cubic inches (3.0 liters)
Block MaterialAluminum
Block DesignDeep skirt block with 4-bolt mains with cross bolts
Bore MaterialPlasma Transfer Wire Arc (PTWA)-sprayed cylinder wall
CrankshaftForged steel, twist forging
Camshafthydroformed tubular design
LiftersHydraulic finger followers
Valve TimingIndependent control for each camshaft
ValvesFour per cylinder, sodium-filled exhaust valves
PistonStandard output: cast aluminum with skirt coating
High output: forged with skirt coating
Cylinder Head MaterialAluminum
Combustion Chamber DesignFour valve per cylinder, pent roof
LubricationVariable displacement vane oil pump with single stage gerotor 
scavenge, chain driven, oil cooler
Fuel DeliveryGasoline direct injection
InjectorsOne per cylinder
Fuel Pressure5,057 psi (350 bar), single fuel rail
Exhaust ManifoldWater cooled
TurbochargersTwin, small diameter
Boost (PSI) 22.4 psi (standard output, 26 psi (high output)
Oil Capacity7.5 quarts, 0w40 Pennzoil Ultra Platinum


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