Deep Dive: What is Jeep’s Hurricane engine?

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The word of the day is ‘cylinder’.

It’s a fun word to say, and a relatively fun shape — particularly when I crack open a nice cylinder of pop after completing a story like this one. To be more specific, this cylinder story concerns Stellantis’ new Hurricane engine family, and where you’ll find its various members for model-year 2023.

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First, let’s get up to speed on gasoline engine basics.

Engines detonate explosive gasoline to make power. This happens inside of the engine’s cylinders. 

Most passenger vehicle engines have 4, 6, or 8 cylinders, each identical to the rest. That’s 4, 6, or 8 little homes for gasoline explosions to take place. If a cylinder is like a little home, you can think of an engine as a little neighbourhood of (identical) cylinders. 

Just like neighbourhoods and the homes within them, engines (and their cylinders) come in different shapes, sizes, and designs. The configuration determines the size and quantity of the gas explosions, which determines how much power is sent to the wheels of your car or truck.

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For most engines, making more power means burning more gas. This can be done in a few different ways.

One method is to add additional cylinders. That’s more homes for more explosions to burn more gas to make more power.

Another is to make the cylinders physically larger. Larger cylinders have room for more gas and more air for a bigger, more powerful explosion to take place inside. 

You can also speed the cylinders up, increasing the number of explosions that can happen in a given amount of time. Making more rapid explosions makes an engine rev faster, which is another way to make more power.

There’s a fourth way to make an engine more powerful, and it doesn’t require changing the size, quantity, or operating speed within its cylinders: you hook the engine up to an air compressor instead. Air compressors come in two primary types: turbochargers and superchargers. 

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When you compress the air entering each cylinders, more gas can be detonated in each explosion. With this denser mixture of air and fuel, even small cylinders can suddenly house explosions as powerful as much larger ones.

The new Stellantis Hurricane engine has six cylinders and two air compressors — in this case, twin turbochargers. One compressor (turbo) feeds three cylinders, while the other feeds the remaining three cylinders.

This all-new 3.0-litre straight-six engine is designed for a power advantage over currently available eight-cylinder (V8) engines used in the automaker’s large (and largest) vehicles. The 3.0-litre designation refers to the combined volume of the cylinders, and the ‘straight-six’ designation makes this engine a neighbourhood of 6 homes (cylinders) lined up neatly in a row. 

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Despite making more power, the high-efficiency Hurricane engine family cuts emissions and overall fuel consumption versus the longstanding Hemi V8 engine family it’s poised to replace. Don’t be surprised to see this engine pop up as an alternative to the Hemi V8 in other applications, and eventually replace it.

Instead of eight large cylinders in the Hemi, the Hurricane has six smaller cylinders which can be crammed full of compressed air to make fewer — but more powerful — explosions.

In 2023, you’ll find the Hurricane engine action centred around the Wagoneer and Grand Wagoneer lineup, where they’re offered as up-level powertrain options above the standard-equipment V8s you’ll usually find under the hood. 

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Compared to the straight-six Hurricane above, a V8 engine is like a one-street neighbourhood with four homes on each side. When it comes to the 2023 Wagoneer, the Hurricane engine comes in two flavours — as does that Hemi V8. 

The 2023 Wagoneer and Grand Wagoneer come with a standard V8 available in two versions: the 5.7L Hemi (with eight smaller cylinders) is standard on the Wagoneer, and the 6.4L Hemi, (with eight larger cylinders) is standard on the Grand Wagoneer. The smaller eight-cylinder Hemi makes 392 horsepower; with larger cylinders, the bigger eight-cylinder Hemi makes 471 hp. Neither of these V8 engines is augmented by an air compressor. 

For much more detail on those machines, and a road test, visit THIS LINK (NOT PUBLISHED YET).

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Hurricane engines come online when shoppers move up to a Series II or Series III Wagoneer, or to a Grand Wagoneer model for 2023.

In the Wagoneer, Series II and Series III models ditch the 5.7-litre, 392-horsepower Hemi V8 engine in favour of the Hurricane ‘Standard Output’ (SO) engine. In this configuration, the Hurricane’s six cylinders and two air compressors generate 420 horsepower.

On the Grand Wagoneer, upgrading to the Series II and III models boots the 6.4-litre 471-horsepower Hemi (with its larger cylinders) in favour of a 510-horsepower version of the new Hurricane engine referred to as the ‘High Output’ (HO) configuration.

These power output figures will vary by model as the Hurricane engine family makes it way into additional products in the coming years.

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Despite their different performance ratings, both Hurricane engines use the same number of cylinders (six) of the same exact size (three litres in total), and the same number of turbos (two).

If the size and number of cylinders and compressors is the same, how is one Hurricane engine more powerful? The answer is more compressed air.

On the Hurricane SO engine, the compressors generate 22 psi of pressure, also known as ‘boost’. On the Hurricane HO engine, the turbos make 26 psi of boost. That additional compressed air allows the HO engine to burn additional gas versus the SO engine, so it makes even more power.

Hurricane engines are designed to accept future power-adding upgrades including hybrid electrification, and also deliver much stronger low-end torque than the naturally aspirated V8 engines they replace. This promises to boost performance and throttle response during low-RPM operation. 

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This is partly thanks to the use of two smaller air compressors, instead of one larger one. Smaller air compressors get to work faster than bigger ones, but aren’t as powerful. Using multiple smaller compressors that get to work faster improves response and performance versus a single larger (but slower-responding) turbo instead.

The Hurricane engines use an oil pan that’s structurally cast into the engine, and features a forged steel crankshaft and connecting rods which make the rapidly spinning insides of the engine very tough. This is like building your neighbourhood on the strongest of bedrock.

Single- or dual fuel pumps (SO and HO, respectively) blast gasoline into the cylinders at over 5,000 psi, while dual, fully independent variable overhead cams ensure precise control and optimization of engine breathing in all conditions. You’ll need to run premium fuel in the Hurricane HO, while premium is recommended (but not mandatory) for the SO version.

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Water-to-air coolers sit between the compressors and the cylinders, chilling the incoming compressed air before it’s blasted inside (engines don’t like to breathe hot air). There’s a high-flow cooling system that pumps with minimal restriction to boost fuel efficiency and durability in the process.

Special targeted coatings on vital parts help further boost durability and fuel economy. One of these is called a Plasma Transfer Wire Arc (PTWA) sprayed cylinder coating. Several automakers use this technology to toughen up their cylinders without adding weight. In this process, a steel alloy is melted at 2,300 degrees celsius and sprayed at high speed onto the cylinder walls, where it cools into a tough layer of microscopic particles. Imagine spray-painting the walls of your home in pressurised liquid metal, and you’re in the right ballpark.

There’s a four-cylinder Hurricane engine, too. Imagine removing two cylinders and one air compressor from the six-cylinder versions we’ve just covered, and you’ve got the idea. The 2.0-litre four-cylinder can currently be found in the Wrangler, Wrangler 4xe, Cherokee, and Grand Cherokee 4xe.

According to Stellantis, Hurricane engines are the primary engine of the future for North American vehicles using the STLA Large and STLA Frame platforms underpinning the automaker’s largest and hardest-working models.