Jeep Hurricane I-6 Engine Deep Dive: How This Twin-Turbo Six Rocks Like a... You Know

The introduction of the 2023 Jeep Wagoneer L and Grand Wagoneer L not only brings a longer-wheelbase, larger body option to the new-last-year Wagoneer and Grand Wagoneer full-size SUVs, it also ushers in an all-new inline-six engine. A once-favored format over at Jeep, the new I-6 is standard on the Wagoneer and Grand Wagoneer Ls and available on the short-wheelbase models. It won't be exclusive to Stellantis' off-road brand—it's headed to the broader Dodge, Chrysler, and Stellantis family overall in the future.

In the new big-boy Wagoneer Ls, this 3.0-liter inline-six, dubbed "Hurricane," has its work cut out: The huge SUVs weigh nearly four tons, and are expected to tow up to 10,000 pounds, too. Powerful V-8s are out at Stellantis, hence these relatively small-displacement sixes also get two turbos delivering up to 26 psi to not only keep up with the Wagoneer's entry-level 5.7-liter V-8 and the Grand Wagoneer's 6.4-liter V-8—but surpass both with up to 510 hp and 500 lb-ft of torque. But there's so much more to the new Hurricane than that, so let's dive into these I-6s and see how they make their power, what advances they bring to Jeep, and more:

As we've mentioned several times by now, V-8s are on their way out at Dodge, Ram, and Jeep, as all three brands start to transition toward electrification. With Stellantis' first full battery electric vehicles still some years away, that transition initially will focus on downsized, electrically assisted internal combustion engines like this Hurricane motor. Forget Jeep's old 4.0-liter I-6 and Hurricane I-4 (this new engine does not have pushrods). No, this is a technologically advanced, truly new engine.

Before we start, at least in the Wagoneers, there are two versions of the 3.0-liter Hurricanes: A 420-hp standard-output and the 510-hp high-output. Which Wagoneer you buy will determine which is available; regular Wagoneers and Ls get the standard version, while Grands use the high-output. However, both engines are known internally at Stellantis as Global Medium Engine (GME T6), and there are common parts between them. Both engines use an aluminum deep-skirt block with Plasma Transfer Wire Arc (PTWA)-coated 3.31-inch cylinder bores. This coating obviates the need for separate iron or steel bore liners like those you might typically find on an aluminum-block engine. The Hurricane's aluminum blocks also feature a closed deck design to maintain and survive the high cylinder pressures of the Hurricane's forced induction. The main bearing cradles of both engines are cross-bolted (much like GM's LS and LT V-8s), and their oil pans are structural pieces.

Another commonality for both Hurricanes are their aluminum heads with pent-roof combustion chambers. Each uses a double overhead camshaft (DOHC) valvetrain layout with four valves per cylinder. Intake and exhaust cams have independent timing, with up to 60 degrees of advance on the intake and 55 degrees on the exhaust. The exhaust valves are sodium filled and all valves are opened using a hydraulically adjusted lash system with roller finger followers. If you're familiar with older Jeep I-6s, this means the cams don't act directly on the valve but on the fingers that push the valves down to open them.

There are some minor differences between the valvetrains of the standard- and high-output Hurricanes, but it's mostly to take advantage of the latter's higher boost pressures and lower compression ratio.

The Hurricanes' crankshafts are forged from twisted steel and are clasped by forged steel connecting rods; the stroke is 3.54 inches, bringing the displacement to 183 cu-in or 3.0 liters, depending on your measurement preference (For Jeep, it's liters, FYI). A diamond-like-coated (DLC) piston pin connects the pistons to the con rods.

Oiling is handled via dual pickup points—the secondary is at the front of the sump and the primary in the back—and total oil capacity stands at 7.5 quarts. Both Hurricane engines use a Mopar 68466307AB filter and are factory filled with Pennzoil Ultra Platinum oil, but the viscosity changes between the outputs. The oil pump not only varies its pressure but also its displacement and feeds as the main lubrication of the engine. Also tied into the oil system are oil squirters that aid in piston cooling—which is normal for turbocharged engines. There are 4.15 gallons of coolant just for the engine.

We should also point out a newish technology being used on the Hurricanes: ion-sense coils. The concept has been around for well over 10 years now, but only recently caught on among mainstream OEMs as the need for even cleaner and efficient engines grew. As one repair industry publication puts it, what these coils do is essentially a more technologically advanced, real-time version of reading the color of spark plugs to gauge combustion quality.

A sensing circuit within the coil detects the electrical current through the gasses inside the combustion chamber before and after the spark plug ignites, using the spark plug's own electrodes. This ion-sense can also be used to determine knock and misfire, too, helping the ECU continuously fine-tune the air-fuel mixture.

Fuel is supplied via high-pressure fuel pumps and direct fuel injection, with the high-output version using two pumps, versus the 420-hp Hurricane's one, raising fuel pressure to 5,075 psi for the single fuel rail system. A pair of twin-scroll turbochargers hang on the cylinder-head integrated exhaust manifold, with charge air feeding into an intercooler located on the intake side of the engine. Yep, unlike the ol' 4.0-liter Jeep I-6, the hot and cold sides of the engine are opposite, not on the same side.

Placing the water-to-air intercooler on the intake side ensures the shortest path for the intake charge between the compressor outlet and the throttle body as possible and avoids oversaturating it while being compressed. The intercooler circuit uses just under three-quarters of a gallon of coolant, while the turbo housings are cooled along with the engine. Attached to the turbos via V-bands are the two catalytic converters for emissions controls, and the standard-output Hurricane also requires an upstream EGR system for emissions control.

Boost control is handled by servo-actuated internal wastegates, and on both Hurricanes each turbo services three cylinders for quick spooling. Jeep says the each version of the Hurricane gets unique turbos, but provided no specifics beyond the obvious: That the turbos are smaller on the standard output. Standard and high output Hurricanes breathe through unique intake systems and the turbos are cooled via a different intercooler design and size on each (On the high output, the charge pipes are separate until they feed into the intercooler, but they join much sooner on the standard output.) The boost tubes from the exit of the intercooler to the throttle body are also different, larger on the high output and smaller on the standard.

In total—not counting fasteners—there are 96 common parts between the two versions of the Hurricane 3.0-liter Twin Turbo I-6. But there are nearly as many (72) parts unique to the 510-hp engine and 90 unique to the 420-hp version.

Now that we've explained the similarities, let's talk about what makes the standard output produce 420 hp at 5,200 rpm and 468 lb-ft of torque at 3,500 rpm and what allows the high-output to produce 510 hp at 5,700 rpm and 500 lb-ft at 3,500 rpm.

Starting with the standard output version, despite using the same bore and stroke measurements, it relies on a set of cast aluminum pistons that allow up to a 10.4:1 compression ratio. The engine is electronically limited to spin up to 5,800 rpm and make "only" 22 psi of boost pressure, though it also can use 87 (regular) or 89 octane. (The quoted power figures of 420 hp at 5,200 rpm and 468 lb-ft of torque at 3,500 rpm are generated using mid-grade, however.) The standard output I-6 also uses 0W-20 viscosity oil.

The 510-hp high output Hurricane uses forged aluminum pistons and gets a 9.5:1 compression ratio—almost a full CR of difference due to piston design—and is electronically limited to 6,100 rpm while making 26 psi of boost. This also means it's stuck using 91 octane gasoline (premium); oil viscosity is 0W-40. The coils and injectors used by each engine also are different, most likely to account for the variances in boost pressure, exhaust-gas recirculation (the high-output lacks EGR), and combustion variances.

There is some tradeoff in fuel consumption between both engines on the Wagoneer Ls. A rear-wheel-drive Wagoneer L with the 420-hp Hurricane delivers an EPA-estimated 17 mpg city, 24 mpg highway, and 20 mpg combined—sufficient for the 30.5-gallon fuel tank to go more than 732 highway miles between fill-ups of 89 octane. Adding four-wheel drive chops 1 mpg off each of the Wagoneer L's EPA figures and just about 30 miles from its highway range. Even so, the Hurricane is more efficient than the Wagoneers' 392-hp 5.7-liter V-8, which is rated for 15-16 mpg city, 20-22 mpg highway, and 17-18 mpg combined.

Step up to the Grand Wagoneer or GW L and its 510-hp Hurricane, which comes only with four-wheel drive, and the EPA estimates plummet to 14 mpg city, 19 mpg highway (20 on the non-L), and 16 mpg combined (L, the non-L gets 17 mpg). Those are good for just under 580 miles of range in the L. Despite barely touching the 20-mpg mark, the high-output I-6 likewise just edges out the 471-hp 6.4-liter V-8 it essentially replaces, which delivers a miserable 13 mpg city, 18 mpg highway, and 15 mpg combined in the non-L Grand Wagoneer. Keep in mind, while the Hurricane's EPA figures aren't hugely better than their eight-cylinder counterparts' numbers, both engines out-muscle those V-8s.

As you'd expect, the new longer-wheelbase Wagoneer and Grand Wagoneer L models are heavier than their short-wheelbase counterparts. The RWD Wagoneer L's factory curb weight nears 6,100 pounds and is in the 7,400 GVWR category. Meanwhile, a loaded Grand Wagoneer L Series III comes in at a whopping 6,700 pounds and is squarely in the 7,950 GVWR category. (These figures offer but a taste of how much Jeep the Hurricane engines contend with—and that's even before they accept rated payloads of 1,410 pounds—Wagoneer L—and 1,330 pounds—Grand Wagoneer L Series III.) That extra weight also explains is why the Grand Wagoneer L has the lineup's lowest trailering capacity of "just" 9,450 pounds, while the rear-drive Wagoneer L has the most at 10,000 pounds.

Like many powertrain control modules (PCMs) from OEMs today, the engine controller for the Hurricane Twin Turbo engines aren't going to be easy for the aftermarket to tune. When asked, Jeep engineers told us that the PCM is factory locked, so it could be some time before the aftermarket finds ways to crack that to allow for, say, modified boost settings on the Hurricane.

Another challenge posed by the turbochargers is the exhaust manifold integral with the cylinder head. Luckily, the turbos are separate and mounted using fasteners, so it might be possible to swap snails. Over on the intake side, there might be some room to improve there by using a different water-cooled heat exchanger, possibly upgrading the stock electronic throttle body, or even creating a new intake plenum. There is even some potential room for improvement for the standard output engine were you to, say, use some of the high-output engine's components, such as the larger intercooler, intake manifold and system, and even the intake tubing leading to the turbochargers. Adding in the high-output's valvetrain, intake cam, and dual fuel pump system along with the entire bottom end would further help—but after all that, you'd probably wish you'd simply bought the Grand Wagoneer and its high-output engine from the jump. With a locked PCM, however, none of those changes would work without the ability to change the fuel, spark, and boost curves of the engine.

We pressed Jeep on whether it plans to offer this as a crate engine, but we didn't receive a straight "yes" or "no." We did catch a kind of a side-eye-with-a-smirk, so consider us excited for the possibility to see this engine thrown in an XJ Cherokee or even a TJ Wrangler just to see what happens. One outta-left-field option would be to substitute a Hurricane swap for an everyday Toyota 2JZ fitment.

Enough technical talk, what are the Hurricane Twin Turbo I-6s like to drive? Fortunately, Jeep invited us to drive both the 2023 Wagoneer L and Grand Wagoneer L around Bozeman, Montana, and we separately tested each (you can read the Wagoneer L and Grand Wagoneer L first tests here) at our own facilities in California. Throughout a multitude of driving locations from city, to backcountry, to highway, even the measly 420-hp Hurricane—strapped to 6,335 pounds of Wagoneer L—felt more than sufficient. Even on decent inclines that those Montana backroads around Big Sky provided us, the standard output proved stronger than "standard," and getting up to the 75 to 80 mph speed limits on short on-ramps of I-90 were a breeze with that torque that comes in at just 3,500 rom.

The Grand Wagoneer L Series III's sheer mass was no match for the high output Hurricane, which has more than enough power to pull a 5,500-pound Airstream trailer. Nor did we feel it needed more power when we had to back it up from a boat landing at a pond. We'll have to get our hands on a Grand Wagoneer and put it through our proper towing test soon.

Here's the big takeaway from our drive with the Hurricane Twin Turbo I-6s: you're not going to miss V-8 power because it makes more torque than even a 6.4-liter Hemi at a lower rpm. It won't be that long before Stellantis finds out just how far they can actually push the GME T6 before it, too, bites the dust for an even more powerful electric motor.

Until then, though, it's hard to say just how much Jeep is really pushing this twin turbo 3.0-liter I-6 engine. Setting aside fever dreams of modified examples delivering 1,000 hp, you can bet Stellantis' own performance gurus—SRT engineers—are going to try their darndest to squeeze every last pony from these new sixes. We certainly can't wait to see it.