A Hurricane Cometh: Stellantis unveils 500+ hp inline-six
Automakers announcing grandiose pivots to lofty electrification forecasts are a dime a dozen these days. Most of these announcements target the next decade—some a bit sooner, some later than that. But what about the next few years? While some have opted to halt ICE development entirely, the folks at Stellantis have decided to make the next few years count in a big way.
Meet the Hurricane, an all-new, twin-turbo, 3.0-liter inline-six that’s set to elevate many of the offerings across multiple brands under Stellantis’ wide umbrella.
Before we dive into the details, a bit of context: At a press event earlier this year, Stellantis CEO Carlos Tavares unveiled Dare Forward 2030, a bold plan for electrification and carbon reduction across the entire company. One of the plan’s pillars was for a 50-percent battery electric vehicle (BEV) sales mix in the U.S. by 2030—spearheaded by a recently-revealed all-electric Jeep and a battery-powered Ram pickup. But quick math shows that by those percentages, 888,697 of the 1,777,394 vehicles sold by Stellantis in 2021 (a year hampered by the pandemic) would still feature some sort of internal combustion engine. As in, it ain’t dead yet.
“Internal combustion engines will play a key role in our portfolio for years to come,” said Micky Bly, head of propulsion systems at Stellantis. “We owe it to our customers and the environment to provide the cleanest, most-efficient propulsion possible.”
Enter the Hurricane. This new mill will be offered in two distinct variants: Standard Output (SO) and High Output (HO). The Hurricane SO is all about efficiency, but still boasts impressive output figures. Stellantis says it churns out more than 400 hp and 450 lb-ft of torque, depending on the specific application. Meanwhile, the Hurricane HO will chase performance without throwing consumption to the wind. Expect more than 500 hp and 475 lb-ft of twist, application dependent. (A note: Performance isn’t just raw pace, in Stellantis’ eyes. They also mention towing applications for the HO. We’ll let you connect the pickup-shaped dots.)
There’s plenty of componentry and engineering to differentiate the two, but let’s look at some of the commonalities first. Headlining the whole ordeal is the block, a deep-skirt cast aluminum affair that features a structural aluminum alloy oil pan and cross-bolted steel main bearing caps. Said block is deck-plate honed to ensure the correct bore shape (engines can twist their bores under heavy load; deck-plate honing aims to curtail that). The block shares bore (3.31 inches), stroke (3.54 inches), and cylinder spacing with Stellantis’ global 2.0-liter turbo four found in products like the Wrangler 4xe and the all-new Grand Cherokee 4xe. The Hurricane also has a common exhaust cam, spark plugs, head gasket, and electric coolant pumps between the SO and HO models. In total, 96 parts are shared between the two.
One key piece of shared tech is the cylinder liners. In place of more common cast-in-place or pressed-in iron liners, the Hurricane uses Plasma Transfer Wire Arc (PTWA) technology to coat the insides of the cylinders with a vaporized mixture of metallic and oxide material. Whereas traditional liners may be between 3-4 mm thick, the PTWA liners are significantly thinner, while providing 10 times as much wear resistance, according to Stellantis. This high-tech lining is done at the Saltillo engine plant in Mexico, where both iterations of the Hurricane are produced. BMW uses similar technology on their B58 performance engine, which can be found in many of Bavaria’s mid-tier models such as the X3 M40i, the M240i, and the Magna-Steyr-assembled Toyota Supra. Ford also uses PTWA for the 5.2-liter supercharged cross-plane-crank Predator V-8 from the Shelby GT500.
The Hurricane SO is primarily focused on efficiency, and Stellantis says this variant produces 15 percent less CO2 emissions than the larger displacement engines in its portfolio—think the 5.7-liter and 6.4-liter Hemi V-8s. The SO has different turbos than its performance-first counterpart but in both variants the snails feed three cylinders apiece with extra air. Peak boost is 22.4 psi, and although premium (91 Octane) fuel is recommended for the engine’s 10.4:1 compression ratio, Stellantis says it can run on regular 87, albeit with a slight reduction to performance. On the Hurricane SO, the 5075-psi direct-injection fuel system (the highest on any Stellantis engine to date) is run by a single chain-driven pump with unique injectors. Other SO-specific parts include the cylinder head, oil pump, intake cam, forged steel crankshaft, cast aluminum pistons, forged steel connecting rods, and a single-inlet charge air cooler. The SO’s redline is an electronically-limited 5800 rpm, but specific power output still rings in at more than 133 hp/liter of displacement. Not too shabby.
If the SO is the soft-spoken variant of the two, the HO is the one holding the big stick. Stellantis knows that the Hurricane HO has big performance shoes to fill—those Hemi V-8s are no pushovers. To that end, it’s taken a few specific approaches to bolster this mill for its intended use cases—whether that’s the raw pace or, as previously mentioned, something less obvious such as towing or hauling. On the HO, compression drops to 9.5:1, and premium fuel is required. Peak boost from the variant-specific turbos climbs to 26 psi, and there’s a dual-inlet charge air cooler in place of the SO’s single-inlet unit. Specific internals, such as the unique cylinder head, forged steel crank, forged steel rods, and forged aluminum-alloy pistons are meant to withstand the added stress that outputs over 500 ponies will require. The HO runs dual chain-driven fuel pumps for its injectors vs. the SO’s single-chain unit. Redline climbs to 6100 rpm in the HO, and specific output is up to 166 hp/liter. The best part: while initial applications will carry over 500 horsepower, Stellantis says there’s bandwidth for even greater output figures in the future.
While it’s not yet known which models are going to find a Hurricane beneath their hood, one can surmise more than a few logical applications for these new six-pots. Stellantis says that the Hurricane is dimensionally similar to longitudinally-mounted applications of the 3.6-liter Pentastar V-6 as well as 5.7-liter and 6.4-liter versions of the Hemi V-8. A brief survey of North American Stellantis offerings—where the Hurricane is primarily destined to reside—reveals a large pool of potential recipients. Everything from the Ram 1500 and 2500 HD, to the Wagoneer and Grand Wagoneer siblings, to the Jeep Grand Cherokee, Grand Cherokee L, and even the Wrangler could wind up with a straight-six between the frame rails. We may even see a Hurricane-powered Challenger before this is all said and done. Stellantis says that brand-specific announcements regarding the Hurricane are in the works, and we should know more in the coming months.
What’s more, although Stellantis says that the Hurricane will not launch initially as a hybridized application, the engines were designed from the outset with PHEV, MHEV, and HEV applications in mind. Expect to see versions of the eTorque belt-driven generator and stop/start system tacked onto Hurricanes, as well as potentially versions of the plug-in 4xe powertrain currently found in Wranglers and Grand Cherokees.
Developing an all-new engine as the prevailing market conditions appear exclusively electric-focused may seem like folly from a business-case standpoint, but Stellantis is confident that the accounting department will be satisfied. From the project’s outset in 2019, some 14 months of digital modeling were used to optimize the new powertrain before any physical components were studied. Additional savings come from Stellantis’ decision to sunset the 2.4-liter TigerShark four-cylinder and convert that production line at the Saltillo, Mexico, engine plant to assemble the Hurricane instead. The plant is capable of producing 250,000 Hurricane engines annually, and Stellantis says it will be all systems go within a few months.
Yes, the impending electric revolution feels like an unstoppable force at this point—at least if Bloomberg headlines are any indication. But it’s that interim period—eight years as measured by some forecasts, more by others—that seems like the space where Stellantis is angling for a big win. If the Hurricane SO and HO can deliver on the impressive promises above, there’s a lot to look forward to.