With the debut of Stellantis’ all-new 3.0-liter Hurricane inline-six, years of hushed rumors and speculation about the powertrain finally ends. The release of a new internal-combustion powertrain is both exciting and somewhat odd in an era where automakers are intensely focused on electrification, so Road & Track sat down with Stellantis technology communication specialist Dale Jewett to discuss how an inline-six fits into the automaker’s future plans, and what it means for the beloved Hemi V-8.
As was made clear by CEO Carlos Tavares earlier this month, Stellantis is moving quickly towards electrification. As part of the automaker’s Dare Forward 2030 strategic plan, 50 percent of U.S. sales should come by way of electric offerings by 2030. That sales figure will be 100 percent in Europe by the same point. That said, the U.S. plays by different rules, and Stellantis needs to be ready to meet the demands of customers who aren’t as willing to make the jump to EV. In order to do that, the company needs efficient gasoline engines in its stable.
“Mobility is changing, and we definitely want to be part of that conversation and part of that effort,” Jewett says. “Nonetheless, 50 percent of sales being EV in the U.S. by 2030 still leaves the other 50 percent. It is a journey, and we have to get there. It’s all about our customers and how they use their vehicles, as well as what they expect from their vehicles. We owe it to them to deliver the best balance of power and emissions that we can. That’s the driving force behind this engine.”
In order to blend the worlds of performance and efficiency, Stellatnis has developed two distinct variants of the new Hurricane inline-six. The automaker says the Standard Output (SO) engine will provide more than 400 hp and 450 lb-ft of torque, all while offering at least 15 percent improved efficiency over a comparable naturally aspirated V-8. The High Output (HO) engine is a bit less concerned with the environment, and offers up more than 500 hp and 475 lb-ft of torque. That said, both engines do feature a ton of technology to help improve fuel economy across the board.
This starts with the cast-aluminum block, which features Plasma Transfer Wire Arc (PTWA) coated cylinder bores. Colloquially known as spray bore, this process interacts with the metallurgy of the aluminum to create an extremely low-friction surface inside the cylinder. The PTWA process allows the cylinder liners to be much thinner than pressing or casting traditional iron liners in place, which leaves more aluminum in place between the cylinders. That helps with thermal management, which is a key theme throughout the Hurricane engines. It also provides big gains in terms of cylinder durability.
Stellantis
“We’ve been running test engines for hundreds of thousands of miles, and when they tear them down the cylinders look practically brand new,” Jewett says.
Stellantis also outfitted both Hurricane inline-six engine configurations with a high-pressure direct injection system. Similar to the unit found on the automaker’s related 2.0-liter four-cylinder, the Hurricane-specific system runs at a ridiculous 5075 psi. According to Jewett, this helps ensure that the fuel is better atomized before meeting with any air, which in turn makes for a cleaner and more efficient burn in the combustion chamber. This high-pressure action is particularly effective at helping reduce the amount of particulates leaving the exhaust system. High Output models get a second high-pressure pump to ensure fuel is never a limiting factor for performance.
Both Hurricane inline-six engines also benefit from a continuously variable displacement oil pump, which reduces the mechanical load on the engine and improves efficiency. The High Output variant also gets a unique set of oil jet coolers to keep the forged aluminum pistons at an optimal temperature. Standard Output engines get cast-aluminum pistons, and no oil squirters.
The Standard Output engine does have a few unique touches of its own. The most interesting of these tweaks comes by way of the cooled exhaust-gas recirculation system. By leaving the exhaust valve open for a moment longer, the SO engine can pull cooled exhaust gasses back into the cylinder. By utilizing these cooled exhaust gasses, the Hurricane inline-six is able to keep temperatures within the most efficient range for fuel economy. Thanks to the valve adjustment required, Stellantis set the compression ratio of the SO at 10.4:1. For comparison, the HO motors run at 9.5:1.
When you combine all of this with more traditional ways of meeting emission regulations like low-interia turbos and start/stop integration, it does seem like the Hurricane engines have a chance to be pretty impressive on the efficiency front. And while Stellantis isn’t ready to confirm one is coming, the automaker made note of the fact that the Hurricane engine platform is hybrid-ready. The automaker also notes that the engine will make its first product debut soon, with a Hurricane-powered vehicle set to hit dealerships this year. Stellantis won’t confirm which vehicle the engine will land in first, but a recent flub on its Jeep Grand Wagoneer configurator page gives us a pretty good hint. That configurator website briefly featured a twin-turbocharged inline-six, which carried a $2000 premium over the standard 6.4-liter Hemi V-8. We expect that inline-six-powered SUV to debut at the New York International Auto Show. The Hurricane engine should proliferate throughout the Stellantis portfolio shortly thereafter, but don’t let that terrify you: Stellantis isn’t ready to kill off the Hemi V-8. Yet.
Stellantis
“We haven’t said that we are discontinuing any engines,” Jewett notes. “The Hemi is incredibly popular, and it’s important to our customers. The Hemi V-8 is in our product portfolio for the foreseeable future.”
Precisely how long the foreseeable future is will have to be seen, but even Jewett notes that no regulators are interested in loosening emissions regulations. Things will only continue to get tougher for automakers on the internal-combustion front, and the Hurricane inline-six aims to be flexible enough to deal with that reality. And so while the Hemi remains an option for the time being, one day it might be the Hurricane inline-six powering your Challenger or Charger. With electric muscle cars just around the corner, some folks might be more willing to accept six-cylinder offerings than they have in the past. If the engine truly does come with V-8 performance, I don’t think we have much room to argue regardless of the segment.
Stellantis
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