How Do These Engines Compare?

When you are considering purchasing a capable new work horse, your first choice will be to choose which one is best. diesel or gas powered pickup trucks are best for youBut what if you’ve decided on a naturally aspirated petrol engine and want to compare a few of the most robust options available?

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For example, the big 6.4-liter HEMI V8 comes stock with 410 horsepower and 429 pound-feet of torque and is available in pickup trucks like the 2024 Ram 2500 Laramie. There’s also Ford’s massive 7.3-liter V8, nicknamed “Godzilla,” that produces 430 horsepower and 485 pound-feet of torque and is offered in models like the 2024 F-250 XLT.

In addition to their output figures, the 6.4 HEMI and 7.3 Godzilla differ in other ways, such as cylinder head shape, number of gears, and fuel-saving technology. Also, Stellantis (which owns RAM and Dodge, among other brands) HEMI engine production is being discontinuedMeanwhile, the 7.3-liter option that a rival automaker has more recently introduced is still in its infancy, and here’s one reason why. Ford’s Godzilla engine is very different from other modern V8s.

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The shape of the top of each cylinder in an engine can affect things like compression ratios, increased combustion efficiency, and power. A HEMI engine is an engine that features a hemispherical cylinder head shape, or hemisphere. Known in the automotive industry for decades, Chrysler branded many of its engines with the impressive output “HEMI” name.

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Featuring a domed top on the cylinder, the HEMI has angled valves, providing more space for the oxygen and fuel mixture, and absorbing less heat than other configurations, providing solid performance benefits. The uniquely formed cylinder head Chrysler’s HEMI engines are very special.

Another cylinder head design has been hotly debated and compared to the HEMI, and that’s the wedge. The Ford Godzilla features wedge-shaped cylinder heads, which have their own advantages. The wedge design can provide more efficient combustion, lighter components, and in some cases, can hold the valves open longer than a HEMI. Of course, these comparisons are entirely dependent on which specific HEMI and wedge engine are being pitted against. Suffice it to say, both cylinder head designs found on the 6.4 HEMI and 7.3 Godzilla are close in terms of muscular potential under the hood.

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The 6.4-liter HEMI is equipped with an eight-speed automatic transmission, while the 7.3-liter Godzilla includes a 10-speed automatic. The pros and cons of gear ratios on these engines can make one option more appealing than the other. In terms of fuel economy and performance, the eight-speed transmission on the HEMI strikes a good middle ground. Still, miles per gallon figures are heavily influenced by driving habits, where actions like aggressive acceleration can reduce efficiency. Additionally, some owners of 10-speed transmissions report a frustration with their driving experience, as they shift gears more frequently than they would with eight-speeds.

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However, the extra two gears in the 7.3-liter Godzilla do offer some advantages over the 6.4-liter HEMI eight-speed transmission. When it comes to towing a trailer, a 10-speed transmission offers a smoother experience and helps keep the engine in the sweet spot for optimum power output. You’ll notice, especially on hills, that a 10-speed transmission doesn’t feel as jarring when downshifting because each gear isn’t as spaced out as an eight-speed transmission. In fact, the Ford 10-speed transmission doesn’t have a wider overall spread than transmissions with fewer gears.

For decades, automakers have walked a fine line between producing big V8 engines with improved output while still meeting increasingly stringent EPA regulations. One of the ways the Ram’s 6.4 HEMI improves its efficiency is by incorporating cylinder deactivation. The Ram uses a technology called MDS (Multiple Displacement System), a surprisingly complex sequence of operations that shuts down four of the eight cylinders, thereby reducing the amount of exhaust gases that use energy to pump out. This also makes the engine more efficient because the MDS senses when output requirements are low and automatically activates. However, if you select a drive mode like Tow/Haul, the MDS is disabled.

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The 7.3-liter Godzilla does not have a similar cylinder deactivation system found on the 6.4-liter HEMI. Instead, it offers an ECO driving mode that must first be manually selected by the driver. Once activated, ECO mode observes your driving habits and offers suggestions on how to improve fuel economy. As one owner of the Godzilla engine explained online in the F150 forum“I have a 7.3 and…these are built for towing, not fuel economy.”