The 392 HEMI is the 6.4-liter V8: “392” refers to its displacement in cubic inches. The 5.7-liter HEMI is smaller, at 345 cubic inches in Mopar’s published crate-engine comparison. In that specific 2016 comparison, the 6.4 makes 485 hp and 475 lb-ft, versus 383 hp and 417 lb-ft for the 5.7. Those are crate-engine ratings, not universal figures for every vehicle or model year.
What “392” and “5.7” mean
Both are Gen III HEMI V8s. “5.7” and “6.4” name engine displacement in liters; “392” is the 6.4-liter engine’s displacement in cubic inches. Mopar lists its 2016 5.7L Eagle crate engine at 345 cubic inches and its 6.4L SRT crate engine at 392 cubic inches—about 13.6% more displacement for the 6.4.
The labels identify engine families and approximate displacement, not a single fixed output. Vehicle, model year, tuning and application affect the factory rating.
How much more power does the 392 make?
For a like-for-like example, Mopar’s 2016 crate-engine sheet rates the 5.7L Eagle (part 68303088AA) at 383 hp and 417 lb-ft, and the 6.4L SRT (part 68303090AA) at 485 hp and 475 lb-ft. In that product comparison, the 6.4 has 102 more horsepower and 58 more lb-ft of torque. Mopar describes both as new engine assemblies, not remanufactured engines. Mopar’s 2016 crate-engine specifications
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Those figures should not be applied to every car or truck with either engine. Dodge’s HEMI FAQ gives broad output ranges of 340–395 hp for the 5.7L and 366–485 hp for the 6.4L, and says exact horsepower depends on vehicle and production year. For example, the 2026 Ram 2500 4×2’s truck-duty 6.4L is rated at 405 hp and 429 lb-ft with an eight-speed automatic—not the crate engine’s 485 hp and 475 lb-ft. Dodge’s HEMI FAQ · 2026 Ram 2500 4×2 engine specifications
How the specified crate engines differ mechanically
Mopar’s 2016 sheet shows differences in bore, stroke, compression, crankshaft material and listed peak rpm. These are specifications for those crate-engine products; they should not be assumed to describe every vehicle installation.
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| 2016 Mopar crate-engine specification | 5.7L Eagle | 6.4L SRT (392) |
|---|---|---|
| Displacement | 345 cu in | 392 cu in |
| Bore | 99.5 mm | 103.9 mm |
| Stroke | 90.9 mm | 94.6 mm |
| Compression ratio | 10.5:1 | 10.9:1 |
| Crankshaft | Nodular iron | Forged steel |
| Listed peak rpm | 5,600 | 6,400 |
Source: Mopar’s 2016 crate-engine specifications
Which one to choose for a vehicle?
The larger engine’s higher output in the crate comparison does not by itself establish which vehicle is quicker, more capable or less expensive to own. Compare the exact vehicle and model year, not just the engine badge.
- Factory horsepower and torque: Use the rating for the specific model, year and configuration.
- Transmission and drivetrain: These affect how engine output reaches the road and can differ between applications.
- Towing rating: Check the vehicle’s rating and whether it is standard or dependent on equipment or a package.
- Fuel requirement, MDS configuration and ownership cost: Confirm these for the exact application. The available figures do not establish a universal fuel-economy, reliability or lifecycle-cost winner.
Example: 2026 Dodge Durango
Dodge lists the 6.4L HEMI for Durango R/T 392 models, with up to 8,700 lb of available towing capability. The 5.7L HEMI is listed for Durango GT HEMI models, with 7,200 lb of standard towing. These are different vehicle configurations, and the available-versus-standard distinction matters; the figures are not an isolated comparison of engine capacity. Dodge Durango towing and capability
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Example: 2023 Dodge Challenger
Dodge’s 2023 Challenger performance page lists both a 392 HEMI V8 and a 5.7L HEMI V8 as options, making that model year a useful context for the familiar car comparison. It is a 2023 model-year page and does not establish that either engine is available in a current Challenger. 2023 Dodge Challenger performance
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What MDS means
MDS stands for Multi-Displacement System. Dodge describes it as a system that temporarily shuts off four cylinders under light-load conditions. Dodge’s FAQ says the technology is found in 5.7L HEMI V8s; that does not establish identical MDS equipment in every 5.7L application or mean that cylinder deactivation is exclusive to the 5.7L. Check the specifications for the particular vehicle and year. Dodge’s HEMI FAQ
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