The Mopar 392 HEMI Crate Engine: A Technical Overview

The Mopar Performance 392 HEMI crate engine represents a modern evolution of Chrysler’s legendary HEMI architecture. Displacing 6.4 liters (392 cubic inches), this V8 engine combines a cast-iron block with aluminum cylinder heads, a forged steel crankshaft, and high-flow intake and exhaust ports. The combustion chamber retains the classic hemispherical design, which promotes efficient flame propagation and reduces heat loss—key factors behind the engine’s strong output.

Factory-rated horsepower is 485 hp at 6,100 rpm, with peak torque of 470 lb-ft at 4,100 rpm. These figures come from Mopar’s own dyno testing using premium unleaded fuel. The engine uses a multi-displacement system (MDS) that deactivates four cylinders under light load, improving fuel economy—a rare feature in a crate engine of this caliber. It also includes variable valve timing (VVT) for broader power delivery. For enthusiasts seeking a direct performance upgrade, the 392 HEMI crate engine ships as a complete long-block assembly, including the intake manifold, throttle body, fuel injectors, valve covers, oil pan, and front cover.

How Much Horsepower Does the 392 HEMI Add to a Charger?

The answer depends on the donor Charger’s original engine. The 392 HEMI crate engine delivers 485 hp at the crankshaft. Once installed, parasitic losses from the drivetrain (automatic transmission, differential, and axles) reduce wheel horsepower by roughly 15–18%, putting rear-wheel figures near 400–410 hp on a chassis dyno. The net gain over factory engines is substantial:

  • Over a 3.6L Pentastar V6 (292 hp / 260 lb-ft): gain of +193 hp and +210 lb-ft at the crank
  • Over a 5.7L HEMI V8 (370 hp / 395 lb-ft): gain of +115 hp and +75 lb-ft at the crank
  • Over the 6.4L SRT 392 factory engine in 2015+ Chargers (485 hp / 475 lb-ft): essentially a direct swap – the crate engine matches or slightly exceeds the factory output depending on calibration

It is important to note that many stock Charger 392s already come with a 6.4L HEMI, but the crate version is often preferred by builders because it is pre-assembled with a balanced and blueprinted rotating assembly, ARP fasteners, and a high-strength timing chain, offering a more robust foundation for future upgrades. For a Charger with the 5.7L HEMI, the upgrade represents a 31% increase in horsepower without forced induction.

Comparing the 392 HEMI Crate Engine to Factory Charger Engines

3.6L Pentastar V6 (292 hp / 260 lb-ft)

The base Charger engine is a capable daily driver but lacks the visceral punch of a V8. Swapping in a 392 HEMI transforms the car’s character entirely. Acceleration from 0–60 mph drops from the mid-6-second range to the low-4-second range, and quarter-mile times improve from the high 14s to the low 12s with proper traction.

5.7L HEMI V8 (370 hp / 395 lb-ft)

Many Charger R/T models use the 5.7L HEMI, which itself is no slouch. The 392 crate engine adds 115 peak horsepower and 75 lb-ft of torque. More importantly, the 6.4L engine’s torque curve is fatter across the entire rev range, meaning stronger mid-range pull and less need to downshift for highway passing. The larger displacement also supports higher compression (10.9:1 versus 10.5:1 in the 5.7L), contributing to more efficient combustion.

6.2L Supercharged HEMI V8 (707 hp / 650 lb-ft in Hellcat)

While the 392 cannot match the forced-induction Hellcat, it offers a naturally aspirated alternative that is lighter, simpler, and more reliable for track-day use. Many builders prefer the linear power delivery of a naturally aspirated engine for autocross or road courses. When compared to the Hellcat’s supercharged 6.2L, the 392 crate engine costs significantly less and avoids heat-soak issues common with high-output blowers.

Installation and Compatibility Considerations

Installing a 392 HEMI crate engine into a Charger is not a weekend bolt-in for the average hobbyist. Critical factors include:

  • Engine Mounts and K-Frame: The 392 HEMI shares the same bellhousing pattern as the 5.7L and 6.2L HEMIs, so existing mounts may work, but aftermarket reinforced mounts are recommended to handle the extra torque.
  • Transmission: The stock 8HP70 eight-speed automatic can handle the power, but a torque converter upgrade (higher stall speed) will improve off-the-line performance. For manual transmissions, the Tremec TR-6060 is a popular choice.
  • Driveshaft and Axles: Upgraded half-shafts and a stronger driveshaft are advisable to prevent breakage.
  • Cooling System: The 392 HEMI generates more heat than smaller engines. A high-capacity radiator, electric fans, and an oil cooler are strongly recommended, especially for hot climate or track use.
  • Engine Management: The crate engine requires a standalone ECU or a re-flashed factory controller. Mopar offers a plug-and-play controller (P/N 68303097AA) that is pre-calibrated for the engine, but it must be paired with a Charger-specific harness. Some tuners use Holley’s Terminator X or HP EFI systems.
  • Fuel System: The 392 HEMI’s fuel injectors flow at 48 lb/hr (nearly 500cc). A stock 5.7L fuel pump may deliver insufficient volume—upgrading to a 6.4L pump or a high-flow aftermarket unit is necessary.

Professional installation can cost between $3,000 and $6,000 depending on the shop and additional parts, making the total investment for a complete swap around $10,000–$16,000, including the crate engine.

Cost Breakdown and Value

The Mopar Performance 392 HEMI crate engine (part number 68303091AC) carries a retail price of approximately $8,200 as of early 2025, though prices fluctuate. Discounts from online retailers can bring it to $7,200–$7,800. Additional costs include:

  • Engine controller kit: $1,400
  • Transmission upgrade or rebuild: $1,500–$3,000
  • Cooling system upgrades: $800–$1,200
  • Fuel system upgrades: $400–$800
  • Installation labor: $3,000–$5,000
  • Dyno tuning: $500–$1,000

Total outlay for a turnkey swap ranges from $12,000 to $18,000. Compared to buying a new Charger Scat Pack ($50,000+), the crate engine swap offers a more budget-friendly path to similar performance—especially if the donor car is already owned and in good condition.

Tuning and Optimization for Maximum Horsepower

To extract every horsepower from the 392 HEMI crate engine, careful calibration is essential. The Mopar factory tune is conservative, prioritizing reliability and emissions compliance. Aftermarket tuning can raise peak output to 505–515 hp at the crank with just a reflash and premium fuel. Key modifications include:

  • Cold Air Intake: An open-element intake (e.g., from AFE or Mopar Performance) can add 10–15 hp.
  • Cat-Back Exhaust: Replacing restrictive factory mufflers with a 3-inch system (such as Borla or Corsa) frees up 15–20 hp.
  • Headers: Long-tube headers (1-7/8-inch primary tubes) and a high-flow mid-pipe add 25–35 hp, but require compatible O2 sensor extensions and tuning.
  • Camshaft Upgrade: A hotter camshaft with increased duration and lift pushes power past 550 hp at the crank, but sacrifices low-end torque and idle quality.

For those seeking forced induction, the 392’s forged internals can handle up to 700 hp safely with a centrifrugal supercharger (e.g., ProCharger or Vortech) and supporting mods. At this level, the engine becomes a serious competitor to the Hellcat, though driveline upgrades become mandatory.

Real-World Performance Gains

Numerous Charger owners have documented their swaps on forums and social media. A 2016 Charger R/T (5.7L) receiving a 392 HEMI crate engine with a mild tune, stock exhaust manifolds, and the factory automatic transmission recorded a 12.4-second quarter-mile at 115 mph—a full 1.5 seconds quicker than the stock car. After adding headers, a cold air intake, and a custom tune, the same car ran 11.9 seconds at 118 mph.

A 2014 Charger SXT (V6) converted to 392 HEMI power, with a Tremec TR-6070 manual transmission, achieved 0–60 mph in 3.9 seconds on street tires and a 12.1-second quarter-mile. These results show the engine’s capability to dramatically transform the car’s acceleration and overall driving experience.

Conclusion

The Mopar Performance 392 HEMI crate engine is a proven upgrade for any Dodge Charger, delivering a net gain of 115 to 193 crank horsepower over factory V6 and 5.7L engines. When installed correctly with appropriate supporting modifications, it yields 485 hp at the crank and over 400 hp at the wheels in a vehicle that originally made far less. The engine’s robust internals make it a reliable foundation for further tuning, and its character—a deep, throaty HEMI roar—adds an emotional reward that numbers alone cannot capture. For Charger enthusiasts seeking a meaningful performance leap without stepping up to Hellcat pricing, the 392 HEMI crate engine remains one of the most effective and satisfying powertrain swaps available.

External Links: