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Chrysler 6.4L 392 HEMI Engine (Design, Issues & Reliability)

Updated: Jan 9

The 6.4L 392 Hemi is a naturally aspirated V8 petrol engine with a displacement of 6.4 litres producing 366-485 hp and 582-644 nm of torque, it is based on the 5.7-liter Hemi V8 design.

For the Ram 2500/3500 pickup trucks as well as the Ram 3500, 4500, and 5500 Cab Chassis, a new 6.4L Hemi SRT engine was introduced in 2014.

The 2011 Dodge Challenger SRT8 utilises this 392 Hemi engine.


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Chrysler 6.4L 392 HEMI Engine

Chrysler 6.4L 392 HEMI Engine Design

Like the 5.7 Hemi, the 6.4-liter Hemi is built on a deep-skirted, 90-degree cast-iron cylinder block. But these two engines' bore diameters and stroke lengths differ from one another.

  • The crankshaft of the 392 Hemi is made of forged steel and the main bearing caps are cross-bolted.

  • There are piston cooling jets in the 6.4 Hemi engine block. 

  • Higher-strength powder metal alloy connecting rods and new, larger-diameter flat-top pistons are used.

  • Cylinder head ports feature a larger cross-sectional area (11% higher intake flow and 13% higher exhaust flow).

  • Electronic drive-by-wire throttle bodies are used on these engines.

Oil jets, commonly referred to as oil squirters, dispense engine oil onto the underside of each piston to reduce combustion heat. This is one of the reasons for the oil-to-water oil cooler found in these engines.

Similar to the cylinder heads seen on the 5.7 Hemi engines. Each cylinder has two valves and two spark plugs, for a total of 16 valves and spark plugs, and the combustion chambers are oval and semi-hemispherical in shape.

The head covers are made of plastic.

Dodge Challenger and Charger's SRT engines use a plastic intake manifold with shorter runners for high-speed performance.

Whereas the truck's 6.4L Hemi has an active dual-runner-length intake manifold for low and mid range engine speeds without compromising the high-end power of the SRT V8s.

The 6.4L truck engine incorporates a Chrysler-designed hydraulic cam phasing mechanism and a cam-in-block variable valve timing (VVT) system. Hydraulic roller lifters and sodium-filled exhaust valves are used in the valvetrain.

MDS (Multi Displacement System) cylinder deactivation technology, designed for enhanced fuel efficiency, is included in the truck engine. The technology switches off four cylinders when maximum power output is not required.

Additionally, pumping losses are decreased by removing valve lifters for certain cylinders. The 6.4 Hemi truck engine could operate on 87 or 89 octane petrol.

6.4L HEMI Engine Specs

  • Manufacturer: Chrysler, Saltillo Engine plant in Ramos Arizpe, Mexico

  • Production years: 2011-present

  • Cylinder block material: Cast iron

  • Cylinder head material: Aluminium

  • Fuel type: Gasoline

  • Fuel system: Sequential multi-port injection

  • Configuration: V

  • Number of cylinders: 8

  • Valves per cylinder: 2

  • Valvetrain layout: OHV

  • Bore: 103.9 mm (4.09 in)

  • Stroke: 94.6 mm (3.72 in)

  • Displacement: 6,407 cc (392 cu in)

  • Type: Four-stroke, naturally aspirated

  • Compression Ratio: 10.9:1 (6.4L Hemi SRT), 10.0:1 (6.4L Hemi Ram trucks)

  • Power: 366-485 hp (273-362 kW) at 4,600-6,000 rpm

  • Torque: 429-475 ft-lb (582-644 Nm) at 4,000-4,800 rpm

  • Engine weight: 500 lbs (227 kg) (dry weight)

  • Firing order: 1-8-4-3-6-5-7-2

  • Engine oil weight: SAE 0W-40

  • Engine oil capacity: 6.7 litres (7.0 qt) with oil filter

  • Oil change interval: 6,000 miles (10,000 km) / 6 months

  • Applications: Ram 2500/3500/4500/5500 and Cab Chassis, Dodge Challenger SRT8 / R/T Scat Pack / SRT, Dodge Charger SRT8 / R/T Scat Pack / SRT, Chrysler 300 SRT8 / SRT, Jeep Grand Cherokee SRT8 / SRT, Dodge Durango SRT8 / SRT

392 HEMI Problems & Reliability

The 6.4-liter 392 Hemi is a reliable V8 engine that delivers significantly more power and torque than the 5.7 Hemi. So far, this engine has not caused any significant issues when used for regular everyday driving.

The 6.4 Hemi V8 exhibits "Hemi ticking", much like the 5.7-liter version, because it employs the MDS system. There's no need to worry; the tick has no implications.

A thin, impurity-free 0W-40 oil is required for the Cylinder Deactivation System (MDS). As a result, only the recommended oil should be used, and it has to be changed frequently.

A five-year or 100,000-mile manufacturer's guarantee is included with this engine.

The 6.4 Hemi is an excellent engine that will last hundreds of thousands of miles in original condition. On the other hand, it was never intended to be increased in power.

There isn't enough material between the piston rings and the top of the piston since the pistons aren't forged. Additionally, excessive heat can stress the exhaust manifold and lead to the studs holding it together bursting.