6.4L Hemi Engine

Chrysler 6.4L Hemi Engine Guide: Specs & Problems You Need to Know

The Chrysler 6.4L Hemi engine is one of the most popular power plants on the road today. With its impressive specs and rock-solid reliability, it's easy to see why. But even the best engines can have their problems, so it's important to know what you're getting into before you buy a car with a 6.4L Hemi under the hood. In this guide, we'll take a look at the specs and problems associated with this engine so that you can make an informed decision about whether or not it's right for you.

History of the 6.4 Hemi Engine

The 6.4 Hemi is based on the original 5.7L Hemi engine, which was first introduced by Chrysler in 2003. The 5.7L Hemi was a success right out of the gate and soon became one of the most popular engines in Chrysler's lineup. But after several years of production, it was replaced with an even bigger, badder version: the 6.4L Hemi engine.

The 6.4L Hemi was introduced in 2011 and quickly became one of the most powerful engines on the market. It features a long block design with aluminum cylinder heads and forged steel crankshaft, making it both lightweight and reliable. The engine also has two spark plugs per cylinder, enabling it to run both efficiently and powerfully.

Another great feature of the 6.4L Hemi is its fuel efficiency. Thanks to advanced technologies like MDS (multi-displacement system), the engine can shut down half of its cylinders when extra power isn't needed in order to save fuel. This makes the 6.4L Hemi one of the most fuel-efficient engines in its class.

The name “Hemi” comes from the engine's hemispherical combustion chamber design, which allows for more efficient combustion and higher power output than traditional engines. This design also helps the engine to stay cool even under high loads, making it one of the most reliable engines on the market today.

The 6.4L Hemi engine first entered production in 2009, and has since been upgraded with different variants over the years. Major changes include the addition of Chrysler's MDS (Multi Displacement System), which allows for cylinder deactivation to save fuel, as well as an upgrade to a higher-output 485 horsepower version in 2011. The engine has also been given different names over the years, such as the 6.4L SRT Hemi, 6.4L Scat Pack and 392 Hemi, depending on its horsepower output.

Different Variants of the 6.4L Hemi Engine

The 6.4L Hemi engine comes in a few different variants, depending on the intended application.

392 Hemi:

The 392 Hemi is the most commonly seen variant, and it’s used in performance-oriented cars and trucks like the Dodge Charger SRT Hellcat. This version of the engine produces an impressive 485 horsepower and 475 lb-ft of torque, making it perfect for those who want maximum power.

392 Apache:

The 392 Apache is a variation of the 392 Hemi that was released in 2012 for use in heavy-duty pickup trucks and cab chassis versions. This truck engine produces 410 horsepower and 429 lb-ft of torque, making it ideal for towing and hauling ram trucks.

In addition to the SRT and chassis cab models, there are also a few special editions that produce even more power. These include the 6.4L Scat Pack, which produces an impressive 485 horsepower and 475 lb-ft of torque, as well as the 6.4L SRT8 Supercharged Hemi, which produces an incredible 707 horsepower and 650 lb-ft of torque.

No matter which variant you choose, the 6.4L Hemi is sure to provide plenty of power and reliability for years to come. So if you’re looking for a reliable and powerful engine for your vehicle, then the 6.4L Hemi is certainly worth considering.

6.4 Hemi Engine Specifications:

  • Displacement: 6.4L (392 cu in)
  • Stroke: 3.72 inches
  • Bore: 4.09 inches
  • Horsepower Range: 366 to 485 hp
  • Torque Range: 429 to 475 lb-ft
  • Compression Ratio Range: 10.9:1 to 10.0 : 1

6.4 Hemi Engine Mods & Tuning:

When it comes to modifying and tuning your 6.4 Hemi engine, there are many options available that can help you get more performance out of your engine. From exhaust systems to intakes, cold air kits, camshafts, dyno tuning and more, you can customize the setup of your 6.4 Hemi engine in order to maximize the power output and performance you are looking for.

Exhaust and intake:

Upgrading the exhaust and intake in your 6.4 Hemi is one of the most popular modifications that can be made and can provide a substantial power increase. A high-flow exhaust manifolds system will allow your engine to breathe more efficiently, allowing for increased air flow which results in a boost in power output. Similarly, an upgraded cold air intake kit will further help to improve air flow, resulting in improved power as well.


Installing a performance camshaft or adjusting the timing on your 6.4 Hemi can also provide significant gains in horsepower and torque. Performance camshafts are designed to maximize airflow and valve train function, allowing for more fuel to be efficiently burned and creating more power. Adjusting the timing or installing a performance camshaft should be done in conjunction with dyno tuning, as different combinations of parts can require specific settings for optimal performance.

Forced induction:

Forced induction is another popular option for improving the performance of your 6.4 Hemi engine with oil jets, and can provide significant gains in power. Installing a supercharger or turbocharger will increase air pressure within the cylinders which will result in more fuel being burned efficiently and ultimately create more power than what you would experience from naturally aspirated engines. Again, dyno tuning will be necessary in order to get the most out of your engine.


If you’re looking for even more power, turbocharging your 6.4 Hemi engine is an option that can provide significant gains in horsepower and torque. Installing a turbo kit will significantly increase the airflow into the engine, allowing for more fuel to be efficiently burned and resulting in higher power output.


If you’re looking for even more power than what a turbocharger can provide, then installing a supercharger is the way to go. Superchargers are designed to deliver substantial power increases by increasing air pressure within the cylinders and forcing additional fuel into the engine, resulting in significant horsepower and torque gains.

ECU tuning:

The last major modification you can make to improve the performance of your 6.4 Hemi engine is ECU tuning, also known as dyno tuning. Dyno tuning involves making adjustments to the engine’s computer in order to optimize the air/fuel mixture, spark timing, and other factors in order to maximize power output. This type of tuning is especially important when making modifications such as installing a camshaft or forced induction, as it allows you to take full advantage of the performance gains they provide.

Whether you’re looking for more power or just want to tweak your engine’s setup, modifying and tuning your 6.4 Hemi engine can be a great way to get the performance you’re looking for. 

Common Problems of the 6.4 Hemi

There are some common issues that can arise with the 6.4 Hemi engine, just like any other complex piece of machinery. The most common problems include:

Multi displacement system (MDS) problems:

Due to the complex nature of the MDS system, many issues can arise. These include malfunctioning solenoids, slow or erratic shifts and false activation codes. In extreme cases, it can cause reduced engine performance due to improper deactivation of cylinders. To avoid these issues, it is important to keep up with maintenance and to use only genuine or quality MDS components.

Lifter tick:

This is a common issue that can occur in the 6.4 Hemi engine and its predecessors. The lifters are prone to sticking, which causes them to tick as they try to move within the valvetrain. This ticking sound can quickly become quite loud and irritating, so it's important to address this issue as soon as you can. If the problem is ignored, it will likely worsen from increased friction and wear.

Ignition misfires:

The 6.4 Hemi engine is prone to ignition misfires, which can be difficult to diagnose and repair. Possible causes include worn spark plugs, faulty coils, or vacuum leaks. It's important to check all components of the ignition system in order to properly identify the root cause of a misfire before attempting repairs. Furthermore, misfires can also cause further damage due to increased stress on other components.

These are some of the most common problems associated with the 6.4 Hemi engine, but there are other issues that can arise as well. It's important to stay up-to-date with regular maintenance, engine oil changes, and to diagnose any potential issues as soon as possible in order to avoid further damage or expensive repairs. By taking proper care of your 6.4 Hemi engine, you can ensure that it continues to run smoothly for many years.

Vehicles using the 6.4 Hemi:

Challenger SRT with the 6.4L Hemi

The 6.4 Hemi engine has been used in many different vehicles since its introduction. Some of the most popular applications include:

392 Hemi:

  • Dodge Challenger SRT 392
  • Dodge Durango SRT
  • Chrysler 300 SRT
  • Dodge Charger SRT 392
  • Jeep Wrangler Unlimited Rubicon 392
  • Jeep Grand Cherokee SRT
  • Jeep Grand Wagoneer

392 Apache:

  • Ram 3500 and 2500 Pickup
  • 3500 Mega Cab
  • 3500 DRW Cab Chassis
  • 5500 and 4500 Cab Chassis
  • 3500 SRW Cab Chassis

Frequently Asked Questions

How much horsepower does a 6.4 L Hemi have?

The 6.4 L Hemi engine has a maximum horsepower of 485HP and a peak torque rating of 475 lb-ft.

This engine is also known for its excellent fuel efficiency, with an average fuel economy rating of 19 mpg in city driving and 23 mpg on the highway.

It offers plenty of power with its impressive torque rating, allowing it to easily navigate tough terrain or pull heavy loads with ease.

This engine is a great choice for those who need power, but also want good fuel economy and reliability.

With proper maintenance, this engine will provide many years of reliable service. So if you're looking for a powerful yet efficient engine, the 6.4 L Hemi is definitely worth considering.

Which motor is better: the 5.7 or 6.4 Hemi? 

It ultimately depends on your needs and preferences. The 5.7 Hemi has a displacement of 345 cubic inches and can produce up to 395 horsepower, while the 6.4 can reach up to 480 horsepower with its larger displacement of 392 cubic inches.

Neither bore diameter nor stroke length is similar in these models of the Hemi engine.

If you want an engine with more torque, the 6.4 Hemi is your better choice due to its larger displacement and higher torque output than the 5.7 Hemi.

However, if you want a motor with better fuel economy, then the 5.7 could be a better option as it has lower fuel consumption rates and emissions compared to the 6.4 Hemi.

ls the 6.4 a real Hemi?

The 6.4L HEMI V8 engine produced by the saltillo engine plant which is found in the 2019 Dodge Challenger and other Chrysler vehicles, may not be considered a “real” Hemi engine by true Mopar enthusiasts.

The 6.4L HEMI engine has more displacement than the traditional 5.7L Hemi, but it does not have the same iconic valve configuration or combustion chamber design as the original Hemi.

That said, the 6.4L is a powerful and capable engine with piston cooling jets to remove combustion heat and sodium filled exhaust valves comparable to that of its predecessor — making it an excellent choice for those looking for a strong and reliable engine in their ride.

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