The Top 5 6.4 HEMI Upgrades. The Chrysler 6.4 HEMI engine debuted in the 2011 Dodge Challenger SRT8 with 470 horsepower and 470 pound-feet of torque. It has now been included into many more Chrysler, Dodge, and Jeep cars. Peak output is 485 horsepower and 475 pound-feet of torque. The 392 HEMI is clearly no slouch from the factory. However, there is still plenty of room to extract additional power from the massive 6.4L V8. This post will go through some of the greatest 6.4 HEMI performance improvements, power gains, pricing, and other factors.
392 HEMI Distinctions
Before delving into the meat of this essay, it’s crucial to first go over the 6.4 HEMI’s variants. Chrysler introduced the 392 HEMI in 2005, and it became available as a crate engine in 2007. It produces 525hp and 510 lb-ft of torque and is substantially different from the production 392 HEMI engine. Despite having the same 392 cubic-inch displacement, the two engines share minimal parts.
The 6.4L HEMI is also available in a truck variant. This engine is substantially identical to the normal 6.4L V8 found in the SRT8 and SRT 392 versions. The 6.4 HEMI in Ram pickups, on the other hand, has been retuned for greater MPG and a power band for better towing performance. This engine produces 366-410 horsepower and 429 pound-feet of torque.
Finally, the subjects and 6.4 HEMI enhancements discussed in this post are applicable to both production versions of the engine but not the 392 crate motor. Parts fitment and specific power increases may vary. However, the majority of the information applies to all 6.4L V8 HEMI engines in production.
The Top 5 6.4 HEMI Performance Upgrades
Some of the top Dodge 392 HEMI upgrades include:
- Tune
- Intake
- The throttle body
- Headers
- Cams
This article’s primary focus for 6.4 HEMI mods is the list above. With the exception of cams, these are all easy bolt-on improvements that provide excellent value for money. Cams are more expensive and more difficult to install, but they are possibly the single most powerful mod short of more major upgrades like forced induction.
Anyway, we’ll go over the top 5 greatest 6.4 HEMI performance enhancements in detail in this article. There are also numerous other excellent enhancements for the 6.4L V8. Because there is simply too much to cover in one post, we have whittled it down to the top five mods. Let’s take a look at some other terrific, common mods for the 392 HEMI.
Other 6.4 V8 HEMI Modifications
Again, the upgrades mentioned above are the primary emphasis of this post. However, we will quickly cover a few more 6.4L HEMI power upgrades, such as:
- Induction by coercion
- Manifold for Intake
- Exhaust
We’ll go through each of these upgrades briefly at the end of the post. For good reason, these enhancements didn’t make the top 10, but they’re still fantastic performance tweaks for the 6.4L V8.
Also, keep checking back because we’ll be releasing a number of specific mod tutorials for the 6.4 HEMI where we can go over these mods in greater detail. After that, let’s go into some of the top Dodge 6.4 HEMI improvements.
1) HEMI Tuning 392
While there is no particular order to this list, a tune is likely the single best performance enhancement for the 6.4 HEMI. It’s not only about the increased power from the tune. Tuning is also the foundation for getting the most out of additional mods. When you start adding extra air and fuel, you must properly tune the computer (PCM) to account for the changes.
Adding a tuner to your 392 HEMI V8 provides the following advantages:
- 5-15+whp
- Gains in torque are comparable.
- Increased rewards from extra mods
- improved throttle responsiveness
- MPG improvement
Tuning a stock 6.4L HEMI may only result in power improvements of 5-15whp. A tuner can only extract so much power from a NA engine. Torque improvements should be comparable, and you should notice improved throttle and engine response. Depending on the tune, you may also notice improved fuel economy. However, if you use your newfound power, this is unlikely to be the case.
To flash the 392 HEMI PCM, you will need a tuner device, which will cost between $400 and $600 and will usually include some basic off-the-shelf tunes. Custom tuning the 6.4 HEMI can result in further power improvements, but this can cost another $200-300+. Finally, a tune is an excellent upgrade for the 6.4 HEMI. It’s reasonably priced for the power gains and aids in the performance of other modifications.
Fueling for the 6.4L V8 HEMI
Fueling is a vital aspect of optimizing the 6.4 HEMI. Tuning for higher quality fuels will result in the most power improvements with a 392 HEMI tuner. Most people have simple access to pump fuels such as 91 or 93 octane. However, if you have access to better fuel, you may be able to get even greater power.
Tuning for higher octane race gas will result in more power improvements. E85 is another excellent fueling choice that is available at some gas stations in the United States. However, because E85 requires a lot of fuel flow, you’ll need some additional modifications to run it.
To summarize, tunes provide the greatest power improvements while using higher octane fuels (or E85). Tuning for 91 or 93 octane makes the most sense because it’s the most easily accessible. However, if you’re ready to cope with the inconveniences of better fuel, you can gain even more power by tweaking the 6.4L HEMI.
6.4 HEMI Tuner Cost: $350-600 (+$150-300 for bespoke tuning)
HP Gains with the 6.4 HEMI Tuner: 5-15whp (20-30+whp with racing gas or E85)
2) Upgrades to the Dodge 6.4 HEMI intake system
The Chrysler 6.4 HEMI engine will get cold air intake modifications next. An intake is expected to provide the least impressive power gains on this list. A 392 HEMI cold air intake, on the other hand, made the list for good cause. Intakes are one of the most affordable performance tweaks, and they’re relatively simple to install.
Expect little horsepower from a lightly altered engine (i.e. tune only). However, if you add additional improvements and power, intakes can provide significant power boosts. Among the advantages of 6.4 HEMI intake improvements are:
- 3-7+whp
- Gains in torque are comparable.
- enhanced throttle response
- Increased engine/exhaust note
For the desired power output, the stock 6.4 HEMI intake flows fairly well. As a result, an intake alone is unlikely to produce much power. However, as you begin to add upgrades such as a tune, headers, cams, and so on, it’s critical to have a better flowing intake. This is where you may expect to see 5-7+ horsepower improvements from a cold air intake.
An intake can also help wake up the engine and improve the sound of the 6.4L HEMI’s exhaust. It won’t be as severe as exhaust or header modifications, but it’s still a great bonus of intakes. We also believe that intake enhancements significantly improve the appearance of the engine bay. More information about cold air intakes can be found in our 6.4 HEMI intake article.
Price of Intake Upgrade: $200-400
HP Gains with 6.4 HEMI Intake: 3-7+whp
3) 6.4L V8 HEMI Throttle Body Modifications
Again, there is no particular order to this list of the greatest 6.4 HEMI performance enhancements. The throttle body (TB) is possibly the most debatable item on this list. Some argue that upgrading the 392 HEMI TB makes no sense unless you’re going with forced induction. An improved throttle body, on the other hand, can be a terrific, economical, and straightforward mod.
If you decide to upgrade, the Fastman throttle bodies are an excellent choice. They use brand new throttle bodies, which cost between $192 and 210 for the 6.4L V8. Fastman charges $250 for the TB changes, plus $12 for shipping, for a total cost of slightly over $450. The following are some of the advantages of a 6.4 HEMI throttle body:
- 3-10whp
- 3-10wtq (far higher on the low end)
- improved throttle responsiveness
The peak power improvements from a throttle body modification aren’t particularly appealing. Gains on a bone stock car will be at the lower end of the spectrum. With the rest of the upgrades, such as cams, headers, and tune, you may gain 5-10whp peak. Throttle responsiveness and instant torque are significantly improved with throttle body modifications.
We believe it is better to save the throttle body for a later mod. It’s typically a good mod to pair with intake manifold porting, which we cover in the “other mods” section below. However, upgrading the 6.4 HEMI TB sooner cannot hurt. At less than $500, it’s a reasonably priced mod that’s also simple to install.
Price for 6.4L V8 Throttle Body: $300-500
Power Gains: 3-10whp for 6.4 HEMI TB
4) 392 HEMI Headers Upgraded
Because there are so many different alternatives for headers (also known as the exhaust manifold), this is a big topic. Just a few of the major headings issues include long-tube, shorty, catless, and high-flow cats. We’ll do our best to summarize and get all of the information in the limited space available here. However, we also prepared a comprehensive 6.4 HEMI headers guide, so be sure to read that for all the details on header upgrades.
In any case, headers provide some of the best power improvements for the 6.4L V8 HEMI, and if you’re seeking to construct a strong 392 HEMI, headers should be near the top of your mod list. The primary purpose of headers is to increase exhaust gas flow while decreasing back pressure. Because it mounts directly to the engine, the exhaust manifold provides the greatest gains of any portion of the exhaust system.
The following are some of the advantages of upgrading 6.4 HEMI headers:
- 10-30+whp
- 10-30+wtq
- Exhaust sounds that be louder and more forceful
The peak horsepower gains are substantial on their own. But it doesn’t stop there. It is not always true that headers sacrifice low-end torque for top-end power. In fact, a well-designed set of long-tube headers can provide significant increases over the whole power spectrum.
On lightly altered 392 HEMI engines, expect to gain 10-20whp. Headers can give even more remarkable improvements of 20-30whp with the entire set of bolt-on upgrades. Headers also significantly improve the sound of the 6.4 HEMI. Another advantage, in addition to the significant performance gains from a set of headers.
Catless versus High-Flow Headers on a Dodge 6.4L V8
The OEM catalytic converters on the 6.4L Mopar engine will be removed with a set of long-tube headers. In general, fully catless headers provide the best top-end performance. Catless headers, on the other hand, are theoretically banned in all states and are unlikely to pass any type of emissions testing.
This is where headers with high-flow cats can help. With a high-flow option, you’ll still experience substantial power gains and your 6.4 HEMI should pass emissions testing. Because catalytic converters are pricey, high-flow headers are frequently $300-500 more expensive than catless versions.
As an aside, shorty headers will keep the OEM cats. Shorty headers, on the other hand, do not provide the same level of performance increases as long-tube choices. With a solid pair of 6.4 HEMI shorty headers, expect to get 5-15whp. The good news is that shorty headers are significantly less expensive, so it may be a decent option if you want something simple.
Cost of 392 HEMI Headers: $400-1,500+
HP Gains on 392 HEMI Headers: 10-30+whp
5) 6.4 HEMI Camshaft Improvements
Last but not least, there are cam improvements for the 6.4L Mopar engine. Cams are the most expensive and complicated improvement on the list, but for good cause. Cam upgrades, like headers, have a lot to unpack and discuss. We plan to create an in-depth guide for 6.4 HEMI cam upgrades in the near future.
With camshafts, there are numerous critical parameters to consider, including duration, lobe size, overlap, and valve lift. All of these variables can have a significant impact on performance and power gains. It’s simply too much information to cover in a single section on 392 HEMI cams.
The following are some of the advantages of camshaft upgrades for the 6.4L V8:
- Massive power improvements of 30-60+whp
- 20-40+wtq
- Fantastic sounds
On the 6.4L HEMI, a good set of camshafts can produce astounding 30-60whp improvements. Without adding more expensive and sophisticated tweaks like a supercharger, that’s about as good as it gets. With the correct cam changes, torque increases are also impressive. Exact gains will vary, and some cams may trade low-end torque for greater top-end performance. Cams sound fantastic on the 392 HEMI, in our view.
Cost of 6.4L V8 Camshaft Upgrade
The major disadvantage of cams is their high cost and complexity. Most novice DIYers may easily complete upgrades such as an intake, tune, throttle body, and so on. Cams are a completely separate story, therefore you may need to visit a store for installation. Even an experienced mechanic may need 10-15 hours.
A set of 6.4 HEMI improved cams can cost between $500 and $2,000. If you only want the cams, you’ll be at the lower end of the price range. However, it’s a good idea to do it well and acquire a whole package that includes valve springs, seats, retainers, pushrods, and so on. This is where you’ll end up spending more than $1,500.
If you hire a shop to conduct the work, you’ll most likely spend another $1,000-2,000. If you don’t perform the work yourself, changing the 392 HEMI cams can easily cost between $2,500 and $4,000.
Cost of 6.4 HEMI Cam: $500-2,000 (+ $1,000-2,000 for installation)
HP Gains for 6.4 HEMI Cam: 30-60whp
Other 392 HEMI Performance Modifications
With the major changes out of the way, let’s move on to some honorable mentions. We feel that the 6.4 HEMI performance enhancements listed above provide the best balance of price, power gains, and simplicity. However, there are plenty other excellent mods for the 6.4L V8. This is by no means a full list, but these are some of the runners-up.
1. HEMI Forced Induction 6.4
The most significant increases for the 6.4 HEMI may be found with superchargers and turbos. With forced induction, the 6.4 HEMI can produce 1,000+whp. There are also “modest” setups for more modest 600whp, 700whp, and so on constructions. Ultimately, regardless of your aims, forced induction is the way to construct a crazy 6.4 HEMI.
This has the potential to be one of the greatest 6.4 HEMI upgrades. When it comes to superchargers and turbo packages, though, there is a lot to cover. There are also numerous more factors to consider, such as internal engine changes, fueling modifications, and so on.
It’s a costly route to take, and there are far too many elements to cover in one post. Both are valid reasons why superchargers and turbos did not make the list of top 392 HEMI upgrades.
Related : The 6.4 HEMI Intake Upgrade Instructions
2. Upgrades to the Dodge 392 HEMI Intake Manifold
Another amazing mod for the 6.4L HEMI that might have easily made the list is intake manifold enhancements. Simply porting the existing 392 HEMI manifold is the most typical improvement. Gains from porting are typically in the 5-10whp range.
The stock manifold may be ported for $400-600. The disadvantage is that you’ll almost certainly need to send in your manifold ahead of time, which means your 6.4 HEMI will be out of operation for a bit. Some shops sell new ported intake manifolds, but they cost an extra $400-500.
Finally, porting the 392 HEMI manifold is a fantastic enhancement. We still believe the top 5 upgrades are a better starting point and would save the intake manifold until the rest is done.
3. Exhaust Upgrades for the 6.4L V8
Another upgrade that may easily have reached the top 392 HEMI performance upgrades list. The possibilities for exhaust enhancements are limitless. We separated headers into their own category because they provide the most power improvements from the exhaust system.
Looking at the rest of the exhaust from the headers back, you’re unlikely to notice any significant power gains. It is still feasible to gain an additional 3-7whp. However, these are minor advantages as compared to a collection of headers.
If you want a louder, more aggressive exhaust noise, modifying the rest of the exhaust is a good option. The little power increases are only a bonus. However, if all you want is horsepower, there are better places to spend your money.
Summary of HEMI Performance Upgrades
The 6.4 HEMI is a fantastic engine that gives excellent performance right out of the box. The huge 6.4L V8 engine, on the other hand, offers a lot of untapped potential. A few upgrades can really liven up the Mopar engine and push things forward.
A tune and intake are excellent places to start when customizing the 392 HEMI. Headers and camshafts are more expensive and complicated, but they provide significant power improvements. Upgraded throttle bodies, intake manifolds, and exhaust systems are also excellent choices. Of course, forced induction has enormous promise, but it comes at a high cost and with other hazards and issues.
Finally, the five finest enhancements covered in this post can boost the 6.4 HEMI to 500whp or higher. That’s an astounding performance for a normally aspirated engine. With better feeding and a few minor modifications, 525+whp isn’t an impossible aim.
