Dodge 6.4 HEMI vs 5.7 HEMI

The Chrysler/Dodge/Ram 5.7L and 6.4L HEMI engines power similar cars and trucks. This makes the comparison common as many wonder which engine is the best fit. Ultimately, 6.4 and 5.7 HEMI engines likely both have plenty to offer for most owners. With two great engine options it can be hard to pull the trigger but worry not. In this guide, we compare 6.4 vs 5.7 HEMI engine specs, reliability, performance, price, and more.

*5.7L and 6.4L HEMI engines are also known as the 345 HEMI and 392 HEMI, respectively. These numbers represent the engines displacement in cubic inches. We may refer to the engines by these names in this article.

Dodge HEMI Engine Specs

Below is a chart showing specs for the 5.7 vs 6.4 HEMI V8 engines:

Specs for the 5.7 and 6.4 HEMI engine are pretty straight-forward. They share many things in common especially when looking at similar year engines. Anyway, both share their V8 HEMI pushrod design with 2 valves per cylinder. 345 HEMI and 392 HEMI engines also both use cast iron blocks with aluminum heads.

We’ll avoid spoiling all of the details regarding horsepower and torque for now. Of course, the 6.4 HEMI is the more capable engine. Its larger displacement and output give it the edge. There is more to look at regarding 5.7 vs 6.4 HEMI power and torque curves. This topic will come up in a few sections when we discuss performance.

*2009+ 5.7 HEMI engines went through a fairly big update. MDS and variable valve timing were two of the major updates. 6.4 HEMI engines use this technology, too. Point is – the older 345 HEMI’s are a bit different since they lack this tech.

What Cars Use These Engines?

6.4 vs 5.7 HEMI engines are in the following years and models:

As shown above – the 5.7 HEMI is an engine option in a few models that do not offer the 6.4L engine. It’s also the older engine dating back to 2003 while the 6.4 HEMI didn’t come out until 2011. However, Chrysler did offer the 6.4L since 2007 as a crate engine with the name 392 HEMI.

Anyway, the common them is that the 5.7 is a base engine in many models with the R/T badge. On the other hand, 6.4 HEMI engines often receive the SRT8, SRT, and 392 Scat Pack designations.

5.7 vs 6.4 HEMI V8 Performance

Writing engine comparison guides can be challenging. Most engines are found in various models and years – as with these two HEMI engines. The following theme will apply to much of this article: it’s tough to get specific on a model and year basis. As such, we won’t be diving into 0-60, 1/4 mile times, or other specific performance factors.

There is still plenty to talk about when it comes to 6.4 vs 5.7 HEMI performance, though. The 6.4 HEMI generally offers an extra 75-100 horsepower over the 5.7 engine. Thanks to larger displacement the 392 is also good for an extra 60-80 lb-ft. Low-end torque is also about 70 lb-ft more than the 5.7 further widening the gap between the two. However, power and torque are a smaller difference on Ram trucks as the 392 truck version is tuned for better economy and towing.

There’s no replacement for displacement. Clearly, this saying holds true in the 5.7 vs 6.4 HEMI comparison. These engines share similar design and tech, and the larger displacement HEMI simply has the edge. That’s not to say the 5.7L V8 is a slouch by any means. Rather, if you’re looking for all-out performance or towing then the 6.4 HEMI is the clear pick.

Winner: 6.4L HEMI

Aftermarket Potential

Bear with a few duplicate comments here as it’s the same concept as above. Larger displacement takes the win when it comes to tuning, modding, and aftermarket performance potential. If power and performance are the end goal the Dodge 6.4L V8 is our pick.

We looked at similar mileage 2016 Dodge R/T Challengers with the 5.7 HEMI vs the 6.4 HEMI R/T Scat Pack. The difference in price ranges from about $5,000 to $10,000 with the 392 HEMI the more expensive option (as you likely guessed).

Buy a 345 HEMI, use the left over money on upgrades, and you can certainly end up with the more powerful engine. Now, it’s fair to point out some of the many counter arguments here. Add the same mods to a 6.4L V8 and it will be more powerful. Also, no matter how many upgrades you add to the 5.7 HEMI it will never be the 6.4L.

Aside from all of that – both of these engines have plenty of aftermarket support. It’s not hard to find what you’re looking for whether you choose the 345 or 392 engine. Don’t miss out on our best 5.7 HEMI upgrades and 6.4 HEMI upgrade guides if you’re looking for more info.

Winner: 6.4 HEMI

Dodge 6.4 vs 5.7 HEMI Reliability

Reliability is an easy subject for me to discuss. I wrote in-depth articles about reliability and common engine problems for each engine; the links are just below in the next section for those wanting to learn more. In this article we’ll just scrape the surface and discuss some of the basics.

The 6.4 and 5.7 HEMI both offer good reliability overall. As with any engine, they’re prone to their share of problems and failures. We think both engines deserve average to above average remarks for reliability. Don’t expect Honda or Toyota-like maintenance and repairs, though.

Keep in mind we’re talking about performance engines. Repairs tend to be a bit more expensive when problems do occur. Basic maintenance items can also be pricier.

Which one is better, though? It’s impossible to say for sure. It’s likely the 6.4 HEMI vs 5.7 HEMI will offer similar reliability. Most of it simply comes down to maintenance and luck of the draw. Some 6.4L engines hold up beyond 300,000 miles while others die much sooner. The same can be said for the Dodge 345 too.

Winner: Tie

Engine Problems

Issues between the two engines are pretty similar. Keep in mind – problems may appear worse or more common on the 5.7L V8. It’s the older and more popular engine on the road. As such, there’s more info out there for the 5.7 HEMI which can make problems seem more widespread. On the contrary, there are more high mileage 345’s out there.

Ultimately, both engines share many of the same common problems – such as the HEMI Multi-Displacement System (MDS). As stated previously, these engines offer similar reliability and which one is better often comes down to maintenance and some luck of the draw. Anyway, check out the below articles for more information on some common engine problems:

345 HEMI Engine Problems

392 HEMI Engine Problems

5.7 vs 6.4 Hemi Price

In the section about aftermarket performance we touched on 5.7 vs 6.4 HEMI price briefly. The price difference when looking at similar model, trim, age, mileage, etc remains around the $5,000 to $10,000 mark. It doesn’t always hold true since there can be other factors that affect price. Regardless, the 5.7 HEMI is generally the cheaper option.

Additionally, 5.7 HEMI engines have been around since 2003. There isn’t a way to make a fair comparison with the 6.4L V8 in this case. It just means the 5.7 is the budget friendly option even if it means buying an older car. The age and higher production also do the 345 HEMI favors when it comes to parts, replacement engines, so on.

Winner: 5.7 HEMI

345 vs 392 HEMI Fuel Economy/MPG

This is a pretty quick topic since it’s impossible to get extremely specific. 5.7 vs 6.4 HEMI fuel economy depends on many individual factors. Year, model, drivetrain, conditions, driving habit, etc all play major roles. That said, the 5.7 HEMI engine will deliver better fuel economy if all else is equal.

There are situations where the 6.4 HEMI actually provides better MPG than the 5.7L engine, though. Does the Dodge car or truck have MDS technology? Some Dodge 5.7 HEMI engines have this tech while others do not. A 392 equipped with MDS vs a 345 without MDS is a different story.

Nonetheless, we could go on all day debating which engine in which configuration provides better fuel economy. However, the point remains. The smaller 345 cubic inch engine should deliver better MPG – all else equal.

Winner: 5.7 HEMI

Towing Capacity

Vague concepts continue when it comes to 6.4 vs 5.7 HEMI towing capacity. There are too many configurations that affect towing as much or more than the specific engine. Anyway, you guessed it. Dodge 6.4 HEMI’s are the better option when it comes to towing.

Not only does it offer more power and torque, but it’s also better tuned for towing. Low-end torque is a big improvement on the 392 cubic inch engine. It’s generally going to offer the most towing capacity and pull similar weights with more ease. Although, the 5.7 V8 isn’t a slouch and may be more than enough for many.

Winner: 6.4 HEMI

Dodge 345 vs 392 HEMI Summary

Chrysler, Dodge, and Ram offer the 6.4L and 5.7L HEMI engines in many similar models. The engines also share similar design and technology. It makes for a common discussion and comparison between the two. Picking the right engine for you can also be complicated since both engines have plenty to offer.

The saying, “there’s no replacement for displacement” holds true here. Dodge 6.4 V8 HEMI engines simply offer more performance and towing vs the 5.7 HEMI. The 5.7 HEMI takes the win for price, parts availability, and fuel economy. They’re both pretty reliable engines, so that’s a wash.

In summary, if all-out performance or towing capacity is your goal then the 6.4 HEMI is likely the best choice. Those who want a great overall balance of performance, MPG, towing, and price will find joy in the 5.7L V8. Either way, we believe it’s hard to go wrong with the 345 or 392 HEMI engines.

What’s your experience with these engines? Are you considering one?

Leave a comment and let us know!