6.4 Intake Manifold On A 5.7 HEMI: What Gains Can You Expect?

As with most decisions in life, there are pros and cons to swapping out the 5.7 HEMI intake manifold for one designed to work on the 6.4 HEMI. So before we dig into any expected gains, let's discuss the elephant in the room: how much is it going to cost? We explored three options for 6.4 HEMI intake manifold swap kit pricing, Moe's Performance, Modern Muscle Xtreme, and Street Driven Performance. Prices start at about $1,600 from Moe's Performance and Modern Muscle Xtreme (MMX) and just north of $2,000 from Street Driven Performance for the complete, ported 6.4 HEMI intake manifold, SRV controller, and wire harness extension.

Moe's Performance advertises gains of 29 horsepower and 16 lb-ft of torque at the wheels from the intake manifold swap. However, in addition to the intake swap, Moe's results came from a 5.7 HEMI equipped with a more aggressive cam and long-tube headers.

Tallguyinahemi questioned whether the swap was worthwhile on his YouTube channel. In the video, he estimates a 5 to 15 horsepower gain from the 6.4 HEMI intake swap, but notes the most significant gains are for low-end torque. YouTuber Neverenuff achieved a seven-horsepower gain from a 5.7 HEMI-powered 2015 Dodge Charger using an 89 octane tune when swapping to the 6.4 HEMI but saw a 20 lb-ft of torque boost.

Keep in mind, the $1,600 kits listed above are good starting points, but you'll need more parts to complete the job. For example, the Street Driven Performance kit is more expensive because it includes manifold gaskets, PCV hose and valve, injector O-rings, and a MAP sensor bracket. We included the optional intake manifold runner porting in all the prices, but you could save around $400 by porting it yourself or skipping it.

The 6.4 HEMI intake's biggest advantage over older 5.7 HEMIs is its active runner system. The older 5.7 HEMI intake runner length is a compromise between horsepower and torque. However, the 6.4's active runners use valves that open and close to alter the runner length for the best performance based on engine demand.

At the end of the day, doing the intake manifold swap is cheaper than completely swapping a 6.4 HEMI in place of a 5.7 HEMI, but you're going to need to pay for a tuner to get it running right either way.

If you've only got two grand to spend on making your 5.7 HEMI car or truck more powerful there are better ways to spend your money in the beginning. While swapping the intake manifold alone could give a modest power increase, its potential unlocks when combined with other upgrades. So, after forking out the cash for long-tube headers, a better camshaft, cold air intake, and a quality tuner, you'll have to ask yourself if gaining another 20-ish horsepower and lb-ft of torque is worth $2K.

Most likely, if your DIY skills are up to changing spark plugs on your HEMI, you'll be able to swap the intake manifold with enough research into the subject. If you've never pulled an intake manifold off an engine, you'll want to shop around for a kit supplier that isn't above answering your questions. The intakes they supply are similar enough that they should be willing to earn your business with customer service. If you can't get them on the phone to take your money, getting them to answer questions after the sale will be more difficult.

Other than a tuner, like the Diablosport Intune I3 Platinum from Amazon for example, all that's needed is a rather simple mechanic's tool kit found in most DIY home garages. However, the project could require more than turning wrenches, splicing some electrical connections, and plugging in a tuner. You could also have an opportunity to do some modest fabrication, especially around the airbox, if you're interested in saving a few bucks while putting a personal touch on the finished project.