392 Cam in the 2015 5.7 Hemi R/T: The Complete VVT Parts List

ByKenji Alvarez

Why the 392 Cam Works in a 5.7 — and What the 2015 Changes

The stock 5.7L in a 2015 Challenger R/T makes 375 horsepower at the crank. Swap in a 6.4L 392 camshaft with a proper tune and community dyno results show gains of 20 to 50 rear-wheel horsepower depending on supporting mods. The swap is popular because the 5.7L and 6.4L share the same Gen III Hemi block platform. But the 2015 R/T is a VVT car, and that changes the parts list compared to the older builds most forum threads were written around.

The “Eagle” Engine — What That Actually Means

The 2015 5.7L runs Chrysler’s Eagle cylinder head configuration, introduced for model year 2009. That update added Variable Valve Timing (VVT), raised compression to 10.5:1, and reworked the intake and exhaust ports for better airflow. The 5.7L has run on this same basic architecture ever since, which is why “it’s still the same Eagle engine” is essentially correct. The catch is that the Eagle platform is the VVT platform — not the simpler pre-2009 fixed-cam setup that most of the early 392 cam thread guides were written for.

The 6.4L Apache 392, introduced in 2011, shares the same Gen III block with compatible bore spacing, lifter bores, and cam journal dimensions. That mechanical compatibility is why the 392 cam drops into a 5.7L at all.

Parts List for the 2015 VVT Build

The Camshaft

There are two factory 392 cam variants, and they matter. The cam from an automatic-transmission 6.4L is MDS-compatible. The cam from a manual-trans 6.4L is not. A 2015 R/T with the 8HP70 eight-speed has MDS active from the factory. If you want to keep MDS working, you need the MDS-compatible 392 cam. Pulling from a junkyard 6.4L without confirming the transmission type can get you the wrong one — they look identical on the bench.

Valve Springs

Not optional. The 392 cam has more lift than the stock 5.7L grind, and factory 5.7L valve springs are marginal at that lift. Running them risks valve float and accelerated wear. New springs, retainers, and shims are part of the deal. Most quality cam kits for this application bundle these in.

VVT Phaser Limiter

This is the part that older build threads skip — because pre-2009 5.7L engines had no phaser. The 2015 engine has a cam phaser that advances and retards cam timing dynamically based on ECU commands delivered via oil pressure. Without a phaser limiter, the phaser can move the cam into positions outside the range the cam profile and tune were designed for. A phaser limiter mechanically restricts that travel. Most VVT-compatible cam kits include one, but it’s worth confirming before you order.

Engine Tune

Non-negotiable. The ECU manages fuel delivery, spark timing, cam phaser position, and MDS activation cycles. None of those calibrations are correct for the new cam profile out of the box. HP Tuners and EFI Live are the standard platforms for this engine; a custom dyno tune on 93 octane is the right way to close the loop. Running the 392 cam without a tune risks detonation and incorrect VVT behavior — and leaves a significant portion of the potential gains on the table.

What You Can Leave Alone

If you’re using an MDS-compatible 392 cam, the factory lifters stay. The pushrods in the 5.7L and 6.4L are the same length, so those don’t need replacing if they’re in good shape. Many builders swap to chromoly pushrods during the job since the top end is already apart, but it is not a hard requirement for a street build.

Deleting MDS changes things. A non-MDS cam — either the manual-trans 392 variant or an aftermarket grind with an MDS delete — requires swapping the entire lifter set to solid non-MDS units. More labor, more parts, and a more involved tune.

Transmission Consideration for the 2015

The 8HP70 eight-speed in the 2015 R/T communicates with the engine ECU. After a cam swap and engine tune, some owners find the transmission hunting for gears or short-shifting because the shift map was calibrated around the stock torque curve. It does not always happen. But if the 8-speed starts behaving strangely after the engine tune, a transmission tune is the next step — not a coincidence.

What the Power Feels Like

The 392 cam is not an aggressive grind. It is widely considered the tamest first cam upgrade on the 5.7L, partly because it keeps MDS intact and sits within a compression ratio the stock engine handles without drama. The character shift is toward the low and mid range — noticeably more torque from around 2,500 RPM up. The car feels stronger on the street before the peak numbers move much. For a daily-driven R/T that still sees the occasional wide-open run, that is the right kind of gain.

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