Cost Breakdown: Building a 6.4 Hemi with a Performance Cam and Supporting Mods for Under $3,000

Cost Breakdown: Building a 6.4 HEMI with a Performance Cam and Supporting Mods for Under $3,000

The 6.4-liter HEMI – also known as the 392 – is a powerhouse straight from the factory, but even this 485-hp monster leaves room for more. A performance camshaft paired with the right supporting mods can unlock substantial gains in horsepower and torque, all while keeping your budget south of $3,000. This guide breaks down every dollar, explains the tech behind each part, and shows you how to get the biggest bang for your buck without cutting corners on quality.

Understanding the 6.4 HEMI (392) Engine

Before spending a cent, it pays to know what you’re working with. The 6.4 HEMI, officially designated the 392 HEMI, is a cast-iron block, aluminum-headed V8 used in the Dodge Challenger, Charger, and Jeep Grand Cherokee SRT. Its stock specifications are impressive:

• Displacement: 6.4 L (392 cubic inches)
• Horsepower: 485 hp (SRT versions) to 525 hp (Hellcat variants, but those are supercharged – our focus is the normally aspirated 392)
• Torque: 470 lb-ft (peak at around 4,400 rpm)
• Compression Ratio: 10.9:1
• Valvetrain: Pushrod, two valves per cylinder, variable valve timing (VVT) on intake cam

The factory camshaft is a compromise – smooth idle, good low-end torque, and reasonable emissions. But the heads flow well, and the short-block is stout enough to handle 600+ hp. That means a cam swap is the single biggest NA power adder you can do.

Performance Camshaft Selection: The Heart of Your Build

Choosing the right cam is critical. You want aggressive enough to make power, but not so radical that you lose street manners or need expensive valvetrain upgrades. For a $3,000 budget, stick with a “stage 2” or mild “stage 3” hydraulic roller cam designed for the 6.4 with VVT lockout or VVT phaser limiter options.

Camshaft Options Under $800

• Brand A – Sport Cam (Part #ABC) – 215/223 duration at 0.050”, .551” / .551” lift, 113 LSA. Street friendly, strong mid-range, good with stock converter. $600
• Brand B – Stage 2 NA Cam – 226/234 duration, .600” lift, 112 LSA. Needs valve spring upgrade and tune. $750
• Brand C – High-Lift Street/Strip Cam – 230/236 duration, .620” lift, 111 LSA – aggressive idle, requires more supporting mods but big top-end power. $700

Pro tip: The 6.4 HEMI uses a unique cam gear for the VVT phaser. If you delete VVT (common for max power), you’ll need a VVT lockout kit (~$50) or a new non-VVT timing chain kit (~$150). Factor that into your cam cost.

External resource: Summit Racing – 6.4 HEMI camshafts

Required Supporting Mods (Without Breaking the Bank)

A cam alone won’t do much if the engine can’t breathe or handle the extra lift. These supporting mods are not optional for a reliable, powerful build:

Valve Springs & Retainers

Stock springs will coil-bind with cam lifts above ~.550”. Plan on spending $200–$300 for a PAC, PSI, or Mopar spring kit with steel or titanium retainers. Do not skip this – valve float destroys engines.

Pushrods

Cam swap usually changes length. A pushrod length checker and new set of .080” wall pushrods: $100–$150.

Timing Chain & Phaser Limiter

Stock chain is fine for moderate cams, but a cloyes adjustable timing set ($200) lets you degree the cam. Add a VVT phaser limiter plate ($40) if you keep VVT function.

Cold Air Intake

A cold air intake is cheap horsepower. Expect $200–$350 for a K&N, aFe, or Mopar Performance intake. We’ll budget $300.

External resource: K&N cold air intakes for 6.4 HEMI

Long-Tube Headers

Factory exhaust manifolds choke a cammed 392. Long-tube headers (1-7/8 or 2” primary) are the way to go. Budget $500 for a set of American Racing Headers, TTi, or JBA stainless headers. These will drop right into most Challenger/Charger SRT chassis.

Fuel Injectors

Stock injectors (39 lb/hr) can handle up to about 520 hp. A cammed 6.4 often pushes 530–550 hp at the crank, so upgraded 52–60 lb/hr injectors ($250–$350) are wise. We’ll allocate $300.

ECU Tune (HP Tuners or Custom)

Absolutely mandatory. A custom dyno tune via HP Tuners or DiabloSport runs about $400–$500. Remote tuning by a well-known shop like HHP or Flying Mopar can be $350–$400. Budget $400.

Complete Cost Breakdown Summary

Here’s a realistic budget that keeps you under $3,000 while using quality parts:

Component	Estimated Cost
Performance Camshaft	$650 (average)
Valve Springs & Retainers	$250
Pushrods	$125
Timing Chain Set (VVT lockout or adjustable)	$150
Cold Air Intake	$300
Long-Tube Headers	$500
Upgraded Fuel Injectors (52 lb/hr)	$300
ECU Tune	$400
Gaskets & Consumables (head gaskets, coolant, oil, RTV)	$100
Total	$2,775

This leaves you $225 under the $3,000 cap – enough for a few extra tools or an oil catch can.

Installation Considerations: DIY vs. Shop

If you’re mechanically experienced and have basic engine-building tools (torque wrench, degre beater, cam bearings tool optional), a DIY cam swap is totally doable in a weekend. Expect 12–16 hours of labor. The 6.4 HEMI requires removing the intake manifold, cylinder heads? No – you can swap pushrod cams without removing heads. But you must remove the timing cover, oil pan (recommended but not always required), and take care with the exhaust manifolds if headers are added later.

Professional installation of cam and moderate supporting mods typically runs $1,200–$1,800. That would blow your budget. So this build is squarely aimed at the DIY crowd. If you must pay a shop, consider doing the cam and tune only (no headers) to stay under $3k total, then add headers later.

External resource: Hot Rod – HEMI Cam Swap Guide

Power Expectations After the Build

With these mods on a healthy 6.4 HEMI, you can expect 550–580 hp at the flywheel (or 465–490 hp at the wheels through an automatic). That’s a gain of 65–95 hp over stock. Torque will climb to around 510 lb-ft at the crank, with a much broader curve. The idle will have a distinct lope, and the car will pull hard to 6200+ rpm.

If you skip headers and injectors, you’ll still see 520–540 hp, but the budget-friendly approach outlined above gives you the full package.

Potential Pitfalls & How to Avoid Them

• Valve Spring Coil Bind: Always check installed height. Use the recommended spring kit from your cam manufacturer.
• VVT Phaser Issues: If you retain VVT, the factory phaser can be damaged by high spring pressures. Consider a phaser limiter or VVT delete.
• Piston-to-Valve Clearance: A .600”+ lift cam on a 10.9:1 piston needs checking. Use clay to verify. If tight, you may need fly-cut pistons (but that’s expensive – avoid cams over .630” lift on stock pistons).
• Oil Starvation During Cam Swap: The hydraulic lifters must be bled properly. Soak them in oil before installation.
• Tuning: Do not start the engine without a tune. Running a cammed HEMI on stock calibration will cause lean misfires and potential engine damage.

Tools You’ll Need (If DIY)

• Torque wrenches (ft-lb and in-lb)
• Camshaft degree kit (optional but recommended)
• Pushrod length checker
• Valve spring compressor (on-head style)
• Timing chain tool
• Engine stand or good jack stands
• Gasket scraper and cleaning supplies

Final Thoughts: Is $3,000 Enough?

Yes, absolutely. By focusing on the cam and the supporting parts that directly enable it – springs, pushrods, tune – you can build a noticeably faster, more aggressive 6.4 HEMI for well under three grand. The key is to buy smart: skip expensive brand names where cheaper alternatives (like reputable brand cams from Summit/Jegs) offer identical performance. And do the labor yourself.

This build is perfect for anyone who wants significant NA power gains without delving into ported heads, stroker kits, or forced induction. With proper installation and tuning, your 6.4 HEMI will sound like a muscle car should and perform like one too – all while leaving your wallet intact.

External resource: Mopar Performance – Official 6.4 HEMI Parts