Finding the best spark plugs for 6.4 HEMI Charger models is more complicated than choosing a well-known brand. The correct plug must match your Charger’s model year, 6.4L engine specifications, factory heat range, thread reach, seat design, and required gap.
Installing an incorrect plug can contribute to hard starting, unstable idle, hesitation, misfire codes, or inconsistent performance. A plug with the wrong reach or heat range can create more serious problems, even when it threads into the cylinder head without resistance.
Don’t have time to read every review? The NGK 97408 LZTR6AP11EG Laser Platinum Spark Plugs are my top overall recommendation for compatible stock 6.4L HEMI Chargers.
NGK designed this Laser Platinum plug for OE-style ignition performance and extended durability. It is also cross-referenced with Mopar part number SP149212AC, which Mopar lists for multiple Charger 6.4L applications. The linked package contains eight plugs, so you will normally need two packages for a complete 16-plug replacement.
To simplify your decision, I compared three options based on fitment, electrode construction, package quantity, durability, installation requirements, and value. This article primarily covers naturally aspirated Dodge Charger 6.4L/392 HEMI models, including compatible SRT8, SRT 392, and Scat Pack applications.
Before ordering, confirm the model year, VIN, engine, and currently installed spark plug number. A 6.2L supercharged Hellcat or 5.7L R/T should not be assumed to use the same plugs as a naturally aspirated 6.4L HEMI.
3 Best Spark Plugs for 6.4 HEMI Charger
| Image | Product Name | Check Price |
|---|---|---|
Best Choice | NGK Laser Platinum Spark Plugs – Best Overall | Check Price |
Second Best | Mopar 16-Piece Spark Plug Set – Best OEM Replacement | Check Price |
Third Choice | Champion Platinum 16-Piece Spark Plug Set – Best Budget Alternative | Check Price |
1. NGK Laser Platinum Spark Plugs – Best Overall
The NGK 97408 LZTR6AP11EG is my first choice for a compatible stock Dodge Charger 6.4L HEMI. It offers OE-style specifications, a recognized cross-reference with the Mopar factory part number, and a design focused on dependable everyday ignition rather than exaggerated performance claims.
NGK uses a Laser Platinum configuration with platinum at both firing surfaces. The fine center electrode helps the plug produce a consistent spark, while the platinum ground-electrode surface is designed to resist gap erosion over an extended service period.
That combination is appropriate for a Charger driven regularly on the street. It supports dependable cold starts, stable idle, and consistent combustion without requiring the frequent replacement associated with some basic conventional plugs.
The NGK stock number is 97408, while the plug designation is LZTR6AP11EG. Available specification data lists an M14 x 1.25 thread, tapered seat, approximately 25 mm reach, and a preset gap of 0.044 inch. Treat that gap as a reference rather than permission to skip verification. Check each plug against the service information for your exact vehicle before installation.
This product also provides a clear OE cross-reference. Mopar SP149212AC is cross-referenced with NGK 97408/LZTR6AP11EG, making it a sensible alternative for owners who want the underlying plug specification without necessarily purchasing Mopar-branded packaging.
The linked package contains eight spark plugs. Since the 6.4L HEMI requires 16, you will generally need two packages for a complete replacement. That makes the checkout price appear lower than a full 16-piece set, so calculate the cost of both packages before comparing it with other options.
These plugs are best suited to a stock or lightly modified naturally aspirated Charger. They should not be treated as a universal solution for boosted builds. Higher cylinder pressure may call for a different heat range or gap selected by the tuner.
Do not expect new plugs to add substantial horsepower to a healthy engine. Their benefit is restoring reliable ignition when existing plugs are worn, fouled, damaged, or due for scheduled replacement.
Pros: OE-style Laser Platinum construction, established Mopar cross-reference, dependable service life, stable ignition characteristics, and correct dual-plug application availability.
Cons: The linked package contains only eight plugs, two packages are normally required, and it is not a custom solution for forced-induction engines.
My Verdict: The NGK 97408 is the strongest overall option for a compatible stock 6.4L Charger. It provides the right balance of fitment confidence, durability, and everyday performance without charging extra solely for OEM packaging.
2. Mopar 16-Piece Spark Plug Set – Best OEM Replacement
The Mopar SP149212AC is the best choice for an owner who wants the factory part number and prefers to minimize aftermarket cross-reference decisions. Mopar catalogs this plug for multiple Dodge Charger 6.4L applications, making it the most direct stock-replacement option in this comparison.
The main benefit is specification confidence. When your VIN-based Mopar catalog identifies SP149212AC, you know the plug was selected around the engine’s required thread, reach, seat, heat range, resistance, and ignition design.
This is particularly useful for an unmodified daily-driven Scat Pack or SRT model. There is little reason to experiment with alternative heat ranges or racing-oriented plugs when the engine remains on its factory calibration.
The linked product is presented as a multi-plug set for compatible 6.4L HEMI applications. Confirm that the current package still contains all 16 plugs before ordering, because SP149212AC is also commonly sold individually or in four-piece packages. The official Mopar catalog, for example, lists this part in packs of four on some vehicle pages.
Mopar SP149212AC and NGK 97408 are closely related options rather than completely different ignition designs. Cross-reference data connects SP149212AC to NGK LZTR6AP11EG/97408. As a result, choosing the Mopar set is primarily about factory-number confidence and packaging, not a guaranteed performance increase over the correct NGK plug.
For a stock engine, that simplicity has real value. You can focus on proper installation rather than trying to determine whether a cheaper plug with similar dimensions has the correct internal resistance or heat characteristics.
The drawback is cost. OEM-branded components can be more expensive than equivalent aftermarket parts, especially when 16 plugs are required. You should compare the total package quantity and price rather than the cost of one box.
As with any plug, inspect the ceramics, threads, terminal ends, and electrodes before installation. Even a correct OEM part should not be installed when it has been dropped or damaged.
Pros: Genuine factory part number, strong fitment confidence for compatible stock engines, reduced cross-reference uncertainty, and complete-set availability.
Cons: Frequently more expensive than the NGK equivalent, package quantities vary, and it offers no automatic horsepower advantage over another correctly specified plug.
My Verdict: Choose Mopar SP149212AC when maintaining the factory part number is your highest priority. It is the most straightforward option for a stock Charger 6.4L, provided the VIN-based catalog confirms fitment.
3. Champion Platinum 16-Piece Spark Plug Set – Best Budget Alternative
The Champion Platinum 16-piece set is the budget-focused option for owners who want the complete quantity in one package. Unlike the linked NGK eight-pack, this set is advertised with all 16 plugs needed for a full twin-plug HEMI service.
Champion is an established ignition-parts manufacturer, and platinum construction can offer improved wear resistance compared with a basic conventional nickel plug. For a compatible stock engine, the set can provide a cost-effective maintenance option without purchasing individual plugs or combining several smaller boxes.
The product listing identifies vehicle-specific compatibility with selected Dodge Charger 6.1L and 6.4L V8 models through 2019. This fitment information is broader and less precise than a VIN-based factory catalog, so confirm the exact Champion part number and specifications before installation.
That verification is particularly important because the 6.1L and 6.4L HEMI engines should not automatically be treated as identical spark-plug applications. A marketplace listing may combine several years and engines for convenience, but the physical fit is only one part of compatibility.
Compare the Champion plug’s thread reach, seat design, heat range, resistance, and recommended gap with the factory plug removed from your Charger. Do not rely only on the “fits your vehicle” message.
The complete-set packaging is its strongest advantage. You receive the expected 16-plug quantity in one purchase and avoid ordering two separate eight-packs. It may also make it easier to ensure that all plugs are from the same batch and product line.
However, lower cost should not be the only reason to choose it. The NGK and Mopar options have clearer OE cross-references for the 6.4L Charger. The Champion listing requires more careful fitment confirmation, particularly for later model years.
This set is most suitable for a stock vehicle whose exact year and engine are explicitly supported by the current listing and confirmed through an independent parts catalog. I would not select it for a modified engine without input from the tuner.
Pros: Complete 16-piece quantity, competitive price, platinum construction, recognized manufacturer, and convenient full-engine packaging.
Cons: Less direct OE cross-reference confidence, narrower advertised year coverage, and greater need to verify the exact part number and specifications.
My Verdict: The Champion set is a reasonable budget alternative when its specifications match your exact Charger. It ranks behind NGK and Mopar because correct fitment matters more than saving a modest amount on 16 plugs.
Critical Fitment Note for Charger 6.4L Owners
The Dodge Charger has been offered with several engines and performance packages. A product listing that simply says “fits Dodge Charger” is not specific enough.
This article focuses on compatible 6.4L/392 HEMI applications. Mopar identifies SP149212AC for multiple 6.4L Charger configurations, including the 2013 SRT8, 2015 SRT 392, and 2022 Scat Pack. That does not mean every plug advertised for a HEMI V8 is interchangeable with it.
The 6.4L HEMI uses a twin-plug ignition arrangement with two spark plugs per cylinder. A complete eight-cylinder service therefore requires 16 spark plugs. NGK’s application catalog identifies the 6.4L dual-plug configuration as requiring 16 LZTR6AP11EG plugs.
Before purchasing, verify:
- The model year and trim
- The 6.4L engine designation
- The VIN
- The factory or currently installed part number
- The number of plugs in the package
- Whether the engine is stock or modified
The recommendations below are intended primarily for stock, naturally aspirated engines. A supercharged, turbocharged, nitrous-assisted, or heavily tuned 6.4L may require a different heat range and gap. Follow the engine builder’s or tuner’s specification in that situation.
What Matters When Choosing 6.4 HEMI Spark Plugs?
Exact Vehicle Fitment
The most important factor is the exact application. Start with the model year, trim, 6.4L engine, and VIN. Compare the recommended factory number with the part number printed on an existing plug.
Do not assume that plugs for a 5.7L R/T, 6.1L SRT8, or 6.2L Hellcat are suitable for a 6.4L Scat Pack. The engines may share HEMI branding while using different ignition specifications.
Electrode Construction
The NGK 97408 uses a Laser Platinum design developed around OE-style durability and consistent gap performance. The Champion option also uses platinum construction but does not have the same clearly documented direct cross-reference in the sources reviewed.
Electrode material is only useful when the rest of the plug matches. An expensive platinum or iridium plug with the wrong heat range remains the wrong plug.
Package Quantity
A full 6.4L HEMI replacement requires 16 plugs. Check whether the product contains:
- One plug
- Four plugs
- Eight plugs
- All 16 plugs
Calculate the price for a complete engine service. The NGK package reviewed above contains eight, while the Mopar and Champion links are positioned as complete or multi-piece sets. Verify the current quantity before checkout.
Stock vs. Modified Engines
A stock naturally aspirated 6.4L normally needs the factory heat range and recommended gap.
Cold-air intakes and cat-back exhaust systems do not automatically require colder plugs. Forced induction, nitrous, major internal changes, or aggressive tuning may change the requirements.
For a modified engine, use the plug and gap recommended by the person who calibrated it.
Spark Plug Gap and Installation Specifications
The NGK 97408 is commonly listed with a preset 0.044-inch gap, but the specification for your exact Charger takes priority. “Pre-gapped” means the plug was set during manufacturing; it does not guarantee that every electrode remained unchanged during shipping and handling.
Inspect each plug with a suitable wire-style gauge. Avoid forcing a wedge gauge against a fine platinum electrode.
When adjustment is necessary, move only the ground electrode. Do not pry against the center electrode or ceramic insulator.
Also verify thread diameter, thread reach, seat type, and heat range. A plug that screws into the cylinder head may still be unsuitable if the firing tip extends too far or sits too high in the chamber.
Start every new plug by hand before using a ratchet. This reduces the risk of cross-threading the aluminum cylinder head.
Use the torque specification from the service information for your exact vehicle and plug design. Do not guess based on feel.
Do not automatically apply anti-seize to the threads. Lubrication changes thread friction and can increase the actual clamping force produced by a given torque setting. Follow the instructions supplied by the plug manufacturer and the vehicle service procedure.
When Should the Spark Plugs Be Replaced?
Follow the maintenance schedule for your Charger’s exact model year. Dodge’s published schedules identify the 6.4L spark-plug interval as mileage-based rather than time-based, but you should consult the manual associated with your vehicle for the actual mileage point.
Earlier inspection may be appropriate when you notice:
- Hard starting
- Rough idle
- Hesitation under acceleration
- Reduced fuel economy
- Misfire trouble codes
- Poor performance under load
These symptoms do not prove the spark plugs are responsible. Failing ignition coils, damaged coil boots, injector problems, wiring faults, intake leaks, or low compression can create similar symptoms.
Scan the vehicle for trouble codes and identify the affected cylinder before replacing parts at random.
When the plugs have reached their scheduled interval, replacing all 16 together helps maintain consistent wear, gap, and ignition characteristics across the engine.
How to Replace Spark Plugs in a 6.4 HEMI Charger
Allow the engine to cool completely before beginning. Removing spark plugs from a hot aluminum cylinder head increases the risk of thread damage.
Verify that you have all 16 correct plugs, an appropriate spark plug socket, extensions, a ratchet, a calibrated torque wrench, and any swivel adapters needed for restricted areas.
Remove the engine cover and any intake tubing or components blocking access to the ignition coils. Photograph the original routing of hoses and wiring when necessary.
Disconnect the coil connectors carefully. Remove the coil fasteners and keep the coils organized by cylinder so that any existing problem can be traced later.
Before removing a plug, clear dirt and loose debris from around the plug well using compressed air or a suitable vacuum. Debris should not be allowed to fall into the cylinder.
Remove the existing plugs with the correct socket and keep them organized by cylinder. Comparing plug appearance can help identify one cylinder running differently from the others.
Inspect each replacement plug. Confirm the part number, thread length, seat, terminal, ceramic condition, and electrode alignment.
Check the gap without placing pressure on the fine center electrode.
Start each plug by hand. A short length of clean rubber hose can help rotate the plug gently while making cross-threading more obvious.
When a plug does not turn smoothly, stop and restart it. Never force it into the aluminum threads with a ratchet.
Tighten each plug to the vehicle-specific service specification. Reinstall the ignition coils and inspect their boots for cracks, oil contamination, or carbon tracking.
Reconnect every electrical connector and reinstall the components removed for access.
Start the engine and listen for an unstable idle. Scan for stored or pending misfire codes and recheck connectors or hoses when the engine does not operate normally.
Because the engine uses 16 plugs and some locations are difficult to reach, professional installation is reasonable when you lack the necessary tools, torque information, or experience.
Frequently Asked Questions
What are the best spark plugs for a 6.4 HEMI Charger?
The NGK 97408 LZTR6AP11EG Laser Platinum is my top overall choice for compatible stock engines. Mopar SP149212AC is the best factory-number option, while the Champion Platinum 16-piece set is a lower-cost alternative requiring more careful fitment verification.
How many spark plugs does a Charger 6.4 HEMI use?
The 6.4L HEMI uses two plugs per cylinder. With eight cylinders, a complete replacement requires 16 spark plugs. Check the package quantity carefully because many NGK and Mopar listings contain fewer than 16.
Is NGK 97408 an OEM-equivalent spark plug?
NGK 97408, designated LZTR6AP11EG, cross-references with Mopar SP149212AC and appears as original equipment for dual-plug 6.4L applications in NGK’s catalog. Always confirm the application by model year and VIN.
What is the difference between NGK 97408 and Mopar SP149212AC?
They are closely related cross-referenced plugs. The primary difference for buyers is branding, packaging, quantity, price, and seller. When both are genuine and correct for the vehicle, neither should be expected to create a meaningful performance advantage over the other.
What is the correct spark plug gap for a stock 6.4 HEMI?
NGK 97408 is listed with a 0.044-inch preset gap. Verify the specification for your exact Charger before installation because model year, replacement part, and engine modifications can affect the requirement.
Can new spark plugs add horsepower to a Scat Pack?
Correct new plugs can restore ignition performance lost through wear, fouling, or excessive gap. They do not normally add substantial horsepower to a healthy stock engine already operating with good plugs.
Can I use colder spark plugs in a stock 6.4 HEMI?
A stock naturally aspirated engine should generally use the factory heat range. Colder plugs are selected for specific operating conditions, often involving increased cylinder pressure or heat. Installing them without a tuning reason can encourage deposits and fouling.
Should all 16 spark plugs be replaced together?
Yes, when the engine has reached its scheduled replacement interval. A matched set keeps the plug type, heat range, gap, and wear level consistent across all eight cylinders.
Conclusion
The best spark plugs for 6.4 HEMI Charger models must match the exact vehicle, not simply carry a premium electrode label.
For most compatible stock applications, the NGK 97408 LZTR6AP11EG Laser Platinum Spark Plugs provide the strongest combination of OE-style fitment, durability, and value. Remember that the linked package contains eight plugs, so a full service normally requires two.
The Mopar SP149212AC set is the better choice when you prefer the factory part number and OEM packaging. The Champion Platinum set offers complete 16-plug convenience at a lower price but requires more careful application verification.
Before ordering, confirm the model year, VIN, 6.4L engine, factory part number, and package quantity. Proper fitment and installation matter more than brand ranking or marketing claims.