Choosing the right spark plug for a 5.7 Hemi engine is critical for optimal performance, fuel economy, and longevity. We researched manufacturer specifications, industry standards, and aggregated owner feedback to evaluate the top options. Our comparison focuses on material, heat range, electrode design, and real-world reliability. Whether you need daily driver durability or track-day performance, this guide helps you decide.
| Photo | Product | Score | Buy |
|---|---|---|---|
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NGK 6510 LZTR5AIX Iridium IX Top Pick Iridium tip, 0.044 in. gap, 14mm thread, heat range 5 |
9.1 | 🛒 Check Price |
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Denso 4504 PK20TT Platinum TT Best Value Twin-tip platinum, 0.044 in. gap, 14mm thread, heat range 20 |
8.5 | 🛒 Check Price |
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Champion 7989 Copper Plus Budget Pick Copper core, 0.035 in. gap, 14mm thread, heat range 12 |
7.8 | 🛒 Check Price |
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ACDelco 41-962 Iridium OEM Alternative Iridium tip, 0.040 in. gap, 14mm thread, heat range 5 |
8.2 | 🛒 Check Price |
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Autolite XP985 Iridium XP Performance Pick Iridium tip, 0.044 in. gap, 14mm thread, heat range 5 |
8.7 | 🛒 Check Price |
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E3 Spark Plugs E3.58 Unique Design DiamondFire electrode, 0.045 in. gap, 14mm thread, heat range 5 |
7.3 | 🛒 Check Price |
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Bosch 4417 Platinum+4 Multi-Electrode 4 platinum ground electrodes, 0.032 in. gap, 14mm thread, heat range 5 |
7.6 | 🛒 Check Price |
1. NGK 6510 LZTR5AIX Iridium IX: Top Pick
The NGK 6510 LZTR5AIX Iridium IX is our top pick for most 5.7 Hemi owners. We researched its design and found the fine iridium tip reduces voltage requirements and provides a consistent spark, which contributes to smoother idle and throttle response. Owner feedback consistently praises its longevity and ease of installation. Based on spec sheets, it meets or exceeds OEM requirements for standard and mild performance applications.
However, this plug is not ideal for high-boost or nitrous setups where a colder heat range is needed. Some users on forums report occasional misfires in heavily modified engines. We recommend it for daily drivers, towing, and light performance upgrades. If you have aggressive modifications, consider a colder plug.
- Fine iridium tip for consistent spark and long life
- Trivalent metal plating for anti-corrosion and easier removal
- OE replacement for many 5.7 Hemi models
Pros: Excellent pre-gapped accuracy; Proven reliability across many owner reports
Cons: Not the best for heavily modified or forced induction engines
2. Denso 4504 PK20TT Platinum TT: Best Value
The Denso 4504 PK20TT Platinum TT offers a strong balance of price and performance. We compared its twin-tip platinum design to standard copper plugs and found it provides longer service life and more consistent ignition. Owner feedback indicates it works well in stock 5.7 Hemi engines, delivering smooth operation and no noticeable power loss.
However, this plug is not the best choice for racing or high-RPM applications. Some owners note that the twin-tip design can be more prone to fouling in oil-burning engines. We suggest it for budget-conscious owners who want a reliable plug that lasts longer than copper but don’t need the extreme performance of iridium. Skip it if you demand maximum spark energy.
- Twin-tip design for extended durability up to 60,000 miles
- U-groove ground electrode for better flame propagation
- Affordable alternative to iridium with good performance
Pros: Lower cost without sacrificing reliability; Long service interval for a platinum plug
Cons: Not as sharp a spark as iridium for high-performance needs
3. Champion 7989 Copper Plus: Budget Pick
The Champion 7989 Copper Plus is the most economical choice for a 5.7 Hemi. We evaluated it based on cost and basic function: it provides adequate spark for a stock engine. Owner feedback shows it works fine for daily driving but requires frequent changes. It is a good option if you need a quick fix or plan to upgrade soon.
However, this plug’s durability is low. Many owners report electrode wear and gap growth after 20,000 miles. It also lacks the anti-fouling characteristics of precious metal plugs. We recommend it only for those on a tight budget or as a temporary replacement. Skip it if you want long-term reliability or have any performance modifications.
- Traditional copper core for good conductivity
- Lowest cost option available
- Works well in stock engines for basic replacement
Pros: Very affordable; Good for short-term use or testing
Cons: Short lifespan, need replacement every 30,000 miles or less; Not suitable for modified or high-performance engines
4. ACDelco 41-962 Iridium: OEM Alternative
The ACDelco 41-962 Iridium is a solid OEM-style replacement. We researched its specifications and found it meets the same standards as factory plugs for many Chrysler applications. Owner feedback indicates it provides reliable ignition and smooth idle. It is a direct fit for 5.7 Hemi engines without any modifications.
However, we noted that a small number of owners received plugs with incorrect gaps, requiring re-gapping. Also, it is not the best choice for tuned engines; its heat range is designed for stock operation. We recommend it for those who prefer an OEM brand and don’t want to experiment. Skip it if you want a plug optimized for performance or have a modified engine.
- OE quality for many GM and Chrysler engines
- Iridium center electrode for long life
- Pre-gapped to spec for easy installation
Pros: Trusted OEM supplier; Good corrosion resistance
Cons: Slightly higher price than comparable iridium plugs; Some owners report gap inconsistency out of box
5. Autolite XP985 Iridium XP: Performance Pick
The Autolite XP985 Iridium XP is designed for performance-minded owners. We compared its fine wire iridium tip to standard plugs and found it delivers a more focused spark, which can improve combustion efficiency. Owner feedback highlights noticeable gains in throttle response and smoothness in stock and mildly tuned 5.7 Hemi engines.
However, durability is a minor concern. Some owners reported needing replacement sooner than expected, around 40,000 miles. Also, the plug requires careful gapping; incorrect gap can cause misfires. We recommend it for those who want a performance edge without going to a colder plug. Skip it if you prioritize extreme longevity or have a heavily modified engine requiring a different heat range.
- Fine wire iridium for enhanced ignitability
- Patented platinum side wire for longer life
- Improved throttle response and fuel efficiency
Pros: Sharp spark for better combustion; Good for mild performance upgrades
Cons: Some users report shorter lifespan than NGK iridium; Can be sensitive to gap setting
6. E3 Spark Plugs E3.58: Unique Design
The E3.58 plug features a distinctive DiamondFire electrode that aims to create a larger flame kernel. We researched the technology and found it has theoretical benefits, but owner feedback is mixed. Some users report smoother idle and better mileage, while others see no difference or even issues with fitment and durability.
We have concerns about long-term reliability. Several forum posts mention electrode wear or cracking after moderate use. Also, the plug may not be ideal for high-performance applications. We suggest it only for curious owners willing to experiment and accept potential shorter lifespan. Skip it if you want proven, no-hassle performance.
- Patented DiamondFire electrode for efficient flame kernel
- Claims improved fuel economy and power
- Direct fit for 5.7 Hemi
Pros: Unique design may reduce misfires; Good for those wanting to try something different
Cons: Mixed owner reviews, some report no improvement; Not as widely evaluated as traditional designs
7. Bosch 4417 Platinum+4: Multi-Electrode
The Bosch 4417 Platinum+4 uses four ground electrodes to provide multiple spark paths. In our evaluation, this design can help maintain spark even if one electrode wears. Owner feedback is mixed: some report smoother idle and better cold starts, while others experience misfires due to the fixed gap being too small for some Hemi engines.
We found that this plug is not suitable for modified engines or those requiring a wider gap. The non-adjustable gap (0.032 in.) is narrower than the typical 0.044 in. recommended for many 5.7 Hemis. This can lead to incomplete combustion and reduced power. We recommend it only for stock engines where the narrow gap is acceptable, and skip it for any performance use.
- Four ground electrodes for multiple spark paths
- Platinum center electrode for extended life
- Designed for smoother idle and reduced emissions
Pros: Smooth idle claimed by some owners; Good for older engines with worn ignition
Cons: Gap is not adjustable, can cause misfires if out of spec; Not recommended for high-performance or forced induction
Frequently Asked Questions
What spark plug gap is recommended for a 5.7 Hemi?
The recommended gap varies by model year and plug type. For most 5.7 Hemi engines, OEM specification is 0.044 inches. However, some aftermarket plugs may require different gaps. Always check your vehicle owner’s manual or the plug manufacturer’s spec sheet. Using the wrong gap can cause misfires, poor fuel economy, and reduced performance.
Can I use iridium spark plugs in my 5.7 Hemi?
Yes, iridium spark plugs are an excellent upgrade for the 5.7 Hemi. They offer a longer service life (often up to 100,000 miles) and a more consistent spark than copper or standard platinum plugs. Many owners report improved throttle response and smoother idle. Just ensure the heat range matches your engine’s needs, especially if you have modifications.
How often should I change spark plugs on a 5.7 Hemi?
For copper plugs, replacement is typically every 30,000 miles. Platinum plugs can last 60,000 to 80,000 miles, while iridium plugs can go up to 100,000 miles under normal driving conditions. However, if you drive hard, tow frequently, or have modifications, you may need to replace them sooner. Always inspect plugs during routine maintenance.
What happens if I use the wrong heat range spark plug?
Using a plug that is too hot can cause pre-ignition and engine knock, which may damage the engine. A plug that is too cold can foul quickly, leading to misfires and poor performance. For a stock 5.7 Hemi, stick with the OEM heat range (usually heat range 5). For modified engines, consult a tuner or plug manufacturer for the correct heat range.
Do I need to gap spark plugs before installation?
Many modern plugs come pre-gapped from the factory, but it is always wise to check the gap with a tool. Even a small deviation can affect performance. For the 5.7 Hemi, the typical gap is 0.044 inches. If the gap is incorrect, carefully adjust it using a gap tool. Avoid bending the ground electrode excessively to prevent damage.
Our Verdict
After researching and comparing the options, our top pick for most 5.7 Hemi owners is the NGK 6510 LZTR5AIX Iridium IX due to its proven reliability, consistent spark, and long service life. For those on a budget, the Denso 4504 PK20TT Platinum TT offers excellent value without major compromises. If you have a modified engine, consider the Autolite XP985 Iridium XP for its performance edge, but always verify heat range compatibility.
