The quick answer: choose long-life spark plugs (iridium or platinum) that match the OEM heat range and thread size for your 5.7 HEMI; popular aftermarket options include NGK Iridium IX or Denso Iridium TT, with a typical gap around .040 inches and replacement intervals that can reach 60,000–100,000 miles depending on driving conditions.
Understanding the right spark plugs for a 5.7 HEMI involves recognizing that this engine family has evolved through several model years and configurations. While the core requirement is the same—use plugs that fit the engine’s heat range, thread size and reach—differences in model year, fuel system (high‑efficiency direct injection in many variants), and maintenance history can influence exact recommendations. This article outlines material options, OEM vs aftermarket choices, and practical installation tips to help you select the right plugs for your vehicle.
Spark plug materials and longevity
- Copper core plugs: typically the least expensive option with the shortest service life, often around 30,000–60,000 miles in modern engines.
- Platinum plugs: offer longer life than copper and reliable performance; a common middle-ground choice for many street-driven vehicles.
- Iridium plugs: provide the longest life and best durability in demanding conditions; widely favored for modern performance engines, including many 5.7 HEMI replacements.
Choosing between these materials generally comes down to budget, maintenance preference, and how long you want between replacements. Iridium or platinum plugs are favored when you want fewer service visits and more consistent performance over time.
OEM specs vs aftermarket options for the 5.7 HEMI
- OEM or OEM-equivalent plugs: these are designed to match Chrysler/Mopar specifications for your exact year and variant (including direct-injection and multi-displacement systems). Ideal when you want a straightforward, maintenance-friendly replacement that preserves factory performance.
- NGK Iridium IX or Iridium TT: widely used aftermarket options that offer good longevity and reliable cold starts on many HEMI applications.
- Denso Iridium TT or Iridium Power: strong performers with durable construction and compatibility with modern direct-injection engines.
- Champion Long-Life Platinum or Platinum Power: popular alternative offering respectable life and performance, often at a lower price point.
When choosing, verify the exact part number for your engine code and year in the vehicle’s owner manual or official Mopar service documentation. The 5.7 HEMI uses a plug with standard 14mm threads in many variants, but heat range and reach can vary, especially with direct-injected or later models.
Practical selection and installation tips
- Match heat range, thread size, and reach to your specific 5.7 HEMI variant: use OEM specifications or a trusted aftermarket equivalent for your model year.
- Gap verification: many aftermarket plugs arrive pre-gapped; confirm the gap (commonly around .040 inches for many engines) and adjust only if your manual specifies a different value.
- Installation technique: clean threads, use the proper torque, and avoid anti-seize on modern plugs if the manufacturer advises against it. Follow the service manual for torque and gasket seating recommendations.
- Maintenance interval: iridium or platinum plugs typically offer longer service life (often 60,000–100,000 miles in normal driving), but heavy towing, high-load driving, or severe conditions can shorten this interval.
In short, select plugs that mirror the OEM heat range and thread specs, opt for iridium or platinum for extended life, and follow proper installation practices to maximize performance and reliability.
Summary
What kills spark plugs quickly?
Pre-ignition can lead to heat building up in the combustion chamber causing the spark plugs to fail. In addition, if the cooling system isn't functioning correctly, it can cause the engine and spark plugs to overheat. This overheating can lead to the spark plug's electrode wearing out faster.
How often should I change the spark plugs in a 5.7 Hemi?
every 30,000 miles
If you drive a RAM 1500 with a 5.7L HEMI V8 engine built before 2014, you should replace the spark plugs every 30,000 miles. Newer models with the same engine can go up to 100,000 miles before needing a change.
Why does the 5.7 Hemi use 16 spark plugs?
The wide chamber makes it harder for a single plug to ignite the air-fuel mix efficiently, so a second plug ensures a faster, more complete burn, resulting in better emissions, fuel economy and engine smoothness. While it adds maintenance, the payoff in performance and efficiency is clear.
What type of spark plugs for 5.7 Hemi?
16 pc Champion Copper Plus Spark Plugs compatible with Ram 1500 5.7L V8 2011-2024 HEMI V8 truck.