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Last reviewed June 27, 2026
TL;DR NGK LTR6CI-8 (97177) is a cold-range Laser Iridium aftermarket cross for the Ford 3.5L EcoBoost twin-turbo family (F-150, Explorer Sport, Flex, Taurus SHO, Expedition, Lincoln MKS/MKT/Navigator EcoBoost, 2011-2017); OEM cross-ref BL3E-12405-DA/CYFS12Y3; pre-gapped to ~0.032 in; rated 90,000-mile service interval. Not for the naturally aspirated 3.5L or 3.7L Ti-VCT V6. Superseded in NGK catalog by LTR6GI-8 (93594), functionally equivalent.
The LTR6CI-8 is an NGK Laser Iridium plug with iridium center and platinum fine-wire ground, designed as an aftermarket cross for the Ford 3.5L EcoBoost (twin-turbo) V6 family · F-150, Explorer Sport, Flex, Taurus SHO, Expedition, and the Lincoln MKS/MKT/Navigator EcoBoost. Thread spec is M14x1.25, tapered seat; factory gap roughly 0.032 in. The "C" heat range modifier indicates a cold offset from standard, matched to boosted EcoBoost operation; this makes it the wrong plug for the naturally aspirated 3.5L or 3.7L Ti-VCT V6, which run a standard heat range. OEM cross-references confirm fitment parity with the Motorcraft SP-534/SP-550 for Gen 1 3.5L EcoBoost applications (2011-2016); cross-reference accuracy for the Gen 2 3.5L EcoBoost (2017+) was not independently confirmed during this review. NGK rates the Laser Iridium class at 90,000 miles; community removal-photo evidence at the rated interval is not yet located for this application. The part number 97177/LTR6CI-8 is superseded by 93594/LTR6GI-8 in the NGK catalog.
Right pick for owners of a Gen 1 3.5L EcoBoost (F-150 2011-2016, Explorer Sport, Flex, Taurus SHO, Expedition, or the Lincoln MKS/MKT/Navigator EcoBoost) wanting a Laser Iridium aftermarket alternative to the Motorcraft SP-534/SP-550. Skip if your engine is the naturally aspirated 3.5L or 3.7L Ti-VCT V6 (the cold 'C' heat range is wrong for those · use a hotter standard-range plug), if your F-150 has the 2.7L EcoBoost (use the SP-594 instead), if you want the Ford OEM-brand plug (Motorcraft SP-534/SP-550), or if your truck has the Gen 2 3.5L EcoBoost (2017+) and you cannot confirm cross-reference accuracy for your year.
No chemical exposure pathway: ceramic-and-steel ignition part, no SDS. Iridium center and platinum ground carry a small combined precious-metal mass offset by the 90,000-mile rated interval. Steel shell recyclable; ceramic insulator landfills. No manufacturer take-back program as of 2026.
The NGK LTR6CI-8 (97177) is the cold-range Laser Iridium cross for the Ford 3.5L EcoBoost (twin-turbo) family via OEM part numbers BL3E-12405-DA and CYFS12Y3: F-150 (2011-2016), Explorer Sport (2013-2019), Flex EcoBoost, Taurus SHO, Expedition EcoBoost (2015-2017), and the Lincoln MKS, MKT, and Navigator EcoBoost. It is matched to the boosted 3.5L EcoBoost specifically · it is NOT the plug for the naturally aspirated 3.5L or 3.7L Ti-VCT V6, which use a standard heat range. Always verify your specific year and engine via the vehicle fitment tool before ordering.
The NGK LTR6CI-8 arrives pre-gapped at 0.032 in (0.8mm), which is within the recommended range for boosted EcoBoost engines. The 'C' designation in the part number indicates a cold heat-range offset from the standard series, appropriate for turbocharged applications.
The LTR6CI-8 (NGK stock 97177) has been superseded by the LTR6GI-8 (NGK stock 93594). The replacement part is functionally equivalent for the same applications. If you find existing stock of the LTR6CI-8, it is the same plug; both share the same Laser Iridium construction and OEM cross-reference applications.
The Motorcraft SP-534 (and its successor SP-550) is Ford's own OEM Motorcraft-branded plug for the Gen 1 3.5L EcoBoost. The NGK LTR6CI-8 is an aftermarket Laser Iridium cross-reference for the same application, confirmed via Ford cross-reference BL3E-12405-DA. Both use iridium center electrodes. The SP-534/SP-550 carries a 60,000-mile Ford OEM interval; NGK rates the Laser Iridium class at 90,000 miles.
Marketing copy from NGK, via Amazon. Not editorial.
Per manufacturer cross-reference, not a physical test fit. A single generation often forks by engine, trim, and market.
Check this against your owner's manual before you buy
⚠ NGK Laser Iridium cross (LTR6CI-8 / 97177, superseded by 93594 / LTR6GI-8) for the Ford 3.5L EcoBoost (twin-turbo) family ONLY. The 'C' cold-offset heat range is matched to the boosted 3.5L EcoBoost · it is NOT the plug for the naturally aspirated 3.5L or 3.7L Ti-VCT V6 (those take a hotter standard-range plug instead (verify against a fitment guide)). Confirmed 3.5L EcoBoost applications mapped to existing vehicle files: F-150 12th gen (2011-2014) and 13th gen Gen 1 (2015-2016); Explorer Sport 5th gen (2013-2019); Flex EcoBoost (2010-2019); Taurus SHO 6th gen; Expedition u324 EcoBoost (2015-2017); Lincoln MKS EcoBoost, MKT EcoBoost, and Navigator u326 EcoBoost (2015-2017). Cross-reference accuracy for the 2017+ Gen 2 3.5L EcoBoost (F-150 13th gen later years) was not independently confirmed · verify against NGK's fitment guide. OEM cross-ref BL3E-12405-DA / CYFS12Y3; Motorcraft cross SP-534/SP-550. Pre-gapped 0.031-0.032 in. Verify your year, make, model, and engine before buying.
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