NGK V-Power Spark Plug – TR5

The NGK TR5 is a V-Power nickel spark plug used in select automotive, marine, powersports, and equipment applications where the engine manufacturer specifies the TR5 / NGK 2238 plug profile. It features NGK’s V-groove center electrode design, which helps position the spark at the edge of the electrode for consistent ignition in compatible engines.

This plug should be installed only where the engine service manual, ignition label, or application chart specifically calls for NGK TR5, NGK 2238, or an approved equivalent.

Key Features

• Genuine NGK V-Power spark plug.
• NGK part number: TR5.
• NGK stock number: 2238.
• Nickel spark plug with copper-core heat transfer.
• V-groove center electrode design.
• Resistor-style spark plug.
• Thread diameter: 14 mm / M14 x 1.25.
• Thread reach: 18 mm / 0.709 in..
• Hex size: 5/8 in. / 16 mm.
• Seat style: tapered seat.
• Heat range: 5.
• Factory preset gap: 0.040 in. / 1.0 mm.
• Commonly compared with NGK TR55, which shares similar plug geometry but is typically supplied with a wider preset gap.

Application Compatibility

Common application context includes select engines that call for the NGK TR5 / 2238 plug profile, including:

• Select General Motors LS-based V8 applications where specified
• Select 4.8L, 5.3L, 5.7L, 6.0L, and 6.2L GM V8 applications where the plug chart calls for TR5
• Select Ford V8 applications where specified
• Select inboard marine, ski boat, powersports, UTV, and outdoor equipment applications where the engine manufacturer lists TR5 / 2238
• Stock or mildly modified engines only when the required heat range, reach, seat style, and gap match the engine specification

Use this spark plug only where the manufacturer’s plug chart specifically calls for TR5, 2238, or an approved equivalent.

Fitment Notice

Confirm fitment by exact year, make, model, engine, service manual, and factory spark plug chart before ordering. Spark plugs with the same thread size can still differ in reach, heat range, seat style, terminal style, resistor specification, projected-tip design, and required gap. Installing the wrong plug can cause hard starting, misfire, poor idle, thread damage, overheating, piston contact, or ignition-system problems.

When This Part Needs Replacement

Replace spark plugs during scheduled tune-up service or whenever the plugs are fouled, worn, fuel-soaked, oil-contaminated, corroded, cracked, damaged, or causing hard starting, rough idle, hesitation, misfire, reduced throttle response, or poor fuel economy. Engines that idle frequently, run under heavy load, or operate in damp marine environments should have spark plugs inspected more regularly.

Installation Notes

Confirm the plug number and gap before installation. Because the TR5 uses a tapered seat, it does not use a separate sealing gasket. Install into clean, undamaged cylinder head threads and tighten to the engine manufacturer’s torque specification. Avoid adding anti-seize unless the engine or spark plug manufacturer specifically calls for it, as lubricant can change the clamping load and increase the risk of over-tightening.

Alternate/Superseded Part Numbers

• NGK TR5 spark plug part number
• NGK 2238 NGK stock number
• TR5 V-Power product style reference
• TR55 related NGK reference with different preset gap; verify required gap before substitution

Parts Desk Insight

The TR5 and TR55 are often discussed together because they are similar in plug style and heat range, but the preset gap differs. The TR5 is commonly supplied at 0.040 in., while TR55 applications often call for a wider preset gap. Always match the plug number and gap to the engine’s service chart instead of choosing by engine family alone.

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