RC Engine Spark Plug O.S. LC4 Medium

Bougie O.S. LC4 medium

This medium glow plug is perfect for RC engines used in both recreational and sport applications.

From the first starts, I notice a smoother engine operation, with clean combustion and very good stability at mid and high speeds.

The O.S. LC4 is particularly useful when outdoor temperatures become moderate or slightly warm.

It helps maintain a consistent engine performance without making the behavior too aggressive.

This is precisely what makes it a highly appreciated glow plug in many RC cars, nitro RC planes, and remote-controlled boats.

A more balanced medium plug compared to the LC3

Compared to the hot O.S. LC3 plug:

• the LC4 heats slightly less,
• it better withstands higher temperatures,
• combustion becomes more stable at high speeds,
• the engine appears more consistent over time.

The LC3 remains more suitable for cold conditions or engines requiring very assisted idling.

The LC4, on the other hand, offers more versatility when the engine revs up more regularly.

I find this plug ideal for drivers who drive all year round and want to avoid constantly changing plugs according to the weather.

Differences with Turbo O.S. competition plugs

Unlike the competition-oriented Turbo O.S. RP6 or RP7 plugs, the medium LC4 prioritizes:

• flexibility,
• ease of tuning,
• engine consistency,
• versatility in use.

Turbo plugs generally offer:

• more aggressive accelerations,
• a livelier combustion,
• maximum performance at high speeds.

The O.S. LC4, on the other hand, maintains a more progressive and tolerant behavior, greatly facilitating carburetor tuning and overall stability of the RC engine.

Stable combustion for a more enjoyable engine

With its medium heat range, this plug allows for:

• stable idling,
• clean throttle response,
• good throttle transition,
• better controlled engine temperature.

I often notice that it reduces irregular behaviors when outdoor temperatures rise or when the fuel contains more nitromethane.

It is very suitable for drivers looking for a smooth engine to drive, without being too aggressive or sensitive to adjustments.

Ideal conditions of use

• Moderate to hot temperatures
• Recreational and sport RC cars
• Nitro RC buggies
• Thermal truggies
• RC thermal planes
• Nitro RC boats
• Moderately nitro fuels

Engine compatibility

• • O.S. engines
    • Force Engines
    • SH Engines
    • Thunder Tiger
    • Vertex
    • Many standard RC nitro engines

Why choose the O.S. LC4 medium?

I consider the LC4 as an excellent all-around spark plug for users who want:

• • • a stable engine,
    • good consistency,
    • simple adjustments,
    • broad compatibility with different nitro RC engines.

It allows maintaining a very good level of performance while keeping a smooth and easy-to-use engine behavior.

The manufacturing quality O.S. Engines is also a real asset to ensure reliable and consistent combustion.

Key Features

• • Highly versatile medium spark plug
  • Good thermal stability
  • Simplified engine adjustments
  • Excellent consistency
  • Leisure and sport compatible
  • Very good performance/reliability compromise
  • Works in many weather conditions