Cometic MLS Head Gasket - Nissan RB25DET 87mm Bore 0.051" Thickness

Achieve maximum sealing performance with the Cometic MLS (Multi-Layer Steel) head gasket. Engineered for high-output RB25DET engines, this premium gasket features multiple embossed stainless steel layers with Viton coating, delivering superior sealing, durability, and reliability for boosted applications.

Key Features:

• MLS (Multi-Layer Steel) construction
• 87mm bore diameter
• 0.051" (1.30mm) compressed thickness
• Multiple embossed stainless steel layers
• Viton rubber coating on outer layers
• No sealants required
• Reusable design
• Corrosion resistant
• Cometic quality and engineering

Performance Benefits:

• Maximum Sealing: MLS design provides superior sealing for high-output engines
• Boost Ready: Handles extreme cylinder pressures from turbocharging
• Increased Strength: Multiple steel layers provide exceptional strength
• Rebound Capability: Resists head lift and maintains seal
• Heat Resistant: Viton coating withstands up to 482°F (250°C)
• Corrosion Resistant: Stainless steel construction resists corrosion
• No Sealants Needed: Installs without additional sealers

Specifications:

• Brand: Cometic Gasket
• Part Number: C4318-051
• Product: MLS Head Gasket
• Bore Diameter: 87mm (3.425 inches)
• Compressed Thickness: 0.051 inches (1.30mm)
• Construction: Multi-layer stainless steel
• Layers: Multiple embossed layers
• Coating: Viton on outer layers
• Center Layer: Uncoated stainless steel shim
• Barcode: 191070020064

Fitment Information:

• Nissan RB25DET (87mm bore)
• Common Applications: Skyline R33, R34, Stagea with RB25DET
• Note: Verify bore size matches your engine build
• Installation: Professional installation strongly recommended

What's Included:

• Cometic MLS head gasket
• Installation instructions
• Note: Head bolts/studs and other gaskets sold separately

Installation Notes:

• Professional installation strongly recommended
• Ensure block and head surfaces are perfectly flat (RA 50-60 finish)
• Clean all surfaces thoroughly - no oil or debris
• Do NOT use additional sealants
• Install gasket dry
• Use proper head bolt/stud torque sequence and specifications
• Follow manufacturer's torque specifications
• Allow proper break-in period before boost

MLS (Multi-Layer Steel) Construction:

Cometic's MLS gaskets feature multiple layers of embossed stainless steel that work together to provide superior sealing. The multi-layer design allows the gasket to conform to minor surface imperfections while maintaining excellent sealing under extreme cylinder pressures. Each layer is precisely embossed to create optimal sealing around combustion chambers, coolant passages, and oil galleries. The MLS construction is the gold standard for high-performance engines, especially turbocharged applications.

87mm Bore Diameter:

The 87mm bore diameter is designed for RB25DET engines. This bore size is critical for proper sealing - the gasket must match your engine's bore diameter. The 87mm size is standard for RB25DET engines, but always verify your specific engine configuration, especially if the block has been bored or sleeved. Using the correct bore size ensures proper combustion chamber sealing and prevents gasket failure.

0.051" Compressed Thickness:

The 0.051" (1.30mm) compressed operating thickness affects compression ratio and piston-to-head clearance. This thickness is suitable for most RB25DET applications and provides a good balance of sealing and compression. Thicker gaskets lower compression ratio, while thinner gaskets raise it. The 0.051" thickness is a popular choice for turbocharged RB25DET builds running moderate to high boost.

Viton Coating:

The outer layers feature Viton coating on both sides. Viton is a fluoroelastomer rubber material that provides exceptional heat resistance up to 482°F (250°C) and excellent chemical resistance. The Viton coating creates a micro-seal that conforms to surface imperfections, ensuring leak-free operation. The coating is designed to handle harsh sealing environments, varying load conditions, and different surface finishes, making it ideal for high-performance applications.

No Sealants Required:

Cometic MLS gaskets are designed to seal without additional sealants. In fact, using sealants can actually reduce sealing performance by preventing proper gasket compression. The MLS design and Viton coating provide all the sealing needed when installed on properly prepared surfaces. This simplifies installation and eliminates concerns about sealant compatibility or application errors.

Reusable Design:

MLS gaskets can be reused if removed carefully and surfaces remain in good condition. The stainless steel construction and Viton coating maintain their sealing properties even after compression. This reusability is valuable during engine development or troubleshooting, though new gaskets are recommended for final assembly. The ability to reuse the gasket can save money during the build process.

Surface Finish Requirements:

MLS gaskets require proper surface finish for optimal sealing. The block and head surfaces should be machined to RA 50-60 finish (smooth but not mirror-polished). Surfaces that are too rough won't seal properly, while surfaces that are too smooth won't allow the Viton coating to grip. Professional machine shop preparation is essential for MLS gasket success.

Why Cometic?

Cometic Gasket is a leading manufacturer of high-performance gaskets, known for innovative MLS technology and proven reliability. Their gaskets are trusted by professional engine builders and racers worldwide for extreme applications. Cometic's commitment to quality and performance has made them the choice for serious RB engine builds. Every gasket is manufactured in the USA to exacting standards.

Installation Tips:

• Have block and head professionally surfaced to RA 50-60 finish
• Clean surfaces with brake cleaner - no oil residue
• Install gasket completely dry - no sealants
• Use ARP head studs for best clamping force
• Follow proper torque sequence and specifications
• Re-torque after initial heat cycle if using head bolts

Perfect For:

• RB25DET engine builds with 87mm bore
• Turbocharged applications requiring maximum sealing
• High-boost builds demanding proven reliability
• Engine rebuilds seeking professional-grade gaskets
• Anyone wanting Cometic quality and performance

Perfect For: Nissan RB25DET engine builds seeking Cometic MLS head gasket with 87mm bore and 0.051" thickness for maximum sealing.

Pro Tip: Proper surface preparation is critical for MLS gasket success - invest in professional machining for best results.

Professional Grade: 87mm bore, 0.051" thickness. Multi-layer steel with Viton coating. No sealants required. Made in USA.

Achieve maximum sealing with Cometic MLS head gasket - multi-layer steel, Viton coating, boost ready, proven reliability.