Magnus Ductile Iron Engine Sleeves for McLaren 4.0L V8

Magnus Motorsports McLaren 4.0L ductile iron engine sleeves help resist deformation under high boost and high combustion loads. Sold as a full set of 8 sleeves.

Vehicle Fitment:
McLaren 3.8L & 4.0L V8 Twin-Turbo
• M838T: 625C, 650S, 675LT, MP4-12C, MSO 688 HS
• M838TE: 540C, 570S, 570GT, 600LT, 620R
• M840T: 720S, 750S, 765LT, Senna, Elva, Speedtail, Sabre
• M840TE: GT, GTS

4.0L Replacement:
These sleeves are a drop-in upgrade for the 4.0L M840T and M840TE blocks to replace the factory liners.

3.8L Upgrade/Stroker Kit:
These allow builders to machine a 3.8L M838T or M838TE block out to accept the larger 4.0L bore diameter.

Purchase Includes:
(8) Sleeves

Install Notes:
• Professional machining and installation required.
• Intended for built engines exceeding factory power levels.
• Don't forget the Magnus Sleeve Puller and Installer Tool!

More from Magnus:
Magnus McLaren Engine Sleeves are engineered to address a known limitation of the factory cylinder design in high-power applications. The OEM steel sleeve, while adequate at stock power levels, has a tendency to bend under extreme cylinder pressure. Once steel bends, it often retains an out-of-round shape, compromising bore concentricity, ring seal, and long-term engine reliability.

Magnus sleeves are manufactured from thick-wall, heavy-duty ductile iron, specifically chosen for its superior rigidity and dimensional stability. This design helps resist deformation under high boost and high combustion loads, maintaining bore shape and fighting ovalling in extreme horsepower applications.

Designed for serious street and motorsport engine programs, Magnus McLaren Engine Sleeves provide the foundation required when pushing well beyond factory limits.  Magnus Sleeves are finish bored to final size so they can be replaced without any additional machining!

Features:
• Heavy-duty ductile iron construction
• Increased wall thickness for added rigidity
• Designed to retain bore concentricity
• Helps resist cylinder ovalling at high power levels
• Superior stability compared to OEM steel sleeves
• Ideal for high-boost and high-horsepower builds

Benefits:
• Improved ring seal
• Increased cylinder durability
• Enhanced long-term engine reliability
• Critical upgrade for extreme power applications