As horsepower climbs beyond factory limits, the BMW S58 engine places tremendous loads on the crankshaft and main bearing structure. High boost, elevated cylinder pressures, and sustained high RPM can cause factory cast main caps to flex or walk, affecting bearing clearances and long-term engine durability.
The VAC Motorsports Billet Main Caps are precision CNC-machined from premium billet steel to dramatically increase bottom-end rigidity. Designed for professional engine builders and serious enthusiasts, these caps help maintain precise crankshaft alignment while minimizing cap movement under the most demanding racing conditions.
For anyone building an S58 beyond factory power levels, billet main caps provide the confidence and stability needed to support extreme horsepower.
Features
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CNC-machined from premium billet steel
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Designed specifically for BMW S58 engines
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Increased rigidity compared to OEM cast main caps
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Helps reduce main cap walk
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Improves crankshaft stability
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Maintains precise main bearing bore geometry
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Promotes consistent oil clearance and bearing life
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Designed for extreme horsepower and motorsport applications
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Manufactured in the USA
Benefits
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Stronger engine foundation
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Improved crankshaft control
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Increased bearing reliability
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Reduced cap flex
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Enhanced durability under high boost and RPM
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Ideal for competition engine builds
Installation Notes
Professional engine machining is required.
Installation requires:
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Line boring
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Align honing
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Measurement and verification of all main bearing clearances
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Complete professional engine assembly procedures
These billet main caps are not intended to be installed without proper machine work.
Recommended Applications
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High Boost S58 Builds
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Drag Racing
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Road Racing
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Time Attack
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Roll Racing
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Standing Mile
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Dedicated Competition Engines
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1,000+ HP Engine Builds
Engine Fitment
Fits all BMW S58-powered models, including:
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BMW G80 M3
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BMW G81 M3 Touring
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BMW G82 M4
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BMW G83 M4 Convertible
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BMW F97 X3 M
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BMW F98 X4 M
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BMW XM (S68-derived architecture not applicable--S58 version only where equipped)
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