BMW S65 4.2L Street Performance Engine with Cams

S65 Engine — Street Performance w/ Cams (4.2L) 

The CarBahn S65 Street Performance with Cams engine is engineered for enthusiasts seeking increased top-end power and improved airflow while preserving the naturally aspirated, high-revving character that defines the S65 platform. Designed for aggressive street driving and track-day use, this build enhances performance without compromising durability or drivability. 

OEM Limitations 

The BMW S65 engine is known for several inherent wear points that can compromise long-term reliability. Connecting rod bearings and valve springs are common failure items on S65 and S85 engines, particularly in high-RPM or track-driven applications. In addition, the factory camshaft profiles limit airflow and power potential at higher engine speeds. 

CarBahn Engineering Solutions 

The CarBahn S65 Street Performance with Cams engine addresses these limitations through targeted internal upgrades and airflow improvements. OEM connecting rod bearings are replaced with high-performance CarBahn bearings designed to improve durability under sustained high-RPM operation. CarBahn high-performance valve springs are installed to maintain precise valvetrain control at elevated engine speeds. 

To increase airflow and top-end power, the engine is upgraded with street-profile performance camshafts, improving volumetric efficiency while retaining smooth idle quality and street manners. The engine also features 2mm oversized 94mm CarBahn-CP forged pistons, increasing displacement and strength compared to the factory cast pistons. New head gaskets are installed to ensure reliable sealing. 

Comprehensive Rebuild & Timing Service 

Each engine receives a complete rebuild and timing service, including a full valve job with new hydraulic lifters, along with new timing chains, timing chain guides, timing chain tensioners, and all associated seals and gaskets. These components are replaced proactively to support long-term reliability and consistent performance at high RPM. 

Enhanced Airflow, Preserved Character 

With the addition of street-profile camshafts, the CarBahn S65 Street Performance engine delivers improved high-RPM breathing and increased power potential while maintaining the responsiveness, sound, and drivability that define the S65. The result is a more capable naturally aspirated engine suited for spirited street driving and track use. 

Proven CarBahn Assembly 

Each CarBahn S65 engine is assembled using the same processes and by the same personnel responsible for CarBahn’s championship-winning race engine programs. With over 46 years of BMW engine-building experience, these engines reflect the same attention to detail and durability that have powered multiple championship-winning efforts, including three prototype racing championships and two overall victories at the 24 Hours of Daytona (2011–2013).