Engine - | | M3
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).
Designed to be both stronger and more cost-effective than the BMW OEM factory engine, the CarBahn Engine benefits from Steve Dinan's 46 years of race engine-building expertise. His engines have powered multiple championship-winning cars, including three prototype racing titles and two overall victories at the 24 Hours of Daytona (2011-2013).
Choose CarBahn for superior engine tuning.
Engine Core Acceptance Parameters
Must be complete core (factory engine, from oil pan to valve cover)
Block Requirements
- No holes or cracks in casting
- No holes or crack in covers
- No bore damage that cannot be honed out
- No thrust surface damage
- No journal surfaces damage
- No bolt hole damage that can’t be repaired
Head Requirements
- No holes or cracks in casting
- No holes or crack in covers
- No thrust surface damage
- No journal surfaces damage
- No bolt hole damage that can’t be repaired
Possible Additional Repair Charges
For damaged items that are not normally changed during an overhaul and cannot be repaired or serviced:
- Valves
- Crankshafts
- Camshafts
- Guides
- ValveTronic mechanism
- Vanos mechanism
Engine Warranty & Additional Information
Our engines are very strong and can often be very reliable even at power levels above what is recommended. The durability usually depends on the quality and the reliability of the tune and other aftermarket components added to the engine management system.
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Engines with CarBahn Software Tunes
All engines listed with a stage number (ex. Stage 1 & Stage 2) are designed to be road car engines and are covered for 2 years, 24,000 miles providing they have a CarBahn tune and there are no other parts on the car that have caused a premature failure. -
Engines with Another Company's Tune
All engines listed with a stage number (ex. Stage 1 & Stage 2) are designed to be road car engines and are covered are covered for 2 year, 24,000 miles providing they you stay under our recommended torque limits. Torque limits are indicated on the product listing. Warranty does not cover failures from the tune or aftermarket fuel injection components that caused the failure. It is CarBahn's full discretion to determine cause of failure. If Torque limit is exceeded, the warranty is for materials and workmanship only. -
Racing Engines
Racing engines are designed to be raced and are covered for materials and workmanship only. Racing engines should be rebuilt periodically based on run time or mileage. Warranty does not cover failures from the tune or aftermarket fuel injection components that caused the failure. It is CarBahn full discretion to determine cause of failure.