Engine - | | M3
S65 Engine — Street Performance Stroker (4.6L)
The CarBahn S65 Street Performance Stroker engine is engineered for enthusiasts seeking increased displacement, torque, and responsiveness while preserving the high-revving, naturally aspirated character that defines the BMW S65 platform. Featuring a 4.6-liter stroker configuration, this engine delivers stronger midrange performance and improved drivability for street and track-day use, while addressing the known durability limitations of the OEM engine.
OEM Limitations
The factory 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 OEM displacement limits torque output and responsiveness, especially in street-driven performance builds.
CarBahn Stroker Engineering
The CarBahn S65 4.6L Stroker engine addresses these limitations through a combination of displacement increase and targeted internal upgrades. The engine features a 4.6-liter stroker rotating assembly paired with forged CarBahn-CP pistons, increasing displacement while improving strength and thermal stability over the factory cast pistons.
High-performance connecting rod bearings replace the OEM bearings to improve durability under sustained high-RPM operation. CarBahn high-performance valve springs are installed to maintain valvetrain control at elevated engine speeds, ensuring reliability during aggressive street and track use. New head gaskets are installed to ensure proper sealing and long-term reliability.
Comprehensive Rebuild & Timing Service
Each engine receives a complete rebuild and timing service as part of the stroker conversion. This includes 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 durability and consistent performance.
Increased Displacement, Preserved NA Character
With its increased displacement, the CarBahn S65 4.6L Stroker engine delivers improved torque and throttle response while retaining the naturally aspirated sound, responsiveness, and high-RPM character that make the S65 unique. The result is a more engaging and capable engine for drivers who want maximum NA performance without sacrificing reliability.
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.