BMW 8678953 Engine Motor Crankshaft M340I B58 3.0L

( Manufacturer Part Number: 8678953 ), ( Part Type: Engine Motor Crankshaft ), ( Country Of Origin: Germany )

Review BMW B58 3.0l Engine Motor Crankshaft Oem Note fits G20 2019–2025

The **BMW G20 M340i (8678953) 2019 2025 model year** represents a refined yet high-performance iteration of the third-generation BMW 3 Series, blending cutting-edge engineering with the brand s signature driving dynamics. At its core lies the **B58 3.0-liter twin-turbocharged inline-six engine**, a masterpiece of modern automotive design that delivers a seamless fusion of power, efficiency, and precision. This naturally aspirated-inspired yet turbocharged powerplant is a marvel of BMW s **High Precision Engine (HPE)** manufacturing process, featuring a lightweight aluminum block, forged crankshaft, and a dual-turbocharged layout that ensures instant throttle response without the typical turbo lag. The B58 s **direct and port fuel injection** system, combined with a **variable valve timing (Valvetronic)** mechanism, optimizes performance across the entire rev range while maintaining exceptional fuel economy and emissions compliance. With a **peak output of 306 horsepower (225 kW) and 300 lb-ft (406 Nm) of torque**, the M340i propels the G20 from 0-60 mph in approximately **5.2 seconds**, a testament to BMW s ability to marry sportiness with practicality.

The **crankshaft** within this engine is a critical component, meticulously forged from high-strength steel to withstand the immense stresses of high-revving operation and turbocharged boost pressures. Its precision-machined counterweights and balanced design ensure smooth operation, minimizing vibrations and maximizing durability qualities that are especially vital in a high-performance application like the B58. The crankshaft s integration with the engine s **direct-drive turbochargers** (one per bank) allows for rapid spooling, enabling the M340i to accelerate with a linear, almost instantaneous surge of power, a hallmark of BMW s turbocharged inline-six architecture. This engine is further enhanced by the **iDrive 8 infotainment system**, which integrates seamlessly with the **Nappa leather-trimmed interior**, **adaptive suspension**, and **xDrive all-wheel-drive system**, ensuring that every aspect of the driving experience is both engaging and technologically advanced.

Beyond its mechanical prowess, the **2019 2025 G20 M340i** benefits from BMW s **SmartDrive suite of semi-autonomous driving aids**, including **adaptive cruise control with Stop & Go**, **lane-keeping assist**, and **active steering assistance**, which enhance both safety and convenience without compromising the driver s connection to the road. The **M Sport Package** further elevates the driving experience with **sport-tuned suspension**, **19-inch alloy wheels**, and **unique body cladding**, while the **optional M Performance Package** takes it a step further with **stiffer springs, dampers, and a limited-slip differential** for a more aggressive, track-ready demeanor. Whether cruising on a highway or navigating a twisty road, the B58-powered M340i delivers a harmonious blend of luxury, performance, and BMW s legendary driving pleasure, making it a standout choice for enthusiasts who demand both sophistication and excitement.

### **Pros and Cons of Buying a 2019 2025 BMW G20 M340i (B58 3.0L Twin-Turbo Engine)**

#### **Overview**

The **BMW G20 M340i** (2019 2025) is a high-performance sedan based on the **G20 platform**, featuring a **3.0L B58 twin-turbo inline-6 engine** paired with an **8-speed Steptronic transmission**. It competes with luxury performance sedans like the **Audi S5, Mercedes-AMG C63, and Lexus RC F-Sport**. Below is a detailed breakdown of its strengths and weaknesses.

---

### **Pros**

#### **1. Strong Engine and Performance**

- The **B58 3.0L twin-turbo inline-6** produces **340 hp (253 kW) and 370 lb-ft (503 Nm) of torque**, delivering **0-60 mph in 4.5 seconds** (depending on trim and transmission tuning).

- **Smooth power delivery** with minimal turbo lag due to BMW s **variable geometry turbochargers** and **high-pressure fuel injection**.

- **All-wheel drive (xDrive)** provides excellent traction in all conditions, improving handling and stability.

- **Launch Control** and **Sport Plus mode** enhance driving dynamics for enthusiasts.

#### **2. Refined and Comfortable Ride**

- The **G20 platform** offers a **spacious, premium cabin** with high-quality materials (especially in higher trims like **M Sport or M Performance**).

- **Adaptive suspension (M Suspension)** improves comfort while maintaining sharp handling.

- **Quiet cabin** with effective noise insulation, making long drives pleasant.

- **Large infotainment screen (10.25" in later models)** with **iDrive 7** (improved in 2022 ) offers **Apple CarPlay, Android Auto, and wireless connectivity**.

#### **3. Luxury and Interior Features**

- **Premium materials** (aluminum trim, soft-touch surfaces, ambient lighting) in higher trims.

- **Heated/ventilated seats** (available in M Performance), **massage function**, and **adaptive cruise control (BCC)**.

- **Panoramic sunroof** (standard in many trims) enhances the driving experience.

- **Digital cockpit (iDrive display)** provides customizable information at a glance.

#### **4. Safety and Technology**

- **Collision Warning with Automatic Emergency Braking**

- **Lane Departure Warning & Automatic Steering Assist**

- **Adaptive Cruise Control with Stop & Go**

- **Blind Spot Monitoring with Traffic Alert**

- **High-speed wireless charging pad** (available in some markets).

- **Parking sensors (rear and front)** and **360-degree camera** (optional in base models, standard in higher trims).

#### **5. Resale Value and Brand Prestige**

- BMW retains **strong resale value** compared to many competitors, especially for well-maintained examples.

- The **M340i badge** adds **desirability**, making it a **good investment** if kept in good condition.

- **BMW s global service network** ensures easy maintenance and parts availability.

#### **6. Driving Dynamics and Handling**

- **Precise steering** with **adjustable damping** (M Suspension) for a **sporty yet comfortable** ride.

- **Electronic Differential Lock (EDL)** improves off-road and cornering grip.

- **Available M Performance Package** (stiffer suspension, sport exhaust, unique badging) enhances track-like performance.

#### **7. Fuel Efficiency and Practicality**

- **Combined MPG (EPA estimate): 18-22 MPG** (city/highway), which is **better than most turbocharged V6s** in this class.

- **Spacious trunk (15.7 cu. ft.)** and **rear seats** (though not as roomy as a full-size sedan like the 5 Series).

- **Available **panoramic sunroof** and **rear entertainment system** improve practicality.

---

### **Cons**

#### **1. High Cost of Ownership**

- **Fuel costs** ( $100 $120/month at $3.50/gal) due to **turbocharged engine inefficiency** compared to naturally aspirated V8s.

- **Maintenance expenses** (timing chain, turbo upgrades, high-end BMW parts) can be **significantly higher** than mass-market competitors.

- **Insurance premiums** are **one of the highest** in its class due to performance and theft risk.

#### **2. Turbocharger and Engine Reliability Concerns**

- The **B58 engine** is **robust but not bulletproof** **turbo failure, oil leaks, and carbon buildup** can occur if **maintenance is neglected**.

- **Timing chain stretch** (if not serviced every **60k 100k miles**) can lead to **engine misfires or failure**.

- **Carbon buildup on intake valves** (common in turbocharged engines) may require **expensive valve cleaning** ( $1,000 $1,500).

#### **3. Infotainment and Tech Lag**

- **iDrive 7 (2022 ) is improved**, but **earlier models (2019 2021) have a clunky interface**.

- **No wireless CarPlay/Android Auto in base models** (requires **aftermarket solutions**).

- **Slow software updates** compared to competitors like **Mercedes MBUX or Audi Virtual Cockpit**.

#### **4. Interior Quality Variability**

- **Base M340i models** have **plastic-heavy interiors** that feel less premium.

- **Lower trims lack M Performance features** (e.g., sport seats, unique badging, stiffer suspension).

- **Some reports of rattles and squeaks** in early G20 models (improved in later years).

#### **5. Resale Depreciation**

- While **better than most luxury cars**, the **G20 platform has seen rapid depreciation** ( 30 40% over 5 years).

- **M340i holds value better than base 340i**, but **not as well as a used M5 or AMG C63**.

#### **6. Competition from More Efficient Alternatives**

- **Hybrid/electric options** (e.g., **BMW i4, Audi A6 TFSI-e, Lexus LS Hybrid**) offer **better fuel economy and lower running costs**.

- **Naturally aspirated V8s (e.g., Mercedes-AMG C63 AMG Line)** provide **more raw power with simpler maintenance**.

- **Japanese luxury sedans (Lexus RC F-Sport, Acura TLX Type S)** often have **lower ownership costs**.

#### **7. Potential Electrical Gremlins**

- **BMW s electrical system** (infotainment, sensors, driver aids) can be **prone to software glitches**.

- **Some reports of **iDrive freezing or sensor failures** (e.g., blind-spot cameras, adaptive cruise)**.

#### **8. Limited Off-Road Capability**

- While **xDrive provides AWD**, the **G20 is not a true off-road vehicle** **lower trims lack traction control and lift**.

- **M Performance models improve this**, but **not as capable as an X5 or X6**.

---

### **Final Conclusion & Recommendation**

#### **Who Should Buy a 2019 2025 BMW G20 M340i?**

**Enthusiasts who prioritize driving dynamics** The **B58 engine, M Suspension, and launch control** make it a **fun-to-drive luxury sedan**.

**Those who value BMW s brand prestige** The **M340i badge** adds **desirability and resale appeal**.

**Buyers who want a refined, high-performance sedan** The **comfort, tech, and luxury features** justify the cost for the right owner.

**People who can afford high maintenance costs** If **budgeting for premium servicing**, it s a **great long-term investment**.

#### **Who Should Avoid It?**

**Budget-conscious buyers** **Fuel, insurance, and maintenance costs add up quickly**.

**Those who prioritize fuel efficiency** **Hybrids/electrics offer better MPG with lower running costs**.

**First-time luxury car owners** **BMW s complexity (iDrive, electrical issues) can be frustrating**.

**People who want a simple, low-maintenance car** **Turbocharged engines require more attention than naturally aspirated V6s**.

#### **Best Use Cases**

- **Daily driver for an affluent owner** who enjoys **performance and luxury**.

- **Track or autocross enthusiast** (with **M Performance upgrades**).

- **Investment purchase** (if **well-maintained and serviced**).

- **Buyers who prefer BMW s driving feel over raw power** (vs. a V8 AMG).

#### **

Details:

LOT #180 - 2020 BMW G20 M340I B58 3.0L RWD 8-SPEED AUTOMATIC TRANSMISSION 41K MILES MINERAL GRAY PAINT COLOR. 2019 2020 2021 2022 2023 2024 2025 BMW G20 M340I B58 3.0L ENGINE MOTOR CRANKSHAFT OEM NOTE 8678953. LIGHT SCORING ON 2 JOURNALS.

part #: 8678953 prices

• $630.71-$7199.99

specifications cranshafengin:

• for models: G20
• for makes: Bmw
• for years: 2019-2025
• mpn: 8678953
• part type: Engine Motor Crankshaft
• country of origin: Germany

payments cranshafengin:

• credit card: Discover
• other
• wallet: Apple-pay

returns cranshafengin:

• policy: No Returns

seller cranshafengin:

• rating: 99.2%
• city: Rancho Cordova, California
• # reviews: 2627

shipping cranshafengin:

• transit: 4-9 Days
• cost: $0.00
• type: Fixed
• service: Standard
• class: Standard

offer cranshafengin:

• quantity: 1
• sold: 0
• availability: In Stock
• options: Ship-to-home
• best offers: True
• started: February 19, 2026

general cranshafengin:

• condition: For parts or not working
• Car Truck Parts Accessories > Engines Engine Parts > Crankshafts

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