Chevrolet’s Winning Formula

Chevrolet’s Winning Formula

Powering Performance on the Track with Chevrolet Engines.

Chevrolet has long been a dominant force in endurance and sports car racing, particularly in the IMSA WeatherTech SportsCar Championship. The automaker's high-performance engines have powered some of the most iconic race cars, delivering speed, reliability, and efficiency. In this article, we take a look into the engines Chevrolet uses in IMSA competition, their specifications, and the cars that rely on them to push the limits of performance.

Chevrolet's IMSA Racing Engines

Chevrolet competes in IMSA primarily through its Corvette Racing and Cadillac Racing programs. The engines used in these efforts vary based on the regulations of their respective classes, but each shares a common goal: delivering maximum power and durability in endurance racing conditions.

5.5L V8 LT6.R - Corvette C8.R (GT Daytona Pro, GT Daytona)

One of the most well-known and technologically advanced engines Chevrolet fields in IMSA is the 5.5L V8 LT6.R found in the Corvette C8.R. Based on the naturally aspirated LT6 engine from the Corvette Z06 road car, the LT6.R has been specifically modified for endurance racing.

Specifications:

  • Displacement: 5.5 liters (5500cc)
  • Configuration: Naturally aspirated V8
  • Valvetrain: Dual Overhead Camshafts (DOHC), 32 valves
  • Power Output: Approx. 500-550 hp (per IMSA regulations)
  • Torque: Approx. 480-500 lb-ft
  • Fuel System: Direct injection
  • Rev Limit: 7,400 RPM (regulated by IMSA)
  • Lubrication System: Dry sump
  • Weight: Approx. 300 lbs (engine alone)

The LT6.R engine is optimized for durability, as IMSA endurance races like the Rolex 24 at Daytona and the 12 Hours of Sebring require engines to withstand extreme temperatures and prolonged high-RPM operation. The flat-plane crankshaft design allows for a higher-revving engine compared to the cross-plane crank V8s of previous Corvette race cars, providing a distinctive exhaust note and improved efficiency.

Cars Using the LT6.R Engine:

  • Corvette C8.R (IMSA GT Daytona Pro and GT Daytona Classes)
  • Corvette Z06 GT3.R (2024)

5.5L V8 LMC55R - Cadillac V-Series.R (GTP Hybrid)

In the premier Grand Touring Prototype (GTP) class, Chevrolet's Cadillac Racing program runs the Cadillac V-Series.R, a hybrid prototype that competes against the likes of Acura, Porsche, and BMW. At the heart of this car is the 5.5L V8 LMC55R, a purpose-built endurance racing engine developed in collaboration with Pratt & Miller.

Specifications:

  • Displacement: 5.5 liters (5500cc)
  • Configuration: Naturally aspirated V8
  • Valvetrain: Dual Overhead Camshafts (DOHC), 32 valves
  • Power Output: Approx. 670 hp (combined with hybrid system per IMSA regulations)
  • Torque: 500+ lb-ft
  • Fuel System: Direct injection
  • Rev Limit: 8,000 RPM
  • Lubrication System: Dry sump
  • Weight: Approx. 330 lbs

The LMC55R engine is paired with a mandatory hybrid energy recovery system (ERS), developed in compliance with IMSA’s new GTP regulations. This system includes a Bosch-supplied electric motor, a Williams Advanced Engineering battery pack, and an Xtrac transmission, producing additional bursts of power while improving efficiency.

Cars Using the LMC55R Engine:

  • Cadillac V-Series.R (GTP Class)

The Cadillac V-Series.R made an impressive debut in the IMSA WeatherTech SportsCar Championship, scoring multiple wins, including victories at the 2023 12 Hours of Sebring and 6 Hours of Watkins Glen.

Evolution of Chevrolet’s IMSA Engines

Chevrolet's engines in IMSA have undergone significant evolution over the years. From the early small-block V8s in classic Corvettes to the modern high-revving LT6.R and the hybrid-powered LMC55R, Chevrolet has continuously refined its powertrain technology to adapt to changing regulations and competitive demands.

Previous Notable Chevrolet IMSA Engines:

  1. 5.5L V8 LS5.5R (Cadillac DPi-V.R) – Used in the Cadillac DPi-V.R from 2017-2022, this naturally aspirated V8 was a powerhouse in the Daytona Prototype international (DPi) era.
  2. 5.5L V8 LT5 (Corvette C7.R) – A pushrod, naturally aspirated engine that powered the championship-winning Corvette C7.R in the GT Le Mans (GTLM) class.
  3. 7.0L V8 LS7.R (Corvette C6.R) – A monstrous big-block used in endurance racing, producing immense torque and power in the mid-2000s.

Chevrolet’s Future in IMSA Racing

With IMSA embracing hybrid technology and efficiency-driven regulations, Chevrolet’s engineering team continues to develop cutting-edge powertrains to remain competitive. The introduction of the LMC55R hybrid-assisted V8 showcases the brand’s commitment to sustainable high-performance racing, while the naturally aspirated LT6.R continues Chevrolet’s legacy of pure V8 power in GT competition.

Whether it's the roar of a naturally aspirated V8 or the integration of hybrid technology, one thing remains certain: Chevrolet’s engines will continue to be a force to be reckoned with in IMSA endurance racing for years to come.