Corvette C7 Z06 LT4 compressor supercharger GM 12666991 EATON LT1

The GM 12666991 is the official factory part number for the Eaton 1.7L TVS (R1740) supercharger assembly found on the 2015–2016 Corvette C7 Z06.

For a high-end inventory like Buy Mustang parts Ltd, this unit is a “tier-one” asset, often sought after for both direct OEM replacements and “LT4-style” conversions on LT1 engines.

1. Technical Specifications: Eaton R1740

This 1.7L unit was a significant evolution over the previous LS9 2.3L blower, focusing on high-RPM efficiency and rapid boost delivery.

• Displacement: 1.74 Liters per revolution.

• Max Speed: 20,160 RPM (over 5,000 RPM faster than the LS9).

• Rotors: 4-lobe, 160° high-helix twist for improved thermal efficiency.

• Cooling: Integrated dual-brick air-to-liquid intercoolers (housed under the lid).

• Boost: Approx. 9.4 PSI in factory configuration.

2. Part Number Context: 12666991

While the R1740 is used across the LT4 family (Camaro ZL1, CTS-V), the 12666991 specifically identifies the 2015–2016 Corvette specific casting.

• The 2017+ Update: In 2017, GM updated the LT4 supercharger (often seen as part #12670278) with a taller lid and angled intercooler bricks to address “heat soak” issues on the track.

• Compatibility Note: The 12666991 uses the “short lid.” If you are selling this to a customer with a 2017+ Z06, they can use it, but it lacks the improved cooling geometry of the later years.

3. LT4 Blower on an LT1 Engine?

This is a very common inquiry for parts specialists. While the LT4 supercharger can be mounted to an LT1 (Stingray), it is not a “plug-and-play” swap:

• Adapter Plates: The LT4 supercharger has a different bolt pattern than the LT1 cylinder heads. Companies like ICT Billet or DSX Tuning make adapter plates to bridge this gap.

• Fueling: The LT1 fuel pump and injectors will max out quickly under boost. Most “LT1-to-LT4” swaps require at least the LT4 high-pressure fuel pump and injectors.

• Clearance: The standard Stingray hood will not clear this supercharger. Customers will need to upgrade to a Z06-style “bulge” hood or an aftermarket cowl hood.

4. Inventory Valuation (March 2026)

Based on current market trends for genuine GM performance parts:

Pro Tip for Buy Mustang parts Ltd: When listing this unit, always specify if the Intercooler Bricks and Bypass Valve Actuator are included. A “bare” blower is worth significantly less than a “drop-in” assembly.

5. Critical Inspection Points

Before shipping a 12666991 unit:

1. Rotor Coating: Peek into the inlet; the black PTFE coating on the rotors should be intact. Significant “peeling” indicates debris ingestion or high-mileage wear.

2. Brick Leaks: Pressure test the intercooler bricks. The internal “dual-bricks” are known to develop hairline leaks, which will cause the engine to consume coolant and misfire.

3. Pulley Condition: Check the snout for play. If the pulley has a “wobble” or the bearings are noisy when spun by hand, the snout requires a rebuild.