GM Performance 454ci LSX Long-Block V8 and 6L80E 6-Speed Automatic Transmission

The combination of the Chevrolet Performance LSX 454 and the 6L80E transmission is the ultimate “heavy-hitter” setup for modern pro-touring and street-strip builds. It pairs a massive, high-revving naturally aspirated big-inch small block with a robust, wide-ratio 6-speed automatic.

In 2026, this remains a flagship choice for those who want Big Block displacement with the packaging and reliability of the LS architecture.

1. The Engine: LSX 454 Long-Block

This is not a standard aluminum LS. It uses the LSX Bowtie cast-iron block, which is significantly stronger and can handle massive amounts of boost or nitrous if you decide to go beyond the stock specs.

Listing Details

• Engine Number: 23083007
• GM Performance 454ci LSX Long-Block V8
• GM Performance 6L80E Six-Speed Automatic Transmission
• Gen IV Small Block
• Cast Aluminum LSX-Branded Cylinder Heads
• Forged Aluminum Pistons
• Plasmaman Billet Anodized Intake Manifold
• Moroso High-Clearance Oil Pan
• Tru-Ram Polished Stainless Steel Headers
• ICT Eight-Bolt Flywheel
• Build Invoice

2026 Market Pricing:

• Long-Block (No Intake/Fuel): $12,500 – $14,500

• Fully Dressed Crate Engine: $16,000 – $18,500

2. The Transmission: 6L80E 6-Speed Automatic

The 6L80E (and its heavier-duty sibling, the 6L90E) was the workhorse of the Silverado and Corvette for years. In 2026, it is favored for swaps because of its integrated Transmission Control Module (TCM), which simplifies wiring.

• Torque Rating: Typically rated up to 650 lb-ft in stock “Performance” trim.

• Gear Ratios: Features a very “short” 1st gear (4.02:1) for incredible off-the-line acceleration and two overdrive gears for highway cruising.

• 2026 Price (New/Reman): $3,800 – $5,200 (including torque converter).

3. Critical “2026 Status” Checklist

• The Weight Factor: The LSX 454 uses an iron block. It weighs about 100-120 lbs more than an aluminum LS3. You may need to adjust your front spring rates if you are swapping this into a car that previously had an aluminum engine.

• Oil System: The 454ci displacement creates high crankcase pressure. In 2026, it is highly recommended to use a high-quality catch can and a windage tray to prevent oil aeration at high RPMs.

• 6L80E “Flare” Issues: These transmissions can suffer from “shift flare” (a slight RPM jump between gears) if not tuned correctly. When pairing it with the LSX 454, a custom TCM tune is mandatory to ensure the shift points match the engine’s massive torque curve.

• The “LS7” Connection: Because the LSX 454 uses LS7-style heads, you must use an LS7-specific intake manifold. Standard LS1/LS2/LS3 intakes will not bolt up.

4. Swap Logistics & Electronics

• The Controller: Chevrolet Performance offers a Connect & Cruise harness kit specifically for this engine/trans combo. This is the most reliable way to get them talking in 2026.

• Cooling: The 6L80E generates significant heat during aggressive driving. A dedicated transmission cooler (separate from the radiator) is a non-negotiable requirement for this much power.

• Drive Shaft: The 6L80E is physically larger and longer than a 4L60E or TH400. You will likely need to shorten your driveshaft and potentially massage the transmission tunnel of older muscle cars.