Chevrolet's Performance division has launched a new crate engine in the form of the L8P, namely a free-breathing small block that combines the best of both worlds. For starters, L8P is derived from the L8T truck motor of the Chevrolet Silverado HD, which is the only series-production small block from this generation to feature iron for the block instead of aluminum.
L8T also differs from other fifth-gen small blocks in a few other ways, including displacement. At 6.6 liters, it's larger than the 6.2-liter truck engine known as L87 with Dynamic Fuel Management and L86 with Active Fuel Management. In the Silverado HD with the L8T, you won't find any of the aforementioned fuel-saving technologies.
Finally, the lack of a stop-start function also makes the L8T a distinct member of the fifth-gen family. Chevrolet Performance already offers a crate version of this lump, which is good for the very same 401 horsepower at 5,200 revolutions per minute and 464 pound-feet (629 Nm) at 4,000 revolutions per minute as the series-production motor in the 2020-and-newer Silverado HD.
The L8P is obviously derived from the L8T, although the P in L8P likely stands for performance. Chevy promises 523 ponies at 5,800 rpm and 543 pound-feet (736 Nm) at 4,600 revolutions per minute from the very same displacement, meaning that Chevy's go-faster boffins had their way with a few internals.
Starting with the cam, the L8P uses an LT2-derived camshaft with a non-Active Fuel Management profile with additional duration. LT2 doesn't come as a crate engine. It's exclusive to the C8-generation Corvette Stingray and E-Ray, where it puts out a maximum of 495 horsepower at 6,450 rpm and 470 pound-feet (637 Nm) at 5,150 rpm with the NPP exhaust.
Photo: Chevrolet
According to Chevrolet Performance parts product manager James Bloss, the Golden Bowtie also switched to performance-oriented valves and springs. The 400-cube motor uses a forged-steel crankshaft, forged powder-metal connecting rods, hypereutectic aluminum pistons, a billet-steel hydraulic roller camshaft, 2.130 hollow intake valves, 1.590 sodium-filled exhaust valves, and an 87-millimeter throttle body.
The coil-on-plug engine features a direct injection system rated at 2,175 pounds per square inch or 150 bar if you prefer metric units. Breathing in through a composite intake manifold, the L8P further sweetens the deal with aluminum rectangular port heads, six-bolt nodular main bearing caps, as well as investment-cast roller trunnion rocker arms. Chevrolet Performance recommends 91-octane premium unleaded at the very least compared to 87-octane regular unleaded for both versions of the L8T.
L8P and L8T both use a 58X crankshaft reluctor wheel, and both run 10.8:1 for the nominal compression ratio. Maximum revolutions per minute? That would be 5,600 revolutions per minute for the L8T and 6,000 revolutions per minute for the performance-oriented L8P.
Chevrolet Performance recommends two versions of the Supermatic 6L80-E transmission for this crate motor, namely part numbers 19432682 and 19432684. The main difference is the stall torque converter: 2400K to 2800K for the 19432682 and 3000K to 3400K for the latter. In case you're planning on boosting the L8P, the Supermatic 6L80-E is rated at 650 pound-feet (881 Nm) as is.
After a 1:43 scale model of a Ferrari 250 GTO sparked Mircea's interest for cars when he was a kid, an early internship at Top Gear sealed his career path. He's most interested in muscle cars and American trucks, but he takes a passing interest in quirky kei cars as well. Full profile
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