The L5P is arguable one of the strongest Duramax power plants ever produced, and rightfully needed as it was originally released with a whopping 445 horsepower and 910 foot pounds of torque, spanking its predecessor by nearly 50 horsepower and 150 torque. Was it a clean slate revision from the LML? Close, but there are still many similarities between the two that surpass merely the 6.6L displacement.
For starters, due to the increased power levels, the block itself was strengthened via a new casting featuring induction hardened cylinder walls, five nodular iron bearings and a four bolt, cross bolted main bearing caps to keep everything in place. Next, the crankshaft's physical diameter was increased to avoid the somewhat prevalent broken crank and heavy duty sintered powdered metal alloy rods and even updated pistons. Next up is a revised camshaft to increase airflow throughout the cylinder heads even at higher RPM's. Finally, upgraded engine cooling comes from revised piston cooling jets that outflow the LML by 50% and even a redeisgned engine oil cooler that also outperforms the LML's cooler by 50%.
And to reduce the potential of a cracked block, a new, two piece engine oil pan was unveiled, featuring essentially a built-in girdle for added ridigity. The upper portion is cast aluminum for weight savings and heat dissipation while the bottom half is laminated steel, again, acting as a girdle.
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