Crankshafts: There are 6 or 7 variations of LT cranks. 5.3L (L82 L83 L84 L8B) cast crank, typical 6.2L wet sump forged crank (LT1 L86 L87), supercharged 6.2L wet sump (LT4), 6.2L dry sump (LT1 and LT2 Vette, each unique), supercharged dry sump 6.2L (LT4 LT5), and 6.6L wet sump (L8T L8P). The dry sump cranks have longer crank snouts and oil pump drive with LT1/4/5 being 0.84" longer than wet sump and LT2 being 2.15" longer. LT4 and LT5 crankshafts are not drilled in the 7-8 rod throw for extra strength. The LT5 crankshaft has an additional heat treat that will give it a gold appearance. L8T crankshafts have two extra bobweights adjacent to the #3 main, often called center counterweight (CCW) for a total of 8 counterweights. All 6.2L and 6.6L crankshafts are forged steel and have gun drilled mains while the 5.3L cranks are cast and do not have gun drilled mains. Gun drilled mains improve bay-to-bay breathing in the crankcase to reduce windage. All LT crankshafts have 8-bolt rear flange, 58x reluctor wheel, and use slip fit oil pump drive on the front.
Connecting Rods: There are at least 3 versions of LT rods. Typical 5.3L and 6.2L L82 L83 L84 L86 L87 LT1. L8T are significantly slimmer beam and use a smaller diameter wrist pin. LT4 and LT5 rods have extra ribs along the beam edges and twin ribs on the cap. All OEM LT rods are 6.098" long, use "cracked caps", and are made from powdered metal forgings.
Pistons: There are at least 4 versions of pistons. 5.3L are 3.780" bore and are cast hypereutectic material with a small dome (L82 L83 L84 L8B) and 0.943" diameter pins. 6.2L are 4.065" diameter and are also cast hypereutectic with small dome (L86 L87 LT1) and 0.943" pins. 6.2L supercharged engines are 4.065" bore and are forged flat tops (LT4 LT5). Finally the 6.6L are 4.065" bore, have smaller 0.927" pin diameter and raised pin location as a result of the extra stroke in the 6.6L, these are cast hypereutectic pistons with a small dish to reduce compression ratio (L8T).
The longer snouts on dry sump crankshafts are to drive thicker oil pumps (scavenge pump along with typical pressure pump), which lead to taller front timing covers, different crank pulleys/front accessories, and include dry sump specific oil pans and external oil reservoirs. Luckily, GM's adjusting of crank pulley offset on the dry sump LT4 results in the same serpentine belt location as the wet sump LT4 so that the remaining front accessories still interchange for C7 Corvette.
What This Means To You.
With an idea of your power goals for your LT swap, it's best to understand the power holding capability of the OEM rotating assembly components when choosing a donor. L8T rods and pistons appear to be the least durable although the L8T crankshafts have proven to be among the most durable with BTR and Scoggin Dickey both demonstrating >2000hp output using that stock crankshaft (with aftermarket rods and pistons). We anticipate that the standard issue 5.6L and 6.2L components can live up to 1000hp with proper tuning, fuel quality, and other supporting parts. The changes GM implemented for the LT4 and LT5 would certainly raise the ceiling for power capability if you can score those parts for your swap!
For a full discussion and visual queues about Gen V LT crankshafts, connecting rods, and pistons, see 10:21-15:30 of the full LT Swap video on YouTube:
