Ultimate Diesel Builder's Guide - - Udbg Tech -


Now six years into its pro­duc­tion run, the ver­dict is still out to how much horse­power and torque the LML Duramax can han­dle. While we haven’t heard or seen a lot of rod or piston fail­ures on stock bot­tom-end en­gines yet, it doesn’t mean they’ll han­dle more power than what the LBZ or LMMS will. In fact, the pis­tons are very sim­i­lar to the LBZ and LMM en­gines, which means the 650hp range may just put you on the car­nage radar.

One edge the LML piston might have over the LBZ and LMM ver­sions is that its de­sign elim­i­nates wrist pin bush­ings. While GM claims it did this to achieve a lighter weight ro­tat­ing assem­bly (along with a lighter crank and lighter con­nect­ing rods), it added strength back into this area of the piston. We’ve seen sev­eral 700rwhp LMLS sport­ing the stock bot­tom end, a few of which were run­ning com­pound turbo ar­range­ments. The key to these trucks liv­ing at this point has been torque lim­i­ta­tion at low rpm via spot-on EFILIVE tun­ing. UDBG

In case you’re won­der­ing, the ver­dict is still out on how much horse­power and torque a stock bot­tom end will han­dle on the ’11 and newer LML mills. With rods sim­i­lar to what you’ll find in the LBZ and LMM’S and slightly stronger pis­tons, it looks promis­ing, we cau­tion any­one build­ing an en­gine past the 700rwhp mark.

Al­though the LML Duramax shares a sim­i­lar piston to what you’d find in the LBZ and LMM en­gines, GM did away with the wrist pin bush­ings that were thought to be the key weak point (ac­cord­ing to those in the af­ter­mar­ket). This might ex­plain why more LML pow­ered trucks are sur­viv­ing the 650 to 700-rwhp range on stock in­ter­nals.

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