What is the difference between GM’s L86 and L87 engines? – Jalopnik

The biggest difference between L86s and L87s is that L86s have occasional complaints and there were 28,000 L87 failures before GM recalled 600,000 trucks in the US alone. The 2014-2018 L86 engines and 2019 L87 engines are part of Chevrolet’s Gen-V LT “small-block” V8 family. Sorry for the quotes, but people love to debate Chevy’s small-block V8 architecture and whether LS and LT engines are successors or part of the same line. Anyway, L86s and L87s are 6.2-liter overhead-valve V8s – or pushrod, if you prefer – V8s with aluminum blocks and heads, direct injection, variable valve timing and oil-jet piston cooling. They each produce 420 horsepower and 460 pound-feet of torque.

The 6.2-liter V8 engines in Corvettes and Camaros are called “LT1”, a name taken from the Gen-I of the ’70s and the Gen-II 350s of the ’90s. GM loves to reuse classic engine designations to make it difficult to find the exact V8 you’re looking for in a Google search. Trucks get the L83 (which was also the nickname of the Cross-Fire Injection Gen-I 350 in ’82 and ’84 Corvettes) with a 5.3-liter displacement, as well as the 6.2-liter L86 and L87. The truck engines are also branded “EcoTec3”.

Where the L86 and L87 differ is in efficiency management technology. L86s have Active Fuel Management (AFM) that shuts down four cylinders under light loads. L87s have Dynamic Fuel Management (DFM) and can run on whatever cylinders they want, which can be as few as two. Unlike the L86, the L87s also received an automatic start/stop function. Oh, and thousands of L87s have shelled themselves due to defective connecting rods and crankshaft main bearings, that’s another difference. And yet JD Power presented Chevrolet Silverados and Tahoes in the 2023 Dependability Awards, even though that year is in the heart of the L87 problem area.

That includes some similarities, but what are the differences between engines like the L86, L87 and LT1? Well, not much actually. Basically, the L86 and L87 have longer runners at the intake to emphasize low-end torque, as opposed to the higher revs the LT1 is tuned for. The LT truck also has a deeper oil pan. Otherwise, the LT1, L86 and L87 engines are identical*.

Oh, there’s that damn sparkler. Obviously they are not identical; After all, LT1s and L86s are not currently under investigation by the National Highway Traffic Safety Administration for engine failures, nor are they the subject of a massive recall. This is not so much because the L87 has design flaws, but rather because of manufacturing flaws. Missing wrist pin clips on connecting rods, improperly finished crankshafts with improper dimensions, and connecting rod bearings that build up sediment keep L87s sidelined. Ultimately, cranks from supplier Questum Macimex and connecting rods from American Axle & Manufacturing may be to blame.

Well, miles per gallon isn’t everything. The L87 may have lower exhaust emissions! Let’s take a look at the window sticker for a 2024 GMC Sierra 1500 Denali Ultimate with the Ford co-developed 10-speed automatic transmission. It says that 539 grams of CO2 are emitted per kilometer. Now let’s take a look at the window sticker for a 2018 GMC Sierra Denali with the old 8-speed transmission. It’s also a crew cab, also 4WD, also has a 3.23 rear axle ratio and has the 6.2 EcoTec3 – which in this case would be an L86. Oh, it emits 524 grams of CO2 per kilometer. That puts it at 15 grams less than the newer, more efficient L87. Still, the smog rating is a 3 out of 10 for the 2018 and a 6 out of 10 for the 2024, so the L87 certainly wins there.

So there. The biggest differences between L86s and L87s are minor efficiency improvements, CO2 and smog emissions, and a global recall of (currently) approximately 721,000 vehicles.