The biggest difference between L86s and L87s is that L86s have occasional complaints and 28,000 L87 failures happened before GM recalled 600,000 trucks in the U.S. alone. The 2014-2018 L86 and 2019-current L87 engines are part of Chevrolet’s Gen-V LT “small-block” V8 family. Sorry for the quotes, but people love arguing about Chevy’s small-block V8 architecture and whether LS and LT engines are successors or part of the same lineage. Anywho, L86s and L87s are 6.2-liter overhead valve — 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 hp and 460 pound-feet of torque.
The 6.2-liter V8s in Corvettes and Camaros are called “LT1,” which is a name pilfered from the ’70s Gen-I and ’90s Gen-II 350s. GM loves reusing classic engine designations to make it hard to find the exact V8 you want in a Google search. Trucks get the L83 (which was also the moniker of the Cross-Fire Injection Gen-I 350 in ’82 and ’84 Corvettes) in 5.3-liter displacement, as well as the 6.2-liter L86 and L87. The truck engines also feature “EcoTec3” branding.
Where the L86 and L87 differ is in efficiency-managing technology. L86s have Active Fuel Management (AFM) that shuts off four cylinders under light loads. L87s have Dynamic Fuel Management (DFM) and can operate on whatever cylinders they want, which can be as few as two. Unlike the L86, L87s also gained automatic start/stop capability. Oh, and thousands of L87s have grenaded themselves because of failed connecting rods and crankshaft main bearings, that’s another difference. And yet J.D. Power featured Chevrolet Silverados and Tahoes in its 2023 Dependability Awards, even though that year is in the heart of L87 problem territory.
Dead lifters and defect investigations
There have been complaints of both L86s and L87s (and even LT1s and L83s) experiencing lifter failures. Reports indicate the AFM and DFM systems cause lifter noise and accelerate their demise, so Engine Labs tore open three L83s and an L86 with failed lifters. They discovered that it was the normal lifters that failed rather than those responsible for cylinder shutoff. Some of the lifter problems could stem from the fact that all direct-injected Gen-V LTs can build up carbon on the intake valves, which is a common problem for direct-injection engines in general. After enough carbon cakes on, usually at the top of the valvestems, the valves can get stuck and put extra stress on the rest of the valvetrain — the lifters, pushrods, and camshaft.
That covers some similarities, but what are the differences between engines like the L86, L87, and LT1? Well, not much, really. Basically, the L86 and L87 have longer runners on the intake to emphasize low-end torque, as opposed to the higher-rpm power the LT1 is tuned to deliver. Also, the truck LT has a deeper oil pan. Other than that, the LT1, L86, and L87 engines are identical*.
Oh, there’s that darn asterisk. Obviously they’re not identical; after all, LT1s and L86s aren’t currently under investigation by the National Highway Traffic Safety Administration for engine failures, nor are they the subject of a massive recall. This isn’t so much due to the L87 having design flaws as much as suffering from manufacturing defects. Missing wrist pin clips on connecting rods, improperly finished crankshafts with incorrect dimensions, and rod bearings that build up sediment keep sidelining L87s. In the end, cranks from supplier Questum Macimex and connecting rods from American Axle & Manufacturing may be to blame.
Prepare yourself for the efficiency improvements of the L87 over the L86
Let’s not focus on L87 failures at the moment. Rather, let’s highlight how start/stop and DFM improved fuel efficiency in the L87 over the L86. The U.S. Department of Energy’s ratings at fueleconomy.gov show that an L86-equipped 2018 Chevrolet Silverado four-door with all wheel-drive (AWD) gets 20 mpg highway/15 mpg city/17 mpg combined. Meanwhile, an identically spec’d 2019 Chevrolet Silverado with the L87 has — and get ready to pick your jaw up from the floor — a rating of 20 mpg highway/16 mpg city/17 mpg combined.
Well, miles-per-gallon isn’t everything. The L87 may have lower tailpipe emissions! Let’s look at the window sticker for a 2024 GMC Sierra 1500 Denali Ultimate with the Ford co-developed 10-speed automatic transmission. It says it puts out 539 grams of CO2 per mile. Now let’s look at the window sticker for a 2018 GMC Sierra Denali with the old 8-speed. It’s also a crew cab, also 4WD, also has a 3.23 rear axle ratio, and it has the 6.2 EcoTec3 — which in this case would be an L86. Oh, it puts out 524 grams of CO2 per mile. That puts it at 15 grams less than the newer, more efficient L87. Still, the smog rating is a 3 out of 10 on the 2018 and a 6 out of 10 for the 2024, so the L87 at least manages to win there.
So, there. The biggest differences between L86s and L87s are minute efficiency improvements, CO2 and smog output, and a global recall of (currently) around 721,000 vehicles.
