LT Engines

L86 6.2L EcoTec3 Engine Specs: Performance, Bore & Stroke, Cylinder Heads, Cam Specs & More

L86 engine swap

This L86 was swapped into a ’56 Bel Air. (Image/

The L86 is a Gen. 5, 6.2L, small-block engine powering 2014-present GM trucks and SUVs. They are known as the EcoTec3 6.2L engines.

These engines use a longer intake runner than its cousin, the LT1. This helped the L86 produce peak torque 500 rpm sooner than the car version of the 6.2L engine. However, it falls about 35 horsepower behind the LT1 at maximum output.

The L86 engines are all-aluminum, feature Active Fuel Management (AFM) and Variable Valve Timing (VVT), and are Flex Fuel-capable (E85).

The engines also use direct fuel injection technology, which shoots fuel directly into the combustion chamber instead of the intake runner.

The information listed here is for a stock engine.

L86 Engine Ratings
Compression Ratio11.5:1
Horsepower Rating420 hp @ 5,600 rpm
Torque Rating460 ft.-lbs. @ 4,100 rpm
L86 Application Information
VIN 8th DigitYearMakeModel
J2015-presentGMCYukon / XL
L86 Engine Block Specs
Part Number12619171
Material319-T7 Aluminum
Displacement6.2L / 376 c.i.d.
Bore Dia. 4.065 in.
Stroke3.622 in.
Deck Height9.240 in.
Bore Spacing4.400 in.
Thrust Bearing Location#3 Main, 1/2 thrust
Main Cap Style6-Bolt
Main Housing Bore Dia.2.751 in.
Cam Housing Bore Dia.Bore 1/5 = 2.346 in. Bore 2/4 = 2.326 in. Bore 3 = 2.307 in.
Cam-to-Crank Centerline4.914 in.
Oil Squirters8
L86 Rotating Assembly Specs
Piston MaterialHypereutectic Cast Aluminum Alloy
Piston StyleDomed (with reliefs for the exhaust valve and direct injector)
Piston Volume0.6cc (net)
Wrist Pin Dia.0.9431 in. (full floating)
Connecting Rod MaterialPowdered Metal
Connecting Rod StyleI-Beam
Connecting Rod Length6.098 in.
Connecting Rod Housing Bore2.225 in.
Connecting Rod BoltsM9 x 1 x 43
Connecting Rod Part Number12654242
Crankshaft Material1538MV Forged Steel
Crankshaft Part Number (Wet Sump)12623492
Crankshaft Main Journal Dia.2.559 in.
Crankshaft Rod Journal Dia.2.100 in.
Reluctor Wheel58X
Harmonic BalancerIron
L86 Cylinder Head Specs
Part Numbers12678633, 12620544, 12620545
Casting Number12620549
Material319-T7 Aluminum
Combustion Chamber Volume59.02cc
Intake Port ShapeRectangle
Intake Runner Volume297cc
Intake Manifold Bolt PatternLT1-Specific
Exhaust Port ShapeFlat Oval
Exhaust Runner Volume107cc
Cylinder Head Bolt StyleTorque to Yield (TTY)
Cylinder Head Bolt Size(10) M12 x 1.75, M8 corner bolts
L86 Camshaft Specs
Part Number12629512
Duration @ .050 in. (int./exh.)200°/207°
Valve Lift (int./exh.)0.551 in./0.524 in.
Lobe Separation Angle116.5°
Cam Gear Attachment1-Bolt
Cam Gear Poles4X
Active Fuel Management (AFM)Yes
Variable Valve Timing (VVT)Yes
L86 Valvetrain Specs
Lifter StyleHydraulic Roller
Lifter Link StylePlastic Lifter Tray
Lifter Body Diameter0.842 in.
Pushrod Dimensions7.85 in. (long) x 0.342 (dia.)
Rocker Arm Mounting StylePedestal
Rocker Arm StyleDie-Cast, Roller Fulcrum
Rocker Ratio1.8
Rocker OffsetNone
Valve Spring StyleBeehive
Valve Spring ColorNatural
Intake Valve Angle12.5° / Splayed 2.61°
Exhaust Valve Angle12.0° / Splayed 2.38°
Intake Valve MaterialSteel, Hollow Stem
Intake Valve Dia.2.126 in.
Exhaust Valve MaterialSteel, Sodium Filled
Exhaust Valve Dia.1.590 in.
Timing Chain Guide StyleSpring-Loaded Tensioner
L86 Intake, Throttle Body, Fuel Injector Specs & More
Intake ManifoldTruck Style
Throttle Body87mm, 4-Bolt
Throttle ControlElectronic (Drive-by-Wire)
Fuel Injector P/N12656931
Fuel Injector Flow123 lbs./hr. (2,205 max psi)
Flex Fuel Capable (E-85)Yes
Crankshaft Reluctor Ring58X
Camshaft Sensor LocationTiming Cover
Oil Pan Capacity
8 qt.
Oil Pump (Wet Sump)Variable Displacement
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  1. Gary Keeling says:

    Very nice. What’s the recommended oil change and what oil should b used in this engine??

  2. Kennan Drake says:

    At the factory 0-20 oil is used.

  3. Where can I find the torque specs for this motor and the sequence for tighten.

  4. Where can I find the torque specs for this motor and the sequence for tighten

  5. Thank you for this valuable info! I need to save this to my desktop. I was surprised to find out it has a forged crank. Are all of the other internals cast?

  6. I have a 2017 GMC Sierra all terrain with the l86 and my truck is not flex fuel capable. Is specifically states in the owner’s manual not to run e85 in this truck.

    • I have a 2015 Silverado with the L86 engine. My owner’s manual says I can run E85. Yet my L86 is not a flex fuel engine. No flex fuel stickers, no yellow fuel cap,no e85 fuel sensor.

  7. Thanks for giving me credit on the photo. For those of you who really need to understand what’s involved, please read my Gen V installation guide (updated yesterday).

  8. I agree with Kevin, I have a 2018 Sierra with the 6.2 liter and I have to run 91 octane or higher no flex fuel allowed. I think who ever posted that article might want to recheck their information.

    • @Jerry, are you saying that your 2018 can’t run flex fuel like E85? Actually it can, you have to add the sensor to the open plug down by the gas tank and turn it on in the ECM. After that you can run up to E85 in the truck. I did some research and also verified the plug was there on my 2018 Sierra 6.2l

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