L20 4.8L engine: specs, donor vehicles & swap notes
The L20 is a 4.8 L iron-block Generation IV engine built 2010–2017, rated 260–302 hp. It came in 3 vehicle applications, including Chevrolet Express/GMC Savana 2500/3500, Chevrolet Silverado 1500. Things to know: it has variable valve timing.
| Spec | Value |
|---|---|
| RPO | L20 |
| Family | Generation IV |
| Years | 2010–2017 |
| Displacement | 4.8 L / 293 ci |
| Horsepower | 260–302 hp |
| Torque | 295–305 lb-ft |
| Bore × stroke | 3.78 × 3.268 in |
| Compression | 8.80:1 |
| Block | iron |
| AFM/DOD | No |
| VIN 8th digit | A |
| Reluctor | 58x |
| Stock cam | Duration 191°/190° @.050 in. int./exh.; valve lift 0.457"/0.466" int./exh.; 114° LSA; 1-bolt gear, 4x; AFM No, VVT Yes. |
| Firing order | 1-8-7-2-6-5-4-3 |
| Oil capacity | 6.0 qt |
| Oil filter | 89017524 / PF48 |
| Spark plug | 12571164 / 41-985 |
| Plug gap | 0.040 in |
| Head casting | 799, 243 |
- Weak cast pistons. Fix: A set of forged pistons should be high on your priority list.
- Piston ring lands snap under boost heat. Fix: Install a four-corner steam kit.
- VVT tuning complexity (VVT delete common). Fix: Fortunately, deleting it is easy if you're so inclined.
Iron/Alum. heads, VVT, E85-capable
The L20 specs above are not yet confirmed against GM documents; GM ratings varied by year and vehicle.
How the L20 differs from the other 4.8 L Gen IV engines
The L20 is one of the two 4.8 L Gen IV engines we list: L20, LY2. From our engine table:
- Compression 8.80:1, the lowest of the group.
- Up to 302 hp from the factory; the LY2 makes up to 295 hp.
- Variable valve timing. The only 4.8 L Gen IV engine with it.
- Built E85-capable (flex fuel) from the factory. Swapping an L20 onto E85 still means wiring the flex sensor and setting up the tune for it.
- Built 2010–2017.
Swapping the L20: what to plan for
- Computer: the L20 has a 58x crank. An E38 or E67 matches it; a 0411/P59 also needs a 58x-to-24x converter box and its own sensor and knock-sensor wiring. Throttle and wiring have to suit the computer too. More: how to wire your LS (the full checklist for your engine and computer).
- VVT: on a VVT L20 the cam phaser and VVT timing cover change what bolts on: only some water pumps clear a VVT timing cover, and a non-VVT cam needs a VVT delete and a tune. More: accessory drives.
- From a truck or SUV (Chevrolet Silverado 1500, GMC Sierra 1500): truck accessory drive spacing (the farthest forward of the three), and the factory truck oil pan hangs low; most car swaps need a swap pan. More: accessory drive spacing · oil pans.
- From a van or work truck (Chevrolet Express/GMC Savana 2500/3500): the accessory drive and intake differ from the pickups; check what comes with it before you plan brackets (not confirmed in our data).
Refresh parts for the L20
From our Gen IV refresh list, the parts that are specific to the L20. Seals, gaskets and the upgrades worth doing on any Gen IV with the engine out are in the full refresh list, next to every torque spec.
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| Part | GM part # | Why for this engine |
|---|---|---|
| LSXceleration Gen IV LS knock sensor 28-23730 | 28-23730 | The L20 has its knock sensors on the side of the block. |
| GM Gen IV camshaft position sensor 12591720 (58x engines) | 12591720 | 58x L20: the cam sensor lives in the front cover. |
| Chevrolet Performance 58x crankshaft position sensor 12703627 | 12703627 | 58x L20: the crank sensor is behind the starter. |
From real tunes: 4.8 L on a Gen IV computer
What these settings look like in the 51 naturally aspirated pump-gas tunes for 4.8 L engines on Gen IV computers (E38, E67 and the 24x E40) in our tune library (as of 2026-10-15). Every RPO of this size is pooled, not only the L20, and so are all cams, heads and builds: that is why the ranges are wide. Use them to spot a value that is far outside what works, not as your numbers.
| Setting | Range | Median | Tunes |
|---|---|---|---|
| Hot idle target | 525 rpm to 825 rpm | 550 rpm | 51 (middle 80%) |
| Warm idle airflow, in gear | 6.2 g/s to 9.1 g/s | 7.0 g/s | 49 (middle 80%) |
| Idle spark (around 800 rpm) | 13° to 18° | 18° | 51 (middle 80%) |
| Power enrichment (PE) lambda | 0.79 to 0.85 | 0.83 | 49 (middle 80%) |
| WOT spark at 5,000 rpm, about 0.9 g/cyl | 9.5° to 23.5° | 16.5° | 51 (middle 80%) |
For starting values matched to your L20's cam, injectors and fuel, use the turn-on tune builder. Always finish on a dyno, and read our safe tuning limits before any wide-open pass.
Donor vehicles with the L20
Where to find an L20 at the junkyard: 3 vehicle applications below. Confirm it from the RPO sticker in the glovebox or the 8th VIN digit (for the L20: A).
| Vehicle | Years |
|---|---|
| Chevrolet Express/GMC Savana 2500/3500 | 2010–2017 |
| Chevrolet Silverado 1500 | 2010–2013 |
| GMC Sierra 1500 | 2010–2013 |
Buying a used L20
A used L20 has no single part number, so this page does not link a search. Confirm the engine from the RPO sticker or the 8th VIN digit (for the L20: A) before you buy.