LR4 4.8L engine: specs, donor vehicles & swap notes
The LR4 is a 4.8 L iron-block Generation III engine built 1999–2007, rated 255–285 hp. It came in 3 vehicle applications, including Chevrolet Tahoe/GMC Yukon, Chevrolet Silverado/GMC Sierra 1500.
| Spec | Value |
|---|---|
| RPO | LR4 |
| Family | Generation III |
| Years | 1999–2007 |
| Displacement | 4.8 L / 293 ci |
| Horsepower | 255–285 hp |
| Torque | 285–295 lb-ft |
| Bore × stroke | 3.78 × 3.268 in |
| Compression | 9.45:1 |
| Block | iron |
| AFM/DOD | No |
| VIN 8th digit | V |
| Reluctor | 24x |
| Throttle | Cable 1999-2002 pickups/SUVs; drive-by-wire 2003-2007 pickups/SUVs; cable in vans through 2006 |
| Stock cam | 1999 LR4: Duration 191°/190° @.050 in. int./exh.; valve lift 0.457"/0.466" int./exh.; 115.5° LSA; 3-bolt cam gear; 2000-2006 LR4: Duration 191°/190° @.050 in. int./exh.; valve lift 0.457"/0.466" int./exh.; 114° LSA; 3-bolt cam gear |
| Firing order | 1-8-7-2-6-5-4-3 |
| Oil capacity | 6.0 qt |
| Spark plug | 12571164 / 41-985 |
| Plug gap | 0.040 in |
- Knock sensor corrosion (water intrusion under intake). Fix: Replace sensors and harness; seal valley; new intake gaskets.
- Oil consumption (rings / PCV). Fix: Monitor level; check PCV and valve seals; rings if excessive.
Iron/Alum. heads
The LR4 specs above are not yet confirmed against GM documents; GM ratings varied by year and vehicle.
Swapping the LR4: what to plan for
- Computer: 24x crank, so the LR4 matches a Gen III computer (0411/P01 or P59); an E38 or E67 only reads 58x. Throttle and wiring have to suit the computer too. More: how to wire your LS (the full checklist for your engine and computer).
- Throttle depends on the year: Cable 1999-2002 pickups/SUVs; drive-by-wire 2003-2007 pickups/SUVs; cable in vans through 2006. Drive-by-wire needs the matching pedal and throttle body; the base Holley Terminator X is cable-only (the X Max does drive-by-wire).
- From a truck or SUV (Chevrolet Silverado/GMC Sierra 1500, Chevrolet Tahoe/GMC Yukon): 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 LR4
From our Gen III refresh list, the parts that are specific to the LR4. Seals, gaskets and the upgrades worth doing on any Gen III 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 |
|---|---|---|
| Chevrolet Performance 4.8L & 5.3L truck head gasket | 12575329 | Listed for the LR4; a new gasket goes on any time the heads come off. |
| Stock cylinder head bolt set, 1997-2003 LS (unequal-length design) | 12498545 | LR4 engines built through 2003 use the first-design, unequal-length bolts. Single use. Engines built from 2004 take the second-design, equal-length set (in the Gen IV list). |
| Chevrolet Performance Gen III LS knock sensor 12589867 (each) | 12589867 | The LR4 has its knock sensors in the valley, under the intake, where water collects. |
| Chevrolet Performance LS Gen III camshaft position sensor 19420911 | 19420911 | 24x engines like the LR4 read the cam at the rear of the block. |
From real tunes: 4.8 L on a Gen III computer
What these settings look like in the 138 naturally aspirated pump-gas tunes for 4.8 L engines on Gen III computers (0411/P01, P59) in our tune library (as of 2026-10-15). Every RPO of this size is pooled, not only the LR4, 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 850 rpm | 750 rpm | 129 (middle 80%) |
| Warm idle airflow, in gear | 5.3 g/s to 13.4 g/s | 6.4 g/s | 127 (middle 80%) |
| Idle spark (around 800 rpm) | 20° to 26° | 21° | 127 (middle 80%) |
| Power enrichment (PE) lambda | 0.80 to 0.85 | 0.83 | 138 (middle 80%) |
| WOT spark at 5,000 rpm, about 0.9 g/cyl | 13.0° to 25.0° | 18.8° | 137 (middle 80%) |
For starting values matched to your LR4'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 LR4
Where to find an LR4 at the junkyard: 3 vehicle applications below. Confirm it from the RPO sticker in the glovebox or the 8th VIN digit (for the LR4: V).
| Vehicle | Years |
|---|---|
| Chevrolet Express/GMC Savana 2500/3500 | 2003–2007 |
| Chevrolet Silverado/GMC Sierra 1500 | 1999–2007 |
| Chevrolet Tahoe/GMC Yukon | 2000–2006 |
Buying a used LR4
A used LR4 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 LR4: V) before you buy.