LQ4 6.0L engine: specs, donor vehicles & swap notes
The LQ4 is a 6.0 L iron-block Generation III engine built 1999–2008, rated 300–335 hp. It came in 8 vehicle applications, including Chevrolet Silverado/GMC Sierra 1500HD/2500/2500HD/3500, GMC Sierra C3.
| Spec | Value |
|---|---|
| RPO | LQ4 |
| Family | Generation III |
| Years | 1999–2008 |
| Displacement | 6.0 L / 364 ci |
| Horsepower | 300–335 hp |
| Torque | 355–375 lb-ft |
| Bore × stroke | 4.0 × 3.622 in |
| Compression | 9.40:1 |
| Block | iron |
| AFM/DOD | No |
| VIN 8th digit | U |
| Reluctor | 24x |
| Throttle | Cable 1999-2002; drive-by-wire 2003-2007 (vans cable through ~2006) |
| Stock cam | 1999-2000 LQ4: Duration 191°/190° @.050 in. int./exh.; valve lift 0.457"/0.466" int./exh.; 114° LSA; 3-bolt cam gear; 2001-2007 LQ4: Duration 196°/207° @.050 in. int./exh.; valve lift 0.467"/0.479" int./exh.; 116° 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 |
Iron/Iron-Alum. heads, 1999–2000 engines have iron heads
The LQ4 specs above are not yet confirmed against GM documents; GM ratings varied by year and vehicle.
How the LQ4 differs from the other 6.0 L Gen III engines
The LQ4 is one of the two 6.0 L Gen III engines we list: LQ4, LQ9. From our engine table:
- Compression 9.40:1, the lowest of the group.
- Up to 335 hp from the factory; the LQ9 makes up to 345 hp.
- Built 1999–2008.
Swapping the LQ4: what to plan for
- Computer: 24x crank, so the LQ4 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; drive-by-wire 2003-2007 (vans cable 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 1500HD/2500/2500HD/3500, Chevrolet Suburban 2500/GMC Yukon XL 2500, GMC Sierra C3, GMC Sierra Denali and 2 more): 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, Chevrolet W-Series/GMC W-Series/Isuzu NPR): 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 LQ4
From our Gen III refresh list, the parts that are specific to the LQ4. 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 |
|---|---|---|
| Stock cylinder head bolt set, 1997-2003 LS (unequal-length design) | 12498545 | LQ4 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 LQ4 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 LQ4 read the cam at the rear of the block. |
From real tunes: 6.0 L on a Gen III computer
What these settings look like in the 490 naturally aspirated pump-gas tunes for 6.0 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 LQ4, 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 | 550 rpm to 900 rpm | 725 rpm | 477 (middle 80%) |
| Warm idle airflow, in gear | 6.5 g/s to 13.8 g/s | 7.4 g/s | 474 (middle 80%) |
| Idle spark (around 800 rpm) | 16° to 27° | 18° | 477 (middle 80%) |
| Power enrichment (PE) lambda | 0.78 to 0.87 | 0.83 | 479 (middle 80%) |
| WOT spark at 5,000 rpm, about 0.9 g/cyl | 10.0° to 26.0° | 16.6° | 489 (middle 80%) |
For starting values matched to your LQ4'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 LQ4
Where to find an LQ4 at the junkyard: 8 vehicle applications below. Confirm it from the RPO sticker in the glovebox or the 8th VIN digit (for the LQ4: U).
| Vehicle | Years |
|---|---|
| Chevrolet Express/GMC Savana 2500/3500 | 2003–2007 |
| Chevrolet Silverado/GMC Sierra 1500HD/2500/2500HD/3500 | 1999–2007 |
| Chevrolet Suburban 2500/GMC Yukon XL 2500 | 2000–2006 |
| Chevrolet W-Series/GMC W-Series/Isuzu NPR | 2003–2008 |
| GMC Sierra C3 | 2001 |
| GMC Sierra Denali | 2002–2007 |
| GMC Yukon/Yukon XL Denali and Chevrolet Suburban 1500 LTZ | 2002–2006 |
| Hummer H2 | 2002–2007 |
Buying a used LQ4
A used LQ4 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 LQ4: U) before you buy.
Next steps
- Plan a swap with the LQ4
- Find a cam for the LQ4
- What the LQ4 tune needs
- Compare every LS donor engine
- Size injectors and fuel pump
- LS torque specs
- Swap guides by vehicle
Questions about the LQ4
- LQ4 vs LQ9: what's the difference?
- Will a 4L60E bolt up to an LQ4 6.0, and will it survive behind it?
- What year did the LQ4/LQ9 become Gen IV?
- What wiring harness and computer options make the most sense for a 6.0 LQ4 LS swap if I don't want to learn tuning myself?
- What is the difference between the LQ4 and LQ9?
- Should I swap in the LS1 from my donor car or trade it for an LQ4/LQ9 6.0L when targeting about 450 rear-wheel horsepower?