LH9 5.3L engine: specs, donor vehicles & swap notes
The LH9 is a 5.3 L aluminum-block Generation IV engine built 2010–2012, rated 300 hp. It came in 2 vehicle applications, including Hummer H3 Alpha, Chevrolet Colorado/GMC Canyon. Things to know: it has variable valve timing.
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| Spec | Value |
|---|---|
| RPO | LH9 |
| Family | Generation IV |
| Years | 2010–2012 |
| Displacement | 5.3 L / 325 ci |
| Horsepower | 300 hp |
| Torque | 320 lb-ft |
| Bore × stroke | 3.78 × 3.622 in |
| Compression | 9.70:1 or 9.90:1 |
| Block | aluminum |
| AFM/DOD | No |
| VIN 8th digit | P |
| Reluctor | 58x |
| Stock cam | Cam PN 12625437; duration 190°/191° @.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 |
- Excessive oil consumption (2010-12). Fix: Disabling the AFM can mitigate this problem.
- Composite intake manifold cracking. Fix: Replace intake manifold and gasket; do not overtighten bolts.
- Knock sensor water intrusion. Fix: Check for water intrusion near knock sensors during intake manifold service.
- Thermostat sticking / cooling system wear. Fix: Replace weak water pumps ($400-$800) and thermostats ($150-$250) before they fail.
Aluminum, VVT, E85-capable
The LH9 specs above are not yet confirmed against GM documents; GM ratings varied by year and vehicle.
How the LH9 differs from the other 5.3 L Gen IV engines
The LH9 is one of the eight 5.3 L Gen IV engines we list: LC9, LH6, LH8, LH9, LMF, LMG, LS4, LY5. From our engine table:
- Aluminum block. Among the 5.3 L Gen IV engines, the LH9 shares it with the LC9, LH6, LH8, LS4; the LMF, LMG, LY5 are iron.
- No AFM. The LC9, LH6, LMG, LS4, LY5 have it, so the LH9 is the easier cam-swap candidate of the group.
- Compression 9.70:1 or 9.90:1, within the group's 9.6–10:1 spread.
- Up to 300 hp from the factory (7th of the eight 5.3 L Gen IV engines we list; the group tops out at 320 hp).
- Variable valve timing. Also on the LC9, LMF.
- Built E85-capable (flex fuel) from the factory. Swapping an LH9 onto E85 still means wiring the flex sensor and setting up the tune for it.
- Built 2010–2012.
Swapping the LH9: what to plan for
- Computer: the LH9 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 LH9 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.
Refresh parts for the LH9
From our Gen IV refresh list, the parts that are specific to the LH9. 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.
| Part | GM part # | Why for this engine |
|---|---|---|
| LSXceleration Gen IV LS knock sensor 28-23730 | 28-23730 | The LH9 has its knock sensors on the side of the block. |
| GM Gen IV camshaft position sensor 12591720 (58x engines) | 12591720 | 58x LH9: the cam sensor lives in the front cover. |
| Chevrolet Performance 58x crankshaft position sensor 12703627 | 12703627 | 58x LH9: the crank sensor is behind the starter. |
What real 5.3 L Gen IV (E38) tunes run
What these settings look like in the 192 naturally aspirated pump-gas tunes for 5.3 L engines on an E38 computer in our tune library (as of 2026-10-15). These files do not record which 5.3 L it was (LC9, LMG, LY5 or another) or which vehicle, so this is the 5.3 L Gen IV (E38) naturally aspirated pool, not one RPO. Most files have no stock or aftermarket cam label, so stock and aftermarket stay in one table. The ranges are wide because every cam and build in that pool is included. 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 800 rpm | 535 rpm | 192 (middle 80%) |
| Warm idle airflow, in gear | 6.0 g/s to 10.5 g/s | 6.8 g/s | 192 (middle 80%) |
| Idle spark (around 800 rpm) | 16° to 20° | 18° | 191 (middle 80%) |
| Power enrichment (PE) lambda | 0.76 to 0.85 | 0.78 | 184 (middle 80%) |
| WOT spark at 5,000 rpm, about 0.9 g/cyl | 13.0° to 22.5° | 14.5° | 192 (middle 80%) |
For starting values matched to your LH9'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 LH9
Where to find an LH9 at the junkyard: 2 vehicle applications below. Confirm it from the RPO sticker in the glovebox or the 8th VIN digit (for the LH9: P).
| Vehicle | Years |
|---|---|
| Chevrolet Colorado/GMC Canyon | 2010–2012 |
| Hummer H3 Alpha | 2010 |
Buying a used LH9
A used LH9 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 LH9: P) before you buy.