LH6. The LH6 replaced the LM4 in 2005. It was the first Gen. 4 LS truck engine and offered Active Fuel Management (AFM). The LH6 was available in GM mid-size SUVs until 2009. It was also available in GM pickups from 2007-09. It was known as the Vortec 5300. LC9. The LC9 was introduced in 2007. Originally, it was a flex fuel version of the LH6.

This means they can be easier to find than some other engine models. The Gen. 4, 5.3L, aluminum engines also had cathedral port heads, similar to the LS1, LS2, and LS6. There are tons of performance parts available, and most will bolt right on. Below are some upgrades that will improve the performance of the LH6, LC9, LH8, and LH9 engines ...

Aug 4, 2004 · Generation IV Internal Engine - GenIV 5.3 LH6 info - Vortec 5300 Gen IV V-8 (LH6) Truck Engine 2005 Model Year Summary New engine for Buick Rainier, Chevrolet TrailBlazer EXT, GMC Envoy XL, GMC Envoy XUV, GMC Envoy Denali, GMC Envoy XL Denali and Saab 9-7 Aluminum-intensive construction Displacement on Demand...

The number one thing we do is tap and plug the oil towers that feed the AFM lifters. Since we’re converting the engine away from that slightly less reliable system to a more traditional camshaft and lifter system, we also want to make sure oil wouldn’t leak out of these towers past the o-rings of the LS2 valley pan we’re going to use.

Engine Block Specifications. Casting Numbers: 125771048, 12601900, 12569513, 12568573. Material: Aluminum. Displacement: 5.3L / 325 c.i.d.

May 4, 2017 · Now we get into some of the parts that finally make this look like an engine again. The LH6 of Project Ron Burgundy is getting the AFM, Active Fuel Management, replaced with a more traditional system with an upgraded camshaft. So, to match that cam we’re adding the Texas Speed and Performance .660” dual valve springs with titanium retainers.

The information below applies to vehicles with the original engine still installed. If you have a second-hand vehicle that doesn't match the info below, the engine may have been swapped out. Follow this link for help Identifying an LS Engine by Inspection. Click on the RPO code in the table to see more details about that engine.

If you don't have the VIN, you can still identify the engine. Below you'll find pictures and descriptions to help you spot the important differences followed by an identification chart organized by displacement. Click the links in the chart for further identification and more details on that series or engine.

Mar 16, 2007 · The L33 is also refered to as a gen III engine, but, despite the similarities with the third generation, it's very much a gen IV engine I believe. GM compares the engine block with the LM4, both being aluminum and lightweigt. It's more like an ls6 block however and it possibly even has the LS2/gen IV structure.

Mar 27, 2025 · Generation IV Internal Engine - Question about piston strength - Hello guys, I have been trying to do a basic rebuild a LH6 5.3 LS engine, unfortunately had to bore out the cylinders to +0.25mm, and was advised by machine shop to use +0.25mm oversized pistons from silvolite because I said I wanted stock strength and...