Bo185

Do the Gen IV 4.8L have the AFM ports in the blocks like the 5.3Ls and are they drilled.

I though about making a 4.8L AFM on it for better mileage on a project car.

L7 Sierra

You'll need the computer wo control the AFM and the wiring harness.

I was looking at my truck deeply last weekend as I changed the oil and cleaned the motor area up, and I saw no extra wiring to control the AFM cylinoids.

Bo185

I have seen the AFM valley covers FS and the think the plug is on them. I can get a 4.8L cheap and just need the a PCM, solenoids, and lifters. I think all Gen IV blocks have the AFM ports. i know the LS2 and L92 have them and even the LS3. So guess I'll try a 4.8L

ForcedTQ

iTrader: (1)

One other thing you would need to check would be the camshaft. I believe the AFM motors utilize a VVT Cam to compensate for torque optimization when running in V4 mode. Check on it, I might be wrong. Also, check the tune (if you have EFI live or HPT) of an AFM equipped truck and look at it carefully! Primarily for separate tables controlling timing, fueling, and transmission torque converter operation when in V4 mode. Good luck, and if you get it to work let us know, I might just have to pick up a new 5.3 aluminum block and try it out!

Bo185

The 5.3l AFM don't have VVT. The L76 6.0L does though. Check out the media site below.

The good thing is looks like they finally got the tuning right for the AFM and the 6l80 as the 5.3Ls will now have both in 09.

Found this on GM media site http://media.gm.com/us/powertrain/en...09/09truck.htm
The Gen IV cylinder block shares two key design elements with GM’s original small block V-8: a 90-degree cylinder angle and 4.4 inch bore centers. Beyond that, the latest small block applies design, casting and machining technologies that were unfathomable in the 1950s.

The Gen IV block debuted in 2005 as the foundation for the 400-hp LS2 V-8 in the Chevrolet Corvette, and Pontiac GTO, and the Cadillac CTS-v in 2006. Although it’s constructed of cast iron rather than aluminum, the Vortec 4.8L engine block applies the same improvements as in the LS2, tailored for the demands of truck application. It was developed with the latest math-based tools and data acquired in GM’s racing programs, and it provides an exceptionally light, rigid foundation for an impressively smooth engine. Its deep-skirt design helps maximize strength and minimize vibration. The bulkheads accommodate six-bolt, cross-bolted main-bearing caps that limit crank flex and stiffen the engine’s structure. A structural oil pan further stiffens the powertrain.


The new-generation small block is cast with oil ports in its V, or valley, to accommodate new technologies offered in the latest Vortec V-8s, and others still to come. As a result, knock sensors located in the valley on Gen III Vortec V-8s have been moved to the outside of the block, while the cam sensor has been moved from the rear of the block to the front cover.


Looks like they are cast I bet they are drilled as well.


Active Fuel Management
All Gen IV Vortec 5.3L V-8s feature GM’s industry leading Active Fuel Management technology (AFM). AFM temporarily de-actives four of the 5.3L’s cylinders under light load conditions. It increases fuel economy approximately 6 percent under the federal government’s required testing procedure and potentially more in certain real-world driving conditions. Yet truck owners don’t sacrifice superior V-8 power and performance to go farther on a tank of gas.

Active Fuel Management stems from a simple premise: most truck owners have more power than they need much of the time. Many choose powerful V-8 engines to be prepared for the occasional heavy load, but during routine commuting that powerful engine operates at a fraction of its capability. Volumetric efficiency is impaired, and that means less than optimal fuel mileage. AFM offers a common-sense solution. It saves fuel by using only half of the Vortec 5.3L’s cylinders during some driving conditions, and seamlessly reactivates the other cylinders when a driver demands full power for acceleration or load hauling.

Managed by the new E38 engine control module (ECM), AFM automatically shuts down every second cylinder, according to firing order, during light-load operation. In engineering terms, this allows the working cylinders to achieve better thermal, volumetric and mechanical efficiency and lowering cyclical combustion variation from cylinder to cylinder. As a result, AFM delivers better fuel economy and lower operating costs. Perhaps the most sensible thing about AFM is that it harnesses the engine’s existing capabilities, starting with the potential designed into the E38 ECM. The only mechanical components required are special valve lifters for cylinders that are deactivated, and their control system. Active Fuel Management relies on three primary components: De-ac (fordeactivation) or collapsible valve lifters, a Lifter Oil Manifold Assembly (LOMA), and the ECM.

One of the most sophisticated engine controllers, the E38 ECM (below) measures load conditions based on inputs from vehicle sensors and interprets that information to mange more than 100 engine operations, from fuel injection to spark control to electronic throttle control. AFM adds an algorithm to the engine control software to manage cylinder deactivation and reactivation. When loads are light, the E38 automatically closes both intake and exhaust valves for half of the cylinders and cuts fuel delivery to those four. The valves re-open to activate all cylinders when the driver demands brisk acceleration or full torque to move a load. The engine’s electronic throttle control (ETC) is used to balance torque following cylinder deactivation or reactivation. The transition takes less than 20 milliseconds, and is virtually indiscernible to most drivers.

Valve lifters are operated by the engine’s camshaft, and lift a pushrod that operates the valves in the cylinder head. In the Gen IV Vortec 5.3L, the De-ac lifters are installed in cylinders 1, 4, 6 and 7, while the remaining cylinders use conventional lifters. The hydraulically operated De-ac lifters have a spring-loaded locking pin actuated by oil pressure. For deactivation, hydraulic pressure dislodges the locking pin, collapsing the top portion of the lifter into the bottom and removing the ability to lift the pushrod. The bottom of each De-Ac lifter rides up and down on the cam lobe but the top does not move the push rod. The valves do not operate and combustion in that cylinder stops. During reactivation, the oil pressure is removed, and the lifter locks at full length. The pushrods, and therefore the valves, operate normally.

The final AFM component is the LOMA. This cast-aluminum assembly is installed in the Vortec 5.3’s V, or valley, in place of a conventional engine block cover. The LOMA holds four solenoids, control wiring and cast-in oil passages. The solenoids are managed by the ECM, and each one controls oil flow to a De-Ac Lifter, activating and de-activating the valves at one cylinder as required for Active Fuel Management.

The Gen IV Vortec 5.3L’s fuel injectors are identical for all cylinders; those feeding the de-activated cylinders are simply shut down electrically by the ECM during de-activation. When the cylinders are deactivated, the engine effectively operates as a V4. AFM operation is load based, as measured by the ECM using dozens of inputs, overlain with the driver’s demand for power as measured by throttle application. AFM’s response time is measured in milliseconds. Operation is always transparent to the driver. The engine returns to V-8 mode the instant the controller determines that acceleration or load requires additional power.

The benefits are substantial. Active Fuel Management reduces overall emissions to the extent that less fuel is used. Further, the savings reflected in EPA numbers may not account for AFM’s full impact. Owners who primarily travel long distances at steady speeds will see further fuel-economy improvements.

The exhaust system for the Gen IV Vortec 5.3L required careful tuning to maintain optimal noise and vibration control. In four-cylinder operation, the engine creates second-order exhaust pulses; in eight-cylinder operation, in creates fourth-order exhaust pulses. The system requires special pipe tuning to account for both.