GEN4 to GEN3 DBC

5.3L Conversion Engines

Conversion Kit - $1850.00

Parts & Installed

+ Camshaft Kit of choice, + Base Engine

We have developed this “Conversion” for various reasons. We can source newer 2008-2013 lower mile engines including a larger selection of aluminum block engines. This generation engine also has slightly higher compression pistons, better flowing LS6/243/799 Heads, better flowing Intake Manifold that also accepts a 92mm Throttle Body. We typically use the larger TSP Stage III Low-Lift Truck Cam in this combination and it will make right around 400HP / 380TQ, about a +10% improvement over the Gen3 5.3L’s.

Gen4 GM Vortec engines almost all have VVT (Variable Valve Timing) & the HIGHLY PROBLEMATIC AFM (Active Fuel Management, aka DOD-Displacement On Demand) - See detailed info on both below. This kit removes both of those technologies while increasing performance with an aftermarket Camshaft of your choice (additional cost). This conversion to the Gen3 EFI also adds flexibility of transmission options. Any manual transmission can be used with no Speed Sensor / VSS (although recommended). The DBC (drive-by-cable) throttle body of Gen3 EFI allows the use of the 700R4 or 200R4 transmissions with required TV Cable as well as either the 4L60/65/70e or 4L80e with 13 pin connectors. Any of the older TH350 or TH400 run perfectly as well with no Speed Sensor / VSS.

The Process: This is a very labor intensive conversion. We first remove the Crankshaft from the engine and replace the Gen4 58-tooth Reluctor Wheel with the Gen3 24-tooth Reluctor Wheel and associated Crank Position Sensor. The Front “Phaser” Timing Cover is removed and discarded along with the VVT Camshaft and Cam Phaser itself. A new 3 Bolt Camshaft of your choice is installed along with a new Camshaft Upper Timing Gear & ARP Bolts. The AFM/DOD Valley Cover with solenoids is removed and discarded. A new L92 non AFM/DOD Valley Cover is installed. The Cylinder Heads are removed and ALL 16 (only 8 are AFM/DOD) are removed and discarded and replaced with 16 New LS7 Style Lifters and Lifter Trays. The Cylinder Heads are reinstalled using new GM MLS head gaskets and new torque to yield Cylinder Head Bolts. The rest of the engine is reassembled using all New Gaskets as well as an Oil Pump O-Ring. A brand new Gen3 DBC Wiring Harness is installed along with a new aftermarket 92mm DBC Throttle Body with new IAC and TPS. See complete list of parts below:

  • GM/Delphi LS7 Style Lifter, 16 Set

  • GM 5.3/5.7 LS1 Multi-Layer Steel Cylinder Head Gasket, PAIR

  • TSP Gen IV Cylinder Head Bolt Kit, 2 Sets

  • GM L92 Truck Valley Cover, No PCV Provision

  • GM LS2 Timing Cover

  • ARP LS1/LS2/LS6 Camshaft Bolt Kit

  • GM 1x Three-Bolt Timing Chain Upper Sprocket

  • GM 24X Reluctor Wheel For LSx Crankshaft

  • GM 24X Crank Position Sensor

  • TSP LS Timing Cover Gasket

  • TSP LSX Rear Cover Gasket

  • TSP LS Oil Pan Gasket

  • TSP Valve Cover Gaskets LS1/2/3/7 with Bolt Grommets

  • Oil pump O-ring

  • TSP LS Front Crank Seal

  • TSP LS Rear Main Seal

  • GM LS2 Lifter Tray, 4 Set

  • DBC Wiring Harness, Manual or 4L60/80 Operation

  • 92mm Throttle Body w/ TPS & IAC

  • ECM, 2002 GM 12212441

AFM / DOD - Active Fuel Management / Displacement On Demand

AFM / DOD is the primary reason to consider converting a Gen4 to Gen3. It is notorious for failing when one of the special AFM / DOD lifters does not extend and return to normal use (V8 mode). When deleting the AFM / DOD a cam swap is required as well since the cam is unique to this operation as well. Therefore we opt to also eliminate the VVT Cam and use a traditional Cam which significantly increases our options.

AFM / DOD Operation & Failure Details

(Information here is compiled from various online forums, Lt1swap.com, etc.)

For the lifter to go into V4 mode, oil is pumped into the lower groove (nearest the roller) When the lifter is sitting on base circle, the spring in the lifter is trying to push the two parts apart, when oil pressure is introduced, the pins in the inner lifter part do not immediately go inward. The opening ramp on the cam lobe has a what i'm going to call a ''lash ramp'' to say similar to how a solid lifter cam works. This small ''lash ramp'' takes the pressure off the pins long enough for hydraulic force to push them inward, than the lifter starts riding up the opening lobe ramp, and the inner part of lifter goes downward for V4 Mode. Cylinders 1,7 4,6 are designed to shut down, and therefore those lobes of the cam have this ramp for the AFM lifter to function correctly. 

To my knowledge there are 3 lifter designs from GM. Lower is factory original out of a 2007. Upper is a replacement GM Lifter with about 5,000 miles on it before it locked down.

VVT - Variable Valve Timing

Although VVT is an improvement in performance it significantly reduces cam selection. Additionally, as increased lift and duration VVT cams are used the amount of VVT must be limited to maintain adequate valve to piston clearance. Therefore when “bigger” VVT cams are used the effectiveness of the VVT technology decreases and the benefits are essentially lost.