5.3L LM7


What and why a 5.3L LM7?

An LM7 is simply a third generation General Motors LS-based small-block engine (or aka a SBC).  Maybe better explained here: Wikipedia.

I chose a LM7 because they are fairly plentiful and easy to find around my region, and for that reason, relatively affordable, if not downright “cheap”.  At least at the time I was doing the build.  There are many, many oem and aftermarket parts available at the parts store and online.

This LM7 is a factory 5.3 Liter displacement engine from approximately a 2004 GMC Sierra pickup with approximately 180k miles.  Internals were left completely stock and original.  I did a basic “rattle can rebuild”, new gaskets and water pump.  I chose to keep the factory fuel injection, electronic throttle body (DBW aka “Drive By Wire”), along with the factory wiring harness and ECU. I modified the wiring harness to remove unneeded wiring and added my own fuse/relay block.  I also changed the factory truck oil pan for better clearance, although it was not completely necessary, and chose an electric cooling fan.

I have not done a “tune” to the original ECU, other than disabling the VATS (vehicle Anti-Theft System), unused sensors and/or codes to prevent MILs (Malfunction Indicator Lamp or Check Engine Light).

Along with this engine, I have installed a modified/updated 4L60E (ECU controlled) transmission.  This combination allow for more HP to the ground than is necessary for this lightweight pickup.  Meaning Fun.  It regularly leaks HP from the rear tires.

Donor engine from GMC Sierra. Click to enlarge – use browser back button to return.