Ls3 crate motor and harness upgrade question

[Dan Shook]

If I purchase the 430 hp version ls3 crate motor and the gm install harness package and later on decide to upgrade the cam shaft and valve spring to the parts used in the 525 hp ls3 crate motor what changes need to be made to the electronics that control the engine package and what are the costs associated with the upgrade? Thanks

[andrewb70]

You can have the engine tuned by a competent tuner or, I do believe, GM sells the LS3 525HP ECU separately. I'd opt for the latter.

Andrew

[Z06vet]

If you are going to use the 525 parts, you are probably better off just buying the 525. You would either need to change to the 525 ecm, or have your existing ecm tuned for the new cam. In the end you will be close to the same price (or more if you pay someone to change the cam). For simplicity & warranty purposes, the 525 just makes sense. I feel like there are better cams out there than the 525 to use on your LS3. However most will require a spring & pushrod change, as well as tuning. In the end you will end up with more power than the 525 for near the same price as the 525, but lose the warranty.

[icemanrd19]

Buy the 480 version rated at 495hp. Enjoy it. Upgrade what you want and get it tuned. Only the tune is different for the engine controllers

[SD67]

Agree with the others, if you are going to upgrade, just buy the 480 or 525 with the factory harness.

[parsonsj]

Myself: I'll never use a GMPP controller or harness again. I'd opt for an aftermarket harness and an OEM controller that matches that harness.

• I always end up re-wiring the relays and fuse box
• The harness is usually way too long and assumes simple fan and fuel pump solutions
• The controllers themselves are simplified to reduce warranty issues
• The actual tune is usually very rich to deal with the simple tuning
• The controller box uses full-size relays, rather than the mini-relays of modern cars