LS3/L99 conversion

Hey guys, been awhile since I've posted. I'm swapping my LS6 with a 2011 l99 that I'm converting to an LS3 getting rid of the DOD and holding on to the VVT for a later time so I'm going to use an LS3 timing chain cover for the CPS. I just picked up a brand new wiring harness super cheap that will take some modifications for the new E38 ECM. I was wondering what transmission module the conversion guys were using. I know Holden has a 6.0 Lumina with a module that works perfect but I was thinking about using a newer truck or car module and I'll build the harness for it. I'm keeping my 2002 4l60E with 3800 stall and installing new LS7 lifters, a cam recommended by Comp with some broad horsepower, .675 lift patriot spring kit and pushrods. I really just want to know what snags members have run into with the LS3 swap. With the mods to the block and add on's I would like to get close to 500 at the crank. I'm leaving the compression ratio the same instead of the LS3 because it's lower and I found a Roush TVS 2300 to go on top If I decide I need more HP. If anyone has any suggestions I'd like to hear them but in the meantime I'll do some reading. Good to see more new faces on LS1 truck!

Typically a 6 speed auto is behind that L99, but you can replace the trans with yours and use a 4L60e TCM from almost any vehicle. You can wire in the CAN lines and other wires, doesn't seem to be too difficult.
If your Harness was wired for an auto, sounds like it's gonna be pretty easy.

Looking forward to seeing this done, it's gonna be a strong(er) truck when done.

Why keep the vvt if you're not gonna use it now?

I did some testing on bud8fan's 2011 5.3L, believe it or not, the truck ended up making more power without the involvement of vvt.

Hey Lance, LTNS. Keep us updated on the swap. Sounds pretty sweet to me. I'm running an E38 pcm on my 2007 GMT900 that originally had a 4.8/60e behind it but now I am running a 2008 truck tune (for tuning since HPT doesn't think I need to tune my 2007) and 408/80e.

Damn dude welcome back :lol:

What's up Lance? Been gone awhile. Keep us updated and need pics.

Thanks for the replies guys, farmtruc I'm plannning on doing excactly what you said with the TCM but wanted to see what everyone eles has done. We just did an El Camino with LS2 and used a truck TAC module. I wasn't sure about the L99 that's why I wanted some opinions. The VVT will come off then a and the wire I'll tuck in the harness just incase but your right if the VVT loses power I'm just going to remove it and put my LS3 cam gear and cover on. I'm not in a hurry on the L99 until I finish getting all the parts and finish the wiring on the Syclone. I'll keep you guys posted and get some pics of the swap for you. Thanks again guys!

Hopefully before long HPTuners will release some 2.5 or 3 bar options for trucks.

Yeah, I'm using TunerPro RT Beta on the Syclone and love it. It's great for OBD I with 3 bar and a WB. I just pinned the Wideband into the PCM and use an Ostrich emulator from Moates and do real time tuning while driving. It makes the changes in the emulator and if I like them I commit and then save to bin. I've got a chip burner and then burn the bin to the chip and put it back in the PCM. You can't beat real time tuning with a 3 bar. I haven't decided if I'm going to use EFI LIve or HPTuners on the new pcm for the L99. I'm going to use a few parts of the LS6 and then maybe stroke it and sell it's still in great shape except for 2 rod bearings. That'll be a while though. I might have to Turbo the 6.2 instead of Supercharge, money's a little tight so it's just a little playing at a time.