It looks like I'm getting rid of the L31 out of my 99 tahoe and going LS. I just picked up (getting it tomorrow, needs to be pulled out of crashed truck) a 2006 LQ4 longblock (has the beefier LS2 rods) with 32K miles for a pretty good price. Comes with the wiring harness, accessories, tb, maf, intake, flexplate, stock manifolds, and intermediate pipe with cats.

I'm going to use my 411 PCM and stock L31 wiring harness and follow Lextech (thanks Jeff) wiring file for the swap. I just need to add a couple of wires for the coils and a couple other changes which look pretty straight forward. I am first to use this file but I shouldn't have any problems. I will use a cable tb for now and I also need to source return style fuel rails. I have a 2002 Denali cal with an LQ4/4l60e to upload onto the 411.

Things I need to buy + questions:
- engine mount brackets: Thinking of getting the S&P ones. Who makes the best ones out there that don't shift the trans position?
- transmission spacer: Do I still need it with the LQ4 that has a 4L80E behind it when mating a LT style 4L60E
http://www.crateenginedepot.com/store/LS1-Flexplate-Spacer-12563532-P1343C0.aspx
http://www.crateenginedepot.com/store/LS1-Flexplate-12551367-P1342C0.aspx <- Will this be the same one attached to the engine from a 2500HD truck?
- A/C compressor bracket: Thinking of the kwik bracket (uses a special sanden compressor). Is there anyway to use the stock A/C compressor?
- Fuel rails for return style
- cable throttle
- fuel lines etc (will use parts from marine intake)

Those that are familiar with this swap, is there anything else I need that I'm forgetting?


Plans are cam, headers and possibly a tvs 1900.

99bluetahoe wrote:

It looks like I'm getting rid of the L31 out of my 99 tahoe and going LS. I just picked up (getting it tomorrow, needs to be pulled out of crashed truck) a 2006 LQ4 longblock (has the beefier LS2 rods) with 32K miles for a pretty good price. Comes with the wiring harness, accessories, tb, maf, intake, flexplate, stock manifolds, and intermediate pipe with cats.

I'm going to use my 411 PCM and stock L31 wiring harness and follow Lextech (thanks Jeff) wiring file for the swap. I just need to add a couple of wires for the coils and a couple other changes which look pretty straight forward. I am first to use this file but I shouldn't have any problems. I will use a cable tb for now and I also need to source return style fuel rails. I have a 2002 Denali cal with an LQ4/4l60e to upload onto the 411.

Things I need to buy + questions:
- engine mount brackets: Thinking of getting the S&P ones. Who makes the best ones out there that don't shift the trans position?
- transmission spacer: Do I still need it with the LQ4 that has a 4L80E behind it when mating a LT style 4L60E
http://www.crateenginedepot.com/store/LS1-Flexplate-Spacer-12563532-P1343C0.aspx
http://www.crateenginedepot.com/store/LS1-Flexplate-12551367-P1342C0.aspx <- Will this be the same one attached to the engine from a 2500HD truck?
- A/C compressor bracket: Thinking of the kwik bracket (uses a special sanden compressor). Is there anyway to use the stock A/C compressor?
- Fuel rails for return style
- cable throttle
- fuel lines etc (will use parts from marine intake)

Those that are familiar with this swap, is there anything else I need that I'm forgetting?


Plans are cam, headers and possibly a tvs 1900.

I would recommend not trying to use the l31 wiring harness... maybe use the one already on the motor or get one already pinned for the 0411 from painless wiring or ebay has some for an ls1 cheap.... l31 is completely different than the lq4.
sounds like a fun project though.... you might explode the 4l60e tranny though...

stroker97k1500 wrote:

I would recommend not trying to use the l31 wiring harness... maybe use the one already on the motor or get one already pinned for the 0411 from painless wiring or ebay has some for an ls1 cheap.... l31 is completely different than the lq4.
sounds like a fun project though.... you might explode the 4l60e tranny though...

I know the l31 harness is different but it shouldn't be too hard to modify mine using parts of the LQ4 harness. The 4L60E is a built FLT lvl4 and has survived 30K miles behind the Whippled l31, so it should be fine for a cammed LQ4 for now. When I boost the Lq4 I will go to a 4L80E.

99bluetahoe wrote:

stroker97k1500 wrote:

I would recommend not trying to use the l31 wiring harness... maybe use the one already on the motor or get one already pinned for the 0411 from painless wiring or ebay has some for an ls1 cheap.... l31 is completely different than the lq4.
sounds like a fun project though.... you might explode the 4l60e tranny though...

I know the l31 harness is different but it shouldn't be too hard to modify mine using parts of the LQ4 harness. The 4L60E is a built FLT lvl4 and has survived 30K miles behind the Whippled l31, so it should be fine for a cammed LQ4 for now. When I boost the Lq4 I will go to a 4L80E.

I hope you have better luck than I do with those grenades..... I think you will like the 6.0L though

This FLT one has been good so far. My previous two 'stock' rebuilds couldn't survive against a stock L31. Good thing I had extended warranty.

Yeah, I would definitely put a 4L80e in while you have everything all torn apart. They really aren't that expensive.

S&P engine mount brackets are nice- I used these on my 5.3. If you have access to a mill, or a drill press and a big band saw, you can make your own pretty easily.

The Kwik AC bracket is nice. I'm not aware of anything that will use a stock L31 AC compressor. You could hack up a TPI AC compressor bracket and use a tbi™ compressor, but I wouldn't recommend it.

You can pick up a corvette fuel filter and avoid swapping your fuel rails. It has a regulator built in. You'll need some fitings to make it work, but nothing crazy.

I'd try to pick up a harness from an '02 6.0. It would be much easier than modifying the L31 harness. Adding things to the L31 harness like the oil level sensor wiring will be a pain.

WOW! I'm going to follow this one religiously!
Pleeeeaze document as much as possible.

Thanks

-Ben jr.

I knew it was just a matter of time before you guys started working on LS motors. By the time my truck needs a new engine you guys will know everything there is to know and can telll me what to do. Awesome project 99Blue, I think you will like the LQ4.

Heh, the Gen III/IV engines have been in production for over 12 years now, I should sure hope we know a thing or two about them!

Oh, and make sure that your PCM tune is set up for a returnless fuel system if you keep the rails you have now. Most of the calibrations for the older engines with cable throttle bodies will be set up for a vacuum referenced FPR (return style) and that will certainly not work if you keep the atmospheric referenced FPR on the returnless system.

I'm with z71 & Crazy on this one.

PM sent to you 99Blue.

Thanks for the input guys.

Most likely my whipple, intercooler, marine intake and long tubes will be for sale once I do this swap but I have no set deadline so it may be some time.

PSWIRED, I know that you have done some cool things with these motors along with few others. I remember your last project/swap. It is just that I am glad that more people are starting to because I like the guys on this forum and don't really like the tone of most of the other forums that deal with LS motors exclusively.

Patrick, I'm lifting some of your pics!
http://www.pswired.com/95silverado/performance/6Linstall/tensioner.jpg
http://www.pswired.com/95silverado/performance/6Linstall/running.jpg

Again, Patrick has already done this... ahem!

Thanks Patrick for being the pioneer on so much of this stuff! You provide a ton of inspiration!

TJ

heh, didn't you just finish all your L31 mods recently? what made you decide to go with a swap? sounds cool though.

I would love to get my hands on your intercooler system and meth injection.

CrazyHoe wrote:

I would love to get my hands on your intercooler system and meth injection.

ooooOOOOOoooo.....

Yes, if you dig though my website there are a lot of pictures in there. I have many more that aren't online if you need to see anything in particular- just ask.

Another thing- if you're going to keep the stock exhaust manifolds, which really aren't all that bad in the first place, go find a set of head pipes from a 2500HD truck. They will fit right in place with minimal modifications, and they are nice stainless mandrel bent pipes. They run all the way to the back of the transmission on the passenger side and attach to the bracket on the side of the transmission.

Is the 2006 Gen3 engine a 24x or 58x reluctor engine? If it is a 58x, the 0411 won't work with it.

Jeff

Lextech wrote:

Is the 2006 Gen3 engine a 24x or 58x reluctor engine? If it is a 58x, the 0411 won't work with it.

Jeff

All the Gen IIIs are 24x. In the full size trucks the Gen IVs started in MY 2007.