Hey all,

I just picked up a 02 LQ4 that I'm going to drop into my 07 Trailblazer after I do some work to it. The 07 Trailblazer SS had an LS2 so I plan on picking up the computers and harness from an SS. Does anyone know if most of the accessories will basically bolt up in the same location? Does buying the computer and harness from the SS seem like the best idea? I've never swapped an engine like this so hopefully y'all have some ideas. And as I do appreciate any and all advice, please none of the "why didn't you just buy a LS2" or "save your time and money and buy a SS."

Thanks!

Aaron

 

A new computer without a matching Body Control Module and key is most likely going to cause some problems. You'll need to have the new computer reprogrammed to at least remove the Vehicle Anti Theft System to get it to run, but you may also find that many of your fuses will no longer light up. You may also find that your wipers may not return to the "home" position when you turn them off. There's a lot of little things like that that may or may not be affected. Most of us doing these LS swaps don't care much about that stuff because we do them in cars that often have their own electrical system already intact, and the brake lights, power windows, radio, and all of that stuff are already functional and remain unaffected regardless of what motor or computer is running the car. Some though, like me, have the entire electrical system replaced with the modern car's wiring, and that's how I know that a mismatched computer/BCM/key setup will present some problems. If you're good with wiring, you can find workarounds, but in my case I had to add an additional fuse box to run several of my circuits.

As far as accessories bolting up in the same location....with a few exceptions, all of the blocks are basically identical. You may find a bolt hole has not been drilled in a location you need, or something like that, but the blocks are all about the same. Heads and intakes....different story.

 

Thanks for all of that. I know I'm going to have some fits along the way but I'm comfortable enough with some wiring and my father in law is a wiring machine. I know I'm going to bore and stroke it but I think I'm going to keep the 243 heads and truck intake. I've heard that they are better for torque and I'd be happy if that were the case.

 

The 07 TB is a 58x engine. Im not very familiar with the LQ4 but being that it's a 02, I'm guessing its probably a 24x engine. Lingenfelter's conversion module converts 58x to 24x but not 24x to 58x. You will either have to pull the LQ4 crank and install a 58x reluctor and a 4x cam gear, or you can run it with a 06 TBSS engine harness and E40 ecm. The 06 TBSS had a 24x engine.

There is no need to change your bcm. You will just need to do a simple security relearn.

If you are planning on running a 4L60, keep in mind the the TBSS used a 4l70 that has an Input Speed Sensor that the 4L60 does not have, so you will need to flash the ecm and tcm with a 5.3L trailblazer OS. The 5.3 trailblazers got the 4L60.

 

Also the frame is definitely different on v8 trailblazers. I'm not sure if the v8 engine mounts will directly bolt up to the i6 frame. I've never swapped a trailblazer from i6 to v8 but I do know that the v8 frames have a v8 tag on the right rear of the frame near the right rear door.

 

LQ4's did not have 243 heads, they have 317's.

 

Dammit that's what I meant. Good looking out

 

243 has been beaten into my repeatedly as everyone has been telling me that those would be the best heads to use.

 

I plan on putting in a stroker kit so I'll make sure to buy a 58x crank.

My TB has the 4L60 and I was thinking about rebuilding it and using that but I'm thinking a 4L70 or 80 would be a better choice.

 

You will need to install a 4x cam gear and swap the crank sensor also. The 24x and 58x use different crank sensors and they aren't compatible.