I'm starting the process of researching what it's going to take to swap out my 4.8/4l60 to an lq4/4l80 with boost. The goal is 700whp. I already have a 225k mile 2004 LQ4 and 60k mile 4l80e in the garage. The engine was from craigslist so I am going to go through it, Probably forged pistons/rods.

I've got a few noob questions here.

1. Where do I start on injector selection? I want to build with the option of E85 in the future. I'm guessing in the 72-80lb range? What style injector does it use? http://fuelinjectorconnection.com/sh...p?productid=26

2. What kind of fuel supply do I need? I've been reading a little about dual walbro 255s, but that's about all I know so far.

3. Can I keep the returnless system? If so, what has to be done as I get into boost?

4. Should I beef up the transmission? I've heard some crazy numbers on what these things can handle stock, but that number seems to change a bit. I plan on daily driving the truck and towing still.

5. How about some good parts suppliers? Summit and jegs don't seem to have a huge parts selection for these engines from the bit I've looked at.

My plan for now is to do the engine and transmission install before summer and run it NA while getting any bugs worked out and working on getting the hang of HPTuners, which I've had some experience with on my Blazer already.

I'm mostly just looking for some guidance to get me going in the right direction. I vortec swapped my Blazer last winter and rebuilt the engine myself but that was just to stock specs. It was my first rebuild and went really well. Now that I'm looking for performance, I have a lot of options and tougher decisions to make.

Links to similar builds would be awesome. Thanks for the help, you guys seem pretty welcoming to noobs like me around here.

 

Or...not?

 

If you are shooting for 700WHP you are going to need more than 70lbers to use E85. Call FIC on the phone and they can get you what you need in a few minutes. They know what they are doing.

For your power goals you are going to need to use a return style fuel system with a boost referenced fuel pressure regulator.

I used a 4l80 at stock level with a shift kit and it didn't last very long at the 550 hp level. As of this week I am on my third 4L80... this one came from Jakes Transmission.

Parts suppliers? What parts do you need? Rods / Crank / Pistons you can get from whoever you want... I've seen a lot use Texas Speed, and many others. I would suggest forged pistons and rods. The stock crank in the 6.0 can supposedly handle 700ish hp.

Summit and Jeggs carry most.. if not all of the stuff you would be looking for but you have to search it by part number out of their book. Not by selecting your year and model vehicle... that will show you hardly anything.

The best thing you can do is do some more reading on this forum, because it is full of extremely useful information and is the basis for all of my forced induction ls knowledge.

 

Thanks for your reply. That was pretty helpful.

That probably explains why I couldn't find much on summit, I was just looking for parts that fit the engine via make/model.

I was planning to do exactly what you said: forged rods and pistons with stock crank. I am also trying to choose which cam will work well. I finally clicked over to LS1tech and have been finding loads of information over there. I am waiting to hear back on some 80# injectors right now.