LQ4 refresh...looking for guidance

[project_x]

I need some guidance....

My Suburban has an LM7 5.3L with 706 heads.. with 178k miles.

I bought a running 2003 Denali Yukon with LQ4 with 200k miles and a recently rebuilt 4L65e...

I'm planning to swap the transmission in..and would like to refresh the LQ4.

I'm going to do an engine oil analysis and check compression on the LQ4 before I do anything.

I was planning to put a new water pump, oil pump, rear main seal, head gaskets, exhaust manifold bolts,etc...

I was thinking of using the 706 heads to get a little higher compression (read in a few places this was advantageous)....

I'd like better performance than my LM7 mostly for a towing... And to refresh the engine for longevity...

Looking to do this economically. What can I do for $1000?

What parts should I replace? Should I just change all the gaskets, pumps, o-ring and seals on the LQ4 and install it....or just keep driving my LM7 until it dies...

 

[Mudsport96]

For a 1000 bucks? If the oil analysis and compression check come back alright.... put an oil pump oring in it, rear main seal, exhaust bolts( can be done with heads on the engine) if needed and that is it. Well...what year is your Suburban? You may need to swap the intakes to keep the cable throttle if it is pre03. But other than that, the 6.0 is already up 40hp and at least 50 tq over the 5.3. You will not recognize your own rig. However, you will need to have your computer flashed to a 6.0 tune to get the full effects of the swap. For a grand, I personally, wouldn't open a running LS style engine that did not show active signs of a problem. Daughter just got home from college yesterday and I looked over the Silverado. And at 417160 miles it still purrs. All that I've done internally is the oil pump Oring. Don't mess with it if it isn't broke man.

 

[project_x]

For a 1000 bucks? If the oil analysis and compression check come back alright.... put an oil pump oring in it, rear main seal, exhaust bolts( can be done with heads on the engine) if needed and that is it. Well...what year is your Suburban? You may need to swap the intakes to keep the cable throttle if it is pre03. But other than that, the 6.0 is already up 40hp and at least 50 tq over the 5.3. You will not recognize your own rig. However, you will need to have your computer flashed to a 6.0 tune to get the full effects of the swap. For a grand, I personally, wouldn't open a running LS style engine that did not show active signs of a problem. Daughter just got home from college yesterday and I looked over the Silverado. And at 417160 miles it still purrs. All that I've done internally is the oil pump Oring. Don't mess with it if it isn't broke man.

Thanks,
Would you change the head gaskets? Or just leave them (pending oil analysis....)?

I have a 2005 Suburban... The LQ4 is out of a 2003.

 

[Mudsport96]

If the oil analysis looks good, I wouldn't do anything to the engine. Doing this economically, under $1000, you are going to be a few hundred into getting the LQ4 tune swapped over to your ecm most likely. And any performance parts are going to eat up the rest really fast.
Don't quote me on it, but I think the Denali will have better flowing exhaust. And if you have both vehicles side by side you could look for yourself. The Suburban may have the exhaust come together into one pipe before the muffler. And the Denali may have the exhaust have two pipes going into the muffler. If so, use the Denali dual setup and have custom exhaust run behind that with the rest of your 1000 bucks.

 

[Marky Dissod]

I was thinking of using the 706 heads to get a little higher compression (read in a few places this was advantageous) ...

If the static compression ratio with 706 / 862 heads turns out over 10.9-to-1,
1. you'll need to convince a tuner to take up the challenge, as they may hesitate to mess with it
2. VERY SERIOUSLY CONSIDER 91 octane, especially if working or playing HARD
3. 243 / 799 pope hat heads should keep the scr under 10.9-to-1, but they cost more than 706 / 862.

 

[strutaeng]

I just finished refreshing the LQ4 on my 06 Suburban 2500. I had an intermittent lifter tick. I started thinking I was only going to do a top end job, but wound up pulling the engine. I'm currently driving it around doing the break-in. A lot of work honestly, but I'm very happy so far. The last page has some costs.

https://www.tahoeyukonforum.com/threads/tty-head-bolts-with-engine-in-vehicle.147231/

I hope this helps.

 

[project_x]

I just finished refreshing the LQ4 on my 06 Suburban 2500. I had an intermittent lifter tick. I started thinking I was only going to do a top end job, but wound up pulling the engine. I'm currently driving it around doing the break-in. A lot of work honestly, but I'm very happy so far. The last page has some costs.

https://www.tahoeyukonforum.com/threads/tty-head-bolts-with-engine-in-vehicle.147231/

I hope this helps.

That's a great thread, thanks.

 

[project_x]

If the static compression ratio with 706 / 862 heads turns out over 10.9-to-1,
1. you'll need to convince a tuner to take up the challenge, as they may hesitate to mess with it
2. VERY SERIOUSLY CONSIDER 91 octane, especially if working or playing HARD
3. 243 / 799 pope hat heads should keep the scr under 10.9-to-1, but they cost more than 706 / 862.

Most calculations or other people's measurements see 10.5-10.68:1 for 706 heads on a LQ4

 

[Mudsport96]

Most calculations or other people's measurements see 10.5-10.68:1 for 706 heads on a LQ4

On a toy/race application it is fine. On a heavy truck/suv I wouldn't do it. You would see some tq advantages but unless you plan on running E85 for the 106 octane it had, ALL THE TIME the extra compression is not worth it. The 706s are worth about 12 lb ft of torque. If you need that much, a good custom tune can probably get you that with the stock heads. Or throw on some long tube headers and get a good custom exhaust and a tune and you will definitely be over the power the 706s will get you.
I'm not telling you that you can't use them. But, as someone who had done many different engine builds... high compression daily driver trucks are no fun.

 

[project_x]

Most calculations or other people's measurements see 10.5-10.68:1 for 706 heads on a LQ4.

On a toy/race application it is fine. On a heavy truck/suv I wouldn't do it. You would see some tq advantages but unless you plan on running E85 for the 106 octane it had, ALL THE TIME the extra compression is not worth it. The 706s are worth about 12 lb ft of torque. If you need that much, a good custom tune can probably get you that with the stock heads. Or throw on some long tube headers and get a good custom exhaust and a tune and you will definitely be over the power the 706s will get you.
I'm not telling you that you can't use them. But, as someone who had done many different engine builds... high compression daily driver trucks are no fun.

Thank you. That is exactly what I was looking for, there is so much information out there. I appreciate your perspective.... the last thing I want to do is throw some money at this and not be at all happy with what I end up with.

I haven't looked at the exhausts yet...