5.3L or LQ4 6.0L Dilemma

[biggsteve97]

I have a dilemma. I have an 03 Z71 Tahoe with the flex fuel 5.3L with several bolt ons including long tube headers. My dilemma is I have a 2000 LQ4 6.0L sitting on an engine stand in my garage and I have been thinking about installing it in the Tahoe. It has the cast iron heads and supposedly has only 300hp. My 5.3L is roughly 295-300hp stock so I don't know if it would be a justifiable swap for the Tahoe. I know the 6.0L has atleast 30-35lb ft more tq than the 5.3L which would help move the heavy Tahoe a lot easier. I would like to keep the 4L60E and plan on doing a stage 3 build from PATC which will allow it to handle up to 600lb ft of tq since it seems to be dying anyway and especially if I decide to install the 6.0L. Anyone have any thoughts on this? Suggestions?

[Benelli]

Well, what are you doing this for? Is this a daily driver? Do you pull heavy trailers? I mean, I just flat out don't see a reason to do this. What is your reasoning? If your after more power I'm sure theres a few other things you could do to improve your 5.3.

IMO a 5.3 to a 6.0 swap doesn't seem to justify the trouble.

[biggsteve97]

It does get used as a daily driver, weekend wheeler, occasional trailer, but mostly road trips to off road parks. I want more torque. On the 5.3L I already have a K&N cold air kit, Jet mass air flow sensor, Power Aid throttle body spacer, long tube "race tuned" headers with off road y-pipe and no cats, 3" dynomax cat back exhaust. Eventually Id like to do a custom tune but that is a little ways off for now. Highway speeds its awesome but from a dead stop till about 20mph it seems sluggish, granted no where near as sluggish as it was when I first bought it. I do not know the history of the 5.3L in my Tahoe but everything was original on the vehicle, and I do mean everything. One thing that does have me curious about the 5.3L is the oil pressure seems a little low at operating temp about 42psi at 2000rpm, I believe it should be closer to 60psi.
I already have the 6.0L it was given to me, has been well maintained and runs very strong. it is ready to drop in and i already know my current wiring harness is compatible with the engine so its just a plug and play swap.
hope i answered your question.

[Clyde65]

You realize the 60e wont handle the torqe of the 6.0, right? even if you "beef" it up, it will not last long. You can get a respectable 400hp out of the 5.3 with a CAM and tune and still be able to pass emissions.

with the 6.0, a cam and a good tune you could have 500hp, but you need a HD tranny.

Good luck!

[biggsteve97]

That is why I want to do the stage 3 build on my trans so it can handle up to 600lb-ft of torque. I need to rebuild the trans anyway and planned on that build no matter which engine I use. Ive seen 700r4 survive behind big blocks in short bed trucks for well over 100,000 miles so a properly built 4L60E will live behind the 6.0L. I don't know if I want more than 400hp anyway its the torque I am after. Besides I personally know that biggest downfall to a 700r4 and a 4L60E is the weight of the vehicle in respect to the torque output. A stock 4L60E max gvwr is less than 6000lbs a properly built one can handle more than 10,000lb. in respect a Stock 4L80E is only good for 8000lbs and to build one that can handle more than 10,000lb will cost me twice as much as the 4L60 and since I do not plan on towing much at all or weighing my Tahoe down more than its current capacity the 4L60E I build will suffice.

[66redw/white]

the ss silverados came with 6.0s and 4l60e. all that stuff that you have on your 5.3 will fit right onto the 6.0. you might build it up just alittle bit before you put it in. or.... you could just give it to me!

[biggsteve97]

Originally Posted by 66redw/white

the ss silverados came with 6.0s and 4l60e. all that stuff that you have on your 5.3 will fit right onto the 6.0. you might build it up just alittle bit before you put it in. or.... you could just give it to me!

Oh I definitely plan to use all the mods i currently have i just havent been able decide if its worth doing the swap, yet. If it was the LQ9 345hp 6.0 i wouldnt even hesitate to do the swap. I was thinkin about upgrading the cam to the 325hp version or if the cam is compatible with the heads using the 345hp cam.

[66redw/white]

call up comp cams and get a custom grind done for it. they are the same price as the off the shelf grinds if i remember right. that way itll be made just for your truck and that low end torque you want

[biggsteve97]

well i just got a gm #12561721 325/345hp cam new for $60 tonight. I know it will be a good upgrade for the 5.3L but at this point im starting to think id be better off to swap in the 6.0L if not just for the better torque or just because ive got the motor and nothing else to put it into yet. Thanks for the info! any other info is gladly appreciated.

[Benelli]

Hell drop it in! I didn't realize it was that simple of a swap.

[biggsteve97]

Originally Posted by Benelli

Hell drop it in! I didn't realize it was that simple of a swap.

ya, the 4.8/5.3/6.0 all have the same block and there are really only minor internal differences between them. so same motor mounts, same intake, wiring so on so forth. though i am finding out the the 99-00 6.0 has a longer crank and a different flex-plate so i might run into a problem there. we will see.

[usmcchevy]

A 4l60e will handle a 6.0.............but not for long in a high performance application. A built 4l60e to me just seems to be postponing the inevitable when you are over 500hp. Under 500 when built correctly they hold up pretty well.

99-00 LQ4's did have the cast heads and the crans spacer built into the crank flange. Being the spacer is built in, the trans can only be bolted up to a 4l80e or a older trans(TH350, TH400....). This makes that motor a better canidate for someone doing a LS swap than to replace a 5.3. Or it just means you need to do a 4l80e swap while you're at it

[66redw/white]

i think they make an offset flexplate for those motors so that they can be bolted to a 4l60. ill look for it.

[66redw/white]

i found this over on ls1 tech

"I have the configuration this post talks about, I installed a 1999 to 2000 LQ4 6.0 Liter into my 2004 chevy Tahoe, and yes i ran into the same problem because the crank is longer, However, after spending over 3200.00 at AAMCO, I found the fix, There is a shop in Huntington beach, CA. that fixed everything up for me, This shop builds its own torque converters and does custom racing transmissions as well, "California Performance Transmission"
http://www.cpttransmission.com/
The owners name is Art Carr and this guy knows ALL.

They built my new torque converter and installed it in a day, I asked Art to save the spec's because i ran acrossed your post before i found the fix, so i thought i would share this info with you incase you still needed it.

The new torque converter cost me about 375.00 + Tax, so if you still need this fix call Art and he will fix you up."

aparently in 01 they changed to a spacer instead of a long crank. so 01 and up just take the spacer off and chage the flexplate, 01 and down call that dude^

[usmcchevy]

Originally Posted by 66redw/white

i found this over on ls1 tech

"I have the configuration this post talks about, I installed a 1999 to 2000 LQ4 6.0 Liter into my 2004 chevy Tahoe, and yes i ran into the same problem because the crank is longer, However, after spending over 3200.00 at AAMCO, I found the fix, There is a shop in Huntington beach, CA. that fixed everything up for me, This shop builds its own torque converters and does custom racing transmissions as well, "California Performance Transmission"
http://www.cpttransmission.com/
The owners name is Art Carr and this guy knows ALL.

They built my new torque converter and installed it in a day, I asked Art to save the spec's because i ran acrossed your post before i found the fix, so i thought i would share this info with you incase you still needed it.

The new torque converter cost me about 375.00 + Tax, so if you still need this fix call Art and he will fix you up."

aparently in 01 they changed to a spacer instead of a long crank. so 01 and up just take the spacer off and chage the flexplate, 01 and down call that dude^

Never seen that before, Cool.

[biggsteve97]

cool, thanks!! I had even thought about just using the heads from the 6.0 and just boring out the 5.3 and using stock 6.0 flat top pistons if i couldn't find a way around the crank issue. ill check into the offset flex plate and the custom torque converter and I might even talk to PATC and see if they have something since they specialize in these trans.