Will 5.3 to 6.0 (LQ4) make a big difference in towing?

[Teamwieland]

My 2003 Suburban with 5.3L has 225k and I just upgraded my boat. 3.73 rear axle. Boat is about 6500 lbs on trailer. Love my Suburban but at 6000 ft elevation I lose about 30% of my power. 5.3L struggles bad with the new boat, especially on hot days and loaded down. Looking at dropping in an LQ4 (salvage or reman) if it will make a significant difference. Not willing to go LQ9 as 85 octane is expensive enough. I know fuel economy will fall off a cliff as my folks have a Silverado 2500 with LQ4, but I'm mainly trying to avoid buying a new truck altogether. Anyone done an LQ4 swap for improved towing?
Also,I bought a 2013 Tahoe this year with the Gen IV 5.3L. After CAI, straight through exhaust, and Diablosport tune, it didn't tow any better than my old Suburban. 5.3 isn't the answer for me at this elevation.

 

[Teamwieland]

Forgot to mention I bought a 2013 Tahoe this year with the Gen IV 5.3L. After CAI, straight through exhaust, and Diablosport tune, it didn't tow any better than my old Suburban. 5.3 isn't the answer for me at this elevation.

 

[S33k3r]

Honestly, since you are losing power at higher elevation, you should add a turbo with very minimal boost. Why? because the turbo will maintain air pressure at altitude. Also, with minimal pressure, you aren't going to nuke your engine. You might even see a little mpg gain.

 

[Scottydoggs]

i used to have a 03 gmc 2500hd pick up, towed my 4,000 lb boat every where with no issues, hardly knew it was back there. im going to have to say gears would be the fix. i had stock 4.10 gears. my 03 6.0 had under 300 crank hp. these newer 5.3 have more hp and tq. you'll just need a tune after a gear swap to keep the speedo reading right, front and rear gears if a 4x4.

 

[Teamwieland]

If I get a new(er) truck it will definitely be boosted, whether diesel or ecoboost. Sticker shock is keeping me from pulling the trigger and I love my old Burb. Any recommendations for a turbo or supercharger?

 

[THarber]

6.0 is going to be better but I think you'd be better off adding a whipple or supercharger. Turbo is a lot more work.

Tim

 

[Bill 1960]

LQ4 will get it done based on my experience towing fifth wheel trailers in the mountains. However the 4L60e won’t be up to it. Better anticipate a trans too.

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving sage advice from the knowledgeable folks on this Forum.

 

[Teamwieland]

Supercharger is about $6k and my Suburban is worth about $3k so probably won’t go that route. i think I will look for an LQ4 with low miles and freshen up the gaskets and such and see how it goes. Did the 6.0 vehicles come with something other than the 4L60E?

 

[S33k3r]

Yes. The Denalis and Cadillacs came with 4L65es. I assume you are going to do your own work, in terms of the engine swap? I misunderstood, previously, and figured if you were paying to have it done that would be the better route.