HELP! Swap in a Vortec 8.1 or build my 5.3??

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Pilot

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I should be getting my Tahoe back from the paint shop soon and now I want to start thinking about performance mods. It’s an ‘02 5.3 L59 (don’t know if the block is iron or aluminum) with 200k miles. Here are my goals:


1. A spectacle: I’m not into the whole “sleeper” thing. I want this thing to stand out


2. Ridiculous: I’m the king of overkill. I want this thing to be unique and over the top. My baseline goal for phase 1 is 500 whp but a platform that I can continue to build on, just as long as I can reasonably achieve number 3, which is...


3. Value: I’m willing to throw some money at this build so long as I get reasonable HP/torque gains in return.


4. Low end: I want this thing to launch off the line with solid torque throughout the entire band. I don’t want a high revving motor whose torque kicks in at 3500. I also want to be able to tow a nice size load.


5. Daily driver manners and reliability: I don’t plan to take this to the track and I don’t want a finicky truck. I just want it to be a blast to drive on 91-93 pump gas.


6. Gas mileage: I mean, come on..


So that isn’t too much to ask for, right? Lolz


I’m tossing around the idea of swapping in a used Vortec 8.1 with a Raylar stage 2 head/cam/intake kit. That should produce 525 hp with 585 tq naturally aspirated. Then I could add a Raylar (Whipple) supercharger later in phase two.


I know there isn’t a huge community around the 8.1 like there is the 5.3, but there does seem to be a cult following. Plus I just think it would be cool—you don’t see many 8.1 Tahoes.


The downsides are my gas mileage would SUCK, I would be more limited on both GM and aftermarket parts, and it’s definitely not cheap. I’m anticipating 2k for used motor, 6k for Raylar build, $2k for ancillary/labor. And that’s before I get into the exhaust or transmission (I’m thinking I’ll swap in a 4L80?).


Or could I check most of my boxes for far less money by building out and supercharging my 5.3? I’m concerned that it has 200k on it. I want this thing to last forever! How do I know if it’s in good enough shape to invest in?


I’m obviously pretty clueless. Any input is much appreciated.
 

01FormulaTA

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L59 is just a flex fuel 5.3 (bigger injectors and stainless fuel rails).

Like you mentioned above one of the biggest downsides of the 8.1 is it doesn’t have very much aftermarket support. It shares more in common with the older big block engines than it does with the Gen 3 LS engines. You could make the same power with a 6.0 build (370 or 408) and get better mileage. IMO Other than being unique there really is not a good reason to go with an 8.1...

Regarding your current 5.3, it will never make the torque of a whipped 8.1 but there are plenty of supercharged 5.3s making 500+ HP. Plus there is way more aftermarket support and in the end it will be much cheaper than an 8.1 build. If you do build the 5.3 I wouldn’t recommend just throwing a cam and supercharger on a 200k motor. If you want it to last you should pull it and tear it down. Go with new rods, pistons and some different heads. And obv replace all gaskets, oil pump, lifters, etc, etc...

If you are willing to drop that kind of coin might I suggest an LBZ swap? More torque than the 8.1 and equal or better mileage than your current 5.3, a diesel Tahoe accomplishes your goal of being unique, would be the most reliable of the 3 options, not too mention it would tow the best as well.
 
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Pilot

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L59 is just a flex fuel 5.3 (bigger injectors and stainless fuel rails).

Like you mentioned above one of the biggest downsides of the 8.1 is it doesn’t have very much aftermarket support. It shares more in common with the older big block engines than it does with the Gen 3 LS engines. You could make the same power with a 6.0 build (370 or 408) and get better mileage. IMO Other than being unique there really is not a good reason to go with an 8.1...

Regarding your current 5.3, it will never make the torque of a whipped 8.1 but there are plenty of supercharged 5.3s making 500+ HP. Plus there is way more aftermarket support and in the end it will be much cheaper than an 8.1 build. If you do build the 5.3 I wouldn’t recommend just throwing a cam and supercharger on a 200k motor. If you want it to last you should pull it and tear it down. Go with new rods, pistons and some different heads. And obv replace all gaskets, oil pump, lifters, etc, etc...

If you are willing to drop that kind of coin might I suggest an LBZ swap? More torque than the 8.1 and equal or better mileage than your current 5.3, a diesel Tahoe accomplishes your goal of being unique, would be the most reliable of the 3 options, not too mention it would tow the best as well.

I love the Duramax idea. I did some Googling on it a couple of weeks ago and saw a quote to Duramax swap a Tahoe for like $40k!
 

01FormulaTA

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I love the Duramax idea. I did some Googling on it a couple of weeks ago and saw a quote to Duramax swap a Tahoe for like $40k!

Realistically I think it could be accomplished for about a 1/4 of that give or take a couple grand (assuming you could do most of the labor yourself) and depending on whether you go with a 4l80e or an Allison trans...
 
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Pilot

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Realistically I think it could be accomplished for about a 1/4 of that give or take a couple grand (assuming you could do most of the labor yourself) and depending on whether you go with a 4l80e or an Allison trans...

Now that’s definitely in the realm of possibility. I won’t be able to do any of the labor myself though, unfortunately. I don’t have the space, tools or time. :(
 

thompsoj22

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just another 02 worth of opinion. forget the 5.3 it will never "effectively" tow anything in the 4k lb range, low end tq is non existant and was never designed to be a tow vehicle. we looked at a couple 8.1 3/4 ton trucks prior to getting the denali xl1500. the allison trans is a quality unit but both the trucks we looked at had been tow vehicles and were well on their way to issues. diesels are money pit's to rebuild! come on $600 for one injector? for uniqueness, big block rumble,reliability i vote for the 8.1, it would truly be a one of a kind monster that you could go get groceries with and leave anyone at a stoplight with the wtf look on their face!
 

Tonyrodz

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I don't really have a valuable opinion, but just the idea of an 8.1 is awesome! But I'm not sure if it's a direct bolt in- physically. Someone posted this link a few weeks ago, maybe it has some useful info for you--https://grassrootsmotorsports.com/forum/build-projects-and-project-cars/1st-ever-big-block-gmt900-frankenburban-20/130992/page1/
 

kbuskill

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I don't really have a valuable opinion, but just the idea of an 8.1 is awesome! But I'm not sure if it's a direct bolt in- physically. Someone posted this link a few weeks ago, maybe it has some useful info for you--https://grassrootsmotorsports.com/forum/build-projects-and-project-cars/1st-ever-big-block-gmt900-frankenburban-20/130992/page1/

It's almost a direct bolt in for the 3/4 ton GMT900s as they share the same frame as the GMT800s.

It is not a direct bolt in for a 1/2 ton.
 

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