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'97 Tahoe Reformation -Official Build Thread 8.1L/4L80E Swap
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James is right the 8.1 with the 4l85e trans will be an easier swap and easier to tune. It might possibly get better milage than one with an allison as well. I said you need deep pockets for fuel cause my towing milage is 7.3 highway empty is 12 but that with a crew cab short pickup heavy bitch.

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jakenatour wrote:
James B. wrote:
An 8.1 from a 2500 Yukon XL, Suburban, Avalanche, Savannah, or Express will have a 4L85-E and be easier to work with and more tunable than an Allison 1000 that would have come with a Silverado or Sierra.


I assume the trained eye can tell from this photo that this is indeed a 4L85-E vs the Allison...



sure looks like a 4L85E to me.

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Post Re: 8.1 Details 
jakenatour wrote:
So, I have confirmed with this guy the following:

- it is a 4WD tranny
- it is Drive by wire
- Cats included
- ECM included

Still waiting for him to confirm the year of the burb it came from.

This is getting even more tempting. $3k is not bad. I suspect I can talk him down a few hundred. He wants to clear out his shop.

Considering @irisservice's comments on his 383 mpg, I shouldn't be too scared off by MPG alone. My vehicle will never be a daily driver so mileage was never a strong consideration. I just might have to add a second gas tank Surprised

Regarding the drive by wire conversion: major or minor? Again, not afraid - just want to make part of the calculus.

Also, a tranny question: Are all these transmissions controlled with the engine control module or do they have a dedicated CM?

Cheers


if you get a gas pedal from a GMT400 that had a 6.5 diesel it will bolt right in place, all you have to do then is modify the connector and swap 2 wires vs bracketing the GMT800 pedal in place. I am running that setup on a 2003 5.3 that i swapped in to a 92 P/U

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All years and applications of the Vortec 8100 have electronic throttle control as far as I've found. The 8100 was once considered an option for the Tahoe back in the day...

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Post Any way to determine mileage on an 8.1? 
Hi all,

I'm about to move forward on this 8.1 sale and when I take a look at it, I'd love to be able to somehow verify that his "30,000 miles" statement is somewhat true.

Are there any wear indicators on this engine or tranny that I might take a look at to determine that this is not a high mileage engine?

Other than turning it over and smelling the dipsticks, I don't have a lot of ideas on how to determine "goodness".

Thanks

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Post Re: Any way to determine mileage on an 8.1? 
jakenatour wrote:
Hi all,

I'm about to move forward on this 8.1 sale and when I take a look at it, I'd love to be able to somehow verify that his "30,000 miles" statement is somewhat true.

Are there any wear indicators on this engine or tranny that I might take a look at to determine that this is not a high mileage engine?

Other than turning it over and smelling the dipsticks, I don't have a lot of ideas on how to determine "goodness".

Thanks


Maybe build a bench harness and power up the PCM to read it with a scan tool. Mileage might be stored in the PCM. Not sure what year did/did not do this though. Of course, you would have to be reasonably certain this is the PCM that goes with this engine.

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easiest and cheapest way... get the VIN and do a carfax. $40 and 5 minutes your done!

TJ

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Agreed and I can run ya the carfax if you wanna get me the vin

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Whipped383 wrote:
Agreed and I can run ya the carfax if you wanna get me the vin


Awesome. If he can get it to me, I will get it to you by. THANKS!

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Do it, pull the trigger if you don't mind the fuel consumption and want the torque. You can always swap the engine later on if you're not satisfied, but at least the drive train will be done and compatible with virtually any 199X-200X engine.

Even if it was 100k, aren't those engines barely broken in at that point?

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Mileage is stored in the computer, but it takes a dealer area rep to be able to read that data as I understand it. The dealers can't read the data as they don't have the correct level of access.

Incidentally, only JamesB may use the nickname "the Beast" on this board as so far he's the only one to build a 4 door big block Tahoe that pulls the front tires off the ground. He can drive straight over a standing beer can and only the rear tires will touch it. Laughing

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Im pretty sure the milage is NOT stored in the pcm in those years. In the later years the milage is stored in the pcm, but not at least till 07+ other wise when changing the pcm it would have to have the milage changed and i have personally reprogrammed an 03 pcm with a Tech 2 with only a vin from an ebay sale truck and needed no other information
.

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Oh and i also had a 2 door gmc yukon that would pull the front tires off the ground with a 355 small block. It was lifted with 35" tires. Pretty easy actually. Hold it in 1st gear and snap the throttle and get inches under the front tires. So James is not the only one to pull front tires lol.

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The older PCMs are supposed to store it, but the computer doesn't do anything but store it. The cluster stores it separately. It was supposed to be something with warranty claims or something. I don't know the details. This is just something that a service advisor told me many years ago.

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Post Got it! 
Dude took my $500 to hold it. He will even deliver! Couldn't get the vin but I'm taking his word for it. He even has the throttle assembly, so that saves me one part I have to go out and get.

Since I'm going for it, might as well go BIG BLOCK!

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no replacement for displacement
Smile

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Just for the sake of discussion here...

Mazda, in their CX5 uses a cam set-up that has large intake duration but normal exhaust duration.

What that does is trap only 80% of intake volume but uses every bit of energy out of that exhaust.

Makes a 2L engine consume like a 1.8L

Make an 8.1L consume like an 6.5L

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Post Delivered! 
My new power plant was delivered to the shop today.


Here it sits, about 4 feet and right angles to where it will eventually bolt in.



Thanks for all your input!

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I like where your head is at with the BBC, I have a 98 K2500 with the 454 and a 97 Tahoe with the 5.7 the L29 is just soo much nicer to drive until you stop at the gas pump.

With the 496 & the 4L80? (or is it an 85E?) have you given any more thoughts towards your suspension mods? I would seriously take a look at that Power Block video. a Solid axle Leaf spring front will, be so much more economical than trying to do a 6" IFS lift. I also noticed you were going to use lift blocks in the rear, are you actually planning on doing any serious wheeling? or will you be using this to haul the family to the Drive in and grocery store?

Great Thread, and I will says what everyone is thinking more pics!

Bowtie

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Bowtiewarrior wrote:


With the 496 & the 4L80? (or is it an 85E?) have you given any more thoughts towards your suspension mods? I would seriously take a look at that Power Block video. a Solid axle Leaf spring front will, be so much more economical than trying to do a 6" IFS lift. I also noticed you were going to use lift blocks in the rear, are you actually planning on doing any serious wheeling? or will you be using this to haul the family to the Drive in and grocery store?

Great Thread, and I will says what everyone is thinking more pics!

Bowtie


Yes, I have given a lot of thought on the suspension mods. With the increased torque of the BB, I have concerns about the rear end, especially since I am leaning toward a locking differential. I've heard that open and limited slip diffs are safer with the increased torque, but the load-bearing axles can't support the focused torque that a locked differential/tippy rear end wheeling situation might incur. With the consideration of a rear end upgrade, an 8 lug wheel pattern is the natural result, which means either carry two spares (never) or upgrade the front.

I'm very intrigued by your comment that the SAS/leaf susp front upgrade would be MORE economical - that wasn't my impression when I spent a little time looking into it. It's clear that it will be more work, but that's not a deal breaker for me. Please elaborate...

As far as what it will be used for: My primary goal is RELIABILITY, UTILITY and ROBUSTNESS. Naturally it will look and sound cool. It doesn't need to clear a standing beer can with only the rear tires, but it does need to get me and my family and 500lbs of gear to Tahoe and back (with some moderate wheeling while I'm there) without batting an eye.

Speeder wrote:

Incidentally, only JamesB may use the nickname "the Beast" on this board as so far he's the only one to build a 4 door big block Tahoe that pulls the front tires off the ground. He can drive straight over a standing beer can and only the rear tires will touch it.


Alright. How about the female version?

More pics coming (but don't hold your breath - there's not a lot to photograph right now.

The 4L60E is on Craigslist, hoping to bring in a few hundred bucks.



Last edited by jakenatour on Sun May 08, 2016 5:51 am; edited 1 time in total
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