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Discussion Starter #1
Fellas -

Have been stationed overseas for 5 years and just returning to the states. Needed a tow rig/daily driver so after a bit of research, I went with a 2001 K2500 4x4 Suburban with the 8.1 engine. This is my 4th Suburban/Yukon, but my first GMT800. My last tow vehicle/daily driver was a 2003 Excursion 4x4 with the 7.3. Loved it, but wanted to go back to gas for this one, and I felt that the 8.1 was a better choice than the V10 in the Ex.

I'll be using the Suburban as a daily driver. Yes, I know the fuel economy will be horrible. I'm ok with that. And I have a few long-distance hauls to do with it -- I have musclecars (and a bunch of parts) in storage in NC and GA; need to bring them to San Antonio.

Figure I'll pick up a new or used open car hauler - 20' or so, dovetail, 5200 lb axles, brakes on both.

Anyway, I started this thread to keep track of any mods that I do to the truck, and for input about what I should/shouldn't do. Curious to hear about mods for the 8.1, including a tune and maybe headers/free flowing exhaust.

Here's a pic of the 'Burb.



Thanks,

Scott
 

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Discussion Starter #5 (Edited)
How many miles are on it? I’d be concerned about the 4L80 if you get rid of the torque management. You can add quite a bit of power to the 8.1’s that have the 4L80.
It has 90,000 miles. 1 owner vehicle. Seems to have been well taken care of.

Are you talking about the 4L80 versus the 4L85? I thought all 8.1 Suburbans had the 4L85, but it looks like my trans code is MT1 and based on that, it's the 4L80.

Here's a post that I found on another site:

"The basic breakdown for the 4L80E goes like this from my books. 91-93 is the first style, 94 is a one off year and got the improved plug in it as well as the PWM solenoid for the TCC was changed to eliminate the cleaning cycle that earlier models had and the 4X4 models no longer had a tone wheel on the output shaft for the PCM as it used the VSS in the transfer case to do all of the work (some 94's still had a tone wheel in certain 4X4 applications). 95-96 is another style, same basic trans as the 94, but it got a boss on the case to mount the NSBU switch(neutral safety back-up switch). 97-early 99 got some improvements in them internally and had the trans cooler lines enlarged and they became known as a rear oiler as the return line was moved further back on the trans case. Mid year 99 the 4L80E received MANY improvements internally which included a new input shaft, wider band, and some oiling changes internally. The 4L80E was used on up into around 05 or so and was badged as the MT1 option whereas the 4L85E MN8 option was used primarily in motorhomes and the 3500HD chassis and other HD applications from about 99 or so. Some models were said to have straight cut planetary gears in some portions, solid input shafts, and the 5 pinion planetaries. I don't know all of this info to be 100%, but it is what I have found from a lot of online researching and my ATSG manuals. You can take most any of the 4L80E's from a newer and swap into an older model as there are adapters for the cooler lines to facilitate this. And the PWM solenoid can be swapped from a 91-93 into a newer model and allow the use of most any of the 94+ 4L80E/4L85E into a 91-93 truck."

If I do have the 4L80, I'm not going to worry too much about it. Might do a shift kit to bump up the line pressure a bit. Also have a trans temp gauge, so I'll keep an eye on the temps and consider a larger trans cooler if temps ever get over 200*.

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I'd think headers/tune (with torque management disabled) and 180 thermostat would be a good place to stop. Maybe a good air filter in stock box vs CAI.

4L80 shouldnt really be an issue until you either get a ton of miles on it or step up power in bigger way like forced induction or cam/head work.
 

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I have dual exhaust, 180 t-stat, k&n air filter with the stock air box opened up and a tune on my 04 8.1 Suburban. It runs good, and is my backup tow vehicle or if we need a 3rd row.
 

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Discussion Starter #10
I have dual exhaust, 180 t-stat, k&n air filter with the stock air box opened up and a tune on my 04 8.1 Suburban. It runs good, and is my backup tow vehicle or if we need a 3rd row.
Yep, that's about what I want to do.

What gears do you have? Just found out that I have the 3.73's. :(

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I got lucky with 410s, but I still felt a significant difference stepping up to 35s. I'm still running stock exhaust and intake though...
Nice looking 'burb! I'm going to stick with stock size tires until I swap the gears for 4.10 or 4.56 (or whatever the next step is past 4.10).

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Discussion Starter #15
FYI - my 'Burb has the Autoride option. Anyone have any thoughts on keeping this or deleting it? Sounds like replacing the shocks is exceptionally expensive with Autoride.

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FYI - my 'Burb has the Autoride option. Anyone have any thoughts on keeping this or deleting it? Sounds like replacing the shocks is exceptionally expensive with Autoride.

Thanks
It has been a long long time but I’m pretty sure I have swapped the shocks on an autoride three-quarter ton. I almost think that the shocks do not have wires going into them like the half ton. Verify but you might not be screwed. I think only the half ton have the really expensive Shocks.
 

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FYI - my 'Burb has the Autoride option. Anyone have any thoughts on keeping this or deleting it? Sounds like replacing the shocks is exceptionally expensive with Autoride.
I love mine. Rides great empty, levels right out when loaded. I wouldn't even think about deleting it if it isn't giving you any trouble yet.

If/when it does, I had also heard that the factory shocks were expensive. I don't know if that's true, but I know there are very affordable "load bearing" air shock available aftermarket. The ones under my jeep were $66/pr. I'm sure there has to be something similar out there that'll work on the Burb.
 

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Yep, that's about what I want to do.

What gears do you have? Just found out that I have the 3.73's. :(

Thanks
I have 3.73's too and 285's. It could definitely use some deeper gearing, but does fine how it is. I have the autoride too, so far no problems from it through.
 

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That will depend on what your using the rig for. I would suggest a good aftermarket single disc/lock converter with a little higher stall.
I wouldn't do this. For a tow rig it'll just add heat.

The 8.1 pulls so hard down low it's stupid to bump the stall speed when they're out of steam by 5k rpm.

A 6.0 needs the bump into the torque curve, the 8.1 is already there.


Do a big trans cooler. The stock coolers are never adequate.

Raylar for all your big torque tire roasting dreams... Vortec 8100 8.1L Chevy GM Performance Parts - 496cid BBC Truck / SUV Performance Packages - Raylar Engineering
 
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