How much does the 6.0 and 8.1 differ in power and fuel mileage? I know the 8.1 specs higher. I guess the biggest question is mileage and if either has had a lot of problems.

Biggest difference is in torque, though I don't have the specs for the 8100 at hand. I have the 6.0 & can't be happier. But, I only tow about 6,000lb max & live at sea level. Nastiest hill on I70 in MO drops me to ~65 MPH with a trailer in tow, then I get a downshift to 3rd, and am back at 75+ by the time I crest the hill. Can't imagine the 8100 being ENOUGH better than that to make the price worth it (it's about a $2,000 upgrade if you want an auto tranny). My old 1/2 ton with a TBI 350 would have required a downshift to 2nd & would have crested the same hill at about 45 MPH :(. For a heavier load or a manual tranny (where the upgrade is only $800), I might have wanted the larger engine. As is, I'm happy with the 6.0.

Best mileage for me is just a hair under 16 - that's running empty at 75 MPH (~2,500 RPM). Worst tank ever was 9.9 - towing at 75+ with the AC on. 4.10's, 245/75's, 4wd, X-cab/shortbed, 2002 GMC 2500HD with the 4L80E automatic.

TEX

Other than TEX I have never heard of anyone who was happy wiht their 6.0. We'll I take that back my buddies wife liked her 6.0 in her Denali!!

Everyone I talked with who has owned a 6.0 has sold it for either the Duramax or the 8.1. From what I understand the fuel mileage difference between the 6.0 and the 8.1 is not proportanate to the power differences. So if you plan on towing heavy the 8.1 is probably going to be a better choice in the long run. Plus you get the allison trany which is well worth the upgrade.

A 6.0 followed me to a run last year and was averaging about 8mpg. We were both towing jeeps on car haulers and I would guestimate the trailer were around the same weight 7000lbs. We were running around 75mph in the hills and he had a hard time keeping up with me. He basically said his foot was to the floor and he was in 3rd gear and even dropped down to 2nd a few times!! :eek: He hated it and sold it for a Duramax and loves it.

I do drive a Duramax and I love it! FWIW I only average 15mpg on a regular basis. Towing I average between 10 and 12mpg. The best I have ever seen was 19.8 mpg of all highway driving.

Go drive each of the trucks and see what you think. I was so impressed with the 8.1 over the 6.0. I drove a brand new 8.1 for a week and thought it hauled ass! For the money I think the 8.1 would be the way to go.

For more info you might check out www.thedieselpage.com

I went on my first long trip last weekend towing my K5 on a 9k GVW trailer with my '03 2500 HD CC SB w/ 6.0L and 4L80E and 4.10 gears. The combined weight of the trailer and K5 should be somewhere around 8,500 lbs.

I averaged about 8-9 mpg with most of the distance being on twisty and hilly 2 land roads and averaging probably 60-65 mph. That was also hitting the gas hard after corners to get back up to speed quickly. Empty I average around 15-16 mpg for normal mixed driving.

Power wise, it will pull most small grades at 75 mph on the freeway in OD but will kick down to 3rd on any type of moderate grade. I haven't been on any really big mountain grades yet. I thought that was acceptable considering the weight of the trailer and the wind resistance from a lifted full-bodied K5 on 38" tires.

The 6.0L doesn't have the low-end torque of the 8.1L or the Duramax but it's not afraid to rev either, just hold the pedal down the let the transmission decide what gear it needs. If it needs 2nd gear to pull a grade at 70 mph then so be it.

Now on the other hand, if I was pulling a trailer more than just about once a month than the 8.1 or Duramax would look more appealing......but I just couldn't justify the $2k option for the 8.1 or the $5k Duramax/Allison combo for a couple hundred miles of recreational towing per month.

The new diesels on the market are great for towing and definitely overshadow the small gas engines, but engines like the 6.0L are worlds ahead of anything available until about the early to mid-90's. Hell, even the first version of the Cummins is pretty weak when compared to what's on the market today.

Originally posted by The Original Diesel
Other than TEX I have never heard of anyone who was happy wiht their 6.0.

Actually, there've been a number of guys on this page who've had positive comments. Your points are valid - I don't believe mileage to be much better than the 8.1, nor is the power as great (obviously). That being said, it's more than enough for my purpose. Shoot, the old TBI 350 was more than adequate & it's nowhere near as good as the 6.0. Again, just depends on your needs.

TEX

PS Have yet to need 2nd gear for any hill in this area with the exception of one that is so curvey you couldn't run faster than 30 MPH even if you wanted. A bigger load or more altitude might change that, but it's not the case for me.

A friend of mine towed behind me with a 6.0 in May of this year. I was in a Duramax. He struggled to run 70 mph. He got 8-9 mpg, which agrees with the number posted above. He now has an older Dodge with the 360 (5.9) and he said it pulls stronger than the 6.0 did. He said the 6.0 was a rev happy engine, and the 360 is more of a grunt engine.

Before the 6.0L 2500HD I had an '01 Ram with the 5.9L, both basically the same specs (auto, 4.10 gears, stock tires). I had limited experience towing the the Dodge but IMHO the 6.0L has noticably more power all of the time, whether empty to towing and consistently gets 3-4 mpg better mileage.

Just goes to show you, opinions are like... :)

i have a 2001 8.1 chevy ext.cab short bed 2500 hd with the allison and 3.73's. empty i get around 10 in the city and 14 on the highway at 65-70. towing my k5 with gear which comes in around 9000 lbs. i get 10 on the highway at 65-70. i am very happy with the performance of this truck. specs on the 8.1 hp-340 tq-455.

I think I am now leaning to an Avalanche 2500, it comes with the 8.1 and it can tow 10k with the 3.73 and 12k with the 4.10's, and that motor should have NO problem moving that truck around.

We have an 01 2500 Suburban with the 8.1L and it has all the pulling power you could ever ask for in a gas motor. The only down side is unloaded gas mileage sucks. I average 10-11 mpg empty, I think I got 12mpg once driving all freway miles doing 65. Since we bought a Burb, I did not have a choice of which tranny to get...auto only, but alteast we got the 4.10s.

The 2500 Avalanche is a great truck! The only draw back is they cannot fit he Allison trany into the truck....... It would be perfect combo if the Allison was avaliable.

I am waiting until the Duramax/Ally is avaliable in the 2500 Sub for my next truck.

Originally posted by The Original Diesel
The 2500 Avalanche is a great truck! The only draw back is they cannot fit he Allison trany into the truck....... It would be perfect combo if the Allison was avaliable.

I am waiting until the Duramax/Ally is avaliable in the 2500 Sub for my next truck.

My Dad has the 1500 Avalanche, but I looked at the capacites for the 2500 Ava and it is the same as the 2500HD, who would of thought. I agree too bad the Allison doesnt fit into it, then it would be SCREAMIN!.

Originally posted by The Original Diesel
I am waiting until the Duramax/Ally is avaliable in the 2500 Sub for my next truck. [/B]

Is that really going to happen? I'd like one too.

There is definate talk about it! I found out on www.thedieselpage.com

Originally posted by TEX
Biggest difference is in torque, though I don't have the specs for the 8100 at hand. I have the 6.0 & can't be happier. But, I only tow about 6,000lb max & live at sea level. Nastiest hill on I70 in MO drops me to ~65 MPH with a trailer in tow, then I get a downshift to 3rd, and am back at 75+ by the time I crest the hill. Can't imagine the 8100 being ENOUGH better than that to make the price worth it (it's about a $2,000 upgrade if you want an auto tranny). My old 1/2 ton with a TBI 350 would have required a downshift to 2nd & would have crested the same hill at about 45 MPH :(. For a heavier load or a manual tranny (where the upgrade is only $800), I might have wanted the larger engine. As is, I'm happy with the 6.0.

Best mileage for me is just a hair under 16 - that's running empty at 75 MPH (~2,500 RPM). Worst tank ever was 9.9 - towing at 75+ with the AC on. 4.10's, 245/75's, 4wd, X-cab/shortbed, 2002 GMC 2500HD with the 4L80E automatic.

TEX

Doubt the nastiest hill in MO compares to what's here in Cali. Lots of 7%+ grades. Even flat towing my Heep drops me to 55mph on a short 2 mile long 7% grade.

I'd go with the 8100 over the 6.0 based on the terrain out here.