As I was driving around in my 2500HD yesterday, I was thinking of your question whether to go 6.0 or 8.1. The 8.1 (and mine is bone stock from air filter to exhaust) moves that truck around so effortlessly, I can't imagine how much of a beast it would be in a K5. Wretched Excess, I say. You're already used to having a BBC in the front of that truck so why not go bigger and possibly get better mileage at the same time? I don't think you made a bad choice with the 8.1.
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.
Engine swap time! GM 6.0 or 8.1 that is the question.
- Thread starter Chip Cross
- Start date
Cornfield creations
1/2 ton status
Aren't the 8.1's prone to using oil really bad, and don't you have to cut the frame rails and box them to re-strengthen them up for the 8.1? I remember reading a great write-up not too long ago.
Personally I would have gone 6.0, it appears the choice was made before the question was even asked.
Personally I would have gone 6.0, it appears the choice was made before the question was even asked.
Chip Cross
Registered Member
I think I did the right thing too. It is a drop in swap were a 6.0 would take some frame hacking or a custom cross member. I am not about hacking the frame up on a 34 year old mint Arizona truck. and that cross member is 3 bills.
No, it is the same size a 454 except the top side of the motor is taller it will drop right into where the 454 was. They do burn oil, My old boss has one in a 03 crew cab 3500 knocking on 200k he adds a extra quart ever 2 months between oil changes.
k20
3/4 ton status
'really bad' is all in who you talk to. Most of what I have seen is about a quart every oil change. But in any case Im about to delve into a 6.0 swap in the gf's 88 2500. Course I got that motor out of one of our trucks at work, bought the whole truck for $500 lol.
Yeah, mine uses 1qt in 3k miles. I add 1qt and change it at 5k, still well below the "oil life monitor" display on the dash. Usually says about 50% when I change it.
On cold start up you can hear the pistons clacking, sounds like a diesel for like 30 seconds and goes away as it warms up. Done it since new and I've read the TSBs saying it's normal.
Other than that my 8.1 has performed flawlessly for 75k miles so far.
On cold start up you can hear the pistons clacking, sounds like a diesel for like 30 seconds and goes away as it warms up. Done it since new and I've read the TSBs saying it's normal.
Other than that my 8.1 has performed flawlessly for 75k miles so far.
Chip Cross
Registered Member
Good to know, thanks !
Cornfield creations
1/2 ton status
Come to think of it, the frame cutting was due to the a/c compressor down below. I couldn't find that thread that had a link of the build up.
Chip Cross
Registered Member
You run into the same problem on a 5.3 and 6.0. I do know that you can mount the A/C compressor up on the top on a 8.1. I am not sure if that can be done on a 5.3 or 6.0
I like the 8.1.
Martin
Martin
Or look a little more and get a 6.2[gas].
sandypants
1/2 ton status
Yea you can put the ac compresser any where you want its all about mounting brackets... mudbog42 steve has just done it on his 87 didnt look to hard and no hacking just drop in hook up lines ad computer and go.
Have fun with your 8.1....
i will go with 6.0 i just dont want those problems
Have fun with your 8.1....
i will go with 6.0 i just dont want those problems
Kjunky5
1/2 ton status
I voted 6.0 but any engine that will run and drive gets the 
.
.
texas4x4rebel
1/2 ton status
Any updates any pics.
shovelbill80
1/2 ton status
i know is a general question, but what kind of feul economy would you expect with a 6.0 vs 5.3 for mostly daily driver duties.....driven like a reasonably normal person?
y5mgisi
1 ton status
Good choice! I think that will be a very grunty motor! Im so glad someone here got that blazer! I remember seeing it on ebay and loved it! That motor in that truck is going to be perfectg! You will no doubt love it! Dont regret your decision! It was a good one!
y5mgisi
1 ton status
Oh and if you should for some strange reason want more power, a turbo or super charger will put you in the 500hp/700ft.lb range!
CherryK5
1/2 ton status
Dude.. Run the Allison 6 speed with it.
Same experience here.....At about 3000 miles, mine needs a quart of oil, too. Either I just change the oil or add another quart and drive another 1000 miles. Other than that, a great engine at 75k as well.
When I was testing out the suburbans, I drove a 6.0L with a K&N filter. It seemed to work harder and didn't have the pep I was hoping for. Once I drove the 8.1L, there was no question. So much more snappy and a lot more fun to drive. Sure, I probably suffered another 1 MPG but it's worth it in my opinion.
Although technology has gone up, I definitely don't get any stellar fuel mileage but that's OK. It serves it's purpose quite well.
Great choice and can't wait to see some pics. That's a beautiful truck as-is!
