8.1 Swap?

[98Murray]

Been looking but have not really found what I am looking for. Wondering if anyone has swapped a 8.1 Vortec L18 496 engine into a GMT400 truck? I cannot seem to find one that has been done, found a nice square body swap but not one on these trucks.

 

[90halfton]

Dunno, would be seriously badass if you did though.

 

[rosco]

Let me start off by saying I'm not expert at engine swaps, but I would think it shouldn't be too much different than swapping a 5.3 or 6.0 LS motor in. I'm also not that educated on the 8.1 motors. I've heard of them, but have not had the opportunity to take a look at one.

Edit, I just did a little googling and found this pretty detailed pdf file of an 8.1 swap into a 88 1ton 4wd http://www.hotrodlane.cc/81 swap.pdf

Edit 2, nevermind, it just clicked that an 88 1ton was still square body. Might be some useful info though, so I left the link.

 

[thz71]

The 5.3 and 6.0 are small blocks. The 8.1 is a big block and not an ls engine. It's a basted child of an ls small block and a old style big block

 

[VCaddy]

Worth a read - http://www.hotrod.com/features/1506-gm-vortec-8100-the-454s-forgotten-big-brother/

Saw that article today and wondered if anybody has put one in a GMT400. Be nice to get the Allison transmission that the 8.1 was paired with too.

 

[98Murray]

Thanks yall! Well the 2001 and 2002 3500HD trucks were offered with an 8.1 so in theory I could use the harness from one of those (if I could find one) and the engine mounts should just be regular big block mounts.

 

[rosco]

The 5.3 and 6.0 are small blocks. The 8.1 is a big block and not an ls engine. It's a basted child of an ls small block and a old style big block

Gotcha. Thanks for clarifying a bit. Like I had said, I'm not that educated on the 8.1 engines. I was just trying to give a semi-educated response.

 

[someotherguy]

Easier to find an LS to swap in, and easier to build more power with it, and bonus of more MPG. Your aftermarket support for the 8.1 is practically zero.

Richard

 

[98Murray]

That is true. I have been looking into a 6.0 swap as well, not much though.

 

[someotherguy]

Not trying to dis the 8.1; I love Chevy big blocks and it's actually a swap I thought about in the past when I hadn't got used to the idea of LS swaps. I'm still not 100% on them as I've seen too many badly-done ones including that LS1-swapped Suburban I got rid of recently. I personally don't have the time or space to pull a swap off myself right now so I can't do justice to one.

The 8.1 has its issues besides being thirsty. The early years (01-03 or so) suffer from high oil consumption, but a member on 3500HD seems to have figured out the likely cause. While he was rebuilding one of his early 8.1's he noticed a vent in the underside of the intake that goes into the lifter valley, aims straight down. Compared to a later unit which has an angle. He carefully bent the straight one so it had a bit of an angle and no more oil consumption. Mind you it could be a coincidence, also may be that the original rings or something weren't fitted properly, or who knows.

I don't have first-hand experience with the 01-02 3500HD's that came with 8.1's but I think they both came with 4L80E's. I think transplanting into a regular GMT400 (non-3500HD) you'd have a hard time shoehorning an Allison in there unless you did trans tunnel surgery or had a body lift. It is correct though that these 2 years of HD's did offer the 8.1, it was either that or you got the 6.5TD. Only 2 engine options those years, no more 7.4.

Richard