8.1 Swap - Reliable core

[Dukagora]

Hello,

Been considering the 8.1 swap from my 454 for some time now and I also want a 4L80E. For those of you looking for this engine or trans, or anything you are swapping in really, how do you approach the "core"? Do you assume it is defective and have someone go through it before install? Did you already know where it came from and knew the stuff was good?

I would hate to go to the trouble, and expense, to discover something was broken.....

Tips for avoiding the duds?

[tucsonjwt]

I can appreciate the need for a more modern engine with FI, but I am not sure why you want to do the swap. If you are towing heavy loads a lot, then the difference in performance between your current 7.4L and a newer 8.1L would not be significant. Of course, if high horsepower is what you want, then the 8.1 would be an improvement.

I had an old 7.4L with a turbo 400 transmission and it was very good at towing, and the acceleration was all I needed.

Apart from the problematic soft cams on the early 454s, I don't know of any other problems (aside from a huge appetite for gas.) However, a commercial Chevy truck dealer in Phoenix advertises their new 6.0 3/4 pickups at 10 mpg, (I assume that is with a heavy load or towing), so i don't think you would gain much MPG with a modern 8.1. I think GM has discontinued the 8.1, but Keith would be the definitive source for that information.

I can't help with any information on the newer 8.1L engines, but I do know that they are a rare animal in the local junkyards. It look like it was a 2001-2006 limited production.

It looks like newer motorhomes on the workhorse chassis would be your best source, per Wikipedia.

L18
The Vortec 8100 L18 was a V8 truck engine. It was a redesigned Chevrolet Big-Block engine and was introduced with the 2001 full-size pickup trucks. It is an all-iron engine (block and heads) with two valves per cylinder. It retained the same bore diameter as the old 7.4 L Big-Blocks, but the stroke was upped by 9.4 mm (0.37 in) to reach 8.1L (496cuin), for a total of 107.95 mm (4.25 in) bore and 111 mm (4.37 in) stroke. Power output ranged from 340 hp (254 kW) to 550 hp (410 kW),[citation needed] and torque from 455 lb⋅ft (617 N⋅m) to 690 lb⋅ft (936 N⋅m).

Other important differences between the Vortec 8100 and older Big Blocks include a changed firing order (1-8-7-2-6-5-4-3), a new 18-bolt head bolt pattern, longer connecting rods, different symmetrical intake ports, different oil pan rails and the use of metric threads throughout the engine. The fuel-injection system for the Vortec 8100 is nearly identical to that used on Gen III engines, right down to the fuel and spark tables in the ECU.[22]

Vortec 8100s were built at GM's Tonawanda Engine plant. The last L18 was manufactured in December 2009.


GM sold the Vortec 8100 to Workhorse (now a division of Navistar), making it one of the most popular engine choices in gas powered Class A motorhomes during the first decade of this century. GM stopped installing Big Block V8s in the Silverado HD trucks when the GMT-800 series was discontinued in 2007.

http://www.dieselhub.com/specs/gm-8.1-vortec-v8.html

[RADustin]

I've done it both ways, actually 3 ways several different times. If you are looking for a rebuilder core, my only concern is a spun bearing. I don't rebuild anything that has spun a bearing. If you want to do as little as possible the purchasing process is a little more difficult.

for instance:

1.) I bought a known core. Immediately rebuilt it. Everything. Didn't really inspect too much, just rebuild it. It's been fine. Bought from some guy on craigslist.

2.) I bought a used 60k mile LS1. Still runs as is today 15k miles later with a blower on it. It's fine. I just assumed it was fine when I got it, it looked clean. And luckily so far it's been fine. oil always looks great. bought from a large company on ebay.

3.) I bought a motor out of pull-a-part. Just took it apart and inspected it. Went through the heads as one was cracked(it was a dodge 360, they are famous for this). And changed the rod bearings as they didn't look great, but not bad. Also did the cam bearings [and cam] as one was nearly split in half. So minimum rebuild. compression was fine before I took it apart. It has also been fine since.

If you buy the motor from a reputable source(company) then usually I have more faith in them. If I buy from an individual it depends what documentation they have. If they can show a video of it running and prove the engine is the same as video, then I'd be ok. If they said they didn't know much about it, I'd assume it to be crap.

I always bring my handy harbor freight compression gauge and check a few or all the cylinders if possible. check the oil. check for any obvious signs, and I feel out the person or company selling. go with your gut.

[Bandit130]

[Dukagora]

Thanks for the welcome!

I don't need to swap in an 8.1. It seems like it might be more cost effective though vs the effort required to put the 7.4 where I think I want it. Whatever I put in there I don't want to leave it stock. Not sure why, but I don't.

I inherited a propane driven 454. Also, I contacted the company, PSI, and they confirmed no modifications were made to the engine for the application it was used in. Dropped in and ran. So however it was assembled is how it should be. Factory I assume, but I know what assuming can do...

All info points to a Gen 6, so roller cam? No spot for a mechanical fuel pump.

Sources for ID. Its what google showed me first....

http://www.enginelabs.com/news/refer...sting-numbers/

http://outintheshop.com/faq/casting/heads.html

Block #10237297
Head# 10141279

I tried to attach a pic of the inside of the head, so hopefully it comes through! Has far as I can tell, it looks brand new. The estimates for this engine are about 200 running hours. They found another way to handle backup power and were literally going to scrap it, the entire generator actually. I managed to get it for free. So *maybe its a bit stupid* to not use what I got for free?

Does that block and head sound like a good platform to work with?

I guess I was thinking maybe a cam/head(If this set isn't worth much)/intake swap for some more power and be done with it. I am fine with fitech or Holley sniper style injection and would rather go that route than a carb. I am not looking to build a hotrod, but I am sure that would be a blast. The idea of having more power just makes me feel good... Tacking on another 100ish Horsepower/torque sounds reasonable to me, but I am not sure what it takes to get there. Parts/cost etc.

What am I intending to do with this truck? Lots and LOTS of mall crawling. Just kidding....kind of. I prefer trucks and love the squarebodies. My wife and I have talked about buying a travel trailer. I figure we should have an appropriate vehicle BEFORE buying the item we want to move around. .
We may or may not do that, don't know. But Id like to be able to pull the trigger on a travel trailer, or anything else we might want to pull. Of course the current 454 in the truck will do the job just fine, but it needs head gaskets etc etc....I want to do, basically whatever I want to do with it. Handle all tasks, with some above stock performance. This is a 79 crew cab. C20.

I have no intention of getting rid of the truck ever(think buried in it). So whatever I do, I don't mind investing. There is probably more info I should provide but I cant think of anything else to add.