Moodified13

I know this is different so for the first time I decided to actually put a swap on here. My buddy Trey and I have now done an Ls1 in a 81 Corvette, a 6.2 in a 2005 Jeep Wrangler, a 6.0 in a tube buggy, he did a 5.3 in a 2008 wrangler and we helped a 3rd buddy with a 5.3 in a tube buggy. This; however, was a little different and I thought kinda cool so I decided to share. Anyway, the Airstream was bought from my wife's Grandfather for what most would consider a brother-in- law deal. It came with a 454 and a 475 transmission which is basically a HD turbo 400.

Moodified13

The 454 ran great and the transmission performed perfectly. The problem for me was that it had no overdrive and sounded like a jet turbine running at 3,500 rpm's at 68 mph. My first thought was maybe a Duramax/Allison conversion. But then I found out that the 8.1 was built on the 454 platform and would bolt up to my existing motor mounts and exhaust. The cost and difficulty of the Duramax vs. the 8.1 made me decide to go this way. So the hunt was on for a donor truck with the 8.1 and Allison tranny. After 3 months of looking I found a 2002 2500 HD for 5k with 103,000 miles.

Moodified13

So the donor was bought a year and a half ago and it sat while waiting for us to finish the Corvette Swap, 6.2 Swap and the 6.0 Swap in the tube buggy. (Yes, my buddy Trey and I have a serious wrenching addiction). Regardless, he decided that after New Years was a great time to start this project. Well the Airstream had thrown half of a fan blade through the fan shroud at 3,500 rpm's on our last trip from Lake Catherine in Arkansas so I was ready!

Moodified13

The first step was to get the donor up on the lift and extract the motor and transmission. This went super quick and easy. The thing that weighed heavily on my mind was how to remove the 454 and install the even bigger 8.1 and the massive Allison in the Airstream. The issue is that you have only inches to lift the engine so an engine hoist is virtually useless. As we tried to work that out, we prepared the 8.1 and Allison for installation. The motor was in great shape so it only got a new timing chain cover gasket, valve cover gasket, and oil pan gasket. (Oh, and powdercoated orange valve covers of course!)

Moodified13

After thinking about it, the trick was to lift the motor from the bottom. I decided that we could bolt up angle iron where the headers bolt to and Trey came up with the idea of using square tubing to slide forklift forks in and out. Well out came the old 454 and transmission without a hitch! This actually worked way better than expected.

Moodified13

Ok, all the work in my previous posts happened in the last 3 weeks! We stabbed the engine and transmission 2 days ago. The 8.1 actually retains the old 454 motor mount bolt holes even though it uses the LS style in the truck. I ordered some poly performance mounts that require you drill out the rivets of the old motor mounts and replace them with the poly units. Well, apparently, there are 2 ways to install the damn things and of course I installed both upside down! Anyway, other than having to redo the motor mounts, the engine and transmission went in like they were made for it!

Moodified13

The main reason I decided to go ahead with this was not for the engine, but for the transmission. I looked at gear vendors overdrive systems and for 4 or 5 grand behind 35 year old technology just didn't make sense. The 5k I spent on the engine and trans. did. Check out the size comparison of the Allison vs. a Turbo 400!

Project GatTagO

iTrader: (7)

Awesome swap!

Andrew

Moodified13

Thanks Andrew! It's been fun so far. The new motor and trans fit great. We had to trim the frame to fit the ac compressor, but pretty much painless other than that.

Michael Yount

iTrader: (1)

So with the new set up, what kind of highway rpm will you be seeing? Great MacGyver solution for getting the motor in/out!

Moodified13

5 speed Allison is .711 overdrive , 31 inch tires, 4.56 gears. That puts rpm at 2460 70mph. I figure this will be just right. Regardless, much better and quieter than 3500 rpm.

Michael Yount

iTrader: (1)

Yup - may even pickup some fuel mileage despite the extra displacement. My buddy has that engine in a Yukon he uses for towing. It's a beast. And a thirsty beast....but, what ya gonna do?

Moodified13

Honestly, can't be worse but gas Milage was never really a consideration. Noise and reliability were the goal. Also picking up 100 hp and 65 ft/lbs of torque.

gofastwclass

iTrader: (2)

Nice, I love different.

Michael Yount

iTrader: (1)

The torque bump and lower rpm should help mileage.

EastTnZ28

iTrader: (20)

Nice work. Probably only one in the world!!!

EastTnZ28

iTrader: (20)

I say youll get a solid 9 mpg. I had a 2001 and if you looked real close while running 80 on the highway, I swear you can see the fuel hand moving. But I wouldnt have bought a 496 cui gas burner if I cared about that.

ryanvv355

iTrader: (17)

Looks really nice! Glad I could be of assistance to your project. If I can be of further help, let me know. - Ryan

Moodified13

The last 2 days have been no fun. Fabricating the transmission mount and reinstalling the 60 gallon fuel tank. I came home filthy and sore! I used a Tanks inc. internal fuel pump but had to add 5.5 inches of length to the pump because it's max depth is 10.5". Easily modified with a welding machine, but the transmission mount needed to be 2 inches lower than the stock mount so this was a challenge. (Up and down sucks! I've gotten spoiled by my lift) The fuel tank was a major pain to get back in because of it's shear size. We had hoped to get both accomplished in one night, but it ended up taking us two. Glad we are done with this.

Moodified13

Almost forgot! Sold the donor vehicle's remains for $1,100. Considering I sold the 454 out of the Airstream for $1,300, I'm going to keep this Swap well under 5k. I figure that's pretty good! If you have never done a Swap always remember your going to spend anywhere from 2k to 3k in misc. stuff to finish your swap. It just adds up, $250 for a fuel pump, $400 for a harness, $200 for a tune. $75 for engine gaskets, engine oil, trans oil, ps fluid, ac fittings and hoses, ps hoses and fittings, new belts, etc, etc. There is really no getting around it, at the end of the day add 2k no matter how frugal you are!