This is really great! I yearn for a few hundred more foot lbs of torque. An extra gear or two packed in to the five already would really help also. We have some steep hills / mountains near the coast where I usually camp in SoCal.

It is frustrating to be @ 30 mph in the slow lane and flashers on when traffic is doing 70mph.

Amazing how some additional performance makes things much better and more drivable! Congrats and ENJOY!

Doug

 

I've enjoyed following along in this thread - it's cool to see something so different documented here. Great to hear that the results have exceeded expectations!

 

Just read along cool deal who'od of thunk bigger motor and trans would net 50% better economy good job!

 

That's actually a great point. What nets the better fuel economy and driveability is THE PROPERLY sized drivetrain. On the total flipside I have driven mid 90's Jeep Wrangler 4 cylinders that got **** pour mileage. Why? Because you have to have the foot to the floor at least 50% of the time just to HOPE to keep up with traffic.

Rocking a 220HP 454 means you're struggling to keep up and keeping your foot to the wood way too often. I think that the 8.1 - despite its bad hot rod classification - is a great big vehicle motor. It blends the old school giant big block philosophy with modern day fuel injection and computers.

And I'll tell you what, I would pay to have driven that originally equipped motorhome before and then driven it afterwards. That is a fantastic comparison and conversion.

 

I really appreciate all of the support and positive feedback I have gotten during and after this swap! It definitely helped keep me motivated.

 

Any updates on the fuel mileage? I'm guessing you've had some opportunities to get it out on the road more in the past couple months.

 

I've taken it on 3 trips since the conversion. Best case is 9.25 mpg. That's flat interstate at 65mph.

Worst case is following my buddy down to Houston at 75 in a pickup truck. I had my side by side on a trailer and at times he was doing 85. I stayed on his bumper easily. No way the old power plant could have kept up. It got 7 mpg.

 

That is OUTSTANDING mileage! AND performance! Nicely done!

 

I agree it is good mileage!

My old detroit diesel two stroke powered rig has returned 6.5 mpg over the last 5k miles. But.. that does include quite a few hours of running the 15kw diesel generator, which obviously reduces effective economy.

and I am mechanically limited to 72 mph.

Congrats on a great project result!

 

Glad to hear it continues to impress! Just looking back at the start of the thread, you need to get some big "8.1 LITER" labels to replace the old "7.4 LITER" on the side of the nose.

 

I'm actually getting some built to match the originals. He made the vortec and the liter version samples. I told him to go wth the liter version. Also put Allison/8.1 badges under the 310.

 

 

Love everything about this build! I can only hope to do something like this in the future. Sub'd for updates and keep up the good work.

 

One thing I noticed in this swap was the need to clearance the frame for the low mounted compressor. Could have swapped the accessory brackets for the Express/Savanna 8.1 or Workhorse/Medium duty truck brackets and used the GMT400 style compressor top mounted on the driverside where the alternator is. My 8.1 had a dual alternator bracket on it with a pair of AD244s. It also had a 2nd compressor, sanden bolted on the engine backwards. Was in a Express cutaway limo/party bus.

I am also really surprised the E-fans keep it cool. I have a 454/8.1 van radiator in my 350 Express van and ran those Tahoe fans at one point. With a 6,000 lbs travel trailer it ran hotter than I liked on a 100+ degree day. I was running 210-220*F at times. Went back to a mechanical fan from a Duramax with a TBSS fan clutch and it ran no hotter than 180*F.

I was going to put a cammed 8.1 in my Express van but there is not a way to put it into a van that started life with a 350 without cutting the floor and firewall. LS based engine is a very tight squeeze, much less a tall deck big block.

 

I researched doing exactly that, and I know I could have bought new brackets and bought a new compressor but it would have been expensive. I notched the frame for free and I didn't have to wait on parts. Additionally, everything I could possibly need on the front of this motor is available at any local parts store.

So far it has run extremely cool, I was concerned about the electric fans as well. I kept the mechanical fan from the donor in case they were not sufficient. That being said, it has yet to make a 100 degree run yet. 88 degrees has been the hottest day I have run it on. The fans cycle on and off as they should.

 

Moodified,
In your travels if you run into someone that has to have a 310 1984 limited 45,000 +miles, a 8.1 ,allison 5 sp donor 0 miles 2005 motor home chassis let them know I have one and could talk about letting it all go.I had visions of doing what you have done ,"Great Job",but cannot find time. Live in Indiana close to the Badlands if you have been there rock crawling.seven six five five eight five thirty eight sixty five
Jim

 

Hey there, I know this thread is from many moons ago but I am doing the same exact swap but different motorhome ( we share the same P32 chassis) and I am getting hug up on which radiator Moodified used.
For some reason I am not allowed to PM or Email so could someone maybe shout out to him to hop on here ?
Also would be cool to hear how his rig is holding up and any changes he had to do.

 

I would guess that there's a minimum number of posts you need to make so that the forum software knows you're not a spambot, then it will allow you to PM. Typically it's 5 or 10 posts, so find some threads you're interested in or can contribute to and get your post count up.

As for Moodified, he hasn't logged into the site in 5+ years, so I don't know if you'll have much luck contacting him. It would be interesting to hear how his RV is doing.

 

Yeah I saw that it had been years since he logged in here and the Airstream forum board also. Was able to add him as a contact then it allowed me to email him.
I ended up magnifying the one image of the radiator and saw the EU850 sticker and was able to go from there and ended up going with a full aluminum vs one with plastic tanks.