FMC #1046 converted from Chrysler 440 to Duramax diesel

[BigRabbitMan]

A year or so ago I posted about my upgrade project with my FMC motor coach. FMC's were built from 1973 to 1976 with 1,050 produced so mine is the fourth from the last one built. I have owned it since late 1999 and have put a little over 50,000 miles on it. It served me well in the original configuration, but sometimes one gets an urge to do something different. A percentage of units have been converted to older mechanically injected diesel engines. Having seen that and having been around diesel equipment, I decided to convert mine to diesel as well.

After much research, I decided that the best conversion would be to a modern computer controlled engine and transmission. Of course that complicated the project, but if I was going to do it I was going to do it all the way. Considering many issues and specifications, I settled on a GM Duramax 6.6L turbo diesel with 6 speed Allison as being the ideal unit to install.

Well, the project started in early 2011 and, with interruptions such as moving from CA to OR and then buying and rebuilding a house, the project is now all but complete. Only a few wires to connect and to finish bleeding and adjusting the brakes. It is now down off of the jack stands!

For anyone who has an interest in these kinds of things, here is a link to a photo album with explanatory captions of the project. There are about 370 photos so feel free to skip over many of them!

The reason I am posting now is that some people wanted to know how the project is turning out. The good news is that we started the engine a few days ago and anticipate starting road tests tomorrow or the next day.

Here is the link to the photo album.

Here a link to my Vimeo account where the videos of the engine running are located: Start up video. Note that we incorporated the ability to start the engine from either up front or from the engine compartment.

Second longer video.

At the FMC Ownerss Club website there is also a discussion thread in the Mechanics section about the Dieselfication of 1046 where the project was discussed over time.

Enjoy,

[BigRabbitMan]

I thank all of you for your kind comments. It felt great to actually drive it while knowing it was something that I created. And as a bonus, it performed just as I had imagined that it would.

[Cloud_Dancer]

I've always admired people who not only can they come up with good ideas/projects, but can also keep working on them until finished. I can imagine the feeling of accomplishment when you first drove it. It's pretty amazing really. I hope you get to see lots of drive time in this great motorhome. Thanks for all the photos and videos. I betcha most of us wish we could've been there. Congratulations

[Tinstar]

I watched your video's. Great project and great outcome.

[EdNdonna]

That's just plain cool Steve. you made a heck of a nice rig out of that.

[BigRabbitMan]

wildmanbaker wrote:
Steve, I doubt you will see much difference with the toad as the MH is the most drag you will encounter, unless you get into some very steep climbs. 12.9 is very impressive mileage for something that weight and frontal area.

You were correct in that on Wednesday when I went home to Oregon with my newly running coach with the Brat in tow, for the 583 mile trip up I-5 I got 13.1 mpg. That was from the DIC and by careful filling of the tank at both ends of the trip.

And, yes, it is more than what I was expecting considering that the trip involved two passes of 3000+- and the Siskiyou Pass at 4300 ft with 7 mile 6% grades on both sides. I need to increase the heat rejection rate for the grades, but it is a very fun and enjoyable coach to drive. It can pull 6% grades at over 60 mph!

[wildmanbaker]

Steve, I doubt you will see much difference with the toad as the MH is the most drag you will encounter, unless you get into some very steep climbs. 12.9 is very impressive mileage for something that weight and frontal area.

[BigRabbitMan]

ronfisherman wrote:
Interesting project. When I was active in the Michigan Knights FMCA club there was always a few FMC motorhomes at the GLASS rally's. Enjoyed spending time talking MH's. One member from western MI. was always talking about installing a diesel in his like others had. I am sure Barney is following your project.

Yes, Barney has been following it. While I live in OR, I expect to see Barney next June at a rally in Carthage, MO.

I have subsequently checked my speedometer against my GPS and they actually match so all of my dash and DIC info is correct within the limits of GM's accuracy. That is convenient as no translations of data are needed. For the first 250 miles I have averaged 12.9 mpg as compared to the 7.0 I got with the 440. That will increase with highway miles and decrease when I hook my toad up.

[ronfisherman]

Interesting project. When I was active in the Michigan Knights FMCA club there was always a few FMC motorhomes at the GLASS rally's. Enjoyed spending time talking MH's. One member from western MI. was always talking about installing a diesel in his like others had. I am sure Barney is following your project.

[BigRabbitMan]

The first test miles have been logged!

All I can say is SWEET!, SWEET!, SWEET!!!!! It has good acceleration, shifts as smooth as butter and is very quiet inside. I don't have a video from inside as of yet so I cannot give you a sound level test, BUT, I can give you an 8:43 min video from the chase car of a portion of the initial test drive. The chase driver (Eric) and I were on speaker phone to each other so if you listen carefully you can hear my side of the conversation.

When it starts we are comparing speedometer readings and it appears that mine is reading about 3 mph faster than actual (his). That will be compared to a GPS at some point in the future. I am turning about 1850-1900 rpm at 65 mph. At about 1:11 min remaining I advise Eric that I am going to see if it makes black smoke. I floored it and it just blew gray and dust off the road. That does show that the engine is running efficiently. My acceleration rate was very good for a motor home!

Here is the link to the video, enjoy: Here is the initial test drive.

[BigRabbitMan]

nomad.297 wrote:
I am amazed at the things some people can do when they put their heart and soul into it.

Your project is an inspiration.

Bruce

I did the extensive documentation for two reasons: the first was to provide a roadmap for anyone else that may want to do something similar. The second reason was to scare away anyone thinking of doing it that doesn't realize what all is involved. There are too many motor homes sitting around without an engine because someone started to do a conversion of some type and then found out what was actually involved and gave up. There is an FMC on eBay right now that is an example.

[BigRabbitMan]

rgatijnet1 wrote:
What a great project. How has the new engine affected the load on the axles? Have you had to do any suspension modifications?

One of many reasons for selecting the Duramax as the engine to insert was the fact that the difference in weight between the original 440 and the Duramax was only a couple of hundred pounds. The rear suspension of an FMC is trailing arms connected to torsion bars. I had previously added Timbrin rubber bushings to help things out in the rear. Given the minimal weight change and the strength of the original suspension, I have not had to do any suspension changes.

[BigRabbitMan]

wildmanbaker wrote:
Steve; you had a lot of problems to overcome with this conversion. Do you have any idea of the total cost to do the conversion? You will let us know how it drives, won't you? Nice job!

Thank you. Yes, I know the cost excluding labor (which was tremendous!)as I kept a spread sheet of everything I purchased.

After 20 mi of test driving I can say that it runs and drives like a dream! It has nice acceleration for a motor home, shifts butter smooth and is very quiet inside. It is as good or better than I expected. Need to get more miles on it to shake out and miscellaneous bugs but right now it is feeling golden.

[BigRabbitMan]

debraindi wrote:
Nice RV the guys in the Duramax forms would like that.

I have threads in two Duramax forums. One has been update and the other one will be before long.

[nomad_297]

I am amazed at the things some people can do when they put their heart and soul into it.

Your project is an inspiration.

Bruce

[rgatijnet1]

What a great project. How has the new engine affected the load on the axles? Have you had to do any suspension modifications?