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Contributor
| Thanks Stephen. Your input saved me a lot of hard work and headaches. |
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Expert
  
Location: Cottage Grove, OR | Actually, it was LCAC Man that responded, but I agree with him. When doing a conversion, many times one looks at an engine/tranny setup in its original location and sees it as a good unit - which is true - and thus thinking it will be good in a new application. But what is more important than how it works in the original application is how it will fit and work in the new application. The first thing to do is look at the restrictions/characteristics of the receiving application and see what best fits that application.
In the case of the FMC and how they are used, weight and torque band are the first things to consider. When I looked at doing a conversion, the first thing I looked at was weight and center of gravity as that is a major factor in the handling characteristics of an FMC. When I did that, I ended up feeling that the added weight of the Duramax/Allison combination would be tolerable, but that anything heavier would create issues that I, without a full shop and unlimited dollars, did not want to deal with.
I also looked at the torque band of the prospective engines as a wider torque band makes the driving characteristics more flexible. The Duramax also had the widest torque band of the prospective engines. At that point I made my decision that if I converted to diesel, it would only be a Duramax - no other diesel met my criteria. Lacking that, I would stay with a gas engine. As I had a fresh 440 in my coach, I would have stayed with that engine as it is a good engine and is engineered for the coach and is fun to drive. I put over 60,000 miles on my coach with that engine so I know how they perform. For 99% of the people, staying with the 440 is the correct decision. If I was going to upgrade to a newer gas engine, I would go with the GM 8.1 liter engine coupled to a 5 speed Allison transmission. That combination was used in many motor homes in the late '90's and 2000's until GM stopped production of the 8.1 so they are available.
But the bottom line is that no conversion is worth the dollars invested unless one plans on driving a lot of miles. One can buy a LOT of gas for less than the cost of any conversion. For a diesel conversion, don't start it unless you are prepared to invest $20-30,000 other wise you will end up with a partially converted coach that becomes unusable and virtually unsaleable. Almost no one wants to buy someone else's project. The most recent example is coach #192 in Santa Maria, CA.
As I tell most people, just drive your coach, maintain your coach and have a great time with it. |
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Extreme Veteran
Location: Scottsdale, Aridzona | Other old sayings come to mind . . .
$400 saddle on a $20 mule.
Cheap, Fast, Reliable . . . pick TWO.
$8,000 later, what have you got ? A fast Volkswagen !
If it won't go . . . Chrome IT!
If you can turn it . . . you ain't going fast enough.
All Engineering Programs will consume all available funds . . . before the time allotted, or the "product" is completed.
It is very expensive to achieve high unreliability. - Norman Augustine
All electronic devices fail in a mechanical mode.
An electron cannot fail . . . only the circuit that it is in can.
The "load limit" of a pickup truck is when the front wheels come off the ground and it is no longer steerable.
Do not add any weight behind the rear axle of a FMC motorhome . . . not even bumper stickers.
The last one I made up. Press ON ! Lou #120 |
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Veteran
Location: Canton, (Sixes) GA | Although 890 is old school with a non computer controlled 8.2L Detroit Turbo Diesel/Allison, I appreciate the power, torque, reliability and fuel milage it provides. Love the discussions. Enjoy your coach, we sure enjoy ours. |
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Elite Veteran
Location: Oceanside, CA | Stephen,
How did you handle the large fuel tank vent connection on the fuel pickup assembly? I'm looking at some universal charcoal vapor canisters.
Thanks
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Expert
Location: Cottage Grove, OR | Since that vent was a closed loop within the tank/fill system and it did not connect to any canister system, I simply plugged it. There is no vapor recovery system needed for the Duramax as diesel doesn't vaporize like gasoline does. Given our very short fill neck, bubble back is a non-issue. You do need to use a vented fuel tank cap for expansion/contraction allowance. Napa has one that fits our tank. |
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Expert
Location: Cottage Grove, OR |
Since I now have just under 5,000 miles on my conversion, I thought that I would do an update. The first thing to note is that I am very happy with what I call the "drivability" of the coach. I like the ease of merging with traffic at speed, not slowing down for most hills, engine starting in a revolution or two, an even quieter interior and other smaller factors. Many people are interested in what my fuel mileage is as that is a significant factor with any motor home. Historically, with the 440 I got about 7.0 mpg most of the time. That is probably about average for an FMC. As expected, I have seen a significant increase. Since fuel mileage varies with driving style, weather, terrain etc. I decided to do some close measurements under specific conditions to help define what was occurring rather than just post a series of numbers. So on a recent trip to CA I decided to do a flat land test and a mountain test. The flat land test was from Redding, CA to Bakersfield then back north to Santa Nella, CA. That was a run of 674 miles over three days time. The first half of the trip was with a storm coming in and a lot of cross wind. The second half was with relatively calm winds. I also made five diversionary trips into towns for various reasons so it was not all straight down the freeway driving. I spent most of the time in the truck lane at 60-63 mph as it was a comfortable driving speed and I didn't want to be in and out of the 70+ mph left lane. The net result was that I got 14.7 mpg for that segment of the trip. I was not towing the Subaru Brat. For the mountain segment, I went from Redding, CA home to Cottage Grove, OR. The beginning and end of the trip were at a similar altitude with an initial gradual climb from Redding to Weed at 3,900 ft. It then dropped down to the Shasta river and back up to 3,000 ft then back down to the Klamath river. Those were 4 or 5 mile 5 & 6% grades after some flat stretches. It then went from the Klamath river down in the canyon up to the top of the Siskiyou pass in Oregon at a little over 4,100 ft which is the highest point on I-5. After dropping down the 7 mile 6% grade into Ashland it became a series of ridge crossing with the first several at the 2,000 ft level then into the vallleys in between. As I continued north, the ups and downs became less significant until I reached home in Cottage Grove. Again, I was primarily in the truck lane except when passing trucks on grades. When descending 6% grades, I slipped the Allison 6 speed tranny into third gear (which is the same gearing as second gear in the 727 tranny) and came down the grades at 50-55 mph without needing to use the brakes. The mountain portion of the trip was 301 miles and the coach got 13.3 mpg which is a respectable number in my opinion. With those two numbers in mind and the conditions that created them, I expect my long term number to be somewhere in between them. Towing the Brat will probably reduce those numbers by a mile per gallon. Even with this kind of fuel mileage, it will take a lot of miles to recover most of the cost of the conversion excluding the unpaid labor cost for myself and the others who invested significant hours as well. But, yes, I am glad that I did it and hope to see all of you on the road or at a future rally. Schedule yourself for the June Mega Rally in Carthage, MO and you may have the opportunity to take my coach for a test drive. |
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Extreme Veteran
Location: Scottsdale, Aridzona | Gates #31640 is a VENTED gas fill cap with finger tabs that fits my #120.
Stant #10292 (7 Lb.), and Balkamp #703-1428 (10 Lb.) is a RECOVERY type radiator cap that fits the stock radiator on my #120.
Stant #10282 is a NON-recovery ope n type radiator cap of same size.
You may also see: https://groups.yahoo.com/neo/groups/FMCMotorCoach/conversations/topi...
for more Part #s.
Press ON ! Lou #120 |
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Elite Veteran
Location: Medford, OR | Quick question.....Since fuel tank vent lines were mentioned. I am putting in a 3-port fuel filter "after" the fuel pump. I am going to tie the existing fuel tank vent line into the "vapor" port on this new filter. Will I need to buy a vented gas cap now? My vent line just hangs in mid air now with smelly fuel, so obviously it's venting. I'm taking the answer to this is yes.... |
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Expert
Location: Cottage Grove, OR | Originally your vent line was connected to two vapor recovery canisters which recovered the vapors given off when temperatures rose. The unvented cap directed the air and vapors through the canisters. If that line is no longer open to the atmosphere then some other means of preventing excess pressure or a vaccum in the tank must be provided. A vented cap would provide that link. You would still get the same vapor smell as you are now. |
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Elite Veteran
Location: Medford, OR | Ok. I will buy one Stephan. Thanks for the part # Lou.
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Veteran
Location: Olympia, Washington | Stephen:
How about the smell, are you learning to like it? I like the smell of gasoline can't say the same about the stench of diesel. Remember, when your hands are black as coal from the diesel use dirt to clean them. I don't think I'll ever get over that one. Diesel on. |
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Expert
Location: Cottage Grove, OR | That is a positive of the newer computerized Diesel engines like the Duramax - very little diesel smell. Only when I have to fill the tank but with a 700 mile range I don't need to do that very often. |
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Expert
Location: Cottage Grove, OR | Time for an update regarding the conversion of 1046!
Over the last two years I have put 30,000 miles on the coach with the Duramax. All has been good with one exception: engine temperature when climbing long grades. It became apparent that I had inadequate cooling so that aspect needed to be redone. After consulting with Len and others, I purchased the same fan that he has and a reworked original FMC brass radiator. The pictures of the process are at this link: http://fmcowners.com/mbbs22/photos/show-album.asp?albumid=77&photoi... with explanations under each picture.
The net result of the change has been that my temperature gauge has not moved since! Even climbing 6-7 mile 6% grades at 60+- mph speeds. This has been in the winter so I may see it move a little this summer but it is obvious that the cooling capacity of the new setup is very adequate. That change does determine the end of the upgrade of FMC 1046. Now I just get the pleasure of driving it!
Speaking of driving it, I have recorded all fuel used since the initial conversion. Prior to the fan change over the 29,000 miles driven I averaged a little over 14 mpg. With the larger fan pushing much more air I expect that to drop to 13+ mpg. Still very good mileage and a 6mpg increase over what I was getting with my 440!
I did this conversion just because I wanted to drive a coach that has the performance and features that my coach now has, not based on cost/benefit ratios. But I have done some calculations. And the first thing I need to state is that it takes a lot of miles to balance the costs and benefits. I have driven a lot of miles and my calculations indicate that I either recovered my investment in miles driven or in dollars. My net cost from start to this date is $18,222.39. Now I spent $29,099.24 but was very fortunate to be able to recover the difference by the sale of unneeded parts from the FMC and from the donor pickup that I purchased and used the engine, transmission and other things from. That is both a higher expense and higher recovery rate than would be normal for a conversion like mine.
I expect that with both the saving in fuel costs and the increased value of my coach, I have recovered the cost of the conversion.
I will be putting more miles on attending the Feb rally in Southern California and the July rally in Chama, NM and I hope to see all of you at one rally or the other!
Happy travels, |
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Elite Veteran
Location: Oceanside, CA | I've seen 195dg one time when topping a long grade(Cajon Pass) and I was loaded, probably close to 23,000lbs total...I haven't driven it completely unloaded for any distance but locally it rarely hits 180dgs (75dgs days), the closest light load trip was that last Felton rally when we had the scooter (about 500lbs tongue weight only) and carrier..I think I saw 190dg on that trip on the steep climbs and on the grapevine grade.
I doubt you'll ever have another cooling issue. |
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Elite Veteran
Location: Medford, OR | 14 mpg! That is awesome. I want a Duramax...and a new motorcycle....and finish my desert over lander....and a bigger house with a garage...and where do I start?? haha |
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Elite Veteran
Location: Oceanside, CA | dkarnath - 2018-01-17 7:16 AM
and a bigger house with a garage
or just a new small house with a (much) bigger garage!!
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Veteran
Location: Olympia, Washington | Screw the house I would go with the L A R G E garage! Heated and air conditioned of course. |
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The Dieselfication of Coach 1046
