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8.2 DETROIT DIESEL
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myalbie
Posted 2009-11-02 7:52 AM (#809)
Subject: 8.2 DETROIT DIESEL



(75.75.131.126)
I have started to look for an Fmc and found one with the 8.2 detroit diesel and Allison transmission.Is this a good package-reliable etc? Does it greatly improve the fuel mileage
over a gas engine?

Thanks Paul in NJ
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BigRabbitMan
Posted 2009-11-02 9:35 AM (#810 - in reply to #809)
Subject: Re: 8.2 DETROIT DIESEL



Location: Cottage Grove, OR
(71.142.244.54)
Hi Paul,
Here's hoping you will be successful in finding the right FMC for you.

Since i have the 440 in mine, I cannot speak directly to the overall 8.2 package. I can say that many of those conversions were done in the 80's and 90's so it is a "known" setup that others are familiar with and can advise and/or work on.

On the mileage question, they generally get significantly better mileage. but how much varies depending on which version of the 8.2 was used and the engine to ground gear ratio that was used. When it comes to cnversions, everything is variable so each case is a little different.

See you on the road,
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myalbie
Posted 2009-11-02 10:52 AM (#812 - in reply to #809)
Subject: RE: 8.2 DETROIT DIESEL



(75.75.131.126)
Thanks
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Bair
Posted 2009-11-03 11:00 PM (#817 - in reply to #809)
Subject: RE: 8.2 DETROIT DIESEL


Location: Santa Cruz, Calif.
(130.65.144.136)
While I don't know about the Detroit, but I can make several observations:

Considering how well the Cummins 5.9 moves my other motorhome, I would expect an 8.2 could really sling a FMC around. However, a lot of diesels are "detuned" to fit a particular application. The Cummins 5.9 is designed for a medium duty, bobtail truck. So when Dodge started putting them in their pickup trucks in the early 90's, they seriously de-tuned them. Partially to keep the pickup under control and partially to not bust up the 727 tranny, which inself is a pretty strong transmission. They do this by smaller fuel pumps, injectors, restricted airways, etc.

Detroit is one of the "Big Three" in diesels. I think most truckers would put them behind the Cummins or Cat, but they are a strong engine in their own right. They use a different combustion chambering which gives them their signature whine. It sounds like a supercharger. You won't notice this up in front.

Allison was the king of big rig auto trannys for the longest time. Lately Aisin (made by Toyota) has been a good alternative. But the Allison has a bulletproof rep, and is still the choice of big rig fleet owners.

In other words, you can't go wrong with the combo, just make sure it has been serviced and taken care of. Even the finest will fail without care.
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Duramaxer
Posted 2009-11-05 7:21 AM (#822 - in reply to #809)
Subject: RE: 8.2 DETROIT DIESEL



Location: Oslo Norway
(84.49.209.89)

What you might want to consider on a diesel converted FMC is not only what engine/tranny combo but how is the conversion done.

All FMC's tend to have a problem with a sagging rear end. Diesels wiht their extra weight and higher torque puts extra load and stress to the construction. I belive some conversions end up having center of gravity further back than the 440 also.
If you go with a diesel find out if the coach i sheer plated along the sides for added strengh tand look for signs of stress or sagging in the structure. Take a look at pictures found in here and elswhere and you will know what and where to look.

Also take it for a spinn to find out if the added weight together with other known (and unknown) steering issues makes it more than a handful down the road.

Kjetil

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denshew
Posted 2009-11-05 4:20 PM (#824 - in reply to #822)
Subject: Re: 8.2 DETROIT DIESEL


Location: Canton, (Sixes) GA
(24.30.36.240)
0890 had a 205 HP 8.2 Detroit Turbo Diesel/Allison transmission when I bought it. Had issues and was replaced with a rebuilt 8.2 230 HP with 15MM studs etc in late 2008. Around 9,000 miles on the new engine, still breaking in. Consistantly get 12-14 mpg with normal driving. Gassers are in the 8 mpg range I think. The 8.2L Detroit Diesel is a 4 cycle engine and was used throughout the 80's and early 90's in school bus's, garbage trucks, medium duty trucks etc. Very popular with the boating/marine crowd, they run them hard. I have 22.5" wheels and replaced the 4.56 differential with a 3.73. 0890 has extensive sheer plating, important, also suspension, steering and brake upgrades. It has been a while since I checked the data base, but seems like there were over 70 coach's converted to diesel. Don't know if the DDA would be the best choice if converting now, but if it's there and solid should be reliable with minimal care and last for years. Provide the coach number and we may have specific info. You may want to check with RVS and MCR for history. The Allison 545(R) four speed is designed for up to 30,000 lbs. The FMC is a little over half that (mine is 17,000) so it's loafing. Does it have a propane or diesel generator? I like mine. Denny
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denshew
Posted 2009-11-05 7:06 PM (#825 - in reply to #824)
Subject: Re: 8.2 DETROIT DIESEL


Location: Canton, (Sixes) GA
(24.30.36.240)
reposting this info, think it is pertinant......I pulled this off the www. Modified and cleaned it up a little. Originally posted by "dozer" on the diesel doctor forum 3/10/2005. Couple of things he suggests I need to do to mine. .. Denny

message;

The 8.2L is a well-designed and well-made engine for its class and vintage. The people running the high-power versions in marine applications generally love 'em.

They are VERY quiet-running engines. They have a very wide power-band. And they are also one of the most fuel-efficient engines of their era and size-class.

The injectors do need service more often than some other engines; and it's important to keep them working right. Anyone who knows the old 2-stroke Detroit's will have no problem adjusting and servicing the injection on the 8.2's.

There are 3 "secrets" to being happy with an 8.2L:

1- Get a turbo version, for sure. That's about 230hp... Be SURE to replace the muffler whenever it starts causing backpressure!

2- DO install an exhaust-pyro gauge and do NOT run the temp past 1100 (pre-turbo) for any length of time. installing a cold-air intake and an intercooler is well worth the effort, to allow continuous full-power on grades. It knocks 100-200 degrees off the pyro). At LEAST add a cold-air intake.

3- Keep the cooling system in GOOD condition, and DO install an additional "on-off type" overheat sensor in the head, and hook it to an in-cab buzzer. Every 8.2L cracked head that I know of was directly caused by an overheat event. If you don't overheat this engine, you probably won't ever crack a head.

And of course, do all the other things that a smart owner does with any diesel: keep the oil clean and full, keep the air-cleaner clean, and do NOT lug it.

It's easy to avoid lugging with this engine, because it makes good power all the way up to 3,500+ rpm. Truck-redline is usually 3250 full-load, 3450 no-load.

These engines like to run between 2000 and 3000 rpm. Some of the people who have trouble with this motor are driving it like it's a big Cummins 855 or something, i.e. always lugging it around 1500-2200 and upshifting it at 2500.

I think that might be part of why they have trouble with them...they're used to lower-rpm diesels. At such a low rpm, and with full power on, maybe this motor isn't circulating enough water thru the heads or something. Anyway, the 8.2 loves to run faster...upshift it at 3000+, downshift it at 2000; and cruise around 2200-2700, depending on load, for best MPG.

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Jerry
Posted 2010-02-04 2:03 AM (#907 - in reply to #809)
Subject: Re: 8.2 DETROIT DIESEL



Location: Clovis, Ca
(80.240.220.154)
Paul, did you decide on a coach?
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