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Author Topic: Repower MC9 Conversion from 8V71  (Read 14443 times)
kyle4501
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« Reply #105 on: October 29, 2010, 11:27:52 AM »

Howard Best did a series 50 re-power on his bus. He has also done several re-powers on other people's buses, so he has quite a bit of experience in this area.
He is pleased with the results of his, but he did say he wouldn't do it again. I got the impression the cost to benefit ratio wasn't as good as expected.

Brian has an excellent point to consider with the 6V92 - would be the most bang for buck & could quite likely be done 'in house'.

arl needs to determine if his existing motor is shot or out of tune. Could make a big difference in his satisfaction with a re-power - if current motor is making a good 300hp & it is too slow, I doubt 350hp would be worth the trouble - If current is below 200hp & can be brought up to nearly 300 - his hatred of the motor may subside. . . .

I replaced a motor one time due to persistant low power - turned out to be a few problems elsewhere & not the motor's fault at all. Live, learn & share the knowledge gained.
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robertglines1
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« Reply #106 on: October 29, 2010, 11:57:24 AM »

Mike Leunstanski (sp?) on the board did the cummins transplant in a mci.seems to be very happy with it.M11( I think.).engine source was a transit bus..can be bought reasonable with some with low mileage motors.2or3 thousand dollars and you have all the parts to make change and maybe 1/2 purchase price in scrap to sell..I've met mike and seen his bus .very nice work and great guy.
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JackConrad
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« Reply #107 on: October 29, 2010, 12:22:47 PM »

Mike Leunstanski (sp?) on the board did the cummins transplant in a mci.seems to be very happy with it.M11( I think.).engine source was a transit bus..can be bought reasonable with some with low mileage motors.2or3 thousand dollars and you have all the parts to make change and maybe 1/2 purchase price in scrap to sell..I've met mike and seen his bus .very nice work and great guy.

Mike used an L10, I have his previous engine (8V71) in our bus. He also used the 6 speed automatic transmission from the transit and changed to a different rear-end ratio.  He did a beautiful installation including custom motor mounts.  Jack
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Don Fairchild
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« Reply #108 on: October 29, 2010, 12:32:00 PM »

Cody;

I will respond in another thread this one is getting long and what i have to say may take up a few pages.

 I will respond here with I am not an engineer ( I had a hard time spelling it,thank god for spell check) nor do I claim to be one. They had to kick me out of high school they were afraid that I would stay around till I was an old geezer, and when I tried collage the girls were to purdy and the skirts tow short so that didn't work either.

The only thing I have to fall beak on is I have been turning wrenches for a living for almost 45 years.

Don
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Don Fairchild
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« Reply #109 on: October 29, 2010, 12:40:21 PM »

Also,

Arl is it you don,t like two-strokes or that you have had terrible luck with yours. Is it you that has the eleven kids, you weren't a cub or boy scout were you. You need to learn how to tie knots better then that. Man I don't need the first two lines of a hockey team living my front room.

Don
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Van
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« Reply #110 on: October 29, 2010, 01:36:40 PM »

Don he shoulda took a ride on your little hot rod motor huh! Wink Grin
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redbus
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« Reply #111 on: October 29, 2010, 01:54:07 PM »

Don
The BEST reply so far.
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RoyJ
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« Reply #112 on: October 29, 2010, 10:11:03 PM »

Isn't there something BETWEEN an ISB and an ISM?  Based on the discussion (ISB too small, ISM too big) I would think that we could narrow this thing and focus on whatever that is.  I asked a while back about it.

That would be the ISL, and slightly more ancient ISC. An ISL would make 400hp in RV duty cycle trim, while 320 hp is more common in high duty cycle applications (primarily transits).

Alan, the reason I like the ISB combo so much is cost. Whereas ISL, ISM only appear in commerical vehicles and RVs, ISBs are in millions of Dodge Ram pickups. This makes engine, transmission, parts, and aftermarket availability much better compared to the larger Cummins.

Now, I don't know the exact weight you'll be hauling (and towing), so the ISB may or may not be a viable solution for you. It largely depend on how much you're willing to spend. If money wasn't an issue, I would never bother with the ISB either.
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arl
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« Reply #113 on: October 29, 2010, 10:22:57 PM »

More great help.  Thanks folks.

I've been told that a rebuild in my 8V71 will cost 2-3K in parts.

Based on all posts I've read, the ISB option is interesting but without much margin.  We drive 30,000 miles a year, mostly east of the rockies, but could easily find ourselves coast to coast .  We go from south tip of texas to Canada twice a year.   Climate changes, terrain changes, altitude, plains, mountains, we see it all.  So I'm inclined to have a little extra when necessary, which the ISB may or may not provide.  Still on the table, but I'd need to hear more folks with 36K lb coaches using it with satisfaction.

If I can get an L10 with tranny for anywhere near that out of a transit bus or scrap truck does it make sense to go that route?  Can THAT be done in two months for under $8K if we could do a lot of the work ourselves under supervision?

How do I connect with this Mike L. person that did the L10 job and is happy with it?

Would an 8.3 Cummins out of a wrecked Country Coach RV be worth considering?  I don't know anything more about that engine... my friend in Ohio just said it was an 8.3, which seems to make it between the ISB and ISM.  Am I demonstrating my ignorance?

Thanks again for staying with this thing.  

Alan
PS.  Yes, 11 children - all blessings.  We wanted every one of them and they're all great.  We often qet the twenty questions from folks when our family is out and about somewhere.  Inevitably someone will ask the really stupid one... "Don't you know how that happens yet?"  One of these days I just wish my wife would put on her shy face and and quietly whisper "Yes, that's the problem, we're addicted."   just so we could see the person's response!  She's WAY too proper for that though - usually.

OK... back out this rabbit hole before it gets crazy.  Stay on track y'all!
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RoyJ
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« Reply #114 on: October 29, 2010, 10:29:37 PM »

I like to see discussions of out of the box thinking, they sometimes lead to something innovative.  Thomas Edison was a big believer in that.  He once said "I can tell you 10,000 things that don't work."

However I do believe that the life span of an ISB in a MC-9 would be severely limited.  I am not a diesel engine expert nor am I an engineer, but there is one point to consider while talking about duty cycle and RV use of a highway coach such as the MC-9 that I haven't seen in this discussion.  In my opinion, the more important duty cycle consideration is about hours/miles of continous operation in a steady run than hours/miles per year.  That is where a heavy duty engine shines.

A school bus in school service will typically operate about 2-4 hours in the morning, rest for a few hours and then 2-4 hours in the afternoon.  During that time it will typically be ranging through its RPM/Power range frequently.  On occaision they may travel 4-6 hours to an out of town game.

There are quite a few folks here that take cross country trips in their buses, driving 8 or more hours per day using over 220-250HP sustained output.  There are some that push 12 hour driving days.  And there are at least a couple that team drive their bus 24 hours or longer virtually continous including up and over the Rockies.  I believe that kind of continous high output use pushing a 34,000 or more load would result in an early death for the ISB.  I do know that in a lot of factory RV's they often end up needing overhauls in 50,000-70,000 miles.  I don't know how many of those are ISB's.

I think most MC-9 conversions end up weighing 35,000+ and they will often pull a toad that weighs 3500-5000. The GVWR for a MC-9 is 38,000 I believe.  My RTS currently weighs 32,000 and my toad weighs 4100.  And my RTS doesn't have the large cargo bays, extra large tanks, generator or large house battery bank.


I don't disagree with most of what you say. Also, I don't want anyone to misunderstand me here, I'm NOT trying to suggest the ISB is the end of all motor swaps, and that it'll work for everyone, every situation, no.

The ISB IMO is a niche market (of a niche); it's for people with lighter 40 footers and 35 footers, who wants a cheap engine swap with readily available parts, at low cost, and massive aftermarket support. The ISL/M/X can't fill any of those requirements.

As to concerns of the ISB's ability to gross mid 30,000 lbs, day in, day out, here's some proof:














The above are pictures of hot shot haulers, grossing 36,000 lbs, using their ISB / 68RE trucks day and night, all over the country. The red truck has 310,000 miles as of today (07 truck), origional motor, still going strong. The only thing he did was a transmission replacement around 260,000 miles.

To me, this is a tougher load (high wind resistance), and much tougher duty cycle, than MOST busnuts would ever face. Yes, I realize there're some folks out there driving a lot more than others, and in their case, an ISM would probably be a better solution.

Again, for myself, a 310,000 mile engine life is more than I can dream of, and probably more than an 8V71 can offer.
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bobofthenorth
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« Reply #115 on: October 30, 2010, 02:55:23 AM »

How do I connect with this Mike L. person that did the L10 job and is happy with it?

The guy you are looking for is Mike Lutestanski.  He's in the member list, under the M's.  I think he's home right now but he must not be following this thread.  If you can't get him by PM then PM me and I'll give you his phone number.  The other guy on here who did an L10 swap is Melbo.  He's in Albuquerque and he's also in the member list under the M's.  Same deal as Mike if you can't reach him by PM.

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rv_safetyman
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« Reply #116 on: October 30, 2010, 04:07:51 AM »

As has been noted, the L10 would do the job.  Only issue is that it has been out of production for many years.  It became the M11 (electronic) and then the ISM. 

Being old, I don't know what you will find in the way of a reasonably good engine.  It would have to have been rebuilt and you will need to get documentation on the rebuild. 

As I recall, the engine does not use an air to air charge air cooler.  That will make the swap easier.  You still have to deal with the gearing issue (if you do it correctly). I don't think you will find one with a Allison World behind it (has two ODs).  You might find one with a truck OD manual transmission. 

I really think you would be lucky to do it for $8K and only if you do all the work yourself.  In terms of getting it done in two months, I think that would be a stretch as well.  One of the biggest issues will be to find a good engine.  Since it is a mechanical engine, that will make the job easier.  But it is still a huge job. 

Jim
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Jim Shepherd
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DMoedave
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« Reply #117 on: October 30, 2010, 05:26:48 AM »

Your best bet with those time restraints is to get your original motor rebuilt by a real 2 stroke mechanic top to bottom and i think you would be happy, maybe not. Faster still would be a rebuilt long or short block from a reliabe engine reman shop with a guarantee. No way i can see a engine swap/repower to a different engine trans set up  in that time frame. And for less than $20k (more like 30K) with someone else doing the work. With you supervising please add another 10 grand, its in the mechanics rule book Wink
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RoyJ
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« Reply #118 on: October 30, 2010, 01:25:53 PM »

More great help.  Thanks folks.

I've been told that a rebuild in my 8V71 will cost 2-3K in parts.

We drive 30,000 miles a year, mostly east of the rockies, but could easily find ourselves coast to coast .  We go from south tip of texas to Canada twice a year.   Climate changes, terrain changes, altitude, plains, mountains, we see it all.  So I'm inclined to have a little extra when necessary, which the ISB may or may not provide. 

Alan, if you can do most of the work yourself, and get parts at that price, then it's probably your best bet.

The 8V71, like the 6V71 in my 35 footer, is probably decent in power at sea level. My biggest complaint is the dramatic drop in power at altitude. I'm one of those guys that hate to see smoke out of my exhaust, which limits me to less than 3/4 throttle above 4000 feet.

My recommendation is to do a rebuild, and design a low pressure turbo setup. Don Fairchild is the expert in this field of course, so you'll want to get some ideas from him as to how it should be done.

My own goal is only 3 - 5 psi, with stock injectors, stock pistons, and no aftercooling. In other words, I won't have significant power increase, but that power will be available anywhere on the planet! My only concern is whether I need turbo spec seals in the blower or not.
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Melbo
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« Reply #119 on: October 30, 2010, 05:05:49 PM »

Quote
No way i can see a engine swap/repower to a different engine trans set up  in that time frame. And for less than $20k (more like 30K) with someone else doing the work.

I had mine done with an L10 and it was less than 20 -- If you are going to avoid the diff change out you need to go with a trans that has the OD -- my diff is the stock 3.70 and my trans is the ZF and it only has a 1:1 in fourth.

I can cruise over 70 but I am running about 2200 rpm so I stay at about 63 which is about 2000 rpm -- I get about 7 mpg at the 2000 and closer to 6 when I think I need to get there quicker.

HTH

YMM "definitely" V

Melbo
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