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Author Topic: Which motor would you choose.....  (Read 2865 times)
Chaz
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« on: July 14, 2008, 10:00:56 AM »

.....if you were to swap out an 8V71 out of a 4108 GMC??

Just curious. I seen the other "motor swapping thread" and it just got me thinking. Someone recently said a 6V92T (I think??) was a good swap.

  Still haven't had a chance to finish figuring out my over heat problem, but a motor rebuild is one of the last options. And before doing that, I wanted to get all the info I can. By the way, she seems to be getting even more "addicted to ether".  Sad Sad Sad

  Thanx,
      Chaz
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kyle4501
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« Reply #1 on: July 14, 2008, 10:11:59 AM »

You need a left hand motor, so that limits your options.  Sad

A 6V92T could add some HP!  Grin

But, you have to feed those horses, even if they aren't pulling the wagon.  Cry
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« Reply #2 on: July 14, 2008, 10:23:01 AM »

Chaz, Addicted to ether is probably one of the worst problems you can have. I would suggest a compression check but make sure they do it correctly. The motor should be at operating temp before they start the test.
Your options are pretty limited but I had a 4905 GMC with a silver 6V92 and it had more or less the same power as my current MCI. I have come to the conclusion that unless we two strokers want to get terrible gas mileage and do a rebuild considerably sooner than stock settings, the 8V92's are the only serious power available.

By the way, I think having those as our only real options without spending at least 20k sucks FWIW.

I wish they would have had more foresight in the way designed the engine bays and that they would have left the transverse mounting in some buses out altogether. That sure would have made parts more interchangable and would have given us more options with future engine choices.

Hindsight is 20/20
Good luck, rick
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skipn
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« Reply #3 on: July 14, 2008, 10:54:34 AM »


 Chaz........

    I'm outside the box Smiley

     how about a M11 Electronic or L10   with a ZF and a 80deg. output they
 have them for both rh and lh  Shocked


   Skip
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Don Fairchild
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« Reply #4 on: July 14, 2008, 10:56:43 AM »

Rick, You can rebuild your 8V71, add the turbo and have almost the same hp as the 8V92 and use just a little less fuel

A 425 hp 8V71 runs real good. hp with the two stroke is not the problem, It's keeping it cool. If you run the big radiators and fan you should not have a problem

Hope this helps

Don
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« Reply #5 on: July 14, 2008, 11:21:06 AM »

I have read or heard somewhere on here that you can get a  Allison V730 that will run in reverse. This may allow you to have more engine options.
Other more experienced people might add to this option.
However  with my limited money  i would find a used  8V71 and go slow up the hills.
This motor have worked for years.  From what others have said its cheap to maintain. 
No turbo or excess heat to worry about.
I guess Nimco in NY  has many LH 8V71 ready to go for  $2500.00.
I am no expert nor am I tell you what to do. 
I did go through a phase of wanting lots of HP from an engine.
Going slow will save gas and allow me more trips in my bus.
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Chaz
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« Reply #6 on: July 14, 2008, 06:10:08 PM »

Interesting thoughts guys. I like thinking out of the box, but not out of my wallet.  Grin Grin Grin  It would probably be different if I could do the work myself, but a DD is more than I can handle.  Could any Cat motors work?? I'm not up on my diesel mills, but I know allot of guys like Cats for some reason.
 I guess I"ll have this ol girl looked over and see what she needs, first. Then we'll see what I can afford.  Roll Eyes   Grin

Thanx Guys,
   Chaz
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« Reply #7 on: July 14, 2008, 06:33:57 PM »

Cost would be a serious driving force in my choosing a new engine, but that does not mean that I would go with the cheapest exchange.  If possible, I would prefer an engine that is still in production.  If that were not affordable, I would want one the is still so commonly in use that I could find mechanics and parts anywhere.  I believe that the number mechanics that really know DD 2 cycles is diminishing.  The mechanic that I was using before I moved south said he hadn't worked on any in many years.  He was, of course, a truck mechanic, but its a good chance that it will be a truck mechanic you will have to depend on when traveling.  Again, I would not totally disqualify another 2 cycle if the price were right, but I would hope to find something more modern if I could.
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Barn Owl
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« Reply #8 on: July 14, 2008, 08:50:35 PM »

I have driven 4106s with the 8V71 and the 6V92 and the 6V92 makes for a very nice upgrade. They are inexpensive, and though not on every corner, there will still be mechanics out there that can work on them.

Not mentioned often; hard starting, and an engine that likes ether, can sometimes be attributed to failing injectors. So if all other test are ok you might need injector work.
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« Reply #9 on: July 14, 2008, 09:40:00 PM »

Chaz- cheapest is to overhaul your engine to a turbocharged and air to air intercooled.  Next would be to swap for a 6V-92TA.  But I'm getting to the point where I believe we should be getting away from the 2 stroke Detroits since they are getting harder to find competent mechanics, parts are getting harder to get, and the straight weight 40 is hard to find
The V730 (mechanical version) and the V731 (electronic version) are both available with a reverser gear that allows you to run a normal 4 stroke engine.  One to consider would be either the ISC mechanical at 300hp, or the Cummins L10 mechanical at 335hp.  If you want to up grade to an electronic engine, then the Cummins ISL (same outside dimensions as the ISC) at up to 425hp and 1250lb/ft torque would be my choice and would be about 700lb lighter then your 8V-71, and probably get close to twice the mileage (aroune 9-12).  There aren't many more choices since the rear of the buffalo is to short for a T drive setup.  Good Luck, TomC
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Chaz
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« Reply #10 on: July 15, 2008, 07:36:10 AM »

Thanx Tom! Great info and good points. Especially since I tend to be one to keep what I buy. (I've had my daily driver 1956 Chevy for 29 years and my Harley 28 years. That's just a couple of what i got.)
  So if the time comes, I may need to look at one of these later model motors.

So how come people get all worried about right hand vs. left hand if a reverser gear can solve the issue? Are they expensive? Hard to get? don't work well?.................What?

I would probably make the decision to stay away from the electronic stuff. (it's just me)

Thanx guys. Great food for thought. I'd love to see a thread/post of all the pros and cons. It's just nice to know.
   Chaz
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« Reply #11 on: July 15, 2008, 10:20:29 AM »

Tom C and others,

If one were to keep an eye out for a bus equipped with a right hand V730 or V731 for a future upgrade to a four stroke, what buses and years would I want.  I would prefer to have the whole rig when doing a conversion just to be sure all the parts are there.

Is there a source for a complete conversion right hand V drive trans?  If the series 50s are being junked, I would think there should be some of the trans around somewhere.

Thanks
Don 4107

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Don 4107 Eastern Washington
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Lee Bradley
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« Reply #12 on: July 15, 2008, 10:52:49 AM »

Thanx Tom! Great info and good points. Especially since I tend to be one to keep what I buy. (I've had my daily driver 1956 Chevy for 29 years and my Harley 28 years. That's just a couple of what i got.)
  So if the time comes, I may need to look at one of these later model motors.

So how come people get all worried about right hand vs. left hand if a reverser gear can solve the issue? Are they expensive? Hard to get? don't work well?.................What?

I would probably make the decision to stay away from the electronic stuff. (it's just me)

Thanx guys. Great food for thought. I'd love to see a thread/post of all the pros and cons. It's just nice to know.
   Chaz

So Chaz,
Have you updated your Harley yet? I'm sure you would get better mileage and performance with a new Japanese engine/transmission. I would go with Mr. Fairchild's recommendation and have a new 8V71 vs. a used different engine but I am a 2 cycle fan. One of my first long trips will be to Mr. Fairchild's shop for a complete tune-up of my 8V92.

Lee
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Dallas
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« Reply #13 on: July 15, 2008, 11:32:45 AM »

Don,

Why limit yourself to the V730R or the V731R?

The ZF transmissions are much more robust and can be configured just about any way you want them.

TomC is always talking about the V730 still having parts available, but with todays economy, I believe that won't last much longer... remember, Automotive Manufacturers are only required to carry a 7 year inventory of parts.. even the 50 series is held to that.

I don't think there are too many manufacturers of buses anymore that even use a V-drive configuration.. why would Allison continue to support it? Just like the VS2-X, (which is my favorite), the V730, HT740, HT741, HT748, HT754 are all going by the wayside.

Here is a picture of a bus that was way ahead of it's time.. Timetogo40 sent it to me and I had forgotten about them... this is a Flx "New Look" with what looks like a 6-71 Tdrive. No reason if that could be done that a real GMC coach couldn't be changed to a T-Drive.

I did a similar change back in the early 80's and put a 4-71 with a 653MT in an Old Look GMC.. wasn't hard, just a bunch of welding in new struts and "Disney Design."

Good luck.

Dallas

Tom C and others,

If one were to keep an eye out for a bus equipped with a right hand V730 or V731 for a future upgrade to a four stroke, what buses and years would I want.  I would prefer to have the whole rig when doing a conversion just to be sure all the parts are there.

Is there a source for a complete conversion right hand V drive trans?  If the series 50s are being junked, I would think there should be some of the trans around somewhere.

Thanks
Don 4107





Sorry, I need to resize the photo, I'll do that this evening
« Last Edit: July 15, 2008, 11:47:50 AM by Dallas » Logged
Chaz
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« Reply #14 on: July 15, 2008, 12:36:04 PM »

Actually Lee, I had thought many times to upgrade to a generator shovel motor but........... no need. I can still work on the ol'girl much easier than the new stuff (it's like a 2 cylinder Briggs and Stratton). I have upgraded the 6v. system, I use an electronic regulator, and a new magneto. Plus, they still repop EVERY part for it yet. So I'm covered as far as my scoot goes.  Roll Eyes

So it's not like I am doing it - IF I would ever do it - just for fun, I'm trying to think ahead and do what would be best in the long run. Maybe it's a normal worry that people have time to time, but I keep hearing about the possibility of trouble in getting parts and good mechanics to work on the ol'girl in the future. Right now I'm ok, but................. (like I said, I tend to keep things a looooooooooong time)  Grin Grin

So, again, my thoughts aren't so much about mileage, but reliability as it seems my motor may be needing some help soon. And if so, while I'm at it, would it be a good idea to upgrade? It's just a thought. I wish I knew more about all the engines and tranys and combinations of both, (like I do Harley's and small block Chevy's) but I don't. So that's where I'm hoping some of you guys would help with some ideas. Oh, and by the way, I'm ok with the power I have thus far,(altho pulling a tire roasting hole shot would REALLY get some heads turning!  Cheesy :Dlololololo) and altho the mileage is not great, (I understand we're just not going to get 30mpg, but it would be nice to do a little better tho Wink Grin) all things considered, what would be a good setup?

Thanx for the info and thoughts,
  Chaz

p.s. Jap bike stuff?!?! NO F**KING way!! The only thing Jap so far is the regulator. (damn shame too)  Grin Grin Grin Grin Grin Grin Grin
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« Reply #15 on: July 15, 2008, 01:09:02 PM »

LOL   I knew the answer on Japanese re-power from a Harley owner.

My bus keeps going backwards everything I open up leads to another. I hadn't planned on doing much to the cockpit area this go round but as long as I had the heater lines disconnected, to lower the passenger deck, I would pull the driver heater/AC and clean it. There were some dead ended wire bundles (factory) so I figured I would track them back to the power panel and get rid of them. I couldn't remove them because some other bundles were in the way so ..... The whole dash, gauges, lights, switches is in a box and all the wiring is out on the ground still connected to the power panel. But I discovered the two air gauges are double needle gauges but they are plumed so that two needles read the same line. Redundancy I guess but I am going to re-plum them so one gauge reads primary air and front applied and the other reads secondary air and rear applied ... and the heater/AC is collecting dust. Reminds me of the book 'Princess' by Joe Richards; Joe had bought a Friendship Sloop prior to WWII and in the process of rebuilding it he lost sight of the original propose which was to go sailing.
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« Reply #16 on: July 15, 2008, 08:46:38 PM »

Chaz,

I don't know how old you are if your 8V71 needs rebuilding it is a very simple engine to work on. and almost Bullett proof and should last you a lifetime of driving with no more miles you will put on it get it to a good 2 cycle man and let them do what it needs and you'll love the old girl they love to be rode hard and put up wet LOL.

Just my 2 cents worth.

Larry Higuera
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« Reply #17 on: July 15, 2008, 09:40:18 PM »

Chaz- I concur with the last post.  Have your engine overhauled by a quality Detroit person.  I would highly recommend you either run it as is with just N60 injectors (best balance of performance and economy) with no turbo, or rebuild as a turbo engine and go with 70 injectors also for economy since you just have a 35ft'r.  Good Luck, TomC
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Chaz
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« Reply #18 on: July 16, 2008, 07:37:05 AM »

Thanx Gents.

Larry,
  I'm 48 yr. old. I have plenty of mechanical backround (and tons of fabrication experience as I owned a weld and fab shop) but I don't really think I want to mess with big girl. Sure, water pumps, stats, hoses, stuff like that - no problem, but I am old enough to have learned to leave the stuff I don't know to people who do. If the guy who works on my bus would want to allow me to hang around while he does an in frame or overhaul, I'd be all about that! But like I've said, this is the first diesel I have ever touched with a wrench. (It's still a little intimidating Wink)
 
  Thanx Tom. More than likely that will be my plan, but if there is a good "beneficial" swap out there, it would be nice to know so I can weigh all options. My plans are to run this ol' girl aloooooong time. I'd probably only "step up" if I hit the lottery. Roll Eyes But they say you have to buy a ticket before that can happen.  Grin Grin Grin Grin Grin ( 'magine that! Cheesy) So it looks like it's going to be another loooooong relationship.  Grin  Actually, even to the point that if I do stay with the 8V71, I have been kinda watching around for a good spare. No hurry there, but if one should happen to show up....why not?

And to be honest, one of the main reasons is because I still work with metal and see where it's going. I take my scrap (which truely is "scrap" if I'm getting rid of it) to the recycler and see all the "good stuff" people are willing to throw away for a couple bucks. Seriously, it blows me away!! (and sometimes pisses me off, but what's a poor boy to do?  Wink) So it's my guess, old DD's could end up getting rarer and more expensive down the road. Maybe I'm wrong, but I do my best to try to think ahead.

 Thanx again,
     Chaz


 
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« Reply #19 on: July 16, 2008, 11:03:56 AM »

Chaz,

I'm sorry I forgot to add that Chiltons.s Motor Manual has a very good book a step by step on rebuilding a Detroit 2 stroker. Unfortunately I don't know where you can find one but I bet others also have em.

PS I'll stick with my goldwing 1984 1200GL  Grin Roll Eyes Tongue Cry

Larry Higuera
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« Reply #20 on: July 16, 2008, 11:32:43 AM »

Chaz heres some specs on the 8V71
Popular Horsepower Ratings (8V-71)
866 ft·lbf @ 1400 rpm 318 hp (237 kW) governed at 2100 rpm (naturally aspirated)
990 ft·lbf @ 1400 rpm 305-350 hp governed at 2100 rpm (turbocharged)
1064 ft·lbf @ 1200 rpm 305-370 hp governed at 1800-2100 rpm (turbocharged/aftercooled)

Mine with the injectors should be right at 345 enough to run at governed speed of 83 checked with GPS and average 6.8 at 70+MPG 65 gives 8.2 average over a 7000 mile tripat Glacier and MT rushmopre was down to 5.5 in 2 and 3rd gear a bunch of miles so I'm happy with it have got as high as 12 in CA where limited to 55 and enforced strictly especially with out of states plates of course your MMV.

LarryH
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