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Author Topic: industrial 8v71's  (Read 3141 times)
phil4501
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« on: April 10, 2006, 10:37:55 PM »

I have seen mil-spec rebuilt and new 8V71 available for very reasonable. They are listed as industrial engines. Are these set up for generator type use? What would be involved to convert it for bus use if there is a difference?
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TomC
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« Reply #1 on: April 11, 2006, 08:32:51 AM »

The main difference is in the governor.  Industrial engines, whether it be used for generator or compressor have a constant speed governor that is very sensitive to keeping the rpm at its' set speed-like 1800 for a generator.  By contrast, a highway engine has a limiting speed governor that mainly works at idle and at high end governing.  In between, the governor basically works off the gas pedal for the feel of like what a car does.  On the other hand, the constant speed governor, if hooked up to the gas pedal, will be very sensitive to pedal movement, meaning it would be either all the way on or all the way off, in a very short pedal travel.  Not to say you can't use it that way.  Also, the timing most likely be different (can be changed) and sometimes use larger injectors than on road engines (also can be changed).  That's the beauty of the old 2 strokers, you could configure them for just about any application you wanted-including running them standing on end!  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
Dallas
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« Reply #2 on: April 11, 2006, 08:46:08 AM »

To add to what Tom said,
Another type govenor used on the industrial engines was a dual speed  that typically was either at 1200 rpm until called on for more power when it went all the way up to 2300 rpm. These were oil operated govenors.
The air operated style would give 1600 at low power then shift to 2100.
Neither one would be fun on the road.
Also, just thinking about it, lot's of times the liners were different than a "highway use" engine. They were more like marine engines with the smaller ports. Also not good for road use.
Dallas
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phil4501
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« Reply #3 on: April 11, 2006, 08:18:45 PM »

Do even the turbo 8V71's have the small ports if they are industrial?
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Dallas
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« Reply #4 on: April 11, 2006, 09:54:58 PM »

Phil,
I'll have to check tomorrow, but ya, I think even the T's had small port liners.
Dallas
SOmeone else out there could check. I can't, the lights off to keep from waking the wife!
Dallas
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edroelle
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« Reply #5 on: April 12, 2006, 05:14:13 AM »

I don't know if mine was unusuall, but the rebuilt 8V71T that I installed in my MCI 8 did have the large ports liners.  It was a truck engine, not an industrial.  It did take a lot of parts swapping to install in my bus.

Ed Roelle
Flint, MI
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tekebird
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« Reply #6 on: April 12, 2006, 06:55:11 AM »

6-71 that is in my 4104 was a new in crate industrial motor.

yes there is some conversion to do.....most of it is swapping bolt on  accessory parts from the bus motor.

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Dallas
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« Reply #7 on: April 12, 2006, 08:04:52 AM »

I've been checking through the books I have and most of the 71's use either a 1.05 port or a .95 port. The difference apparently applies only to the particular application. I was also surprised to see some of the TA's, TI's, and TTA's using the 18.*:1 pistons. And a real surprise, a 12V71 for bus and coach use.
I wish I had more complete data on a bunch of this stuff.
Dallas
http://www.busconversionstuff.com/eventpage.htm
http://www.catsscratchinpost.com
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phil4501
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« Reply #8 on: April 12, 2006, 06:42:58 PM »

Im guessing on all but ta:

TA-turbo aftercooled

TI-turbo intercooled (I'm guessing)

TTA-twin turbo aftercooled (I'm hoping and dreaming)

Please correct me if I'm wrong. I'm new.

I'll check with the people at usdeiselengnes.com where I saw it. What else should I ask?





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NJT5047
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« Reply #9 on: April 12, 2006, 08:18:55 PM »

Those "mil spec" engines were used in tanks, marine applications, for deck power units, and generators.  Some of them were high HP and would be a challenge to keep cool in a bus.   Would seem to be desirable to know what the engine was intended for prior to purchase....may get really expensive by the time it's installed in a bus and useable.   I don't know what coach you have, but the turbos on mil specs are often located in odd places...like above the bell housing or in front of the accessary drive pully.   May have to plan on replacing all the exhaust and turbo...maybe not.  Military uses odd stuff.  May have to find a bus donor for all the bits to complete the install...coolers, bell housing, harmonic balance, air compressor, alternator, fuel pump, and all the various drives that are used in a bus.  May be able to use your engine for a donor?
Most military engines  have been sitting around for years...believe a Pedco or Reliabuilt (or other known good rebuilder) would be a better source for a good engine.   If you plan to keep your bus for a while, don't want to visit the engine event too often.  Don't want to worry with overheating either..that can get very expensive.   
Find a 6V92T takeout and you'll be happy for less $$...however, an 8V71T is a powerful engine. 
My dos centavos, JR     MC9 with "slow spec" 6V92TA
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JR Lynch , Charlotte, NC
87 MC9, 6V92TA DDEC, HT748R ATEC

"Every government interference in the economy consists of giving an unearned benefit, extorted by force, to some men at the expense of others.

Ayn Rand
NJT5047
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« Reply #10 on: April 12, 2006, 08:24:50 PM »

One other comment, what rotation is the mil-spec engine?  That could be a problem...looks like you have a GM V drive?  That's a LH rotation...you don't want to try to change the rotation of a DD 2 stroke.  That's major work. 
JR
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JR Lynch , Charlotte, NC
87 MC9, 6V92TA DDEC, HT748R ATEC

"Every government interference in the economy consists of giving an unearned benefit, extorted by force, to some men at the expense of others.

Ayn Rand
phil4501
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« Reply #11 on: April 12, 2006, 08:52:40 PM »

I have a GM T-drive, scenicruiser. My old engine is available for acc. or what ever else I need from it. RH rotation
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NJT5047
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« Reply #12 on: April 13, 2006, 07:26:26 PM »

You could probably make good use of any RH DD in your coach. I see "GM" and automatically think V drive. Duh!
You have all the accessories off your 8V71, that's most of the problem solved for any RH 8V71N.
Good luck with your project! JR
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JR Lynch , Charlotte, NC
87 MC9, 6V92TA DDEC, HT748R ATEC

"Every government interference in the economy consists of giving an unearned benefit, extorted by force, to some men at the expense of others.

Ayn Rand
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