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Author Topic: 8V71 options  (Read 2710 times)
Fredward
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MC-5A #5401 8" roof raise 8V71 with MT647




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« on: August 13, 2009, 08:11:53 AM »

When people ordered MC-5s, MC-7s, MC-8s and MC-9s they had the option of ordering an 8V71. Did an 8V71 in an MC-9 for example, have different injectors and blower gearing versus an 8V71 in an MC-5? Bigger bus comes with more HP?

MY 8V71 in my MC-5 does just fine but I can't imagine pushing a bus that weighs maybe 10,000 pounds more with the same engine configuration? Add an automatic and A/C and I really can't imagine.

Fred
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Fred Thomson
bevans6
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« Reply #1 on: August 13, 2009, 08:17:48 AM »

I've wondered the same thing, and so far I've learned that they came with by and large the same 270hp bus type engine.  People may have hot-rodded them with injectors and injector timing after delivery, but most people talk about them being delivered with the same basic bus-tuned engine.

Makes me not worry quite so much about towing a 6k or 7k trailer...

Brian
1980 MC-5C with an 8V-71
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
Vintage race cars -
1978 Lola T440 Formula Ford
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luvrbus
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« Reply #2 on: August 13, 2009, 08:25:11 AM »

Guys even the 6v92TA engines in MCI's were 270 Hp and lower had something to do with the cooling on a MCI not a great cooling system.
I have saw 6v92 and 8v71 set at 244 hp in MCI 8's and 9's and the 8v92 set 304hp   

good luck
« Last Edit: August 13, 2009, 08:30:57 AM by luvrbus » Logged

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Airbag
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« Reply #3 on: August 13, 2009, 08:39:03 AM »

Guys even the 6v92TA engines in MCI's were 270 Hp and lower had something to do with the cooling on a MCI not a great cooling system.
I have saw 6v92 and 8v71 set at 244 hp in MCI 8's and 9's and the 8v92 set 304hp   

good luck

Can't be too bad they built thousands of the bloody things. I have zero cooling issues with mine even going up the steepest long grades in 100 degree days, never see more than 200 and my gen shares the same coolant. I know we don't have that massive gearbox and truck size driveshafts running the fan and AC compressor  Cheesy It's all in good fun you know. My favorite bus? The one I'm driving that day.
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luvrbus
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« Reply #4 on: August 13, 2009, 08:53:18 AM »

Sure they built thousands I owned a 5 and 8 and when you bump the HP up watch out they are going to get hot why do think they have so much aftermarket parts for the cooling.
It is not a normal system pushing water 2 ft above the engine to radiators to cool.
Glad you don't have cooling problems but most do   


good luck
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Lin
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« Reply #5 on: August 13, 2009, 09:43:38 AM »

I did not have any cooling problems on my MC5a, but I know that trying to get more power out of it is likely to start to cause a problem.  I am not sure though that having the radiators high up really adds anything to the problem.  Doesn't the siphon effect on the way down cancel the pump input on the way up?
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Airbag
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« Reply #6 on: August 13, 2009, 10:46:30 AM »

I really don't need more power or fuel burn. I have been around too many airplanes that have been upgraded with larger engines and what I have found is the factory engineers usually come up with the most harmonious power plant installations. I have often thought it would be nice to go up a hill a little easier but I'm Ok with what I have.
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Don Fairchild
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« Reply #7 on: August 13, 2009, 11:09:35 AM »

the 5's 7's and some of the 8's had the old low block or dry block and would not support more then around 275hp

Don
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Rick 74 MC-8
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« Reply #8 on: August 13, 2009, 01:51:29 PM »

 sorry
don't hit tab and enter
« Last Edit: August 13, 2009, 02:00:14 PM by Rick 74 MC-8 » Logged

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Rick 74 MC-8
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« Reply #9 on: August 13, 2009, 01:58:00 PM »

Don
     That's the first I heard of dry block how can you tell them from the late 871 I have a 1974 MC-8 . I know it has N-65 injectors and assume A timing witch is I think 318 hp I have never had a problem but 


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                                                            Rick 74 MC-8
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luvrbus
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« Reply #10 on: August 13, 2009, 02:12:49 PM »

Not Don but Rick they are easy to tell the difference in the two the old style dry block has large oval shaped air box inspection covers with a bolt in the center.
The later 8v71 has oblong covers ruffly 2in w x 4 inches long with 2 bolts below the heads.
It should be in the archives I remember Cole trying to explain the difference to Gus in one of the famous antifreeze debates here.    

good luck
« Last Edit: August 13, 2009, 02:15:45 PM by luvrbus » Logged

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Fredward
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MC-5A #5401 8" roof raise 8V71 with MT647




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« Reply #11 on: August 13, 2009, 08:35:44 PM »

So based on what I've read so far, if my buddy buys the MC-8 with 871 auto, I'll be able to keep up with him on the Interstate with my MC-5 8V71 N65 with 4 speed Spicer.
Fred
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Fred Thomson
Ed Hackenbruch
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« Reply #12 on: August 14, 2009, 06:58:46 AM »

So Clifford, any idea as to what year they changed from the old style to the newer?
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1968 MCI 5A with 8V71 and Allison MT644 transmission.  Western USA
bevans6
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« Reply #13 on: August 14, 2009, 07:11:44 AM »

your buddy has an 8V71 auto in an MC-8 and you have an 8V-71 Spicer in an MC-5, you should be able to have the coffee made by the time he catches up with you at the lunch stop!   Grin  Unless you have transit gearing and a top speed of 50 mph, of course... Shocked

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
Vintage race cars -
1978 Lola T440 Formula Ford
1972 NTM MK-4 B/SR
bevans6
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« Reply #14 on: August 14, 2009, 07:18:05 AM »

On the cooling thing with the rads up top, water pumps like to push, they don't pull very well.  So having a decent head of pressure to force the water down into the engine is a better thing than making the water pump push the water back uphill again.  yeah, it does consume some of the energy imparted to the waterflow by the pump, but that is reducible by correct water pump sizing.  Secondly, the head pressure of water in the engine creates a natural reluctance to cavitate, so cooling is naturally maybe not improved, but at least presented optimum conditions.  Finally, one of the big bug-bears of designing cooling systems is creating an automatic air bleeding capability.  you need to naturally allow air to flow upwards out of the nooks and crannies in the block, etc.  Having a big header tank up high is a great way to get started on that, as is having the rads up high.  So I think, on balance, having the rads up high is probably not optimum, but not the worst thing either. 

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
Vintage race cars -
1978 Lola T440 Formula Ford
1972 NTM MK-4 B/SR
luvrbus
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« Reply #15 on: August 14, 2009, 07:24:40 AM »

Ed, I think it 1973 0r 74 about the time the 92 series hit the market and FWIW the 92 series have 3 different blocks     


good luck
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TomC
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« Reply #16 on: August 14, 2009, 08:44:29 AM »

Surprisingly, the bus manufacturers did use the same 8V-71N in most of their buses.  Usually two horsepower settings.  For lighter buses, the N55 injector was used for 257hp and 680lb/ft torque.  In heavier buses the N60 was used for 280hp and 740lb/ft torque.  I can remember in the early 70's going in an Eagle 01 to Mammoth and pulling the hill with a very full bus at 25 mph in second gear.  This is also why any increase in horsepower, like turbocharging the engine results in big increases in performance.  My engine with turbocharging and air to air intercooling is putting out 375hp and 1125lb/ft torque at the dyno.  It really wakes up the 8V-71 and flattens out the hills making driving much more enjoyable.  While my mileage has not improved, it still is the same-but with the increase in performance and less smoking at altitude, I simply love it.  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
RickB
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81 MCI 9 smooth side 8V71 Allison 754




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« Reply #17 on: August 14, 2009, 02:42:34 PM »

TomC,

I am reminded of the movie Broadcast News when William Hurt's Character asks Albert Brooks Character:

"What do you do when your real life exceeds your dreams"?

to which he replies:

"Keep it to yourself"...

We are gonna make that Don Fairchild 8V71TA of yours pee in the same cup Barry Bonds used if you don't quit reminding us that you are the guy passing us with a big ol' grin as us mere mortal non-turbo folks limp our way up the grades of the planet.

Just kidding,  But I am a bit jealous I must admit. You cure that jealousy instantly every time you tell me how much you spent for that grin!!!  Wink Grin Grin Grin

Rick
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Lonnie time to go
Lonnie
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« Reply #18 on: August 14, 2009, 03:16:51 PM »

   
Re: Personal experience w/ 2 cycle Detroit's & Propane injection
Reply #2 on: August 05, 2009, 05:49:48 PM
Quote
Run it Thur a skinner valve and fog it into the blower as a gas not a liquid.

On my truck, I run  an RV regulator then to a skinner valve then just spray it in after the air filter. It boils off in the charge air cooler before entering the engine. I am using a 3/32 orifice and get 60hp out of it. I can go bigger with the orifice and get as much as 250hp but I don't need it. Propane for me is a play toy.

Go for it

Don




I just wondered if you could get the same HP by adding a propain injection
It sure would save the cost of a turbo.

but then again i dint have a clue how this works  LOL


Lonnie





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1976 4905
Dallas
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« Reply #19 on: August 14, 2009, 03:52:28 PM »

Lonnie,

Without the added air from the turbo you'll add a bit more power, a lot more heat to the exhaust, and waste a lot of propane.

Why not just run your 4905 the way it was built, learn what your engine can do, then worry about a lot of upgrades, rebuilds and turboing.... bty the way, all of the aforementioned are expensive.

Put a couple thousand miles on your engine before you try to do anything that isn't stock. Learn about what DD's can do and can't do. Before you know what an engine is, or isn't, you have to run it. You really haven't done that yet.

By the by, I had a great little 8V71 (N-70's and "A" timing), in a '68 White-Freightliner with a 4X4 air shift and a 300" wheel base. I did great hauling hay in Washington state, climbing Snowqualmie pass 4 times a week on average.
I decided I wanted more power up the hills so I used a 20# propane tank with a hose to the air intake sitting in a side box of the truck. The hose went behind my seat, and I had a valve I could use to add or subtract propane.
In all actuality, I could get up the hill about 5 minutes faster, but, .... I burned down three loads of hay from flames blowing out the stack when the propane that wasn't burnt, ignited in the exhaust manifold.

The moral of this story is that propane injection works, but it's not a free ride to more power. Those loads cost me a bunch in the short run, and forcing the engine to do what it wasn't built to do was the beginning of an early death for it.
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Ed Hackenbruch
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« Reply #20 on: August 14, 2009, 04:06:22 PM »

Dallas, you almost got it right.  there is no  "w"  in Snoqualmie   Grin   A flaming hay truck not once but 4 times? That must have been exciting!!!!!!
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1968 MCI 5A with 8V71 and Allison MT644 transmission.  Western USA
Lonnie time to go
Lonnie
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« Reply #21 on: August 14, 2009, 04:12:36 PM »

Lonnie,

Without the added air from the turbo you'll add a bit more power, a lot more heat to the exhaust, and waste a lot of propane.

Why not just run your 4905 the way it was built, learn what your engine can do, then worry about a lot of upgrades, rebuilds and turboing.... bty the way, all of the aforementioned are expensive.

Put a couple thousand miles on your engine before you try to do anything that isn't stock. Learn about what DD's can do and can't do. Before you know what an engine is, or isn't, you have to run it. You really haven't done that yet.

By the by, I had a great little 8V71 (N-70's and "A" timing), in a '68 White-Freightliner with a 4X4 air shift and a 300" wheel base. I did great hauling hay in Washington state, climbing Snowqualmie pass 4 times a week on average.
I decided I wanted more power up the hills so I used a 20# propane tank with a hose to the air intake sitting in a side box of the truck. The hose went behind my seat, and I had a valve I could use to add or subtract propane.
In all actuality, I could get up the hill about 5 minutes faster, but, .... I burned down three loads of hay from flames blowing out the stack when the propane that wasn't burnt, ignited in the exhaust manifold.

The moral of this story is that propane injection works, but it's not a free ride to more power. Those loads cost me a bunch in the short run, and forcing the engine to do what it wasn't built to do was the beginning of an early death for it.


Trust me i am not going to touch the engine for awhile.
I like it the way it is, Just wanted to compare the two methods of creating extra horsepower.

Don stated he added 60 hp from the propain thought that was good

From many talks with you and others i will keep my engine slow and simple for along time LOL

Lonnie

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1976 4905
Ed Hackenbruch
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« Reply #22 on: August 14, 2009, 04:13:14 PM »

OOPS,  3 times not 4.   When and where did you haul hay to?  I grew up/lived in the lower Snoqualmie Valley.....Duvall, Carnation, and Fall City  From 1950 to 1988.  Unloaded a few hay trucks in my time.
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1968 MCI 5A with 8V71 and Allison MT644 transmission.  Western USA
Dallas
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« Reply #23 on: August 14, 2009, 04:21:44 PM »

Dammmmit, some day I gotta learn how to spell.

Dallas, you almost got it right.  there is no  "w"  in Snoqualmie   Grin   A flaming hay truck not once but 4 times? That must have been exciting!!!!!!
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Dreamscape
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« Reply #24 on: August 14, 2009, 04:23:44 PM »

Maybe TomC should just include his super duper DD in his signature, then he wouldn't have to remember what was done and have to put it in print! Wink Maybe when he gets his truck done he'll donate the engine to ME! Wink I would love to hear a YouTube Video of that, how about it TomC?

Don't get me wrong, I just can't imagine all those ponies pushing me up a hill, you have to feed them. I'll settle for less, sit back and smile as he flys by. I could drive a lot of miles and see this great country for what it cost. That would be more fun too!

Paul
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Becky and Paul Lawry, On The Road
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Bus Blog - http://dreamscapesilvereagle.wordpress.com/
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Our coach was originally owned by the Dixie Echoes.
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