Torque capacity limits of MC-5C with spicer and drop box...??

bevans6 · November 25, 2009, 07:31:01 AM

I took the Spicer I got from Ken apart (trick - RTFM and shift it into reverse BEFORE you spend half an hour trying to get the top off) and it looks very good inside. The dogs are about 90% perfect, the only wear is actually on the reverse gear train, where you do actually slide and engage the actual teeth of the gear. The first 3/16" of the teeth are rounded, but my feeling is they start with a rounded aspect on those teeth from new, to aid in engaging the gear.

Presuming I buy that turbo 8V-92 that we all lust after, what are the torque limits of the rest of the drivetrain? The Spicer, the drop-box and diff, the axles?

Brian

TomC · November 25, 2009, 08:01:40 AM

Typically the Spicer 4 spd manual had a torque rating of 1200lb/ft. To find out we need the model number. That's why many times they went to a 5 spd or Allison automatic with the 8V-92TA that puts out closer to 1,400lb/ft torque-unless you have a 75 injector engine, and that puts out 370hp and 1150lb/ft torque. With normal 90 injectors, your at that 445hp and 1400lb/ft mark. Good Luck, TomC

luvrbus · November 25, 2009, 08:25:44 AM

Brian, don't know about the 4 speed gear box but you are not going to hurt the dropbox.
I put 1580 lbs of torque from my 8v92 in a Eagle to the dropbox without problems.
I know other Eagle owners that over 600 hp s60,Cummins and Cat engines never any problems and the MCI 5 has the same dropbox as Eagles.
Both dropboxes rust about the same also LOL

good luck

Busted Knuckle · November 28, 2009, 10:10:06 AM

Quote from: luvrbus
and the MCI 5 has the same dropbox as Eagles.
Both dropboxes rust about the same also LOL
good luck

ROFLMAO!

BK

Gary '79 5C · November 28, 2009, 03:55:04 PM

Brian,
After solving all the torque problems, attention will be needed to the additional heat rejection of the larger engine. Optimum radiators and air flow will be critical. Great undertaking however.

Good Luck,

Gary

Fredward · November 29, 2009, 07:07:51 PM

SO I'm assuming an 8V92 and its turbo will fit in the space of an 8v71 in an MC-5?
If so where do I sign up? I've got room for a third radiator. That part is easy.
Fred

Ed Hackenbruch · November 30, 2009, 07:05:42 AM

Why not just throw a turbo on your 8v71? You already know the 71 fits the space although it is tight.

Just need to add cooling capacity. Turbo is supposed to make a 71 come alive from what i have read and doesn't have the problems of the 92.

bevans6 · November 30, 2009, 07:26:50 AM

I guess the only reason I can imagine doing anything radical to the engine is if it has a calamitous misadventure... In other words, I hope like HECK it is in there as is for a very long time...

But if I do decide to change something, understanding what the parameters are is obviously the first step to enlightenment. And a successful change from 8V-71 to something, with some transmission, would then occur after suitable mourning period for the lump in their now!

I am quite taken by the idea of just adding a low pressure turbo to what's there, if I determine that the existing engine is in good enough shape. I wish there was an FAQ for that, I think I will start by doing some searches on the board.

Ken up the street from me has an 8V-71 TA in his MC-5, out of a fire truck. It will be a barnstormer for sure, with 400 hp!

Brian

luvrbus · November 30, 2009, 07:50:00 AM

Guys you start pumping the 8v71 up to preform with a 8v92 the 8v71 will have a very short shelf life keep the 8v71 around 350-375 hp with a turbo and they do fine, 400hp they are getting on the edge
Not a problem to get 100hp per hole on a 2 stroke but their life span is not very long when you do that

good luck

Bestekustoms · November 30, 2009, 04:39:04 PM

100 Horse Power Per Hole...

800 Horse Power...WOW !!!!!

Lasts About A Day LMFAO..

JOHN

RJ · November 30, 2009, 04:53:49 PM

Brian -

Just some supplemental info for you to ponder:

1. If you stick with the four-speed Spicer manual gearbox, any of the V-block two strokes will fit (6V71, 8V71, 6V92, 8V92). If you add a turbo, not only will you have to deal with cooling issues, but you'll have to get creative with the plumbing, since the blower compartment floor is lower in your coach compared to the 8s, 9s, etc.

2. If you decide to change over to an automatic, then things get a little more complicated. The only automatic that will physically fit with the 8V71/8V92 block is the MT series, but they cannot handle the torque of the 8V92. The one powertrain combo that seems to be the "best bang for the buck" is the 6V92/HT-740, and it fits!

FWIW & HTH. . .