mci5

[jaypullen]

Has anyone ever pulled out a 671 motor in a 1977 mc5c and replaced it What other motor will fit Thanks JPULLEN

[RJ]

Jay -

The MC-5C came from the factory with two different powertrains:

8V71 with a Spicer 8844 manual 4-spd

6V71 with an Allison HT-740 4-spd automatic.

The 740 will not work with the 8V71 - the combination is too long.

At Busin' 2011, there was an ex-USAF MC-5C that had the original powertrain in it, surprisingly it was an 8V71 coupled to an Allison MT-644 automatic.  (The MTs are lighter duty than the HT models.)  Must note, however, that this particular coach wouldn't do over 55 mph due to it's rear axle gearing.

I'm guessing that the 5C you're talking about has an automatic? 

If so, the best replacement is to go with a 6V92TA.  It can easily be set up for 350 hp, and the HT740 will handle the power without complaints.  You will have to mount the turbo to the driver's side of the engine, as there isn't enough room above.  Not a big deal, just a heads up.

FWIW & HTH. . .

[christopher]

Jay,
I have a 1978 mci 5c. the prev owner put in a 6v92 t. the coach does 80 easily with plenty to spare. it has the orig 643t trans. the orig engine was the 6v71.
email me and i will give you my number if you want
Thanks
Chris
capeislands@gmail.com

[Gary '79 5C]

2X what Jay said,
My PO installed the 6V92TA, Allision 644 Trans, with 92 injectors and it will haul.

I do not have any pics of mine, sorry, but the turbo is located above the engine. It is tight. I know the air intake system was engineered, as the aftermarket element air filter is located on the curb side.

I do not know the original setup as delivered, This was a Saudi Bus, and still has that thirst...