8v92 upgrade

[cutnhorse]

thinking of putting in a 8v92 in a mci 8 , putting a ht 754 behind it does this fit for length anyone know in a model 8

[buswarrior]

What's your plan for cooling upgrades?

Fitting won't be your problem.

Happy coaching!
Buswarrior

[chessie4905]

Had a friend that had Leid Diesel upgrade his MC8 new conversion upgrade to 8V92 from 8V71. Gained 10mph on our 7 mountain grade. He did complain that mpg dropped from 6 to 8 to 4 to 5. Ht740. Never heard whether he had heatingvproblems, but probably. Expensive to upgrade to larger radiators and blowers. May make more sense to go with a 60 series.

[cutnhorse]

thinking of either using the 102 rad or removing the squirel cage fans , putting a truck rad down on the side putting a angle gear box on it saw one on ebay done in a 7 person said he used a rad out of a freightliner, does  not warm up on grades, any thought would be appreciated , what upgrades can a person do on the blowers, cut mine out to the bigger hole a few years ago, have the smaller pulley on gear box

[buswarrior]

Smaller pulley, larger fan exhaust, check.

Condition of cones inside the fan intakes?

How have you got the space around the rads sealed, and how are the fan doors sealed?

The other big MC8 weakness is the engine intake. An old pioneer builder, Fred Hobe, advocated cutting the exterior skin into the cavity between the top of the air cleaner, and that tiny square intake in the radiator cavity. The engine is sucking through a straw, with the stock routing. Rectangular cut, after a small hole to find the edges, and install the mesh of your choice to keep the birds from nesting in it.

Bigger rads involves tearing the back corners out of the interior, to support and box in the larger rads, big job, depending on your skills.

Going the sidwinder fan route, measure the space available, not nearly the space between tag fender and rear bumper as on the newer buses, the rad may have to mount higher up? And same thing, interior has to be torn up to box it in.

Beware that a newer truck radiator may not be capable of cooling a high HP 8V92, 2 reasons, 4 strokes make less heat, and it is sized to be out in the wind, not sidewinder.

Check the BTU ratings closely, the btu of your proposed engine package, the btu of the allison, and the radiator's rating to discard all that. Don't forget the fan size/pitch that you'll need to pull all the air through, again, monster sized. All that work without some engineering decisions and still overheat would be really frustrating.

If fabrication is your gig, and you are going to engineer it right, build it your way, never mind the naysayers!

Happy coaching!
Buswarrior

[rancher]

If it was me and I were going to go to all that work and time I would go with the series 60 or a Cat C series engines. That 7 that was on Ebay I had a truck mechanic friend that is in the area of were that bus was for sale in, look at it. The motor conversion wasn't all that nice and I would wonder if he had heating issues.

[luvrbus]

The 8v92 works in a MCI good if you use the MCI specs for the 8v92 and that is 365 to 400 hp with 1300 ft lbs of torque ,you are not going to install a series 60 or C-cat engine in a MCI 8 without spending a ton of money

[TomC]

Turbocharging an 8V-71 REALLY wakes it up. I turbocharged my 8V-71 with high compression pistons since it had the clean burning transit bus rings. I added a custom air to air intercooling, turbocharger from an early 12.7 Series 60 with waste gate, changed injectors from N65 to 7G75, by pass valve on blower, bigger air cleaner, bigger muffler, bigger radiator with misters. Went from 300hp at 800lb/ft torque to 375hp and 1125lb/ft torque. Get the same fuel mileage, but much better performance. If you rebuild the 8V-71 to turbo specs, with 7G80 injectors (which was the last version Detroit made) 400hp and 1200lb/ft torque. Good Luck, TomC

I would just stick to the HT740. HT754CR is not as strong as the HT740. My 3406B Caterpillar works just fine with the HT740. I down shift from 4th to 3rd at 1500rpm-perfect for 8V-71 or 92.

[chessie4905]

One thing that will REALLY help is to install an air cooled trans cooler.(radiator) instead of running it through your engine coolant.

[luvrbus]

The 754CR is match made in heaven for a 8v92 in a bus the close ration without the wide gap between shifting is ideal for the torque band on a 8v92 

[lovetofix]

In a best case scenario with all the fins clean, rubber seals good and engine turning at 2100rpm, how many CFM do the squirrel cage fans move through the radiators?

[cutnhorse]

any different gear ratio avaible that do any good on the fuel mileage

[buswarrior]

Ratio choice for existing differential doesn't go as far as you'd like for an 8V92 and direct drive Allison. Can't remember, maybe a 3.3? Hard, very hard, to find.

There are busnuts who have flipped suitable axles for coach duty, that have much more suitable taller ratios. Revs down for economical cruising, higher top speed for the times and places one would want that.

Not because it makes economic sence... because of the challenge to source, adapt and build it.

Not every axle is suitable, lubrication running upside down... all the welding, suspension mounts, chamber mounts...
I always thought it a good way to get a locking diff, along the way, if one would withstand being upside down... never did hear of a busnut getting a locker...

Flip it correctly, or it will go very quickly in reverse...

The arrival of overdrive automatics and 4 strokes put an end to the motivation to make an old coach perform like this.

Happy coaching!
Buswarrior

[RJ]

thinking of putting in a 8v92 in a mci 8

Cutnhorse -

Your MC-8 will climb a 6% sitting on the governor in 2nd gear at about 30-35 mph. Just like practically every bus built from 1945 on.

You can go out and spend several thousands of $$ on an 8V92T and you'll be able to go up that same 6% grade sitting on the governor in 3rd gear at about 45 mph. . .

BUT

Because of the MCI's basic design, you'll spend that whole period of time stressing over the rapidly climbing temperature gauge, hoping you'll crest RockyTop before the engine either shuts down or self-destructs due to overheating. 8V92s do NOT like heat! Especially in a bus!

OTOH, you could take all the $$ that a repower would cost and upgrade the interior to make sure that Mama's happy? 'Cause we all know about Mama not being happy!

Pick your poison?

[sledhead]

I wanted more power out of my 6v92ta and had it up to 350 hp and the only way I could do it for the less cost was to get the coach I have now and sell the old coach . I am happy with the 1875 lbs of tq and all done I have less $$$ in the coach I have now then I had in the MCI