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Author Topic: Cat C7 for a 40' Bus?  (Read 1579 times)
coachconverter
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« on: April 27, 2013, 07:05:50 AM »

I know I'm opening a can of worms here, but...

I have a 96a3 here that I want to repower for myself, I am NOT a mechanic.

Someone down the street from me bought some rv chassis during the Elkhart implosion, he has a new chassis with a C7 and ht 3060 that I can get cheap.  The engine valve cover stickers show the HP at 350 which is enough for me, but I'm not sure if this is even feasible and will have enough torque to push the bus.  I'll get absolutely everything, just transplant from chassis. 

Sound crazy?  I'm not really into completely re-engineering things, I see the cooling system as a big changeover either to use the mci radiators and drive, or to fit the attached rear mounted radiators of the chassis somehow into my engine bay.

Just curious....
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luvrbus
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« Reply #1 on: April 27, 2013, 07:19:29 AM »

It will move the 40 ft bus without problems most run on 2400 rpm and last between 4 and 500,000 miles in the trucks fwiw they had a few problems with the emissions but that is no big deal you can program that part out installing in a older bus 

The marine versions are 455 hp @ 2800 rpm people like the engine in the marine world and I like the engine in the land world
« Last Edit: April 27, 2013, 07:29:59 AM by luvrbus » Logged

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TomC
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« Reply #2 on: April 27, 2013, 07:28:34 AM »

The 350hp C7 is an RV engine. It put out 1,000lb/ft torque (if I remember correctly [maybe 860lb/ft]). The engine would accept an exhaust brake. They were rated to power up to 50,000lbs-so it would push your bus along. Keep in mind this is a non cylinder liner engine. And with the 3060 Allison with its' .75 and .65 overdrive, to take full advantage of the transmission, you'd have to change out the rear end. You want to gear the engine to be at 2100rpm at 65 (they will easily rev to 2600rpm-only a 7.2 liter engine). With 12R-22.5's at 485rpm, you'd need 6.14 rear end-which is made (this is the ratio we put in the Cummins ISL natural gas engines with 320hp and 1,000lb/ft torque pulling 80,000lbs). With the 6.14 ratio, at 2,600rpm, you'd have a theoretical top speed of 80mph.
If you keep in mind that this engine puts out about the same as a 6V-92TA, you'll be alright. Your cooling will not be a problem-4 stroke engines always need less cooling then a 2 stroke. You will need to facilitate an air to air intercooler. Grayhound took the 6V-92TA's out and replaced them with Series 50 4 cylinder. They simply removed one of the radiators and replaced it with the air to air intercooler.
Also-the C7 is a small engine. If you keep this in mind and don't beat it to death trying to get 500hp performance out of it, this engine will work for you. And can get over 10mpg running around 55mph. I'm saying this since Freightliner put this engine in the SportChassis pulling big 5th wheels. I have one customer that weighs in at 52,000lbs and gets 8mpg!  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
coachconverter
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« Reply #3 on: April 27, 2013, 08:40:01 AM »

Thanks for the info guys.  I think I'll have a lot of toys to play with from this setup already...
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RickB
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« Reply #4 on: April 27, 2013, 12:10:16 PM »

Hey guys is there any chance he can use the rear end out of the existing chassis?

What an amazing stroke of luck.

"I'm thinking about doing a repower in the bus, hmmm doesn't that guy down the street have a complete chassis with a brand new motor and transmission for sale cheap?"

Some guys have all the luck

Rick
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TomC
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« Reply #5 on: April 29, 2013, 11:05:31 AM »

I did more research and the 350hp RV rated C7 puts out 860lb/ft torque. So it will be about the same power as a 8V-71 non turbo at sea level. But with the turbo and air to air intercooler on the C7, your performance will be the same at any altitude. You'll probably get around the 8mpg range.

I bet you can use the entire rear end assembly of that motorhome chassis. The rear diff pumpkin quite possibly will bolt into your diff. Good luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
luvrbus
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« Reply #6 on: April 29, 2013, 11:55:52 AM »

A 360 hp rating will get you 925 lbs of torque easy task to do on a 350 hp C-7 the Workhorse Chassis are set at those numbers for Rv's
« Last Edit: April 29, 2013, 12:00:46 PM by luvrbus » Logged

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coachconverter
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« Reply #7 on: May 01, 2013, 01:10:42 PM »

Well my luck ran out...  I went to talk to him Monday and he had sold it to someone to build a hay hauler???


Plan B. my bus has a 50k reliabilt 6v92 mechanical in it and I have a 50k ht4060 sitting on a skid, with computer, harnesses and shifter.  How much of an exercise am I looking at to make this work in my 96a3?  Again, I'm not a mechanic but one of my guys is pretty good at mechanical tasks.

Appreciate the help.

Todd
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luvrbus
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« Reply #8 on: May 01, 2013, 04:11:22 PM »

Just program the tranny to work with a mechanical engine not very expensive either you may have a drive shaft to buy depending what was removed from the bus


good luck
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coachconverter
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« Reply #9 on: May 01, 2013, 05:46:54 PM »

Also need a throttle position sensor?
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luvrbus
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« Reply #10 on: May 01, 2013, 05:57:12 PM »

Yea forgot about the TPS lot of Eagle buses had the electronic transmission behind the mechanical engine fwiw
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« Reply #11 on: May 01, 2013, 06:35:18 PM »

Removing a 5 speed, so I should have enough driveshaft to work with.  I have a rear end from a series60/b500 available too.
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« Reply #12 on: May 02, 2013, 07:32:28 AM »

Ok, I'm going to start a new thread, as this is the route I'm sure I'll be taking now.

Thanks
Todd
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RickB
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« Reply #13 on: May 02, 2013, 05:11:31 PM »

Us curious folks like to add insult to injury. When you said you could get it cheap. How cheap are we talking?

Maybe I don't wanna know...


Rick
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I will drive my Detroit hard... I will drive my Detroit hard.
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