Author Topic: 4905 Repower Report  (Read 1822 times)

Offline Rick Brown

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4905 Repower Report
« on: December 30, 2007, 05:50:54 PM »
Greetings Friends:
I recently repowered my 4905 with the original 8v71 rebuilt as an
8v71-T. The entire job included rework of the exhaust, cooling and
induction air systems. The link is a description and a few photos of
the effort.
http://home.att.net/~intermountainac/BusRepower.html
-RickBrown in Reno, NV



Dallas

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Re: 4905 Repower Report
« Reply #1 on: December 30, 2007, 06:21:22 PM »
Well, Rick, that looks like quite a job you did there.

Are you planning on leaving the twin stacks the way they are or are you planning on chrome covers or expanded metal to cover them up.
If you decide to go with chrome covers, why not put some 8" chrome straight pipes up the back with muffler inserts?  ;D ;D

Nice job so far, we can't wait to see the rest of it. More Pictures, More Pictures, More Pictures!

Dallas


Offline Barn Owl

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Re: 4905 Repower Report
« Reply #2 on: December 30, 2007, 08:47:41 PM »
Cool read, nice pics!

Thanks

Laryn
L. Christley - W3EYE Amateur Extra
Blue Ridge Mountains, S.W. Virginia
It’s the education gained, and the ability to apply, and share, what we learn.
Have fun, be great, that way you have Great Fun!

Offline TomC

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Re: 4905 Repower Report
« Reply #3 on: December 31, 2007, 01:19:54 PM »
Nice first design.  But- I'd like to interject a couple of points from my conversion to a 8V-71TATAI (turbocharged air to air intercooled) and from 21 years of 1.3 million miles of cross country driving.  First off- GET RID OF THE K&N AIR FILTER!!  It has been proven unsuccessful in large diesel engine application-in that while it does flow well, it also allows fine dust in and effectively grinds down your piston rings prematurely.  I used a Donaldson 7" inlet and outlet air cleaner.  When dirty, just pay the $60 or so for a new air filter-far cheaper than a new engine.
The twin 4" exhaust is not needed.  I used a single 5" oval same side inlet and outlet Donaldson Turbo muffler that flows extremely well and puts out a very nice exhaust tone.
While the twin radiators are novel, and do work, did you try to rework the original radiator?  I had mine changed from a 5 row straight fin to 6 row serpentine fin for a 20% increase.  I did have to install 15 misters when climbing long grades when it is over 90 degrees out.  I also added an additional transmission cooler with an electric fan (V730).  It is plumbed so that the hot oil first goes through the auxiliary cooler then back through the original shell cooler.  This takes some of the strain off the cooling radiator.
Your conversion has some cleaver ideas.  Hope all goes well with longevity.  If you have some questions, call Don Fairchild at CCTS in Bakersfield, Ca.  Good Luck, TomC
Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.

Offline HB of CJ

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Re: 4905 Repower Report
« Reply #4 on: December 31, 2007, 03:11:20 PM »
Rick...great post and pics.  I need to learn how to post like that.  I did not see an air to air intercooler---do you have a water-to-air below the blower?  Very cool installation, I love stuff like that, expecially the outside pipes.  ROAD WARRIOR!!!  Happy New Year. :) :) :)

Offline Don Fairchild

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Re: 4905 Repower Report
« Reply #5 on: December 31, 2007, 03:58:24 PM »
Rick;

Is this the engine spencer built for you. Is it and aftercooled engine. I see the otm turbo and air horn. what blower did you use, is it set up for the turbo and air horn.The turbo's don't like to be mounted off plane like that, they need to be set level for oil drain back. look for the set up from an rts with the 8V71ta and use that off set turbo mount. I agree with tom, get rid of the K&N and go with a donaldson air filter.

what did you have to do to get the truck exhaust manifolds in there, Did you have to notch the cradle.

over all looks good. You do nice work.

Don

Offline gomer

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Re: 4905 Repower Report
« Reply #6 on: December 31, 2007, 07:29:49 PM »
the heck with the coach!  When does the ice thaw so we can go FISHING in the lake{?} behind the coach.  Very interesting project tho, I am interested in the final results.  Love the stacks.  Imagine pulling up behind that on the big I road and try to figure it out LOL  LOL ??? ;D
 gomer
as you slid down the banister of life,may the splnters point the other way
TRUST IN GOD ALWAYS. riverjordanmusic@aim.com
Gomer

Offline Rick Brown

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Re: 4905 Repower Report - Thanks for the Comments
« Reply #7 on: January 01, 2008, 05:46:29 PM »
Thanks for the comments.  Here's my response
*Are you planning on leaving the twin stacks the way they are ...
Yup.  Pretty is not an issue.
*The twin 4" exhaust is not needed
I agree dual 4" pipes are overkill, but that was the easy solution for replacing the factory muffler (done some years before the conversion).
*did you try to rework the original radiator?
That was re-cored several years ago.  I'm not sure the aux radiator is even working.  I plan measurements soon to see if so.
*I did not see an air to air intercooler---do you have a water-to-air below the blower?
No intercooler
*Is this the engine spencer built for you
Yup.  I don't know the details of the turbo mounting.  I must trust Spencer on that.  At the moment she runs smooth and strong.
*what did you have to do to get the truck exhaust manifolds in there, Did you have to notch the cradle
Manifolds exhaust up.  I don't know if they are the original manifolds turned over or something Spencer came up with.  Required a notch about 1"x4" in the bumper.
*GET RID OF THE K&N AIR FILTER
If I was going to drive 1000 miles a month; maybe.  Right now I like the K&N.  I was an easy solution for installation, it's accessible from inside the coach so I can squirt a shot of starter on it for those cold morning starts and I can inspect it as part of 'preflight'.  I've got a suction gauge going into the induction with a new instrument display so I'll be able to keep an eye on its flow restriction.  Yea, I've got to clean it, probably every 50 hours, but that's the trade.

Thanks again for the comments
-RickBrown in Reno, NV


Offline TomC

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Re: 4905 Repower Report
« Reply #8 on: January 01, 2008, 06:03:48 PM »
Rick- you can keep the air filter element in the same location-just loose the K&N filter since it does not filter out the damaging silt that will wear out your engine prematurely.  Just replace the K&N with a Donalson paper element-almost the same size.  Believe me-you'll be kicking your self when your engine is worn out in 3-5 years for not changing it out.  Good Luck, TomC
Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.