Eagle Cummins Repower

[Bobby]

I have had for 5 years a 1966 Model '01 Eagle Conversion by Bill Kingston.  Love the coach but is time for a refit and I have found a Cummins N14 and want to install this in place of the 8v71. I want to mate to the allison 750 automatic that is in the coach now.  Can anyone direct me on where I can get the information for this conversion.  I am sure it had been done several times.  Appreciate any and all help.

Thank You

Bobby

[ChuckMC8]

Bobby, Heres a good place to gather some info- http://www.bernhardbus.com/

an ad on his home page sez:

We have just acquired a very nice, low mileage, 400 horsepower, Cummins engine and Allison transmission package that would make a great conversion for an Eagle coach. We can sell the unit outright or do the conversion for you.

Lots of interesting reading on this site for everyone, he puts a series 60 in am MC9, lengthing the body, and then another conversion, does the same, but w/o lengthing the body by using a shorter Allison trans....

hope this helps, Bobby, call this guy and I'd bet he could tell you what you need to know-

[rv_safetyman]

Bobby, the swap will not be for the faint of heart. 

You will need to raise the bed area because of the tall engine. 

The other major issue is the gearing.  The four stroke want to run at least 500 RPM less than the two stroke at cruise speed (need to aim for about 1300 to 1500 RPM at your typical highway speed).  With your 01 you can change the rear end to a truck rear end and and get gearing in the 2.9 range.  The Cummins should pull that gear just fine with the HT750.

You will have to have the control cable made, but that is not a huge deal.  If you buy the engine from a wrecked truck, make sure you get all of the electronic related parts out of the cab.  There are lots of switches for the Jakes and cruise control, the "throttle", etc that are costly to buy new.

The HT 740 can be made to work with an electronic engine, so the HT750 should be no problem as well

You could also consider the Cummins M11/ISM engine which is smaller and will not have to have the bed raised (along with modifying the rear bulkhead/cross member).  It can be beefed up to over 400 HP and 1500 ft lbs torque!

You can go to my bus project page listed in my signature and see how I modified the bed area in my Eagle 10 and fabricated the control/data cable for my Series 60 (should be about the same for the Cummins)

If you have someone do the job, make sure they have done this kind of conversion before.  Lots of horror stories about botched conversions.  Plan to pay a minimum of $20k plus the cost of the engine for the conversion if you have it done.

Another thought.  You will need to VERY closely check the tubing in the engine cradle structure.  Eagles rust (duh) and that area can be a real problem with the heavier engine and the front mount being further back than the 8V71 (more "lever arm" on structure).  Again, you can see how I double tubed the structure on my website.

[TomC]

Here are some facts.  As stated before, with the drive axle in front, you'll have more momentum to over come way in the rear end.  The Cummins N14, while an excellent truck engine, is WAY overkill for powering a bus.  It weighs 500lb more than the 8V-71N, is a tall engine, so servicing the overhead will be from inside with the bed up, it is not made for trucks anymore, but Cummins is still making it for industrial uses, it is thee most expensive engine parts wise to work on-more than Cat or anyone else. Even though you have located this N14, please consider to use a lesser sized engine.  My choices would be a Cummins M11/ISM engine that can get up to 500hp for motorhome use (200lb lighter than the 8V); a Caterpillar C12 that can be pumped to 455hp or rebuilt to 525hp (150lb lighter than the 8V); or even the new excellent Mercedes-Benz engine with 450hp (no other engine on the market gets fuel mileage like this engine does and has a turbo and compression brake up to 600hp of braking)(400lb lighter than the 8V).  All three of these engines will fit where the 8V is with little modification.  You'll have to add an air to air intercooler, but that's with any of the engines now.  The most popular engine would be the Cummins M11/ISM since a vast majority of the trash trucks are equipped with this engine with Allisons.  My personal choice would be the MBE (Mercedes-Benz Engine) 4000 with a B500 (or a HD4060 with a shorter oil pan).  Then you'd really have a runner AND a fuel mileage champ (pushing 10mpg).  Good Luck, TomC

[Brian Diehl]

TomC,
How much do you suppose a person could pick up a MBE (Mercedes-Benz Engine) 4000  engine for? 

How efficient would it be running about 1600 RPMs at 65MPH?

-Brian

[TomC]

Brian- the MBE4000 has been out long enough where you could get one at a wrecking yard or a wrecked truck.  How much? I don't know.  But in truck RV's like the Renegade, they've been seeing up to 12mpg at 60mph with that engine.  Course that is more aerodynamic to.  If you just can't find the MBE, then the Cummins M11/ISC would be my second choice-and that will be very prevelent in junk yards.  Good Luck, TomC

[Bobby]

Well, This does give one food for thought.  Even if the cost of the N14 is less, looks like the overall cost would be enough higher to really look for one of these other options.  Thank you all for your input and all those who will be sending in more information later.

Good evening
Bobby

[TomC]

Brian- Something to consider.  How long are you going to keep the bus?  How many miles do you thing you'll put on the bus?  Personally, I don't think I'll put on over 100,000miles in the next 10 or 15 years.  I was considering changing my 8V-71N out to a Series 50, since other transits that are cousins of mine with the same engine cradle demensions, would make swapping relatively simple.  The only thing in my way would be converting it over to an electronically controlled engine.  I have a real problem with that since if something goes, call the tow truck.  Whereas a mechanically controlled engine rarely will let you down.  Plus the 71 series Detroits were quite possibly some of the most reliable engines ever made.  Granted the power and fuel mileage isn't at the top.
Because of the combination of low power and smoke at high altitude, I'm having a low pressure boost "smoke turbo" installed on my bus.  While I can live with the performance at sea level, at higher than 5,000ft, it really falls on its' face and smokes if you get into it.  If the bus was a rocket going over the hills I could live with it.  But bad fuel mileage, smoking at altitude and going up the hills with the trucks, can't.  I already have the custom made air to air intercooler mounted in front of my radiator, have to have the plumbing made for it, then Don Fairchild will do the turboing.  We'll use an early Series 60 turbo with a waste gate tuned to put out 7-9lbs of boost in the air box (inside the engine), increase the injectors from my brown tag N65's to the more modern 7G70s.  This will boost the power from 318hp and 800lb/ft torque to a conservative 345hp and about 950lb/ft torque. Not a big jump, but will be there up to 10,000ft elevation, and more or less no smoke.
May I suggest you have your 8V-71N rebuilt to full turbo specs, or locate a 8V-71TA block and rebuild it up to a full turbo.  If you use your same engine, you'd have to add an air to air intercooler (which actually makes for the coolest intake air temperature), or just increase your radiator size for the 8V-71TA block.  You'll be able to get an easy 400hp and 1,200lb/ft of torque from the engine, which will be a 50% increase in torque (torque is what gets you up the hill-horsepower gets you down the flat road at speed).  Then you'll have the same engine without the big expense of changing the whole thing, having to add all the electronic BS, and still have a reliable engine that will most likely get at least 1 more mpg.  BUT-you'll do it your way.  Good Luck, TomC

[Bobby]

Tom,  Thanks for your input.  pretty good logic

bobby

[Rick Brown]

After looking at other options, I had the 8v71 in my 4905 rebuilt as a 8v71T.  Makes the 4905 scamper pretty good.
-Rick Brown in Reno, NV

[Tom Y]

Bobby, I bought a truck this summer with a N14, It is a huge motor.  The motor went to Mass. I had looked at a S60 a lot bigger than a M11.  There was a guy with a 35 foot MCI w/8v92 on Ebay.  I am putting a Cummins in my 5c if I can find time to work on it, I think it can be done for a lot less than 20k if you do all the work. If you go this route emai me and maybe I can save you from some mistakes.  Tom Y