engine swap 6v92

[82 MCI-9]

I think this has been asked before but couldnt find any thing can you take a none ddec 6v92 and install it into a ddec3 bus? i think that the engine are the same its just the electonics that are different. What do you guys think?

[NJT 5573]

I don't see why not. When my 6V92 ever wears out I have a mechanical Cummins waiting for work. DD told me my HTB748R Allison ATEC only needed a throttle position sensor to work alone, (no link to DDEC}. You could work out the throttle with air or put in a bone yard unit from an older Eagle.

[Sammy]

Why would you want to do this type of swap?
I'd stay with the DDEC engine.
Are you sure you have DDEC 3 controls?
All the 6V-92's I worked on were DDEC II.
You will need some type of throttle control - air or cable operated.
You will need engine control for run and shut down - an electric solenoid and a source of air.
You will need another electric solenoid for the fast idle cylinder too.
Now you will have to set up electrical circuits for engine control and fast idle.
What type of trans do you have?
You may have to address issues with communication between engine and trans.
You may have to address issues with speedometer - depending on how it gets its signal.
There are a few folks that have done some real nice swaps and conversions to their coaches on this board. Some are in the process of their swap / conversion right now too.
Best of luck with your project.
Sammy 

[82 MCI-9]

The 6v92 that i have in another bus is a none ddec that is in good shape but i am looking at an 1993 mci which i think is a ddec 2 or 3 that has a blown 6v92 and i was thinking to buy the mci and put my engine in it. I was just wondering if the basic block and mechanical parts of my engine are the same as the egine in the mci.

[Gary '79 5C]

Gatta Ask, Why, (in a sense go backwards with technology) with a non DDEC 6V92 engine for a replacement???
I purchased a converted coach with a non DDEC 6V92 w/ a turbo. PO was adament that this was a superior combination(he was also selling the coach.
My jury is out, I am without an opinion. I must say after 25 K miles I have had no problems with the non DDEC turbo.

Hope all is well with every one....

Gary

[TomC]

Non DDEC or mechanically injected or MUI (mechanical unit injector) have the big advantage of always being able to run as long as the engine is in running shape, it gets clean air, clean fuel without electricity.  Most of us will not see enough miles to make up the difference in mileage (about 1mpg) to justify the cost.  With a DDEC engine, have it towed once and pay for a shop to fix something that has burned out on the DDEC and you have just negated all the fuel mileage benefits from the electronics.  Personally will stay with a mechanical engine until forced into an electronic one.  This is one of the big reasons I had my engine turbocharged-to keep it from visibly smoking.  Good Luck, TomC

[Gary '79 5C]

Thanks TomC for this and all of your contributions,
Another of my many many questions, How does the addition of a turbo lessen the smoking of the engine?
To me the turbo spools up and becomes effective after a few seconds of acceleration.
However, If smoke is unburned fuel, then the additional air (turbo press) will provide the air needed to burn the additional fuel.
Just got up, going for additional coffee, to sort this out.
GP

[TomC]

Most of the bus engines are detuned versions of the truck engines for longevity and better fuel mileage.  For instance the 8V-71 was detuned to 280hp when it can put out 318hp (in non-turbo form), and the 6V-92TA is also detuned to 280hp when it could put out 350hp, the 8V-92TA was detuned to 400hp when it can put out 500hp, etc.  On my 8V-71 I initially took out the 55 injectors (253hp) and had brown tag N65's installed for 300hp.  When at sea level and up to about 4000ft, it would not smoke much.  But last year we went to Flagstaff, Az at 7000ft elevation and it was putting out serious black smoke if I pushed down to far on the gas pedal and the power/fuel mileage was way down.  With the only 7,000ft doing that much smoking, what was the Eisenhower tunnel at over 11,000ft on I-80 going to do-or if I could even get up it?  I had my engine turbo'ed and 75 injectors put in to boost the power to 375hp and mainly keep it from smoking at higher altitudes, also maintaining most of the power at least to 10,000ft.  Turbos have long been used to compensate for altitude changes-first in piston engined airplanes, then in trucks, now also in some cars, used in boats for more power out of a smaller engine.  I had to install a fuel modulator since when the turbo was not pumping at idle, when I accelerated, it looked like a locomotive with the big black cloud coming out of the stack (I have a through roof up exhaust). With the fuel modulator, it prevents the injector racks from opening until it feels the turbo boost come up cutting way down on the black smoke on initial acceleration from idle.  Now when I climbed the Grapevine (at 40 compared to 30), all I see coming out of the stack is heat.  As I have said-before going through the headache and cost of changing out your 8V-71-especially if it is on the tired side-have it rebuilt into a turbo engine with air to air intercooling, and you can get an easy 400hp and 1200lb/ft torque reliably from it.  Believe me when I tell you that turboing really wakes up the 8V-71!! Good Luck, TomC

[skipn]

Gary,

   From my point of few... (correctness is optional)

  Electronic versus Mechanical..  Electronic will control feul flow so there isn't smoking The electronic can be programmed to smoke just like a mechanical.
                As seen by what the kids do to the dodge cummins pickups programmable units that when they step on the accelerator they can
                pump black smoke with the best of them (assumed they are pumped up to 500hp paper only).

 Now for the Turbo.
     Let's say the turbo is running at 10psi. That means there is more air available than what the engine is using at that RPM. As one steps on the throttle
     the pressure drops as the engine RPM increases. If the RPM increase is faster than what the turbo can recover then smoke and turbo lag.
     On my engine with no load idle to tromping on the throttle to high idle all I get is a small puff of smoke where as without the turbo my engine
     will smoke until air and rpm equalize. (I do have a non-turbo 7.3 international that if I turbo'd wouldn't smoke as much)

 FWIW
  SKip

[Gary '79 5C]

Skip,
If I apply a gentle accelerator I will not smoke, if not I put out a very noticeable plume for a short bit. I also have a air throttle, which as I understand provides a bit of a delay and slowing to the throttle application, cutting down the smoke output as well.
I try to not lose sight of a car sitting next to the exhaust when starting in traffic. Very overly exaggerated
Take care,
Gary