How much effort to do a repower 6v92 to series 50

[paulcjhastings]

First post ever on this board.  Mike has that MCI  C3 for sale for $12k, if one was to find a DD series 50 engine for a decent price, what other issues would one have to consider to do a repower?
Is it a straight drop in, or do multiple things need to be changed out to convert to a 4 stroke? I have done engine upgrades in cars but I have never touched a bus. Thanks in advance for any advice you guys can give.

Paul Hastings

[DuaneMC7]

Hi Paul,

It is a lot of effort, but that's all it is, effort. From what I hear they fit in very nice.

It can be very costly if you are paying someone to do it for you.

I am in the middle of an M11 re-power and for me it is just a matter of time involved.

So if you are comfortable and capable with some creative fab and electrical work then I say GO FOR IT!!

The cheapest way to get the major components is to scrounge up a doner truck

Good luck!     Duane

[NJT5047]

It's a ton of work and expense.  Unless you're a fab guru. 
Got to build new motor mounts,  find an S50 with a automatic ECM, build a cooling system, build an intercooler, build an exhaust sytem, and the list goes on and on. 
It is doable, be nice to find a donor and strip what you can. 
Why not leave or repair the existing engine?  This would be so much easier to do.
Unless you have access to truck parts at a deal, this could get really expensive...anywhere from $10K (DIY) to almost $30K (pay to have the retrofit done).   
If the existing engine is a 6V92, there are plenty around, and intalling another complete 6V92 take out is a one day job.
The two stroke would be smoother, use a little more fuel, and, unless a really nice retro job was done, the 2 stroke may be more dependable as a package.  S50s are 4 cylinder S60s.  Move around quite a bit when idling.  May be a little shake when idling.
$12K for a C3 is pretty cheap.  I'd buy it if it was on the Right Coast.    I'm waiting for the "bad engine" 102D3s!  I'll get one of those things one day. 
Good Luck, JR

[TomC]

Highly recommend you either repair or replace the 6V-92TA.  While the Series 50 is more fuel effiecient, it is the same power as the 6V-92TA.  So for all the change over, including now having an electronically controlled engine, you will see at least 1mpg better, maybe as much as 2 more mpg.  Personally, don't think it is worth it.  A freshly rebuilt 6V-92TA will give you at least 300,000 miles of very faithful service with the right maintenence (translated oil changes, filters, and tuned up every 100,000 miles).  That C3 would make a great motorhome-it is probably the one I'll use next.  Good Luck, TomC

[Sammy]

A repower from a 2 stroke to a Series 50  is major work. I have done these conversions on transit buses.
I would not recommend it to anyone that does not have a shop or the resources (not just $$$$) to do it safely.
You also have to consider transmission issues - not sure how you would get a mechanical trans to work with an electronically controlled engine. There will be many plumbing issues, fuel,air cooling,etc. Obviously thereis some major wiring work required too.
Hope this helps you. 

[Lee Bradley]

You will probably have to change the bus gearing (rearend) as the 50 series doesn't turn the rpm of the 2 cycles.

[paulcjhastings]

Thanks for all the responses. After hearing from you guys and running some very optimistic rough numbers, I figured it probably isn't worth it. If I use a very conservative $10,000 to do it and a change in mileage from 7mpg to 9mpg it would take about 100,000 miles to break even.  This is just based on cost of conversion and an additional 2mpg, differences in maintainence costs are not included because I have no idea what either would be. Thanks again.

Paul Hastings