If you had a choice........

[OpposedPistone]

between a Cat 3616 and a FM 38-1/8 x 12 OP both burning natural gas/ methane, which would you choose? It would be running 24/7 in a municipal cogeneration application.

Something like this:

http://dupageco.org/publicworks/generic.cfm?doc_id=878


Thanks for your input!

[mxdata]

Actually I would prefer TWO of the CAT 3516 natural gas engines, rather than one 3616 or one Fairbanks Morse OP. The parts for the 3500 series natural gas engines are much less expensive, they are much easier to work on due to the smaller and lighter components, and I could probably retire quite comfortably on the money I would save compared with an installation using either of the larger engines.

[OpposedPistone]

I hear what you are saying and am with you on the quality of the 3500 series especially the diesel version. I guess I am thinking more along the lines of a larger, slower speed 900RPM heavy duty installation and I was interested in the OP for the following reasons:
No cylinder heads or valves

-No sparkplugs,coils etc.

-The OP is dual fuel and would switch to full diesel mode in case of a gas system interruption and stay online until the problem could be corrected.

-Available as standby power/black start in case of power outage.

- Compression ignition with pilot fuel = better thermal efficiency

Sorry, can't pocket the savings to buy a motorhome!

I still am curious about how difficult they are to maintain and especially loading those lower pistons.

Here is an article I found that shows some of the maintenance issues with gas engines.....
http://www.practicingoilanalysis.com/ar ... ilAnalysis

We see receded valves like that ALL the time burning digester gas....except when the head of the valve comes off and works its way through the piston and /or cylinder head and then the turbo.......ugly! AND expensive.

Not so sure about the drain intervals they discuss on the OP towards the end of the article.....

Thanks again for your thoughts!

[mxdata]

If dual fuel capability is of particular importance then the OP might be a good choice. If you accumulate methane daily and then operate to meet a power peak, you can operate on the methane until your tank pressure reaches low limit and then swing over to diesel for the rest of the run. I have not seen an OP installation set up this way, but there were EMD 567 dual fuel engines that were arranged to do this.

Just be aware that the largest remaining customer operating Fairbanks Morse OP engines is the Government of the United States (GOT-US), and they are acutely aware of that and price their parts accordingly. A friend who owned a tugboat with an OP recently found that for the price of a just a set of pistons and liners alone (without the labor to install them) he could purchase a freshly overhauled EMD 645 of the same horsepower.

[OpposedPistone]

The EMD parts do seem to be a bargain....too bad the dual fuel EMD can't meet emissions with the 5% pilot fuel ignition. But then again they have exhaust valves which we are trying to get away from due to siloxanes.

I saw these ads on the 'net and if your friend still had his tug he could go ahead with his overhaul! :

5.14.26. FAIRBANKS MORSE MARINE ENGINES; MODEL 38D, 1,440 HP (180 HP PER CYLINDER); 8 1/8 INCH; SN 827419, 8322599; 8 CYLINDER; DIRECT REVERSING; NEW NEVER USED SURPLUS SUBMARINE ENGINES; HAVE 2; $30,000. FOR THE PAIR; PENNSYLVANIA; JL-VW-NNNOLT WAS 2.23.350.

5.14.27. FAIRBANKS MORSE MARINE ENGINE; MODEL 38D, 1,800 HP (180 HP PER CYLINDER); 8 1/8 INCH; 10 CYLINDER; DIRECT REVERSING; MISSING 4 PISTONS AND RODS, AND CORNER PIECE ON EXHAUST; WAS USED ON DREDGE GENERATOR; $15,000.; PHOTOA(40K); PENNSYLVANIA; JL-VW-NNNOLT WAS 2.23.350A.

5.14.28. FAIRBANKS MORSE MARINE ENGINE; MODEL 38D, 1,080 HP (180 HP PER CYLINDER; 8 1/8 INCH; 6 CYLINDER; DIRECT REVERSING; COMPLETE; NEW, NEVER USED SURPLUS SUBMARINE ENGINES; HAVE 2; $24,000. FOR THE PAIR; PENNSYLVANIA; JL-VW-NNNOLT WAS 2.23.351

[Alcoman]

If dual fuel capability is of particular importance then the OP might be a good choice. If you accumulate methane daily and then operate to meet a power peak, you can operate on the methane until your tank pressure reaches low limit and then swing over to diesel for the rest of the run. I have not seen an OP installation set up this way, but there were EMD 567 dual fuel engines that were arranged to do this.

Just be aware that the largest remaining customer operating Fairbanks Morse OP engines is the Government of the United States (GOT-US), and they are acutely aware of that and price their parts accordingly. A friend who owned a tugboat with an OP recently found that for the price of a just a set of pistons and liners alone (without the labor to install them) he could purchase a freshly overhauled EMD 645 of the same horsepower.

In that case, I rather have an Alco 251 engine.