I wondered how long it would be before Cummins or one of the other engine makers would make CNG-LPG/diesel available. http://www.cummins.com/na/pages/en/p...ativefuels.cfm Actually I saw one rig the other day. Cool man.............$1.39/gal for LPG.

 

A B-5.9 with spark plugs! Who would'a thunk it! The torque ratings are better than I would have thought they would be.

 

How long?

Cummins & Detroit Diesel have been making natural gas (CNG or LNG) powered engines for over 10 years.

The horsepower and torque ratings are comparable to a diesel engine. Yes, they have spark plugs, too.
BTW, fuel economy is ½ to ¾ of a comparable diesel fueled engine.

 

Depending on how much more the CNG/LNG engine costs over the normal diesel it might take a long time to recover the costs....

If it's anything like the dual fuel unleaded/CNG vehicles we have at work, there is no comparison - they were all total dogs on CNG. The only time we used anything other than unleaded was when it was time to have them smogged or certified. Maybe a dedicated CNG/LNG would peform better since it doesn't have to function on both?

 

Good point. Many transit companies have sidelined their alternate fueled coaches in crunch times.

A true CNG engine will out perform a diesel. Nature of the beast for a spark versus compression ignition engines.
BTW, a natural gas engine doesn't discern between compressed or a liguified fuel storage. Fuel is delivered to the engine as 80 psi natural gas.

 

OK , I will have to disagree with the same power out of a CNG engine , not even the B or C gas plus Cummins can compare to the diesel version..... and maintenance cost is way up there. Now there is a Gas engine out there that I was involved with from Cummins Westport that we took a ISX diesel version and remove the injector rockers and shafts , install a dual fuel injectors , and ECM that had 12 injector drivers, which shoots a 5% diesel injection to start the combustion process and then the natural gas injection. we did 17 conversion and dynoed each one before conversion and then after, they came in rated at 400 h.p. and left rated the same. we even played around with the pulse width of injection timing and had no problem getting over 500 h.p. , once they figure out a better LNG pump tank system , checkit out at this site
http://www.westport.com/expertise/westport_cycle.php

 

We did a lot of side by side comparison of C Gas + and ISC powered vehicles. The CNG engines slightly outperform the diesel in acceleration tests. Of course, the larger ISL is better than C Gas+

Maintenance, yes. Not many places happy with the spark plug & coil life. That lean burn combustion really eats them up. But, simple as regapping the plugs every 2-3k miles to prevent burning out the coil overs.

I'd love to get into the dual fuel engines, but don't see that in the near future.

We used Taylor-Wharton LNG tank & delivery systems recently. Outside of getting the excess flow valve sized correctly, we didn't have any problems. Customer is happy, too.

 

Cummins was somewhat forced into greatly expanding CNG engine development when the South Coast Air Quality Management District (SCAQMD) in So Calif was trying to ban diesel engines.
Diesel interests fought the SCAQMD all the way to the Supreme Court and won due to technicalities but the SCAQMD says they will be back with a law that can't be overturned.
In anticipation many So Calif diesel fleets started converting to CNG and are very pleased with it, many fleets say they will continue changing over even without a new law.

http://www.dieselnet.com/news/0404us.html

 

What I meant with the dual fuel system is not that what we have been seeing produce by Cat. where they can run either on Gas or Diesel , these dual fuel injectors are shooting a small pilot of diesel to start the combustion in the cylinder and then continuing the combustion with a large shot of natural gas. therefore eliminating the high expense of ignition system normally found in the natural gas engine.

 

I know what you mean. More a co-fueled than a dual fueled?
This type of pilot injection has been used for many years on large gensets & co-generation facilities.

Yes, the Westport developed dual injector is a break through design.

 

Over here there are some mfgs making CNG engines- basically gassers with increased compression (CNG has 130 octane). With the engines developed specifically for CNG the efficiency is getting close to the turbodiesel, but the fuel is cheaper. If weight is not that much of an issue- like commuter busses- the operators are happy. (cost and performance-wise)

AlpineRAM

 

Now what is surprising about that little statement!!!


Keith