X-15 Cummins thread

new x15 with 97,586 miles. just spun a bearing. hear they changed the rollers in oil pump. supposed recall.

 

Performance or effeciency motor?

 

How about International lt with Cummins x15 525 hp and 13 speed automatic, 1850 torque ,ratio 2,53. Any ideea,on this engine,on fuel consumption average?

 

I was told that they are have more problems with local trucks. but if you do have to idle to bring it up a 1000 rpm. what is your take on that. thank you in advance.

 

We set the idle on the truck to automatically idle at 800, but I do kick it up to around 1000 when idling for longer periods of time. I know it still makes the noise at 800 rpm, guess I’m not positive if it does it when I set it at 1000 rpm, I’ll try to pay more attention and let you know.

 

Can someone please tell me why my new x15 stops pulling at 1800 rpm?

 

According to the chart on the Cummins website, peak torque is 1000-1400 rpm and peak horsepower at 1700 rpm, after that, it falls off substantially, and that’s with the 500hp 1850 rating on the efficiency series. If you go to their site and click brochures, the graph is in there.

 

Mesilla Valley is very forward thinking fleet in terms of fuel mileage; they run the X15 efficiency with direct drive Fuller Advantage auto 10 speed and 2.31 and seem to be happy with it. If you’re downspeeding, 1100-1150 is ideal, if not, 1250-1300 should be your target rpm at cruise.

 

The problem with local trucks and limited highway driving will not be remedied by an increased idle rpm. I haven’t read anything to suggest it will provide any benefit. The only benefit could be increased HVAC performance in hot weather, maybe. The problem with an emissions motor not operated under the proper engine load for extended periods is decreased performance of the EGR circuit and the caking up of carbon in the tube, valve, and cooler. I don’t see how increasing idle rpm will help that.