Engine innovation: Cummins ISX15
Cummins has also taken advantage of more powerful electronic engine controls to make drivers’ lives more comfortable during long days behind the wheel. To that end, the new ISX15 will feature multiple new driving tools.
One major one is a new gearing system, says Jason Owens, customer performance technical manager. He’s the guy who teaches Cummins customers how to drive these new engines for optimum efficiency. For most drivers, he says, that means learning to shift at the proper lower engine rpm levels and – most importantly – leaving the truck in top gear as much as possible.
“A lot of the older drivers don’t feel like they have any available power in top gear,” he explains. “But with these new engines, fuel economy and durability are greatly enhanced by running in top gear as often and as long as possible.” That’s where the new Gear Down Protection feature on the ISX15 comes into play. It limits vehicle speed in lower gears to keep drivers from winding out the transmission and encourages timely upshifts into the “sweet spot.”
On I-65 heading up toward Indy, Owens instructed me to shift the 13-speed Eaton in 12th gear to see what would happen. Sure enough, the truck wound out to about 58 mph and then just lugged along. That’s the smart electronics kicking in and retarding vehicle speed. But the intervention isn’t aggressive. A quick upshift results in impressive acceleration up to 70 mph.
Indianapolis’ heavy traffic was the perfect opportunity to showcase the ISX15’s new cruise control. It’s easily programmable by the driver to meet a wide array of settings – from high and low cruise speeds to high performance on grades or optimized fuel economy.
The ISX15’s Load Based Speed Control, Owens explains, is designed to improve fuel economy and lower engine noise by matching engine performance to your load.
In my case, GVW was approxi-mately 75,000 pounds. On flat stretches – and there are plenty around Indianapolis – Cummins’ ECM limits the amount of usable engine speed the driver has to optimize fuel economy.
I can already hear veteran drivers grousing.
But the ISX15 accelerates so smoothly and quickly you’d never know any power was being held back. The idea is to give ample on-demand power to get a load moving, yet limit the chance of a costly, unnecessary fuel burn brought on by a heavy foot or over-revving. Not to worry, though. If the ECM senses you’re starting out on a grade or pulling a heavier than normal load, the available rpm is automatically increased to compensate.