Right truck, right time: Cummins-powered International ProStar+ test drive

The International ProStar+ test truck was nothing special – simply a pearl-white daycab tractor with a 500-horsepower Cummins ISX15 under the hood.The International ProStar+ test truck was nothing special – simply a pearl-white daycab tractor with a 500-horsepower Cummins ISX15 under the hood.

In February, I made the short drive over to Columbus, Miss., to visit International dealer Waters Truck & Tractor, which had just taken delivery of one of the first ProStar+ daycab tractors to come off the assembly line. I was there to take the new rig and a fully-loaded 53-foot trailer on a drive through middle Mississippi and see what I could learn about a new partnership between two old friends – International and Cummins.

This 500-hp Cummins ISX15 powered the ProStar+ driven during the test run.This 500-hp Cummins ISX15 powered the ProStar+ driven during the test run.

International cut Cummins loose a few years ago and focused on efforts to launch and establish its own proprietary MaxxForce diesel engine line. Part of that effort included a highly publicized decision to stick with an exhaust gas recirculation-only solution to meet 2010 U.S. Environmental Protection Agency emissions standards for both its 13- and 15-liter MaxxForce engines.

For a variety of reasons, International’s EGR-only push failed, and late last year, in an effort to turn its fortunes around, the company announced that it would be partnering with Cummins to provide a fully EPA-compliant 15-liter option using selective catalytic reduction technology in the first quarter of this year, with an SCR version of the MaxxForce13 to follow.

My ProStar+ test truck was nothing special. In many ways, that was the point: It wasn’t a specially tricked-out truck designed to impress journalists. It was simply the first Cummins-equipped ProStar+ Waters had received; a pearl-white daycab tractor with a 500-horsepower ISX15 under the hood – the type of truck suited for many pickup-and-delivery or regional-haul fleets across the country.

The Cummins ISX15 is exactly the engine International needs now to turn its fortunes around: an established, consistently reliable powerplant with horsepower to spare and world-class product support behind it. Given International’s recent technological and reliability issues with its EGR MaxxForce engines, the company clearly understands the necessity to get the ProStar+/ISX15 launch right from the get-go.

Given that the company has been able to do so in the short amount of time available – less than six months – is a testament to the commitment and talents of the design engineers at both International and Cummins. It helps that the two companies have a 75-year history of working together, but that shouldn’t detract from the accomplishment they’ve made in getting these ProStar+ trucks to market in such short order.

The ISX15’s reputation as a low-decibel diesel, combined with International’s sound-dampened cab, makes for a quiet interior, so drivers don’t have to deal with any shaking, buzzing or rattling panels – either at low rpms or highway speeds.

Power comes on smoothly, with shift points set at about 1,200 rpm. The 500 horses mean the tractor gets moving in a hurry, so drivers find themselves hustling through the low-range gears quickly; even fully loaded, the ProStar+ accelerates to highway speed in impressively short order. Once at 70 mph – Mississippi’s legal speed limit – an occasional split-shift is sufficient to handle any grades, and the ISX15 still has plenty of available power if needed.

On the return leg, I decided to pass a slower tractor-trailer on a mild grade. I was planning to split-shift down in top gear, but that turned out to be unnecessary; simply adding throttle gave me almost instantaneous engine response and impressive acceleration. We breezed past the rig in no time.

International has taken a hard hit over the past year, and while it’s safe to say the company probably would do a few things differently if it had them to do over again, it’s clear the decisive move to get Cummins back into its trucks was a good one. Whatever one thinks of the company’s MaxxForce engine push, the ProStar+ is a proven product – as is the Cummins ISX15. Putting Cummins power back under ProStar+ hoods gives International the truck it needs to restore confidence in its products and reaffirm its commitment to its customers.