Driving Kriska’s ProStar with SmartAdvantage powertrain

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Truck News / January 4, 2015

"We went from 6.5 miles to the gallon to 9.5 miles to the gallon, just by handing (drivers) the keys to a new truck. At 1,000 miles a day, that’s a lot of money"

He used to spec’ all the trucks himself. One truck for every job. But Marcel Boisvenue, fleet maintenance manager with Kriska Transportation, has recently changed all that. He now leans more heavily on the expertise of the OEMs – their wind tunnels, their laboratories, their engineers – to design the best truck for each specific route and application.

“Years ago when we spec’d a truck, one truck did everything,” Boisvenue explained. “It did this job, did that job. Did the hills, did the flats. It hauled 30,000-lb payloads and it hauled 110,000-lb payloads. We realized this last few years that we can’t do that anymore.”

This year, when it came time to replace several units hauling glass on an Indiana-Ontario/Quebec route, Boisvenue had just one request: 10 mpg.

“I said if I can’t get 10 miles to the gallon (Imperial) then we’re going to be talking,” Boisvenue said.

No pressure.

This request landed five new International ProStars with Cummins-Eaton SmartAdvantage powertrains in Kriska’s yard. They’re rated at 450 hp and 1,550/1,750 lb.-ft. of torque. They are among the first SmartAdvantage-powered trucks to be deployed in Ontario.

The trucks are being used to serve a customer whose payloads rarely exceed 30,000 lbs, delivering glass from a factory in Indiana to manufacturers in Ontario and Quebec. The trucks head back to Indiana even lighter, with empty racks going back to the glass plant.

The trucks are getting a full 3 mpg better fuel mileage than the ones they replaced – International ProStars with EGR-only MaxxForce engines.

It’s easy to dismiss the SmartAdvantage as an American spec’. After all, it’s limited to a GVW of 80,000 lbs. It’s not the truck you bring into your fleet to do everything, but it has its place. The SmartAdvantage powertrain is a result of a heightened level of collaboration between Eaton and Cummins.

As independent component manufacturers, the two companies are kindred spirits of sorts, facing the same daunting challenges in an industry whose suppliers are regularly espousing the benefits of vertical integration. The hyper-collaboration between the two companies now even includes the exchange of trade secrets to better optimize their respective components for the greater collective good. It seems to be working out.

These ProStars are getting just shy of 10 mpg (Imperial). But how do they drive? I wanted to find out and with the help of Cummins and Kriska, I had the opportunity to take Unit 1500 for a four-hour drive the week before Christmas. Yep, Christmas came early this year.

This being a slip-seat truck running 20 hours a day, I wanted to get some drive time with the SmartAdvantage without disrupting Kriska’s busy delivery schedules in any way. So I met up with driver Norm Conant around noon on Dec. 17 and we headed over to All Weather Windows to pick up a few dozen racks for delivery to Sarnia, where we’d pass it off to another driver who’d take the load down to Indiana overnight and return early the next morning with another load of glass.

It was 3 p.m. by the time we got loaded and onto Hwy. 401, which was surprisingly fluid, given the time of day.

On the drive to Sarnia, the SmartAdvantage did everything I was told it would do. Prior to my drive, Christoph Horn, Ontario territory manager with Cummins, explained the downsped engine would cruise at about 1,259 rpm at 62 mph (100 km/h). This is slightly higher than Cummins wanted but at the time the trucks were ordered, Meritor’s 2.79:1 rear axle ratio wasn’t an option, so they opted for the 3.08.

“When we were spec’ing this, we wanted this to run between 1,150 and 1,240 rpm, so we’re on the high side of where we want it to run – we’re about 19 rpm over where we’d like it to be,” Horn acknowledged.

It’s okay to drop a gear

Horn cautioned the transmission would readily downshift to ninth gear, but this was no cause for concern because the ISX15’s broad sweet spot means the engine is still operating within that range – even in ninth. While engineers used to emphasize the importance of getting into top gear and staying there as long as possible, the focus has since shifted to getting into the sweet spot and remaining there – even if that entails dropping a gear.

“For the first time, we’re really okay with downshifting because we’re still in the sweet spot when we downshift,” Horn said. “And when we downshift, we have the advantage of being in direct drive and there’s a 3% fuel economy benefit to be picked up on the transmission side when we’re in direct drive as opposed to overdrive.”

But this never happened on my drive, with just 16,000 lbs of racks in the wagon. It didn’t happen on the return trip either, with 36,000 lbs of glass in the back. We held tenth gear the entire time, but the steepest grade we encountered was approaching Hwy. 8 eastbound on the 401 – not exactly the Roger’s Pass. Normally an engine evaluation calls for some hill hunting and the pursuit of challenging terrains with heavy loads, but there was little reason to do so with this truck. This truck was never built to haul heavy payloads over big hills. You wouldn’t spec’ the SmartAdvantage to run the West Coast with a 110,000-lb payload; it wouldn’t be smart and there’d be no advantage.

This spec’ is intended for gross loads of no more than 80,000 lbs and that’s exactly what Kriska was looking for when it placed the order. That, and 10 mpg.

They’re nearly there. By fall, the five SmartAdvantage-powered ProStars were averaging 9.42 mpg (Imperial) with about 43,000 miles of pavement having passed underneath their tires.

But it’s the consistency that really impresses Boisvenue.

“These things come in and every time I check them, there is less than a 0.1 mpg spread between the worst and the best (SmartAdvantage units),” he told me.

Where do the savings come from?

The work Cummins and Eaton have done to better integrate the engine and transmission are yielding real improvements when it comes to fuel economy. One example of this is that the engine can now access the transmission’s level sensor, allowing it to more quickly and accurately adjust torque based on the actual road grade rather than an estimate derived from a complex calculation.

Better integration contributes about one third of the 3% fuel economy gain Cummins and Eaton say the SmartAdvantage can deliver over a non-optimized, but similar, engine/transmission combo. Another 1% is derived from improvements to the design of the 10-speed Fuller Advantage Series automated manual transmission – the first to employ a precision lubrication system that eliminated the need for an oil cooler and shaved about 80 lbs from the transmission’s weight.

The final piece of the puzzle is downspeeding, where another percentage point is gained by running the engine at lower rpm.

But in addition to all this, both Cummins and Eaton have made significant improvements to their own respective products in recent years. The Fuller Advantage Series employs small step gearing for better shifting performance and Cummins has continuously improved the fuel economy of its ISX15 as far back as 2007.

“If a customer is coming out of a 2007 product into a 2014 product, they’ll see a 10% increase in fuel economy – and that’s not with the SmartAdvantage, that’s just the standard powertrain,” Horn explained.

There are many reasons for this but one of the most impressive may be the reduction in diesel particulate filter (DPF) regenerations required today. The ISX15 typically requires a DPF re-gen once every 96 hours of operation – down from about once per eight hours in 2007 and every 20 hours in 2010. When you consider that every re-gen burns about 1.5 gallons of diesel, you don’t need a calculator to realize there’s a lot of money to be saved simply through optimization of the aftertreatment system.

If you like the Cummins-Eaton pairing but require a heavier GVWR, you can get an ISX15 with 16-speed Eaton UltraShift Plus, which provides greater flexibility for a wider range of payloads. This combination works well, as you can read here, but the engine and transmission are not yet as fully integrated as they are with the SmartAdvantage. The 16-speed still requires an oil cooler and the engine doesn’t yet tap into the transmission’s level sensor.

How it drove

The SmartAdvantage is a powertrain that doesn’t have to be spectacular – it just has to be efficient. Several hours on Hwys. 401 and 402 at 100 km/h and mixing it up with a little bit of traffic was enough to experience the transmission’s smooth shifting and the responsiveness you’d expect from an ISX15 engine.

Vehicle Acceleration Management (VAM) is a key ingredient to the SmartAdvantage recipe, and it effectively limits the power available upon acceleration when lightly loaded. This, in turn, limits the fuel economy carnage a lead-footed driver can incur by treating every green light as though it’s a green flag.

The end result is that even when you’re lightly loaded, you’ll feel like you’re grossing 70,000 lbs.

Drivers won’t like this, but some may need it. The logic behind it is sound – there’s significant fuel economy to be gained by forcing a more gradual acceleration when lightly loaded. But there were a couple instances where I felt we missed an advanced green because of VAM. Did any fuel we saved go out the stack while we sat there waiting for the traffic lights to cycle through?

Horn acknowledged VAM is still being fine-tuned in an attempt to strike the perfect balance between efficiency and performance. Even though VAM encourages more gradual acceleration, a truck with VAM enabled and one without, will both reach the same speed within 33 seconds.

Yet VAM provides a fuel savings of 1-2%, Horn claims, adding the fuel savings are greatest in regional haul applications. Aside from its controlled acceleration at launch, the SmartAdvantage never felt underpowered in any way.

SmartAdvantage engines also come with SmartTorque2, which provides a dual torque rating (1,550/1,750 lb.-ft. on the truck I drove) depending on how much is required at any given time. It seamlessly switches between the two torque ratings based on the gear the transmission is in, the weight of the load and the road grade, as dictated by the transmission’s level sensor.

The ProStar itself provided a comfortable ride. I was surprised there were no chassis fairings on this truck, but Boisvenue told me they’re not offered on this configuration, probably due to the short wheelbase.

My only complaint, and it’s a small one, is with the design of the hood-mounted mirrors.

I found them to be a touch large and I don’t love the tripod-style mount. Sure they provide great visibility down the side of the truck but they also obstruct what’s ahead and they can’t be good for aerodynamics.

For a fleet spec’ day cab, this ProStar was very nice to drive. Visibility over the short, sloped hood was excellent, the heater kept the cab toasty and buttons and switches were logically arranged on the dash and the steering wheel.

Light loads. So what’s with the 15L power?

Because these trucks rarely haul payloads greater than 30,000 lbs, I wondered if the trucks were overspec’d with 15-litre power. Cummins and Eaton do offer a SmartAdvantage package with the ISX12, which I thought might be sufficient in this application. When I posed that question to Cummins people it lead to a long discussion that circled back to this one conclusion: the 15L is simply more fuel-efficient.

It’s more fuel-efficient than the ISX12 and beyond that, it’s more fuel-efficient than any 13-litre engine out there, according to Cummins. But this is counterintuitive and contradicts the messaging you will have heard from other OEMs about the benefits of 13-litre engines.

An unabashed proponent of the “there’s no replacement for displacement” theory, Horn offered credible explanations as to why a 15L engine can still be the best option – even in lightweight applications, or perhaps especially in lightweight applications.

He conceded there’s a weight penalty to be considered – about 300 lbs – meaning a 13L engine could be the right choice in weight-sensitive applications. And he also admitted the 15L is less efficient within the cylinder than a smaller-displacement engine, simply due to the greater surface area within the cylinder and the resulting friction that occurs against the larger liner.

But downspeeding helps mitigate this, because fewer strokes equal less parasitic losses.

On the flip side, the 15L engine offers a greater compression ratio (19.1:1 vs about 17:1), resulting in better-optimized cylinder pressures and improved smoke control. There’s also less parasitic loss within the air handling system, according to Horn. And he added a 15-litre will also provide better startability and gradeability. The 15L, generally speaking, is more durable and in Canada it commands greater value at resale, Horn mentioned. And regardless of the power rating, the full 600 hp of engine braking is always available on an ISX15, providing greater engine braking capabilities.

A like-to-like comparison of Cummins 12- and 15-litre engines showed the 15L got 4% better fuel economy than its smaller sibling in a mainstream application grossing 80,000 lbs.

When comparing torque curves and sweet spots, Horn said the 15-litre comes out ahead. Recent enhancements to the ISX15 have given it a broader sweet spot with peak torque available starting at 1,000 rpm.

“Our point is that with a larger displacement engine – whether it’s ours, or any engine – the torque curve is probably going to be stronger throughout the operating range,” he said.

The ISX15 has also been enhanced to sip less fuel at idle and when lightly loaded. And in lightweight applications, a naturally aspirated air compressor is now available, delivering a further 1-2% fuel savings.

You could debate the merits of 13L vs 15L power all day, but there’s no arguing with the fuel mileage data. At Kriska, which operates a pretty diverse fleet of trucks, the SmartAdvantage with ISX15 is currently the second best mpg performer out of 28 existing spec’s – albeit, hauling modest payloads.

Conclusion

Evaluating the Cummins-Eaton SmartAdvantage is a tricky proposition. We don’t expect it to be racy upon acceleration or to charge up steep grades or to make six-figure payloads feel like nothing at all. The benefits of this powertrain will be seen on the ECM read-outs and the financial statements and all we ask as a driver is that performance isn’t painfully compromised for the sake of improved fuel efficiency. It easily passes this test.

I still had all the power and performance I’d expect from a 15-litre Cummins engine, even if the vehicle acceleration management (VAM) was a touch aggressive for my liking. More importantly, Kriska, whose evaluation is worth more than mine, couldn’t be happier with the truck.

“We went from 6.5 miles to the gallon to 9.5 miles to the gallon, just by handing (drivers) the keys to a new truck,” Boisvenue told me. “At 1,000 miles a day, that’s a lot of money.”

It should be noted, Cummins and Eaton aren’t promising a 3 mpg improvement, they’re touting a gain of 3-6% over your base ISX15 and Eaton UltraShift Plus without all the extra integration work that’s been built into the SmartAdvantage.

“We went from 6.5 miles to the gallon to 9.5 miles to the gallon, just by handing (drivers) the keys to a new truck,” Boisvenue told me. “At 1,000 miles a day, that’s a lot of money.”

Even a 3% gain is a lot of money, but you must also consider the residual value of the trucks, which will always be handicapped by the 80,000-lb GVWR. Kriska avoided this potential fly in the ointment by leasing the trucks on a 36-month term, so it will be up to the dealer to find a secondary buyer.

Leasing the trucks also ensures Kriska is able to respond quickly when an even better specification comes along.

“Who’s to say in two years the trucks won’t be getting 11 miles to the gallon?” Boisvenue said. “Then you’re really hurting yourself in the fuel economy that you missed out on if you buy a truck and you have to keep it for five years.”

Did he just say 11 mpg? Looks like the bar’s about to be raised again.

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