By James Menzies LAS VEGAS, Nev. – International wants to enter the big bore engine market with a bang, but when you start up a MaxxForce 11-or 13-litre engine, what you’ll hear is more of a whisper.
Quiet operation is one of the value propositions International Truck and Engine is touting with its new engines, now available for order on International’s ProStar, TranStar and WorkStar Class 8 trucks.
At a recent trade press ride-and- drive in Las Vegas, editors had the chance to compare the sound levels of a MaxxForce and a popular competitive engine. The MaxxForce doesn’t rattle and knock like a traditional diesel; instead this engine hums. It’s a distinctly different sound than what you’d normally hear emanating from under the hood of a diesel-powered big rig.
International officials explained the quiet operation is due to some fundamental design characteristics, starting with a compacted-graphite (CG) iron engine block. It seemed appropriate the MaxxForce was being introduced to us in the shadows of Las Vegas Motor Speedway. It was NASCAR legend Dale Earnhardt who first introduced the use of compacted-graphite iron to the racing circuit. By adding a small amount of magnesium into the base iron compound, a new, harder compound is created. Because of this added strength, castings don’t have to be as thick (or heavy) as traditional iron engine blocks.
CG iron’s light weight gave Earnhardt a competitive advantage on the track and as the first engine maker to use the technology in the North American trucking industry, International hopes its customers will share the same benefits.
While the primary advantage of CG iron is reduced weight and improved durability, it also helps dampen sound. Engineers also added pronounced ribbing to the crankcase to further reduce engine noise and incorporated a thick rubber gasket between the oil pan and the engine block to prevent block noise from resonating in the pan.
“Big flat panels are not good for noise, we want to break up those patterns,” explained engineer Dave Bergman, when asked about the ribbed oil pan design.
Also contributing to the lack of traditional diesel engine noise is a new high-pressure common rail fuel system. International engineers explained that traditional diesel fuel systems inject a single full blast of fuel during each combustion process. As a result, a large amount of fuel must be rapidly digested, which causes that knocking sound within the cylinders.
The MaxxForce’s new fuel system, however, is “completely programmable” and can dose the fuel in stages or sequences for each combustion cycle, eliminating the need for the engine to combust large amounts of fuel at once and reducing engine “clatter.”
International’s Steve Perkins said the use of CG iron allows the MaxxForce 13 to weigh-in dry at just 2,244 lbs. On your typical ProStar, that’s a weight savings of up to 500 lbs compared to some other engines when also taking EPA2007 emissions hardware into account, according to International officials. Perkins also pointed out CG iron is 70% stronger than run-of-the-mill “gray” iron and it is 40% stiffer, with twice the fatigue limit. Because of the fuel system’s ability to
inject fuel into the cylinders in stages, International engineers explained that peak fuel pressure of 26,000 psi is maintained
at virtually any engine speed. This allows the engine to
reach peak torque at 1,000 RPM, enabling drivers to operate the engine at lower speeds without sacrificing pulling power, which naturally contributes to better fuel efficiency.
The MaxxForce also features twin-series turbochargers and an integrated heat management system called Eco-Therm. The small, primary turbo takes care of takeoff at low engine speeds while its larger twin maintains peak power at high speeds, International engineers explained.
Eco-Therm controls the exhaust temperatures to optimize the DPF regeneration process and also allows for faster warm-ups and improved operation in cold weather, the company said.
What customers are saying
International invited several customers to the event to share their real-world testing experiences. Among them was Wayne Viessman, fleet manager for Minnesota-based Cliff Viessman Inc., a 450-truck operation hauling mostly food-grade products.
Viessman said the company took delivery of a MaxxForce 13 with 475 hp and 1,700 lb.-ft. of torque in a TranStar day cab last April. The company has put 112,000 miles on the engine with no reliability issues. But it’s the driver himself who offers the most telling review.
“It pulls well, there’s a really good torque curve,” driver Tim Antony told me. But he’s most impressed by the low noise levels, especially when making nighttime deliveries of corn gluten to farms. “I can come into a yard at night and the farmers don’t know I’m there unless the brakes squeak.”
For Viessman himself, it’s the fuel consumption that captured his attention. He said the MaxxForce is achieving 5.52 mpg hauling heavy loads compared to a fleet average of 4.85 mpg. Incidentally, he now has eight more MaxxForce engines on order.
The biggest challenge, according to Antony, was re-learning how to drive the truck. He said he had to learn how to shift all over again because he previously shifted by engine noise and that’s no longer possible. “It took about a week to get used to shifting without hearing it,” he said.
On the road
Well, I didn’t have a week. And the thought of filing the gears while knocking the rust off on a brand new truck possibly destined for some poor, unsuspecting customer didn’t appeal to me on this day. So I decided to ride along with seasoned shifter Dave Hutson in a TranStar day cab equipped with a MaxxForce 13 with 430 hp and 1,450 lb.-ft. of torque.
Our route would take us up a subtle but lengthy grade and we were grossing about 60,000 lbs – a good test for the new engine. The fact we were in a day cab negated some of the noise reduction characteristics built into the MaxxForce.
Day cabs are inherently noisy and generally don’t have the same insulation packages found in most sleeper cabs. Nonetheless, it was still remarkably quiet as we climbed through the gears and merged onto the highway.
The MaxxForce’s turbo response was immediate and impressive, you didn’t have to wait for it to spool up. The engine pulled constantly, even when lugged down to low RPMs.
I noticed Hutson generally kept his RPMs lower than you’d expect, and he confirmed he drives the MaxxForce at a lower average RPM than other, similar sized engines that he’s more accustomed to. This helps with fuel economy.
The RPM needle rose and fell sharply, in immediate response to pedal input – it’s one responsive engine.
Like the engine itself, the engine brake was quieter than normal. It’s barely audible from inside the cab and some old-school truckers may miss the sound of the old ‘Jake.’ But at least you can keep the engine brake activated in urban areas with little fear of reprisal. All in all, the MaxxForce performed on the highway exactly as International officials promised it would in the build-up. It’s hard to find fault in an engine that does what it’s supposed to do and lives up to its hype.
The MaxxForce 11 is currently available in horsepower ratings
RAVE REVIEW: Cliff Viessman Trucking’s TranStar equipped with the MaxxForce is getting better fuel mileage than the fleet average, the company says.
ranging from 330-390 hp with torque between 1,250 lb.-ft. and 1,400 lb.-ft. The 13-litre offering is available with 410-475 hp and 1,450-1,700 lb.-ft. of torque.
International has enhanced its support network and launched a technician training program to ensure its dealers are prepared to service the new engine when called upon.
Speaking of serviceability, maintenance intervals on the MaxxForce have been synchronized, to reduce downtime and improve productivity, a subtle detail that’s bound
to be appreciated by customers.
For more information on the newest player in the big bore engine market, visit www. maxxforce.com.
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