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MaxxForce 13

Talk about cross-border shopping.

International shopped around the world looking for a partner in the big-bore engine that would become the MaxxForce 11 and 13. The company knew it didn’t have the scale to engineer and build a cost-effective, high-performance engine, so it went looking for a partner that had a great product and wouldn’t be competing in North America.

The result was a joint development agreement between International and Germany’s MAN Nutzfahrzeuge. Overseas, the engine is called the MAN D20. More than 200,000 of them are in currently in service.

The North American version of the engine features the same basic infrastructure as its European counterpart (block, crank, head, etc.), but with electronics, and fuel and air management systems engineered to meet North American emissions standards and customer expectations.

The engine block is interesting in its own right. It’s made of compacted graphite iron (CGI), which International claims is 70-percent stronger and 40-percent stiffer -- with double the fatigue limit -- than traditional cast iron. CGI is a precision casting process where a small amount of magnesium is added to the molten iron. The resulting increased stiffness and strength allow for a lighter casting. At 2,244 lb, it’s 300 lb lighter than Cat’s current C13.

A series of vaulted panels on the side of the block is designed to minimize noise, and the result is quite amazing. That, along with several other noise-reduction strategies make MaxxForce a very quiet engine.


EASY ACCESS: While it appears complex, it’s an easy
engine to work on. It won’t take more
than 15 minutes to get to most external areas.

Air and Fuel Control

While quiet won’t get you down the road, MaxxForce’s solid low-end torque will. While the engine has a European heritage, the make-it-go stuff is tailored to meet North American requirements and expectations. Having said that, engineers have given the engine a distinctly European personality because, well, because it works.

Full torque output is available at 1,000 rpm, with more than 80 percent of that available at clutch engagement. Drivers will find high torque at low engine speed an economical way to operate.

“The key to combining fuel economy and performance is to bring engine speed down. There’s a lot more internal friction at high engine speed, but on the low end, you have less friction and parasitic loss as well as full torque, making the engine very drivable,” says Helmut Endres, International Truck and Engine Corp.’s VP of engine and product development. “We really have to convince our customers to adapt to the new, European torque curves of this engine.”

Several fleet representatives were present at the MaxxForce product launch in Las Vegas a couple of months ago discussing their experiences thus far with the product. Ray Williams of Estes Express Lines of Richmond, VA told us he had to break with tradition an spec an overdrive transmission to get the engine revs down.

Estes has been running 300 hp Cummins ISMs with direct transmissions. That spec had the 11-litre MaxxForce wound all the way up to 1800 rpm at 60 mph, which is way outside the optimum cruise speed. They let it go for a few months, and saw fuel mileage in the 5.3-5.4 range. After switching to an 0.78 overdrive transmission and getting the revs down to 1,300, fuel economy improved to 6.27 -- nearly a mile-per-gallon difference.

“Those engines don’t like to run fast,” Williams says. “We’ve got them down to 1,300 at 60 mph and the drivers say they pull just fine. Now we’ve gotta get them used to driving a low revving engine. That’ll be a job for our driver trainers”

To achieve good performance at low rpms, MaxxForce has combined dual-stage turbocharging with high injection pressures and optimized intake air temperatures.

There are two turbos on the engine, operating in series, but independently of each other. Each are “simple” turbos, i.e., not variable geometry designs. The primary has a small compressor wheel which spools up very quickly to provide adequate volumes of air in lower gears when power demand is modest. The secondary turbo, while allowing the free movement of air through it from the primary turbo, is larger and capable of moving larger volumes of air when power demand is higher, like at cruise speed and when climbing hills.

“On a single stage system, a larger turbo might be spinning at 20,000 rpm at low engine speed, whereas with the smaller first stage turbo in this system, we get speeds of 60,000 rpm, making the turbo much more responsive,” Endres points out. “Turbo speed is what gives you boost (higher intake manifold pressure).”

One of the unpleasant offshoots of EPA’s emissions restrictions was fairly poor transient performance, especially when downshifting or climbing hills. The driver would feel a lag after the shift before the power came back because the system was programmed to not deliver substantial amounts of fuel until it had the airflow from the turbo to support the proper fuel-to-air ratio. Otherwise, you get a lot of smoke.

MaxxForce’s smaller fast-spooling primary turbo delivers enough air quickly, so more fuel can be fed to the injectors, and that gives the engine very quick throttle response.

Fueling is managed by a Bosch 26,000-psi common rail fuel injection system. There’s constant high pressure at the injector even at low engine speeds, and MaxxForce engines use an injector with carefully engineered hole configurations that’s said to be 85 percent efficient. The fuel injection system is also capable of multiple injections per combustion event, which yields a more complete, more efficient burn, with less noise.

The last piece of MaxxForce’s combustion optimization strategy is carefully controlled intake air temperature. MaxxForce uses two water-cooled air intercoolers in series after each turbocharger. There is no charge-air cooler on this engine.

As a result, air intake air temps can be kept very close to ambient temperature, International says. That’s good for the fuel-to-air ratio, good for efficiency, and good for drivability.

We drove this truck in stop and go
traffic and freeways in Chicago and rural roads in Indiana.

But Does it Work?

I recently tested an International TransStar (formerly known as the 8600 model) equipped with the 13-litre version, rated at 410 hp / 1,450 lb ft, running a trip from Chicago’s western suburbs over to Fort Wayne, Ind. I grossed 66,000 lb under a flatdeck loaded with concrete Jersey barriers.

Winding my way from International’s Melrose Park facility out the freeway gave me a taste of some city driving. There’s pull under the pedal right from clutch engagement, and hitting peak torque at a mere 1,000 rpm means there’s absolutely no need to take the revs much higher than that on the bottom side of the gearbox.

At highway speeds of 60 mph (1,300 rpm), I applied a little trailer brake a few times (there are no hills between Chicago and Fort Wayne) just to get a sense of the engine’s pull and it was respectable. Even down at 900 rpm under load, it pulled solidly.

Since fuel economy is best at lower engine speeds, MaxxForce has a broad enough torque band to cruise at 1,300-1,400 rpm with more than a little in reserve for the hills. Peak torque sits between 1,000 and 1,200 rpm.

The lack of engine noise made for a pleasant drive, too. I drove a MaxxForce equipped ProStar a few weeks earlier at a product launch event in Las Vegas, and while it was much quieter than the TransStar day cab, I have to give the TransStar/MaxxForce combination very high marks for sound attenuation.

While in Las Vegas, journalists had a chance to talk with the fleets guys who are doing reliability testing with the MaxxForce engines, and a couple of them reported fuel economy numbers in the high sixes (US), which isn’t bad for engines with less than 50,000 miles on them.

My first impressions of the MaxxForce engine are good. It may be new to North America, but it’s got a good track record in Europe. It’s light and torquey, and more than able to move typical linehaul or regional loads efficiently. If your operation doesn’t demand a big block engine, MaxxForce is worthy of consideration.

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maxxforce test drive

Unlike the what was wrote before, after driving the prostar with the new Maxxforce motor I am very disatified. I pull flatbed and most loads are within 2,000 of gross or higher. Trying to take off from a stop I find I must use lower gears because they motor will try and stall in a gear as high as third. The truck is set up with a shift indicator that does more than tell you when it is good to shift. The system can lock out pedal feed. So if stop and go traffic or reducing speed for a sharp corner, the peddal feed can lock keeping a driver from accelerating. In my opinion this is a safety issue that can induce a late roll over coming out of a curve when weight shift back to center. RPM limits on the gear before top gear limit acceleration merging into traffic or pulling hills. General rule for fuel economy is this. When pulling a hill you know you will have to downshift on, do it sooner than normal to maintain climbing speed to reach the top and get back into high gear. This truck makes you run below 1100 causing you to be low going into the nexy lower gear. this causes more than one down shift on a steep hill which keeps the truck out of high gear longer. The engine can not handle RPM's below 1000 if running heavy and pulling a hill. My motor begins to buck and jerk at 1000. At no time have I ever found this engine able to operate below 1000 except in low range. My truck is set to run 65mph. It does this at 1350 rpms. Being able to run in a lower RPM is fine if your on flat ground. But most roads aren't flat.

I drive for estes express in western pa and run mountains all night. I can tell u after 100,000 mi with a maxxforce 13 that i despise driving that truck. Its added 20min. each way to my run.The cummins ism 370hp will run circles around that truck it is quiet and smooth but im tired of getting blown off on hills by the old trucks and watching them pull off in to the distance with me in the slow lane with my flashers on.I talk to other drivers regularly that have these trucks and havent found 1 that doesnt hate driving them.At this time our hub has 25 of these new trucks give or take a few 15 of them are broke down including mine. my truck has been to international 6 times for major problems and has been on a wrecker twice.My avg. mpg is 5.6 there are no upsides to these things as far as i see it there junk.

I to drive for Estes Express Lines and have a new Max Force. In the past 10 weeks mine has been at International for for 9 weeks out of 10. There are only 3 pros I see about this tractor the smooth ride, quietness, and telescopic steering. As I drive this junk down the road I wonder how long it will take before I get ass ended and someone gets killed. They may be a low RPM tractor, but on a 35 mph road. The reguired down shift RPM is 1100 RPMs at which im doing 52 mph. Why??? I just become another highway hazard!!!! At 410 horsepower you would think it would atleast keep highway speed. You have to second guess yourself before making passes on other trucks for you never know how it is going to pull the next hill. And just to think I really use to enjoy driving truck. Now when I leave home my ehole attitude changes. In closeing I could add more, but no one listens. My though "return to Mexico!"..

maxxforce is pure shit. i haul shingles at 80k daily. and when i go up a grade i go up it in 9th gear with rpms redlined because i know the trucks going to drop dead. peice of shit no balls.

I drive local in the Pacific Northwest, so I have some hills to deal with. I hate these engines with a passion. The ECU is torque managed to hell, and the exhaust brake simply does NOT work-the engine fan slows the rig down more. I just came back last night from a 300 mile run (deadheading back empty) and only got 4.8mpg. As mentioned in a previous posting, the truck won't allow for any driver input with shifting-you must up and downshift at specific rpm's or the throttle simply won't work, so I'm getting that bad of mileage from the programming. In addition to that, the throttle response is very sluggish to start, but will continue to fuel the engine after you release the throttle, making smooth shifting a function more of chance than skill. In neutral, the engine will accelerate to redline with only 1/2" of throttle applied...this is after it idles for a second or two even after you have pressed the throttle!

Did I mention that I hate these engines?

Maxforce 13 is not a good truck. Can't advice someone to buy. I hate the new engine

Well Im running a 2013 maxxforce in a lonestar. 6.2 mpg running Ab/Bc Canada. Pulling avg 100,000lbs avg 70mph. Its a little lighter than my 460 N14 cummings was but it pulls fine. All the previous comments are comments about their company they work for and engine settings not the Maxxforce. It has so many computer variables like dead pedal, shift ratio blah blah blah. Sorry guys your company set that engine that way. As far as engine brake I have Jakobs and they brake fine. Biggest complaint so far is I have to look at the tack for shifts because the engine is really quite. Sometimes I can make out the turbo and the electric mirror switch is where I put my arm. Overall Im happy with it. Oh and it takes a bit to relearn the shift pattern with the low rpm torque but once ya get that its fine.

I drive ProStar with 10spd,and Maxxforce 13,470hp,1700 torque.
Before I had 1998 Volvo with Cummins N14,435 hp.
Maxxforce, don't even come close to cummins.
Try Maxxforce in Pennsylvania, or somewhere, where you need power,
Maxxforce is underpower, fuel thirsty engine.

I have a maxxforce 13 in a 2013 with 270000km. Over the last year and a half I've had 3 censor failures, fan hub, egr, complete wiring harness replacement, engine knock code, air compressor, excessive coolant leaks, and a pile of down time because the shops are full of MAXFORCE. I don't think its that strong of an engine. Also four and a half to five mpg. I also run canadian weight. As well they charge 525$ for air filters for the lonestar. So I guess if this industry standard Im getting old because I don't recall this many issues in any other truck Ive operated.

Are there any Canadians experiencing these problems?

I have been looking into these issues with the Maxxforce engines. If you are interesting in sharing more about your story, please contact me at

I have been looking into these issues with the Maxxforce engines. If you are interesting in sharing more about your story, please contact me at