10 Most Powerful Semi Truck Engines, Ranked By Torque

If you've ever ridden a mountain bike, you'll know that the lower gears help you get up to speed more easily. Conversely, the higher gears help you go faster overall, maintaining that speed. It's the same conversation with torque and horsepower. Torque helps you get the wheels rolling, and horsepower keeps those wheels rolling fast. When talking about horsepower vs. torque, torque is arguably the more important metric in semi-trucks and big rigs, because you're not often speeding along highways. It's more of a stop-and-go situation, and to start after every stop, you need torque — the more, the better. There are quite a number of benefits to having high torque available at low RPMs, the most important of which are fuel efficiency, better control on rough terrain, more towing power, and getting an easier start with heavy loads.

Big diesel engines with high torque can pull their loads in lower gears for longer, and that's where they burn fuel more efficiently, which means better MPG. You can also pull heavier loads because the torque is right there from when you start the engine, without needing to get up to speed to get the momentum you need. Also, on gradients, hills, and other rough terrain, you don't need to gun the engine to stop from rolling backwards if you have enough torque, because the low gearing will do the heavy lifting for you. So then, with all that in mind, here are 12 of the most powerful semi-truck engines, ranked by torque.

Volvo has been making truck engines wholly in-house from 1975 onwards, though one can argue that 1935 is the date things started, which is when Volvo acquired its long-time engine partner, Köping. Coming back to the present day, Volvo is a force to be reckoned with when it comes to engine manufacturing, building engines for cars, trucks, and even boats.

It's no surprise that the first engine on our list comes from Volvo, with nearly a century of engine-building expertise. You can get a Volvo D11 in many different configurations, starting at 325 hp and 1250 lb-ft of torque, all the way up to its maximum of 425 horsepower and a not-insignificant 1,550 lb-ft of torque. 

All versions of the D11 come with a variable geometry turbocharger (VGT) that enables the Volvo Engine Braking (VEB) system to produce high retarding horsepower at low RPMs, reducing wear on the engine. It also features a smart fan clutch, which engages the cooling fan only when needed and can vary the fan's speed. The D11 has both primary and secondary fuel filters, can be optioned with a preheater, and has a dry weight of 2,259 lbs. Overall, the D11 tends to be favored by drivers who are weight-sensitive, as the D11 punches above its weight (literally), often producing more power than bigger block engines. It's also relatively good value for money, with used examples of D11 engines starting around $9,000.

You may or may not have heard of Paccar, but you will undoubtedly have heard of its truck brands, Kenworth and Peterbilt. Indeed, it is hard to mention the words semi and truck without either brand coming up. Now, interestingly, Paccar has used Cummins engines in its trucks since about 2001, before gradually prioritizing its own in-house engines later on. That said, you can still get Cummins diesels in many Paccar trucks, which we'll cover further down. For now, let's talk about the Paccar MX-11, which is the little brother to the tried-and-true MX-13 and is one of the most popular engine models used in Peterbilt trucks, and in sister-company rigs from Kenworth as well.

The MX-11 was launched in the North American market in 2015, becoming available from 2016 onwards, and at the time, it made 430 horsepower and 1,550 lb-ft of torque. Today, the newer generation MX-11 makes 445 horsepower and 1,700 lb-ft of torque from a 10.8-liter inline-six engine. It also has a variable torque output at 430 horsepower, and 1,450 or 1,650 lb-ft with a multi-torque (MT) rating. And as expected for the mini version of an engine, the warranty offerings are borderline bad, with a 250,000-mile two-year base warranty and 500,000 mile five-year major component warranty. The MX-11 can be optioned on trucks like the Kenworth T680 and Peterbilt 579, though you can sometimes find an example on the aftermarket for between $15,000 and $18,000.

Just like the MX-11, the Cummins X12 is a little sibling, in this case to the Cummins X15, which has become a bit of a cult icon in the semi-trucking world. Think of any truck that is iconic in your mind, and the Cummins X12 diesel will probably be a powertrain option. It can be optioned on trucks like the Freightliner Cascadia, Freightliner 114SD, Western Star 47X, and Peterbilt 579, among others.

The X12 pushes out 500 horsepower and 1,700 lb-ft of peak torque, while weighing just 2,050 pounds dry. In addition, the X12 comes with a great many best-in-class features, such as on-ramp detection that provides more power while navigating on-ramps, predictive engine braking, predictive gear shifting, and dynamic powertrain adjustment. Cummins advocates the X12 as being the productivity champion for intermodal, regional-haul, and weight-sensitive applications, being a whopping 600 pounds lighter than comparable power units. It is similar to a wide selection of powertrains, and can be used in automatic, automated manual, or pure manual modes. 

What most people don't know is that the X12 is actually a joint venture between two companies, the transmission company Eaton, and Cummins. It's also worth noting that Cummins is no stranger to partnerships, having teamed up with Ford in the past. The X12 comes with all the regular Cummins bells and whistles, like remote diagnostics, over-the-air software patches, and the Cummins digital service application, Guidanz.

The G13C shares the same bones as the D13, which is the larger sibling to the Volvo D11 that we kicked this list off with. The main difference between the G13C and the D13 is that the G13C runs on liquefied natural gas rather than diesel. It produces slightly less torque (1,800 lb-ft) than the D13, and slightly less horsepower at 460 due in part to having a slightly smaller displacement at 12.8 liters. All this is done, of course, with a view to reducing the tailpipe emissions produced by diesel engines of this caliber. To that end, Volvo claims that depending on the fuel choice, emissions for the G13C can be anywhere from 20% to 100% lower compared to a similar diesel engine.

The G13C is also offered in two crankcase ventilation systems, called the CCV-C and CCV-OX, with the former being rated for temperatures up to -25 degrees Celsius and the latter being recommended for trucks that operate primarily in cold weather. Whether or not the G13C can be considered a commercial success remains up for debate, but the power unit is slowly gaining traction as more and more fleets are opting for it. For instance, a Lithuanian company called Vlantana has added 65 G13C-powered trucks to its fleet, DHL has 13, Kuehne Nagel has eight, and other small companies are also adding to the order books.

Now we come to one of the most iconic engines on this list, the heavy-hitting Paccar MX-13. As we mentioned, Paccar now manufactures a high number of its truck engines in-house, and the MX-13 is the powerplant of choice for most models. It is a 12.9-liter displacement inline-six engine that makes 510 horsepower and a whopping 1,850 lb-ft of peak torque. All new MX-13 engines will be Euro 6 compliant and provide additional torque while operating at low RPMs in the two highest gears for overdrive gearbox systems. 

For direct-drive gearbox systems, the additional torque at low RPMs is added only in the highest gear in the transmission. To comply with Euro 6 standards, modern MX-13 units add selective catalytic reduction (SCR) technology, a soot filtration system as standard, and the engine recirculates exhaust gas a few times before expulsion. 

You can find the Paccar MX-13 in several fan-favorite trucks such as the Kenworth T880, Kenworth W990, Kenworth T680, Peterbilt 567, Peterbilt 579, and Peterbilt 589, among others. Overall, if you were looking at a Kenworth or Peterbilt truck and didn't need the extra grunt from the optional Cummins X15 unit on your model, the MX-13 would likely be the reliable, durable workhorse for your needs.

The Detroit DD15 is easily one of the most legendary engines made by Detroit. It can be found in trucks like the Freightliner Cascadia, Freightliner Coronado, Western Star 49 line, and the Western Star 5700XE. As far as semi-truck engines go, it's pretty powerful. The 14.8-liter inline-six unit makes 505 hp and 1,850 lb-ft of torque. Many truckers agree that the DD15 is the all-rounder semi-rig engine to beat, delivering on nearly every front you could want. For instance, the DD15 can give 90% of its peak torque within 1.5 seconds, whereas comparable engines would take north of four seconds to achieve the same. The DD15 can offer this remarkable torque courtesy of its unique ball-bearing simple geometry turbo, because competitors often prefer variable geometry turbos instead. 

In addition, recent-model DD15s are supposed to be one of the most fuel-efficient 15-liter blocks on the market, with Detroit claiming that the new pistons on the DD15 lead to it being 3% more fuel efficient on average. Detroit also claims that the DD15 has the "longest service intervals" for maintenance of any engine in its class, meaning that DD15 engines should spend less time in the shop and more time on the road. Also, like any other Detroit engine, the DD15 comes with several creature comfort features for the driver, such as a remote diagnostic system, which Detroit calls Detroit Connect, a new aftertreatment system to comply with emissions ratings, and a thermocasting system that stops the aftertreatment system from cooling down too quickly.

The MP8 comes from the legendary company Mack, which recently updated its much-loved bulldog hood ornament. With its new generation, the MX-8 is 88 pounds lighter and more fuel-efficient than the previous iteration. It is used in virtually every major heavy-duty Mack truck, from garbage disposal to long haul, mining, and construction. 

The MP8 is a 13-liter inline six unit that makes 505 horsepower – the same as the DD15 by Detroit, but 1,860 lb-ft of torque, which is 10 lb-ft more than the DD15. And don't forget that the DD15 has a 14.8-liter displacement, which is 1.8 liters more than the Mack MP8. If you manage to nab one of the higher-power units like the 505 hp variant, you'll also get around 500 hp of engine braking horsepower, which is impressive considering that the MP8 only displaces 13 liters. 

The aftertreatment system that comes with the MP8 is also amazing, especially in cold places. Diesel exhaust fluid (DEF) is 68% water, and water tends to, you know, freeze. So, if your DEF freezes while in the system lines, you'll have a massive problem. In the MP8, when you turn the engine off, you'll hear the aftertreatment system run for about a minute. It is pumping all the DEF back into the tanks so that none is left in the lines, and the DEF can safely freeze in the tanks. When you turn the engine back on, hot coolant (yes, it sounds odd) will be pumped around the tank walls, thawing it out. Neat.

The D13 is Volvo's most powerful truck engine currently, until the D17 makes its way onto the scene sometime next year. It has been the standard power plant of choice in Volvo's legendary long-haul VNL line since October 2021, and there aren't any signs of that changing soon. Sure, Volvo is coming out with a (much) more powerful D17 engine, but it isn't out yet. So, for now, the D13 remains Volvo Trucks' most powerful unit in the States, making 500 hp and 1,900 lb-ft of torque from a 13-liter inline-six engine. 

The latest addition to the D13 family is the Volvo D13TC. The TC stands for Turbo Compound, and the version adds a fixed-geometry turbo and an additional 50 lb-ft of torque, bringing the total up to 1,950 lb-ft of peak torque, with the 500 horsepower unit. The new TC engines are claimed by Volvo to be 11% more fuel efficient than the previous (2015+) generation Volvo D13 engines. However, the extra MPG will only be unlocked in a special extra efficiency (EE) drive mode that would naturally come at the cost of some performance. While we don't have on-road real-world figures, the claimed economy for the D13TC is 8.5 MPG while cruising at 85 mph.

The X15 is a behemoth 14.9-liter inline-six making 565 hp and 2,050 lb-ft of torque from Cummins, which, interestingly, also makes train engines. The X15 is used in iconic trucks like the Freightliner Cascadia, International LT and HX series, Kenworth T880, Peterbilt 579, 589, and 567 line, and the Western Star 49X, among others. And given that all of these are among the best-selling semi-trucks in the U.S., chances are high that one of the big rigs you've seen trundling along on I-95 has been powered by a Cummins X15. The X-15 also comes with a variable geometry turbocharger (VGT), OTA remote software updates, a two-year 250,000-mile base warranty with an option to get a five-year 500,000-mile extension, remote diagnostics, EPA 2024 certification, and is expected to get a slight spec bump for 2027.

For the 2027 spec bump, Cummins says it will increase the maximum hp on the X15 to 605 hp, give it a 4% MPG boost, change the piston bowl design to increase the compression ratio, and be EPA 2027 compliant. The X-15 also matches the number one engine on our list, the Detroit DD16, in terms of torque (2,050 lb-ft), but falls behind in horsepower (565 hp versus the DD16's 600 hp), so it slots into second place. All in all, it's an excellent engine, has been tried and tested for multiple generations, and will seemingly be around for a long, long time.

The DD16 is the top-of-the-line, most powerful engine that Detroit has made to date. It powers models like the fourth-generation Cascadia from Freightliner, and the 49 and 69 lines from Western Star. In terms of power figures, the DD16 is a 15.6-liter inline-six unit that makes up to 600 horsepower and a whopping 2,050 lb-ft of torque, all while meeting the latest emissions standards. Naturally, to achieve that, a great many different systems have to mesh together. Undoubtedly, one of the most impressive is Detroit's proprietary Amplified Common Rail System (ACRS) that injects fuel at over 38,000 PSI, which is on the higher side for class-8 trucks. The DD16 also comes with a compound turbo layout, with a primary turbocharger in the engine bay, and a secondary turbo near the end of the system that captures heat and air that would have otherwise been lost, and turns that into a power boost. 

The after-treatment system enables the DD16 to meet ever-more-stringent emissions requirements. It includes a particulate diesel filtration system, selective catalyst reduction (SCR) system, oxidation catalyst, and diesel exhaust fluid (DEF) injection, all in one package. 

The DD16 is matched for torque by the legendary Cummins X-15, but the X-15 has fewer horsepower, making the DD16 the most powerful engine on our list. The only Achilles heel that the DD16 has is its dry weight of 2,837 pounds, but when you produce 2,050 lb-ft of peak torque at 2,100 RPM, all can be forgiven. 

Honorable mention 1: Weichai WP17H

The Weichai is available in China's markets only and is used in a truck called the Shacman X6000 800 hp, which is actually the world's most powerful production series truck. It is a 16.6-litre behemoth of an inline-six making 800 hp and 2,766 lb-ft of torque, and has an impressive service life of 2 million kilometers (1.24 million miles).

Honorable mention 2: Volvo D17 A780

The D17 is supposedly Volvo Trucks' replacement for the D13 (and maybe G13) range. It is a 17.3-liter Inline-six making 780 horsepower and 2803 lb-ft of torque(claimed). The engine has been announced, and we have claimed figures from Volvo, but it is not officially on the market yet. However, it currently powers a few of Volvo's new FH-series trucks that have been released in Australia, which are probably test rigs for the engine pre-launch.