10. Volvo D11 -- 1,550 lb-ftVolvo 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 $9,000.7. Volvo G13C -- 1,800 lb-ftThe 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.6. Paccar MX-13 -- 1,850 lb-ftNow 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.3. Volvo D13TC -- 1,950 lb-ftThe 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.1. Detroit DD16 - 2,050 lbsThe 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.