If you're buying a late-model Ram truck, there's a good bet that you're looking at the high-end Cummins 6.7L engine models. These trucks offer the power and capability necessary to serve numerous roles, making them an excellent choice for contractors and anyone who needs a day-to-day work vehicle. However, buying a used truck always comes with caveats.

Whether you're buying your truck for work or personal purposes, it'll pay to understand a bit about these high-powered engines. While there's more to know than a short internet article can ever teach, these three critical facts will help get you started on your truck buying journey.

1. 6.7L Engines Use Variable Geometry Turbos

Nearly all modern diesel engines use a turbodiesel design. Incorporating a turbocharger into the engine boosts efficiency by utilizing waste energy contained in the exhaust stream. More importantly, diesel engines produce sufficient torque to overcome the initial lag found in many turbo engines, allowing them to gain all the benefits of forced induction with few downsides.

The 6.7L engine found in many heavy-duty Ram trucks utilizes a variable geometry turbocharger (VGT) to offer even more benefits. VGTs combine the advantages of small turbochargers that work best at low RPMs with large turbochargers that work best at high RPMs. As a result, your truck can generate more consistent turbo boost with less lag across the entire powerband.

2. Multiple Variants Are Available

The displacement of an engine and its model year are the only things you need to know for many manufacturers. However, the 6.7L Cummins came in several formats across the Ram heavy-duty line-up. The primary difference between the three models lies in their torque output, and you'll generally find these variants referred to as low output, standard output, and high output.

The low output version came equipped with manual transmission trucks to match the engine output to the capabilities of the 6-speed transmission. Likewise, the other two variants match the power-handling capabilities of their respective automatic transmissions. The highest output engine was only available with the Aisin AS69RC transmission.

3. You'll Have Plenty of Upgrade Opportunities

The popularity of these engines means that you'll find a deep aftermarket with plenty of potential performance upgrades. If the power of a stock Cummins isn't sufficient for your needs, there are plenty of bolt-on options to add more horsepower and torque. Additionally, options such as improved intercoolers can help extend the life and reliability of your variable geometry turbocharger.

The wide availability of aftermarket component upgrades makes these engines a great platform if you need to modify your truck for a specific purpose or just want a little more oomph when you hit the accelerator pedal.