OK, for starters, if you’re towing anything sizeable, you need at least a V-8 in gasoline form, or virtually any diesel currently offered, six or eight cylinders. In truth, there is no diesel currently offered, from any manufacturer that offers one, in a full-size truck that won’t do the job, so lets focus instead on getting the right V-8 gasoline engine.
First and foremost, you want torque, not horsepower. Torque is the “measure of the tendency of a force to cause rotation, equal to the force multiplied by the perpendicular distance between the line of action of the force and the center of the rotation.” At least, that’s how Webster’s New World College Dictionary defines the term. In simpler terms, torque refers to the strength of crankshaft rotation, and its resistance to torsional loads. In even simpler terms, the more torque you have, the bigger the stump you can pull—or in your case, the bigger the trailer.
Most manufacturers offer at least two different V-8 engines in their trucks. Most often, a larger displacement means more torque, but it’s a good idea to verify the figures on the Web. Most automakers offer horsepower and torque figures on their Web sites, but if they don’t, you can find it on any number of automotive Web sites. Edmunds.com is a good place to start.
Be aware, however, that even if two trucks offer the same amount of torque, there is still yet another distinction that can make a big difference in how a truck or SUVs tows a trailer. At what rpm does the engine develop peak torque? It seems like a minor detail, and it is, but then again it isn’t. A truck that develops peak torque at 3,500 rpm will be a lot more “drivable” and tow more competently than a truck that doesn’t create peak torque till 4,500 rpm.