Truck Engine Sizes (And What They Mean for Pickup Owners)

Looking to buy a truck to tow an RV with? Here's everything you need to know about engine specs. Which matter more and which less and how to figure out the right truck for your needs.

Wondering what size engine you actually need for your pickup truck? We did to, so we set out to explore the various truck engine sizes and figure out what these numbers mean.

This post will review the main parameters of engine size: 

  1. Engine Type
  2. Number of Cylinders and configuration
  3. Engine Volume
  4. Turbo Chargers
  5. Torque
  6. Horsepower

Pickup Truck engine sizes - and what they mean for you as an owner

Anytime you end up taking a huge weight on the road, having a massive engine is really important. It could make all the difference in the world in some situations.

You can choose your tow vehicle for its ride or features but if you are serious about pulling a travel trailer or 5th wheel, the right engine will give you enough power to tow your load. So keep reading as we explain the various technical terms relating to engine size.

What you need to understand about truck engine sizes - and why

The heart of any vehicle is its engine. It's easy to be impressed with the size and design of a vehicle - after all, that's what we usually see when we look at one - but there is actually beauty under the hood too.

If you're new to car mechanics, understanding the basic metrics is crucial. That's how you can know which truck to look for in the used trucks section, or tell whether a salesperson is trying to push an expensive upgrade on you - when you don't really need it.

1. Engine Type - Gas or Diesel

Probably the first thing you need to know about a truck's engine is whether it's gas or diesel. If you're going to be driving the vehicle, you should know for the most practical of reasons: You'll need to pull into a gas station and know which pump to use!

We've researched this topic in depth and posted about gas vs. diesel engines and which is better for towing. Here's the bottom line: Gas trucks are great for towing lightweight trailers. When you move to a larger/heavier trailer or 5th wheel, you should consider switching to diesel.

Diesel wins when it comes to towing/hauling really heavy loads. You won't see a semi-trailer with a gas engine. They just don't exist in the caliber needed for producing enough power to move 22,000 pounds or more on the road.

For people who tow an RV, the weight is usually smaller. Camper Report has a nice post where he comes to the conclusion that the average trailer weight is just under 7,000 lbs. Granted, you can have a much larger 5th wheel that will take you way beyond 10,000 lbs.

As long as we're talking 7-8K lbs, it doesn't matter if you choose a diesel or gas engine. You should opt for a strong engine, sure, but gas engines today are often adequate for lighter towing needs. Just make sure the truck you buy has the right packages and overall adequate towing capacity (with some extra - to spare).

2. Number of Cylinders and configuration

When discussing the types of engines for trucks, we talked about cylinders. If you're a car owner who ever bothered to learn how an engine works, you know full well what they are.

In case you need an engine 101 refresher course, here's a clip that explains how an engine works -

The point is, you can see the cylinders there as they constantly go through their different strokes to generate movement.

Inline Four Cylinder Engines

Regular cars, i.e. sedans, hatchbacks etc, usually have four cylinders configured in a single line. That's what some trucks used to have up until 20 years ago. Today, most modern trucks have more than four cylinders, which brings us to the V-shaped engines.

V6, V8, and beyond

What's with the Vs? If you've been reading about modern pickup trucks, you probably noticed they all have V-something engines. The same goes for any large SUV too.

More cylinders means a more powerful engine. So if you want to haul heavy loads, you want more cylinders. However, if you just keep lining up more and more cylinders along the same line, your engine will break down under the pressure. With so many explosions hitting the same long shaft connecting to the crankshaft, it simply won't hold up.

The solution is to arrange the cylinders into a V-shaped engine. That way, the energy from the explosions gets through without creating the same amount of pressure. These engines are just much more reliable, even when they produce insane amounts of energy.

Keep in mind that the number and configuration of cylinders appliest to diesel and gas engines alike. V6 and V8 engines are usually gas engines unless mentioned otherwise but this doesn't mean the diesel engines aren't v-shaped.

The most common engine sizes in pickups are the V6 the V8 - gas or diesel. Unless you're looking for a small truck or SUV, V8 is actually the current standard.

Read more: What does a V8 engine mean for me as a pickup owner

3. Engine Volume

Moving forward with the list of engine specs, we've reached the more important engine volume parameter. It's more important because now we're talking about decision making.

Diesel vs. gas on its own doesn't matter that much. The number of cylinders and their configuration is pretty standard. And in the end, it all totals in the engine volume.

The engine volume is that metric that's expressed in a number of liters. That number is the total volume of all cylinders. In a sedan with four cylinders, it's going to be 4 times some relatively small number, so usually in the 1.4-2.something range in total.

In a V8 engine, we're talking 8 times the volume of a larger cylinder. A V8 engine usually has a volume of 5.3-6.7 liters. The larger the number, the larger each cylinder is.

What does this mean for you as a potential truck owner? The larger the number, the more powerful the engine. That power is generated by burning more fuel (gas or diesel) with every cycle, so that's not good news if you're looking for better fuel economy.

4. The Turbocharger

A turbocharger is a clever part of an engine - diesel or gas - that increases its efficiency.

Engines work by moving each cylinder through a four-strokes cycle -

  1. The intake stroke - bringing in air or a mixture of air and gas.
  2. The compression stroke - squeezing the mixture to heat it up to the point of igniting it.
  3. The power stroke - Using the force of the explosion to move the crankshaft (and eventually the wheels).
  4. The exhaust stroke - clearing the cylinder by sending the excess gases through the exhaust pipe.

The actual phase where energy from fuel gets converted into movement energy is the power stroke. With a turbocharger, the engine utilizes the additional energy of the excess post-explosion gases in the exhaust stroke. In essence, creating more movement energy from the same amount of fuel used to create the explosion.

This is a good animation that shows how a turbocharger works.

Turbochargers come with their own set of issues, of course. These systems require a high level of precision to work properly. And going back to our topic of truck engines, well, some have it and some don't. With pickup trucks, you'll usually find turbochargers in diesel engines.

Take the Chevrolet Silverado 2500 for example. The standard 2020 model comes with a 6.6-litergasoline V8 engine. That's a powerful engine, for sure, but you can get an even more powerful Silverado 2500 if you opt for one with a Duramax® 6.6L Turbo-Diesel V8 engine.

And yes, it's not just the turbocharger. It's also the higher engine volume and the fact this is a diesel engine with more torque. But also the turbocharger.

Which brings us to the next item.

5. Torque

Torque relates to how your engine transfers all of that power to the crankshaft. It's the amount of leverage the vehicle uses to amplify the power generated by the engine.

The higher the torque, the stronger the engine. The torque comes into play especially when the vehicle is accelerating and working against other physical forces: The weight of the vehicle dragging it down, or gravity (if you're driving uphill).

Pickup trucks excel where it comes to torque because they're built with towing and hauling in mind.

6. Horsepower

So far we've talked about the basic numbers of truck engine size: type of engine, number of cylinders, total engine volume, turbocharger, and torque.

These all boil down to the one really important number: Horsepower. In the end, when you're looking into truck engine sizes, that's the number you really need to understand.

Horsepower - what does it actually mean?

Horsepower is a unit that measures power. As the name suggests, the unit was coined back in the 18th century when the first engines came into being and actual draft horses were the ones towing and hauling loads.

Today horsepower is defined by an engine's equivalent of output in watts - not actual horses. There are various specific measurements to horsepower but the bottom line when it comes to vehicles is that horsepower allows you to compare the strength of engines.

Horsepower specs are usually mentioned along with the RPM they were measured at. RPM stands for revolutions per minute, relating to the number of times the engine rotates the crankshaft in one minute. The more you push the gas pedal, the more fuel goes into the engine and the faster it goes. More revolutions per minute ultimately mean more power goes to your wheels.

All that horsepower can be used by the vehicle for all kinds of needs. First and foremost, it produces acceleration. When towing or hauling weights, that power will go into pulling the extra weight without slowing the vehicle down. And if you're driving uphill, all of that horsepower will kick in to keep your vehicle fighting against gravity.

Horsepower & Torque

Some people ask about horsepower vs. torque, but it's not actually a case of one or the other. Torque contributes toward the overall horsepower of the engine. To get a bit technical - horsepower equals torque multiplied by rpm.

Torque matters the most when the engine is working at low RPM. Essentially, as you're beginning to press the gas pedal, without switching to a higher gear, the torque is what gives the vehicle that initial massive push.

As you continue feeding fuel into the engine, the rounds per minute increase and torque becomes less significant - as long as you're still in the same gear. At some point you switch to a higher gear (or your automatic gear does that for you) and torque comes into play once again until the engine picks up force and gets to a higher RPM again.

What does that mean to you as a driver?

Assuming you have an automatic gear, the higher the torque, the less "strain" you'll notice on your engine as the vehicle kicks into the next gear. Which means the vehicle will accelerate faster, even when towing or hauling.

Once you've reached your target speed and are no longer accelerating, things go quieter and the engine doesn't need as much torque to just maintain speed on a level road.

Matching your Pickup Truck to your Needs

So, when you're looking at truck engine sizes, how to tell which one you need? Should you go for a V6 or a V8? A 5.3-liter or a 6.7-liter?

It all depends on your needs. The bottom line is you really need to look at the overall horsepower produced by the engine. Keep an eye on torque, but really, in a truck -  as long as you make sure you have enough horsepower under the hood - the manufacturer has already taken care of torque.

What you're looking for is a truck that will be powerful enough to tow your RV, and then some more.

Why some more? Safety issues. A strong engine is crucial when it comes to taking over a vehicle on the road or even braking. If you're going to be towing an RV and traveling, you'll be going uphill sometimes. You don't want to discover that your truck is having trouble pulling the weight right when you're driving along that beautiful mountain pass.

Remember, your towing capabilities are not just about engine size. The truck needs to have the right towing package, hinges, hitches and gears. These all come into play when you need to figure out how much the truck can actually pull safely (don't worry, the manufacturer provides all of these specs).

Having said that, truck engine size is definitely something to take into consideration. A powerful engine that's well within its towing range can create an entirely different driving and towing experience. This is where you need to invest. Don't try to save money when it comes to horsepower. If you can't afford a heavy-duty truck, then maybe you should think about getting a smaller rig to tow.

Additional Reading

Still looking into buying a pickup truck? There's much to learn, for sure. You should head over to the Buying a Pickup hub page to view all of our guides on the topic in one place. Or just click on these articles to learn more on related topics -

7 types of pickup trucks you should know

Types of truck cabs and which one to choose?

What does Payload Capacity actually mean in a Pickup Truck?

Buying a Used Truck? 5 Essential Things You Must Consider

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