Diesel outboards are coming back into style due to their increased torque. Outboard motors are becoming more popular on medium to large-sized boats, and many boat owners are choosing diesel outboards for their added power.
Do they really carry an increased torque though? Yes, they do – and that’s why they’re so popular on today’s waterways. Simply put diesel outboards have more torque because they’re able to burn fuel more efficiently.
This is due to the fact that diesel engines use compression ignition, which means that the air inside the cylinders is compressed first and then injected with fuel. This allows for a more complete combustion process, resulting in increased power and torque.
Both gas-powered and diesel outboards are internal combustion engines, but the increased efficiency of diesel outboards gives them an edge when it comes to torque.
An internal combustion engine is a type of engine where fuel and air are mixed in the cylinders and then lit. This makes the piston move, which makes the boat go. How well the fuel burns in the cylinders determines how much power and torque the engine will have. Let us now dive in a little deeper and see how compression ignition affects an engine’s torque.
What Exactly Is Torque?
Well, we won’t define Newtonian physics here but in short, torque is a force that causes an object to rotate. The amount of torque an engine produces is what determines how much power it can output.
Mathematically speaking, torque is equal to the force applied to an object multiplied by the distance from the fulcrum or pivot point. This means that if you have a powerful force but it’s far from the fulcrum, you won’t get much torque and vice versa.
Torque is important for outboards because it determines how much power the engine can produce. Commercial yachts and boats need all the torque they can get to move through the water quickly, so diesel outboards are becoming increasingly popular.
Carrying huge loads or towing a large vessel requires a lot of torque, and that’s something diesel outboards excel at. For recreational boating also, torque is still an important factor. If you want to waterski or wakeboard behind your boat, you’ll need enough torque to get the job done.
Why do Diesel Outboards have More Torque?
There is a number of factors that affect an engine’s torque but the most important one is how complete the combustion of fuel is. The more complete the combustion, the more powerful the engine will be. Let us now look into the factors driving the increased torque in diesel outboards.
Type of Ignition
As we stated before, diesel outboards use compression ignition while gas-powered outboards use spark ignition. In a gas engine, the air-fuel mixture is first drawn into the cylinders where it’s compressed. Then a spark plug ignites the mixture and the piston is forced downward.
In a diesel outboard, on the other hand, the air is compressed first. Then fuel is injected into the cylinder where it combusts spontaneously due to the high temperature and pressure. This means that there’s no need for a spark plug which makes diesel engines more resistant to fouling.
The type of ignition also affects how complete the combustion is. In a gas engine, some of the fuel will be left unburned because the spark plug can only ignite a portion of the air-fuel mixture. In a diesel engine, on the other hand, the fuel is injected into the cylinders at just the right moment for it to combust completely.
This results in more complete combustion and therefore more torque. Diesel engines also tend to run a little cooler which also contributes to their increased efficiency.
The compression ratio is another important factor that affects torque. It’s a ratio of the volume of the cylinder when the piston is at the bottom of its stroke to the volume of the cylinder when the piston is at the top of its stroke.
In general, the higher the compression ratio, the more torque an engine will produce. This is because a higher compression ratio means that more air and fuel can be drawn into the cylinders. This results in more complete combustion and therefore more power.
Diesel outboards typically have higher compression ratios than gas-powered outboards. This is one of the reasons why they’re able to produce more torque.
The calorific value of a fuel is a measure of how much energy it contains. The higher the calorific value, the more energy the fuel can release when it burns. This results in more power and torque.
Diesel has a higher calorific value than petrol which means that it can produce more power and torque. This is one of the reasons why diesel engines are often used in heavy-duty applications such as trucks and buses.
Speed of Cumbustion
The speed of combustion is another important factor that affects torque. The faster the fuel burns, the more power and torque the engine will produce.
Diesel outboards have a higher speed of combustion than gas-powered outboards. This is because diesel ignites spontaneously due to the high temperature and pressure in the cylinders. Gasoline, on the other hand, needs a spark plug to ignite the air-fuel mixture.
The speed of combustion also affects how complete the combustion is. In a gas engine, some of the fuel will be left unburned because the spark plug can only ignite a portion of the air-fuel mixture. In a diesel engine, on the other hand, the fuel is injected into the cylinders at just the right moment for it to combust completely.
The stroke length is the distance that the piston moves in one complete cycle. In general, the longer the stroke, the more torque an engine will produce. This is because a longer stroke means that more air and fuel can be drawn into the cylinders.
Diesel outboards typically have longer strokes than gas-powered outboards. This is one of the reasons why they’re able to produce more torque.
These outboards generally are bigger and heavier than their gasoline counterparts, which is why they’re not as popular for recreational boating. But for those who need the extra power and torque, diesel outboards are the way to go.
So Why Gas Outboards Are Still Popular?
Even though diesel outboards have a number of advantages over gas-powered outboards, gas-powered outboards are still more popular. This is because they’re typically cheaper and easier to maintain.
Diesel outboards also tend to be heavier and louder than gas-powered outboards. This can make them less suitable for smaller boats.
Diesel outboards have come a long way in recent years and they’re now more popular than ever. New diesel outboard manufacturers are making commercially viable products that are available to the general public.
The commercial boating industry is keeping a close eye on the developments in the diesel outboard market. Many believe that diesel outboards will eventually replace gas-powered outboards altogether.
Only time will tell if this prediction comes true but one thing is for sure, diesel outboards are here to stay.
Diesel-powered outboards have more torque than gasoline-powered outboards for several reasons. One is that diesel fuel has a higher energy density than gasoline, meaning that there is more potential energy in a given volume of diesel fuel. This means that more complete combustion can occur, resulting in more power and torque. With recent development in diesel-powered outboards, they have become more popular than ever before. New manufacturers are making commercially viable products that are available to the general public and the commercial boating industry is taking notice. There is a potential that diesel outboards could replace gasoline-powered outboards altogether in the future.