Engine performance depends on a number of factors. When you’re driving in the cold, the air you intake will be cooler. On the surface, that would seem to improve an engine’s efficiency.
However, you’ve got to consider your engine’s fluids as well. Fluids tend to become more viscous whenever it’s cold outside. That would decrease efficiency.
Driving a short distance in the cold might be less efficient. But, if you’re driving longer, it could be more efficient in the cold.
Hot vs. Cold Weather Performance
All engines have a specific temperature where they’re the most efficient. This is its ideal operating temperature. Driving at that temperature allows the engine to perform at its peak.
Cold temperatures can make the air denser. As such, your pistons will have access to more oxygen. The more oxygen in your pistons, the more power your engine should generate.
However, other things don’t perform as well in the cold. For example, your oil will be much more vicious at temperatures below 20 degrees F.
Viscous oil takes more energy to pump throughout your engine, decreasing performance.
Depending on your engine’s specs, cold weather could be better for it. But, that’s not always the case. Certain engines will always perform better in the heat.
Are Car Engines More Efficient in Hot or Cold Weather?
According to Fueleconomy.gov, cold weather tends to decrease efficiency. That’s because your engine must work harder to pump fuel through its fuel lines.
Driving at 20 degrees F could decrease efficiency by up to 15% overall.
Cold weather affects a lot more than just your engine, too. Even your tire’s air pressure will decrease if it’s cold. Rolling on flatter tires takes more energy, impacting fuel economy.
Also, cold air is denser. You might get more oxygen in the pistons, but you’ve got to drive through denser air, too. The denser the air you’re driving through, the more energy it takes to drive.
All of these factors impact your fuel economy, negatively. As such, you’ll experience decreased efficiency in most cases.
Are Car Engines Faster in Cold Weather?
Your engine might not be as efficient in the cold. But, it could be a little faster!
That’s because the colder air delivers more oxygen through the engine’s intake.
Supercharged vehicles increase oxygen density in the intake as well. That’s how they’re able to accelerate so much faster than regular vehicles. But, they’re also less efficient compared to them.
Even turbocharged vehicles work by increasing the density of oxygen in your engine. Simply putting more oxygen into the air increases the power of combustion.
Because cold air is denser, you might notice an increase in your acceleration. You might be able to get up to speed a little quicker, too. The colder the air is, the denser it’s going to be. So, your engine should perform faster as it gets colder.
Do Engines Make More Power in the Cold?
There are a few factors that impact your engine’s horsepower when it comes to the weather. First, let’s describe how your engine’s horsepower is determined.
Engines create power through combustion inside of their pistons. Each time your pistons rotate, a fuel mixture injects into them. This mixture determines how much power each combustion can produce.
Not all of your fuel combusts during every rotation, though. There must be enough oxygen available for the fuel to combust thoroughly. Otherwise, some of it will be left behind as gunk. Anything left behind decreases overall performance.
Getting the ideal fuel mixture ratio can be difficult for an engine. However, driving in colder air should improve its ratio.
Because there’s more oxygen in the air, there should be more of it in the fuel mixture as well. That’s how your engine’s performance can increase in the cold.
Another factor you’ve got to consider would be engine timing. Pistons generate the most power whenever fuel combusts at their peak. Most engines don’t have perfect timing, though.
That’s why higher octane fuels can generate more horsepower. The higher your fuel’s octane, the less likely it is to combust early.
Fuel combustion is more difficult in the cold, too. So, you should notice an increase in your engine’s performance because of that.
Cold air prolongs the amount of time it takes for the fuel to combust. By making it take longer, it can improve your piston’s timing. As a result, each piston will generate a little more power.
Changing the temperature by 80 degrees could increase the air’s density by up to 11%. That means there will be 11% more oxygen in the colder air by volume.
The more oxygen there is in the air, the more power your engine should be able to generate.
Should You Warm Up Your Engine When It’s Cold Out?
A lot of people believe you’ve got to warm up an engine whenever it’s cold. However, that’s not actually the case anymore…
This common piece of advice is something from back when cars had carburetors. Modern cars don’t usually have them anymore, though.
Carburetors do need to warm up before they’ll work well. Modern cars use something called electronic fuel injection.
Most manufacturers switched to electronic fuel injection sometime during the 80s. Some of them continued using carburetors until the 90s, though. However, all modern cars have done away with them.
If you’re driving a modern car, you shouldn’t let it idle for longer than 30 seconds. It’ll warm up faster if it’s being driven.
The EPA studied how idling affects fuel economy and performance in cold weather. According to their results, there was no benefit to performance whenever idling.
In fact, idling for more than 30 seconds could actually decrease your fuel economy. Idling for 10 minutes could decrease it by up to 19% based on their findings, too.
How the Weather Affects Your Engine’s Performance
The biggest impact cold weather has on your car is because of the air’s density. Denser air delivers more oxygen to your vehicle’s pistons. This could improve your horsepower, but it might decrease efficiency.
Cold air can also make your engine’s oil more viscous. That tends to decrease performance overall.
Modern cars don’t need to idle for longer than 30 seconds. That’s because they’ve got electronic fuel injection systems. Vehicles with carburetors had to idle longer in the cold. That’s no longer the case, though.