Heat Soak: Engine & Turbo Heat Soak

Engine Heat Soak

In the automotive industry, “heat soak” refers to a broad concept. To put it simply, it means that a part of the engine is running hot enough to overwhelm the rest of the system. However, engine heat soak is complicated. It’s also a bit perplexing due to the fact that different people define it in different ways.

Fortunately, there’s no need to fret. We’ll explain what heat soak is in this article. We’ll also take a look at the symptoms and ramifications of heat soaking in engines.

What Is Heat Soak?

Heat soak, in the simplest terms, is when an engine component – or the engine as a whole – becomes excessively hot. The heat generated by combustion engines has to be dissipated somehow. It penetrates metals and liquids with ease. When it gets too hot, heat absorption decreases, and the engine loses its ability to effectively remove heat.

This is a common occurrence on race tracks, canyon runs, in high altitudes, and when towing large objects, among other places. When the engine is working hard for an extended period of time, it’s in this situation.

What Is Heat Soak

It’s particularly common on engines with forced induction, such as turbochargers. To cover all the bases, we’ll come back to turbo heat soak in the final section of this article.

Intake air temperatures are the primary source of heat soak (IAT). Because hotter air is thinner and contains less oxygen, it causes a reduction in power.

Pre-detonation is also a possibility with this engine, increasing the likelihood of a catastrophic failure. As a result, the computer will lose even more power as it tries to keep up with the timing. Heat soak is a slow-moving cycle that can harm an engine’s health and efficiency.

Why Is Heat Soak Bad?

We’ve only scratched the surface of heat soak here, but it’s a complex topic. As previously mentioned, many people mistakenly believe they are IATs. If a heat soak begins with one part of an engine, it can become a never-ending cycle.

A turbocharger, as an illustration, begins heat soaking. As a result, the intercooler is overloaded, which raises IATs. More heat is generated internally when the intake temperature is raised. Heat soak begins for the oil and coolant.

Metals expand with heat, losing viscosity, increasing friction, and tightening clearances. The turbo(s) are being cooled and lubricated, which means even more heat is being absorbed.

As long as the engine has enough time to cool down, engine heat soak usually isn’t a big deal. However, allowing the engine to soak in excessive heat for an extended period of time puts the engine under a lot of stress and wear. Any time there is a heat soak issue, it’s important to look into making the necessary upgrades.

Symptoms of Engine Heat Soak

Symptoms of Engine Heat Soak

A few symptoms that point to heat soak include:

  • Power loss
  • Poor performance
  • High IAT’s
  • Coolant/Oil Overheating
  • Struggling to cool back down

Heat soaks cause power loss primarily as a result of increasing IATs. Because hot air is less dense, the computer’s timing is slowed. Power loss and poor performance will be obvious if the IAT is overheated.

Make sure to pay attention to your oil and/or coolant temperature gauges. Because different engines operate best at varying temperatures, you should know what those are for yours.

After a few quick WOT runs, your engine will likely be hot to the touch. It’s possible, but not guaranteed, that you’re experiencing heat soak. As fluids and metals are overwhelmed by heat, they can take a long time to dissipate it, which is why the engine struggles to cool down.

Turbo Heat Soaking

Many factory cars suffer from heat soak when equipped with turbocharged engines. Stock cars are less likely to have it. Certain automobiles and engines, on the other hand, may be more or less susceptible.

However, the real problem with turbocharged engines soaking up heat is that they’re so simple to tune and modify. Most modern turbo engines can be improved with a simple tune and a few bolt-on upgrades.

Forced induction engines, such as superchargers, are more prone to heat soak. Compressing air generates heat. Turbos, on the other hand, use extremely hot exhaust gases to exacerbate the problem. Increases in boost and heat quickly overwhelm factory intercoolers.

Minimizing heat soak with intercooler upgrades is a great way to save money on track cars and other high-performance vehicles. Some additional cooling modifications will be required, such as oil chillers or radiators.

FMIC vs Air-to-Water Intercoolers

Okay, the final section will hopefully give you a better understanding of what heat soak is. When it comes to charge air cooling, FMICs (front mount intercoolers) are a popular choice. Air-to-air intercoolers are the technical term for them. FMICs are widely used by racing teams and automakers. Factory turbo engines, on the other hand, are increasingly using air-to-water intercoolers.

There are numerous benefits to using an air-to-water intercooler. The heat-carrying capacity of a water/coolant mixture is greater than that of pure air. As a result, heat soak is less of a concern for an air-to-water intercooler.

However, heat soaking can still occur, and when it does, it’s far worse than with an air-to-air FMIC. They are still susceptible. This is due to the fact that the water will take a lot longer to cool down after being exposed to high heat levels. Water takes longer to cool than air.

As a result, FMICs remain a popular choice in motorsport. There are numerous factors that go into engine and turbo heat soak, as illustrated by this simple example: Heat soak isn’t just about how hot something is; it’s also about how quickly something cools after it’s been exposed to heat.

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