What Is Heat Soak?
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Chris studied information systems and marketing at Drexel University and writes about a wide range of topics ranging from car buying tips to troubleshooting common mechanical issues.
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Heat soak is a common problem that can occur in cars, especially those with high-performance engines. Heat soak occurs when the engine or some part of it gets too hot, causing a decrease in performance and potentially damaging the engine.
The engine produces heat during combustion, and if it is not properly dissipated, it can cause a range of issues, from reduced horsepower to engine failure.
Let’s explore what heat soak is in a car, including the common causes and symptoms of heat soak, as well as how to prevent and fix it.
So, come with me as we learn more about how to deal with the issue of heat soak in your car and keep your engine running smoothly.
Table of Contents
What Is Heat Soak?
Heat soak pertains to excessive engine temperature, where the intense heat generated by combustion engines must be dissipated effectively to prevent detrimental consequences.
This thermal energy permeates the metallic and fluid components, saturating them with heat.
However, as the temperature reaches critical levels, the ability to absorb additional heat diminishes, impeding the engine's capacity to dissipate excess heat efficiently.
This phenomenon is commonly observed in demanding driving scenarios such as race tracks, canyon runs, high altitudes, and towing heavy loads, where the engine operates vigorously for extended durations.
It is particularly prevalent in forced induction engines, specifically turbocharged engines, where turbo heat soak emerges as a significant concern.
The primary manifestation of heat soak manifests in the form of elevated intake air temperatures (IAT). As the air becomes hotter, it becomes thinner, resulting in reduced oxygen content and a loss of power.
Moreover, heightened IAT makes the engine susceptible to pre-detonation, posing a risk of engine damage.
Consequently, the engine's computer may retard timing, further exacerbating the loss of power. Heat soak thus triggers a vicious cycle with detrimental implications for engine performance and health.
Symptoms of Heat Soak
Indications of heat soak are often manifested through these various symptoms:
1. Power Loss
The escalation of Intake Air Temperatures (IAT) due to heat soak leads to reduced air density, resulting in diminished engine power.
Additionally, the increased IAT may cause the engine's computer to retard timing, further exacerbating the power loss and adversely impacting performance.
2. Poor Performance
Severe heat soak can impair engine performance, resulting in suboptimal operation and reduced overall efficiency.
3. High IATs
Elevated IATs, resulting from heat soak, can be detected through temperature gauges for coolant and oil.
Knowing the optimal temperature ranges for your specific engine is essential, as different engines have varying operating temperature requirements.
4. Coolant/Oil Overheating
Heat soak can also cause the coolant and oil temperatures to rise beyond normal operating levels, potentially leading to overheating and detrimental effects on engine performance and longevity.
5. Struggling To Cool Back Down
Heat soak may cause prolonged heat retention in the engine components, resulting in a delayed cooldown period.
This struggle to disperse excess heat can indicate heat soak, as fluids and metals may take an extended duration to dissipate the accumulated heat once overwhelmed.
Vigilantly monitoring these symptoms can help identify and address heat soak, significantly impacting engine performance and longevity.
Turbo Heat Soak
Heat soak is a prevalent concern among turbocharged engines, commonly observed in many factory cars, although less frequent in completely stock vehicles.
However, certain cars and engines may exhibit varying susceptibility to this issue. The crux of the problem with heat soak in turbo engines lies in their inherent tunability and modifiability.
A simple tune and basic bolt-on modifications can elevate the performance of most modern turbo engines to new heights.
Similarly, forced induction engines such as superchargers are also prone to heat soak. Air compression during the induction process raises its temperature, but turbocharged engines further compound this issue as they rely on scorching exhaust gases.
Consequently, factory intercoolers can quickly become overwhelmed by the intensified boost and heat generated.
While upgrading intercoolers can be a viable solution to mitigate heat soak, more is needed for track cars and other extreme applications.
Additional cooling modifications, such as oil coolers, radiators, and other advanced cooling systems, may be necessary to manage the excessive heat generated during intense performance scenarios effectively.
How To Keep Your Engine Cool
The following are several effective ways to keep your engine cool and make your ride more pleasant and comfortable:
1. More Air Flow
The efficiency of heat dissipation in a radiator or heat exchanger is directly proportional to the amount of air that can be effectively moved across its surface.
While a mechanical fan with a thermostatic clutch and a well-sealed shroud is highly effective, electric fans may be necessary for specific situations, such as engine swaps, additional equipment installations, or changes in engine compartment layout.
In addition to their adaptability, electric fans also offer the advantage of reduced indiscriminate parasitic drag.
Unlike constant mechanical drag on the engine, electric fans impose an intermittent drag on the alternator and electrical system, which can be advantageous in specific scenarios.
High-performance electric fans can rival the performance of top-notch mechanical setups while also reducing weight and improving engine accessibility, making them a viable option for high-performance applications.
2. An Efficient Radiator
It's widely acknowledged that a high-performance engine in a hot rod requires an efficient radiator to keep its operating temperature well below the critical 200-degree threshold, even under demanding throttle conditions.
However, what's often overlooked is that copper-brass alloys, despite being heavier, actually exhibit superior heat dissipation compared to aluminum.
The catch is that copper-brass radiators typically have thinner tubes and employ dissimilar metals in their construction, which can lead to various issues over time.
Conversely, a meticulously engineered aluminum radiator can achieve parity with, in certain instances, even exceed the performance of a copper-brass heat exchanger while concurrently exhibiting a substantial weight reduction of 30 to 40 percent.
This significant weight reduction can be particularly advantageous for muscle cars with a performance-oriented focus.
Therefore, opting for a well-designed aluminum radiator can be prudent for those seeking optimal heat management in their high-performance hot rod engines.
3. Hose Wraps
Hose wraps serve a dual purpose, protecting both the hoses and their contents from the harmful effects of heat and safeguarding individuals from the scorching temperatures emanating from within.
We have employed such products in the past, subjecting them to rigorous testing, including prolonged exposure to direct flames from a butane lighter, in a quasi-torturous manner.
This category of materials exhibits exceptional resilience, withstanding a gamut of environmental hazards, barring only the most extreme conditions akin to nuclear fission.
Their efficacy is particularly pronounced in shielding fluid lines and electrical connections from the detrimental effects of excessive exhaust heat.
4. Cooler Oil
Oil in a mechanical system serves a dual purpose, serving as both a lubricant and a heat sink.
It is crucial to note that even the finest oils possess an optimal operating temperature range wherein their efficacy is maximized.
Surpassing this range poses a risk of compromising the protective film and precipitating a loss of overall protection.
On the other hand, employing more fantastic oil can yield many benefits, including extended change intervals, heightened durability of the lubricated systems, and reduced thermal stress on all engine components and compartments.
5. Coatings
Applying a specialized coating to the headers or manifolds represents a practical approach to confining heat within the pipes, preventing its external radiation.
These coatings reduce the steel's conductivity to heat, thereby minimizing heat transfer.
Moreover, these coatings offer the advantage of serving as a durable barrier against corrosion, safeguarding the headers or manifolds from deterioration.
6. Exhaust Wraps
While the engine block can generate significant heat, the exhaust system is undoubtedly the primary source of radiant heat in any vehicle's engine bay.
The reasons are apparent with exhaust gas temperatures soaring into the several hundred-degree ranges during throttle operation (reaching up to 1,500 degrees at the hot side of a turbo housing).
While it's not possible to eliminate this heat, we can take measures to confine it within the exhaust system and direct it away from other critical components.
One highly effective method is to insulate the hottest areas, such as the headers or exhaust manifolds, to minimize heat transfer to surrounding systems.
