The Impact of Fuel Temperature on Engine Performance

In this episode of Engine Masters, Freiburger, Dulcich, and Brule embark on a quest to unravel the mysteries surrounding fuel temperature and its impact on engine performance.

This trio of automotive enthusiasts sought to answer three crucial questions: Why does colder fuel produce more power? How can one consistently maintain lower fuel temperatures, and what real-world difference does it make?

Cooling Your Way to More Power

Their exploration into the significance of fuel temperature started with a prior episode that delved into the effects of coolant temperature on engine power. During this episode, they even experimented with placing ice cubes on the intake manifold. Surprisingly, they discovered that cooler gasoline, not the icing of the intake runners, was responsible for the power improvement. This revelation prompted a follow-up episode, complete with an infrared camera and other tools to delve deeper into the effects of hot gasoline on engine performance.

One significant issue discussed during their experiments was vapor lock, an age-old problem in which fuel in the system boils, leading to the release of gases that mechanical fuel pumps struggle to handle. This issue not only immobilizes the vehicle but also poses challenges for engines under boost. Hence, the need for cooler gasoline is evident.

To find a solution, the team decided to investigate methods for cooling gasoline under the car’s hood and measure their effectiveness. The primary goal was to replicate real-world fuel system conditions as closely as possible.

First, they use a nitrous bottle heater filled with water and a heating element to heat the water simulating under-the-hood conditions. A 10-foot fuel line ran through this water, allowing them to measure the temperature of the fuel in the line.

They outlined a couple of approaches to cool the fuel:

1. Employing a transmission cooler with an integral electric fan, which had the potential to cool the fuel efficiently without requiring ice changes.
2. Utilizing a traditional fuel cooler with coils, except this time, they filled it with ice to cool the fuel as it passed through.

Additionally, the team planned an impractical but intriguing experiment involving a CO2 bottle to freeze the carburetor bowls and run an engine pull.

Their tests commenced with hot fuel blocked off, followed by the transmission cooler, the ice-filled cooler, and finally, the CO2 experiment.

The results of their tests were astonishing. The transmission cooler, equipped with an electric fan, managed to reduce fuel temperature by a substantial 45 degrees, significantly enhancing performance without any downsides. Notably, this solution was not just suitable for drag racing but also held potential benefits for road racing, making it a versatile and practical choice.

As for the CO2 experiment, it resulted in a 10-degree temperature reduction in the fuel, though the practicality of carrying a CO2 bottle in a typical car for such a small gain remains questionable. Nonetheless, the team noted that under more extreme conditions in a car, the temperature difference could be more substantial.

In conclusion, their findings highlighted two essential takeaways. First, the simplicity of using a switch and an electric fan to cool fuel can yield remarkable results, and it’s a practical solution for enhancing engine performance. Second, the experiments demonstrated that colder fuel can indeed lead to power gains, though the magnitude of these gains may vary based on the initial fuel temperature.

The team’s exploration into fuel temperature and its impact on engine performance unveiled some intriguing insights, ultimately providing car enthusiasts with potential solutions to optimize their engine’s power output.