This is a photo of the (injection) fuel rail of Skoda Felicia.

 

https://www.ekodiely.sk/photos/1/1012695/rijroe49tm.jpg

 

Since the years as a student have passed long time ago, i wonder: what is the effect of engine bay's temperature on fuel flow?

The gasoline in low or higher temperatures flows or evaporates faster?

 

Here in Greece we don't have heavy winters but we have quite hot summers, what effect does the rising temperature have on the fuel flow?

There is a pressure regulator, yes, but if with insulation we lower the temperature a little bit in this cylindrical tube, does this have anything to do with the easy flow of fuel to the injectors?

 

 

There would be a (even the tiniest) benefit by heat insulating that tube from A to B?

or i must leave it as is because that tube must let cool normally?

There will be no evaporation in the pressurised fuel injector lines.

11 hours ago, J.R. said:

There will be no evaporation

 

I used a wrong word, i ment it's better for the fuel to be in higher temperature entering the combustion chamber or not?

By insulating that tube the inside temperature will be one click lower, that's good for the fuel flow or does not matter at all?

Edited 25 August, 20241 yr by D.FYLAKTOS

As the temperature rise the volume of the fuel does not rise a bit?

In a hot summer day the temperature of the engine bay will rise more so that will affect the flow of the fuel inside the tube or not?

2 hours ago, D.FYLAKTOS said:

As the temperature rise the volume of the fuel does not rise a bit?

 

Not in a pressurised system, the pressure will increase according to Boyles law.

 

The flow of fuel will be a function of the system pressure and the injector orifice diameter, the fuel rail will be sized to not restrict the flow to the injectors.

 

Dont make the mistake of thinking that 40°c is twice as hot as 20°c, the gas laws and thermodynamics use absolute temperature measured in degrees Kelvin, 40°c (313°K) is less than 7° hotter than 20°c (293°K)

 

If you really want to continue this you should be looking at the viscosity of petrol vs temperature, you will find that the injectors will flow two tenths of three sixteenths of **** all extra fuel making the mixture minutely richer, at which point the ECU responding to the change in Lambda sensor reading will command less injector duration or rail pressure to lean the engine out back to Lambda 1.0.

 

In short you will be pi55ing into the wind!

Edited 25 August, 20241 yr by J.R.

Thank you.

I thought that with less (engine bay) temperature on the fuel rail the gasoline will be injected one click better and especially in a journey at summer this will affect positive the performance.

By the way, article this

https://www.sciencedirect.com/science/article/pii/S2214157X22005056

is ''too much'' for me.

 

On the other hand this

https://www.quora.com/Do-car-engine-temperatures-affect-how-the-fuel-injectors-work

 

Do car engine temperatures affect how the fuel injectors work?

 

Yes, car engine temperatures can significantly affect how fuel injectors work. Here are several ways in which engine temperature impacts fuel injector performance:

-Fuel Atomization: Fuel injectors spray fuel into the combustion chamber, and the temperature of the engine can influence how well the fuel atomizes. At optimal temperatures, fuel atomization is efficient, leading to better combustion. If the engine is too cold, the fuel may not atomize properly, resulting in incomplete combustion and increased emissions.

-Fuel Viscosity: The temperature of the fuel itself can change its viscosity. Colder temperatures can make the fuel thicker, which can affect how easily it flows through the injectors. Thicker fuel can lead to poor injector performance and uneven fuel delivery.

-Injector Calibration: Fuel injectors are often calibrated based on specific temperature ranges. If the engine operates outside of these ranges, it can affect the injector's spray pattern, duration, and overall performance. This can lead to issues like stalling, rough idling, or poor acceleration.

-Engine Control Unit (ECU) Adjustments: Modern engines are equipped with ECUs that monitor various parameters, including engine temperature. The ECU adjusts the fuel injection timing and quantity based on the engine's temperature to optimize performance and efficiency. If the engine is running too hot or too cold, the ECU may not be able to adjust the fuel delivery effectively.

-Heat Soak: After the engine is turned off, residual heat can cause fuel in the injectors and lines to vaporize, leading to a condition called "heat soak." This can cause difficulties in starting the engine after it has been turned off for a short period.

In summary, maintaining optimal engine temperatures is crucial for ensuring that fuel injectors operate efficiently and effectively, promoting better engine performance, fuel efficiency, and reduced emissions.

super cool gas has benefits

Your engine has closed loop Lambda control and will run at the Stochiometric ratio despite your fiddling.

 

If you want to be cooling anything it is the induction air. Cooler air is denser, more oxygen = more fuel injected to maintain Lambda 1.0 = more power for a given throttle opening.

 

I doubt that it would be measurable though, the manufacturers will have done their utmost even back then.

7 minutes ago, J.R. said:

Your engine has closed loop Lambda control and will run at the Stochiometric ratio despite your fiddling.

narrow band m8 only at cruising, super cold gas as it changes phase it sucks heat from the surrounding environment thus cooling the charge and in turn the cylinder

So yes I was right once again the colder the fuel (on a warm engine) the more power you get.
Every 5C or so you seem to be getting around 1hp worth

Quote

At optimal temperatures, fuel atomization is efficient, leading to better combustion. If the engine is too cold, the fuel may not atomize properly, resulting in incomplete combustion and increased emissions.

 

In Cold start at winter the heat insulation of the tube won't make things a bit worse?

It will take more time to get heated so in short distances things will be worst than without heat shield, am i right?

 

12 minutes ago, J.R. said:

If you want to be cooling anything it is the induction air.

 

I have brought from grille a second tube inside the air filter box and i have worked inside of it.

I am happy with the results.

Just now, D.FYLAKTOS said:

In Cold start at winter the heat insulation of the tube won't make things a bit worse?

no, it will be at ambient, heck, there is going to be a point before the retail heat soaks that the performance is going to peak. 

fully warmed engine and as cold as it gets gas

If I was to insulate though it would be the rubber line to protect them although the COHLINE 2192 seems far superior than ALFAGOMMA L671

1 minute ago, Thefeliciahacker said:

fully warmed engine and as cold as it gets gas

 

Yes but except heat-shielding the rail tube what else can we do about it?

12 minutes ago, Thefeliciahacker said:

 

 

In 8:32 of the video.

 

 

 

13 minutes ago, D.FYLAKTOS said:

 

Yes but except heat-shielding the rail tube what else can we do about it?

With the current routing nothing 

2 minutes ago, Thefeliciahacker said:

With the current routing nothing 

 

OK then.

When i find time i will put a heat shield on that tube and ''Case Closed". 🙁