Fuel Heater Question

[BArmstrong]

I am experimenting with a fuel heater and am looking for some thoughts. I have put it on and am getting cylinder misfire codes. Likely from the heater making it run lean. The heater is getting the fuel to the cooling system temp, apprx 200 degrees. The idea was to get the fuel to vaporize more easily and improve the efficiency of combustion. Any thoughts on what might be going on?

[Christ]

You could be vapor locking the injectors, which would cause a misfire. The fuel, generally, is already something like 90% atomized when it comes out of the injectors anyway, which is part of the reason fo a high-pressure fuel system. (Higher pressure atomizes the fuel better). The way to attempt what you want to do is actually to just heat the intake air, because as you're finding out, you can't vaporize the fuel completely unless you have injectors that can either handle vaporous fuel, or extreme pressures required to keep the fuel liquid at that temperature.

If you want to continue the experiment, try monitoring temps of the fuel and starting out at normal temp, then heating the fuel slowly until you start getting the misfire code again, then back off the heat a bit.

[greasemonkee]

I was cleaning some injectors with my homemade vacuum injector cleaner and carb cleaner not too long ago. I realized the gasoline present inside the intake manifold is probably boiling under normal operating temps, this was after I witnessed the carb cleaner exiting the injector went from a spray pattern to a mist once the vacuum exceeded 15 in/hg

[Christ]

Originally Posted by greasemonkee

I was cleaning some injectors with my homemade vacuum injector cleaner and carb cleaner not too long ago. I realized the gasoline present inside the intake manifold is probably boiling under normal operating temps, this was after I witnessed the carb cleaner exiting the injector went from a spray pattern to a mist once the vacuum exceeded 15 in/hg

It's a little different in an intake manifold... engines aren't really ever under vacuum, because there is always air going in. The "vacuum gauge" is just giving you an idea of how much pumping is going on, or what you would feel/see if air were not present in the manifold.

Under conditions of true vacuum, yes, the fuel would boil and vaporize instantly, and it may partially do that in the intake manifold, but because of the quantity of fuel and the inflow, it doesn't happen fully, which can be evidenced by burn pattern analysis, which shows that fuel actually pools around the crevice areas of the combustion chamber, such as the gap between the piston and the cylinder wall above the top compression ring.

[greasemonkee]

True vacuum? you mean continuous vacuum?

I would expect to see a cyclic vacuum taking place (under lower than ambient manifold pressures), similar to a sine wave; the gauge should be an average pressure reading, but then again the velocity of the air at the injector port itself makes it more complex.

[Christ]

Originally Posted by greasemonkee

True vacuum? you mean continuous vacuum?

I would expect to see a cyclic vacuum taking place (under lower than ambient manifold pressures), similar to a sine wave; the gauge should be an average pressure reading, but then again the velocity of the air at the injector port itself makes it more complex.

EDIT: This is "as I understand it". I welcome other input, suggestions, or data which suggests otherwise.

No, I mean true vacuum. The vacuum in the manifold is only readable because of the velocity of the intake flow, which is why the vacuum reading in your manifold actually could change depending on where you plumb the line, although most gauges won't register the change (which is going to be fractional, at best).

Vacuum can only truly occur in a sealed container which does not contain atmosphere, which means that since an intake manifold constantly has some amount of air in it, there is no actual vacuum, only a reduction in ambient pressure of the volume of air present.

If you checked the vacuum at each port of each cylinder, you would see the cyclic effect you're suggesting, but only for milliseconds per revolution, right before the air has a chance to react and begin moving into the cylinder.

I guess the point is that induction is not vacuum, by definition.

The flow of air through the manifold would prevent the pressure of the fuel from being reduced to the point where it boiled, except maybe for a few milliseconds until it actually got to the airstream, at which point it would instantly become liquid again.

Interesting to note -
The largest percentage of the noise from submarines in motion comes from steam, which is produced in bubbles which follow the trailing edges of the propeller. The bubbles "pop", which creates the noise signature that other submarines and radar/sonar systems recognize as a submarine.

The bubbles are a low-pressure zone in the wake of each prop blade. The pressure is low enough that water boils instantly in that area, then as it cools via the surrounding water and pressure change, it changes back to liquid and the bubble formed makes a pop noise.

[qwertydude]

Pure gasoline boils at a much lower temperature, as low as 100F. I'd keep it at about 150 tops especially if I was getting misfire codes due to vapor lock.

[greasemonkee]

Originally Posted by Christ

Vacuum can only truly occur in a sealed container which does not contain atmosphere, which means that since an intake manifold constantly has some amount of air in it, there is no actual vacuum, only a reduction in ambient pressure of the volume of air present.

How exactly are you defining "vacuum", by the technical definition - space absent of matter? The term seems to be tossed around loosely these days. A perfect vacuum isn't possible on earth, questionable even in deep space. Maybe I have been wrong for using the term "vacuum" for any absolute pressure less than one atmosphere.

[gone-ot]

...to "pull a vacuum" = to have an absolute pressure less than one atmosphere.

[Domman56]

I think there are alot of other things you can do to get better mileage

Try hypermiling. Driving style often makes up for more than 50% of the gains on here

Check that your car is tuned up Filters spark plugs oil change Etc.

And max ur tires up to full pressure for lower rolling resistance those all will likely help more than just a fuel heater will