--- What temp to heat Gas to? ---
 

I will be testing the "fuel heating" myth soon.

One thing I need to know is how much to heat the fuel to, what do you guys think will be a good, safe temp? I have heard anything from 150 to 300 degrees.


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Also If you have any ideas of how to heat (and possibly control) the fuel I will take into account any of these ideas and maybe use them.

What I am thinking is simply using the coolant, since it is always at 180 degrees.

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Sources

"The colder the fuel, the larger the fuel fragments. This is why MPG drops as the temperature gets colder. However, too much heat (about 270F) may damage fuel molecules and cause knock. The optimum fuel temperature is 200F. "
https://www.sigmaautomotive.com/perfo...fuelheater.php

"For gasoline the, Design Temperature would need to be about + 200 deg Centigrade" = 392 fahrenheit!!
https://freeenergynews.com/Directory/...ny_P_ODonnell/

"Henry "Smokey" yunick of NASCAR fame designed, built, and patented a Hot Air engine which heated the air/fuel charge to over 400 degrees F before igniting it using waste heat from the coolant and exhaust, and a modified turbocharger to act as a one way valve to keep expanding gas and air going towards the cylinders. He tested it in a pontiac fiero 2.5L "Iron Duke" 4 cyl engine and achived nearly 300 HP and 100 MPG. This car was actually featured in a number of automotive magazines back in the mid 1980's. "
https://cr4.globalspec.com/thread/144...emp-less-m-p-g


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I checked my thermostat and it appears to have a 195 degree thermostat btw.


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I would hate to hear that you had an engine fire so I think you should start with a comparison between 180 degrees F and "non heated". Even though the "non" heated will likely absorb some heat from the fuel rail. It seems like you might need to remove any grill block and do some highway testing to be sure the engine compartment is as breezy/cool as possible for the unheated.

Probably the best way to heat it would be to wrap a long piece of copper tubing around the top rad hose and then wrap it all with thick rags to keep the heat from coming out of the copper line.

Do you have a way to record the fuel temp from the driver's seat while you are driving? Maybe a indoor outdoor thermometer with a 10 foot cord and have the probe wrapped to a metal part of the fuel rail with plenty of aluminum foil and then put a rag over the foil.

The way I plan it is to use a Water to Air intercooler (used for intercooling on performance turbo cars)...

https://www.fuelly.com/attachments/fo...9906ca4226.jpg

But instead of passing the water through the little wholes and the air through the big holes (to put it in simple terms), I will pass fuel through the little holes and the radiator water through the top holes.

And yes, I made a little inline fuel temp sensor that I will mount on the fuel rail to monitor fuel temps from the inside of the car. I made it from a typical oil temperature gauge for performance cars.

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One thing to consider is that those air/water intercoolers are only around 70% efficient which means that my temps would only get to around 13o degrees (I have a 180 degree thermostat).

However, once heats starts building up I would think that it would transfer and hold in heat much better and hopefully get it up to 140-150 degrees. I could also wrap the fuel line with copper wire in the exhaust (just one turn) to pre heat the fuel going into the air/water intercooler; but I will only do this if the temps dont get hot enough i do not want to risk anything :D

some waste veggie cars have fuel filters that are also heaters to liquify the oil. i dont think they are very expensive and i know their easy to put in. plus their thermostatically controlled.

If they're only 70% efficient transmitting heat from air to water, I suspect they will be more efficient with two liquids.

It's gonna be a another of those "depends on your vehicle" things.

Some vehicles get a lot of heat into the fuel rail, particularly Vee engines with the rail snug between banks.

Then, the typical modus operandi for a multipoint fuel injection system is at low demand to spray fuel into a port with a closed valve, before the valve opens. The fuel then evaporates from the heat from the head. Low demand is typically up to 20% duty cycle on the injectors, and at highway cruise speeds, that's about as much as you'll use. Ergo, if 90% of your driving is steady state highway driving, then it's only the other 10% that extra fuel heat will help you with.

Don't forget that when you heat the fuel, the pressure in your gas tank will increase. I'm sure different tanks have different venting systems, but don't forget to consider it.

-BC

I imagine the fuel exiting that heater will be whatever the water going through it is at. MAYBE off by a degree or two depending on your fuel system. If it's return-free then I can almost guarantee you it'll be full temp by the time it leaves to the injectors.

If it is a return fuel system you will have a few things to contend with. Your fuel will be returning to the tank heated, this will cause an increase in vapor pressure not only while you are driving, but after you are stopped. This will lead to big fuel losses by evaporation unless you pressurize the tank. This can be a huge mistake depending on the construction of the tank itself. While it is running you will most likely want the tank venting into the intake but that might richen up the mixture a bit.

Additionally, your fuel pump uses the gasoline flowing through it to cool it so it will be running hotter as well.

It is certainly a valid point that the fuel returning to the gas tank will be heated... but the comment about pressurization--aren't pretty much all modern gas tanks pressurized anyway?

This could be concerning. I don't know what the operating specs of a fuel pump are, but if they are anything even remotely like the sump pump in my basement, you do NOT want to pump high-temp fluids with it. That sump pump gets hot pumping 50*F water... of course, it has a much higher flow rate, and has to move the liquid much farther.

I meant pressurizing beyond what the tank normally runs.

I can't find a chart anywhere but at 126 degrees in the Mojave desert on a motorcycle we had enough pressure in a portable gas tank to blow the lid off the thing. Before that, we'd noticed that the bottle looked like Kirby but every time we released the pressure it just got it right back a minute or so later, if that.