If We Cool The Fuel Down Will We Get More Econ + Pwr

[jetpilot]

Hypothesis: If there was a system on ur vehicle to cool the temperature of the fuel down prior to reeaching the injectors would it give the vehicle;

i) more fuel economy?

ii) more performance?

iii) What are the disadvantages?

iv) has anyone tried it ?

I dont need a 100 ideas and ways to cool the fuel down I am after some raw facts of the concept.

What do u guys think?

[NewKleer]

i thought most studies on fuel atomization vs temperature show low fuel temps = not so good. perhaps this is the use of the fuel temp sender on 300zx and/or GTR's, in order to richen injector pulsewidth when the fuel is too cold

thus if low fuel temps arent good:

1) no

2) no

3) 1 and 2

4) unlikely due to 1 and 2

[blind_elk]

When the fuel is cooler, it is denser, so more fuel molecules in the same volume. Therefore the engine should run richer, which is not overly desirable for making power.

[Mr. Oizo]

When the fuel is cooler, it is denser, so more fuel molecules in the same volume. Therefore the engine should run richer, which is not overly desirable for making power.

But couldn't you increase timing or lean it out through the tune?

Also, to cool fuel down, ceramic coat the fuel rail, heat wrap the fuel lines?

[sh@un]

only beneficial when the engine is under extreme levels of thermal loading for extended periods, too keep pre-ignition under control.

Alan Horsley did this on the RX-7 endurance racers in the 90's (kept fuel in storage tanks in a cool room for chilling before use)

[bj_dove]

I remember hearing about one of the Porsches Jim Richards used in targa a few years back using the Air Con system to cool the fuel, in an interview he said they race with the A/C on to produce MORE power.

might be worth looking into.....

[RANDY]

lol! more power than what you lose by running the A/C compressor? =-o

In any case, I always thought a hotter fuel is easier to combust. I think the R33's have water lines running towards the plenum somewhere to heat the fuel up.. mainly for cold days. That's just what I read somewhere.

Hot motor + cold air = power.

[djr81]

Back in the day...

They used to cool the fuel when F1 was racing under the stupid fuel volume constraints in the mid eighties. It gave them a little extra capacity.

Basically as long as the fuel in the rail is sufficiently cool not to vaporise in your system you don't have a problem. The small difference in density for a change in temps of, say 10 degrees will not make your AFR change in any noticeable way. So it is a waste of time.

Keeping excess heat out of the system can come in handy, however. Note though, that there is a larger volume of fuel charging around the system (& returning to the tank) than goes to the motor. So don't worry overly about it.

Lastly, in the DR30 Skylines that Freddie Gibson campaigned they used to use the fuel to cool the ECU.

[mtopxsecret6]

I am running a fuel cooler on my car, and it does make a difference particularly if you have a highly worked engine. For australian conditions you dont need the coolant lines running through the inlet manifold, its australia, not japan.

[gts4diehard]

cold air is denser and holds more fuel, if fuel is atomising well then theres probably no need to cool the actual fuel. I don't think cooling the fuel is going to help unless you are noticing fuel problems due to heat.

Brings back memories of cars not starting/being hard to start on hot days because the fuel was vaporising in the carby before it went into the engine e.g. heat soak in engine over heating the fuel in fuel bowl in carby but I don't really think it applies to injected engines. For a start the electric fuel pump will supply the right pressure regardless whereas a mechanical fuel pump needs the engine to be turning to get the fuel pressure up, and the fuel is mostly sucked into the engine.

[mtopxsecret6]

ok, well it works for my setup.

[TurboX]

I do know back about 50 yearas they used to make a metal gasket that went on the head between the intake and exhaust (same Side back then) with some bars going ascross the air and exhaust flow to transfer heat into the already fueled airflow that gave 20% more mileage. Not dsure about power though, it was for economy.

[GreddyGo]

Your fuel will already be kept cool due the to valves in your fuel pump, when fuel is pressurised it in turn keeps cool. If your really keen you can take the fuel inlet off you injector rail and feel how cold it is, even if the car has been running for hours.

Cheers

Josh

[mtopxsecret6]

It would feel cold because of evaporation to atmosphere on your hands.

[mad082]

whenever you pressurise anything the temp raises. so when you depressurise something (like letting the air out of a tyre) it cools.

that is how a fridge works.

a fuel cooler is used in high performance engines because the fuel is running at higher pressures (so its hotter) and they don't want vapourisation.

Edited November 29, 2006 by mad082

[djr81]

whenever you pressurise anything the temp raises. so when you depressurise something (like letting the air out of a tyre) it cools.

that is how a fridge works.

a fuel cooler is used in high performance engines because the fuel is running at higher pressures (so its hotter) and they don't want vapourisation.

Well you learn something everyday. When I went to school it was the latent heat of vaporisation that allowed a closed cycle refrigeration system to function. Maybe my school was too old skool or something.

[GreddyGo]

Well what I said above was from straight out of a TAFE teacher's mouth when I was an apprentice mechanic.

So who do u believe? I don't know anymore!

Cheers

Josh

[NewKleer]

its simple, both are correct.

the refridgerant is continually compressed into a liquid (results in heat in the hot coils) and then expanded to a gas in the cold bit (latent heat of vaporisation helps add to the coldness as it "takes in" more heat from surrounds to change liquid to gas, hence reducing temp), or something along those lines

the latent heat of vapourisation explains why when water gets to 100C, it doesnt suddenly explode into a gas all at once (or change to a gas more quickly than it does) - it needs more heat input before it has enough energy to change states

but for something thats a liquid the entire time at different pressures, the difference in heat isnt all that great (ud need a reasonably high pressure fuel system for it to be an issue, nothing that production cars have)

Edited November 29, 2006 by NewKleer