?nevermind

 

what would be the end goal?

 

The fuel in the lines would be the same temperature as what is in the gas tank. The only reason, that I can see, to insulate the lines is if you were having a vaporlock problem. Then you would insulate it near the heat source.

 

EFI won't vapor lock.
Fuel is an efficient cooling medium, so the lines are already going to be cooler than their environment.
The lines in the engine bay are plastic and rubber, so they don't conduct that much heat to begin with.

 

heat is added by the pump, so the length of tube gives it a chance to cool off.

 

Its only efficient when its evaporating, which its not doing in the lines.

 

So you are saying fuel is only an efficient at cooling when its evaporating?

 

Well, mine are cooler than ambient, so some thermodynamic action is at play.

 

old dragger: i remember reading somewhere if shopping for a used FD that a few have recalls that you should not overlook... and that one being the fuel line above the exhaust manifold getting too hot, making the car prone to overheat,detonate, and catch fire...

if thats the case with our car...i see it worthwhile to do so. but i don't think they'll make the same mistake again...do you?

now you make me wanna just double check the security of it...

but other than that, yeah, i think FD's used to have that problem if thats where you're getting the idea from. the fuel lines on the affected FD's are insulated off from the hot turbo exhaust manifold...

hope i was of any help, if my memory was correct.

 

I believe the major problem on the FD was the use of rubber lines that would eventually dry out and split spilling fuel.

 

The '8s lines are short, to the point and miles away from anything hot.
They got it right this time.
The rails are steel, which isn't my favorite, but I'll be addressing that with these aluminum return-style rails from KGParts soon:

 

MM, whats the thoughts on the aluminum fuel lines?

 

Are the OE lines aluminum or are you thinking of swapping?
I presumed that the OE lines are steel, but they are all under the car, so the airflow is pretty good.

 

I just realized I put lines instead of rails. What I was asking was basically why are you swapping to aluminum rails?

 

I thinksits called a heat ex.

 

Oh. Because I am going to a return style fuel system soon.

 

Yes, thats when its most efficient, when its being converted from its liquid form to a gaseous form. When its being sprayed into intake chambers, etc... Meth injection. All very good cooling because solvents have a very high vapor pressure.

Example: when I was working at the lab, we use ether for invert sugar testing.

So we had to evaporate it off. So the best way to do it quickly and safely (because its so volatile) is to put it in a wide beaker and blow compressed air on the surface of it to evaporate it. Long experiment short, the beaker freezes because ether has such a high vapor pressure (it will actually blow the lids off its containers if you just place your hands on the jar(adding slight heat)).

In a closed system like compressed to 50psi in fuel lines, the fuel could absorb some of the heat of its surroundings (less than water, 212 degrees), but it would gain or loose very quickly because its a lot less dense than water or other good heat conducting compounds.

Now here begins the debate of:

Heated fuel = good at vaporizing instantly upon ejection from fuel injector, but low quantity because of expansion properties of the liquid. = very good engine efficiency.

Cooled fuel = greater quantity able to be injected at the same pressure because of the slightly higher density of the liquid = more potential power with FI.

 

i believe caroll shelby did experiments with pre-heating fuel.

 

thanks for the replies guys--one reason I asked is --actually around the fuel rails is crowded. The secondary injectors are separate and dont fire all the time?--Right?--it has a separate fuel rail. Its a dead end. Does it heat soak? I know vapor lock is not something to worry about but heated fuel MAY could cause a short "lean" condition in a FI car?
Just wondering here?
oscd

 

A state change does absorb heat very well, but liquids in general are pretty good at it.

 

Quoted your smaller post, no need to qoute the larger one. Fuel might be more efficient after being vaporized, but it can be used with out vaporizing. A prime example is the Fuel-Oil Cooler on TF-33 Turbofan engines. The cooler uses the fuel to cool the engine oil, while absorbing its heat before it gets to the combustion champer, making it easier to ignite.. Granted, I don't know if this could be used in any shape or form be used on a car, but fuel can be used to cool..

 

Sounds like a very efficient system!!!

 

What about my other ?
oscd

 

Is that internet sarcasim coming from your keyboard Dan?

 

None, it does sound like it would work quite well to increase engine efficiency by both pressurizing the fuel and cooling the oil.

To make it work on a car the main drawbacks would be needing a fuel temp sensor, and beefing up the tank, lines, and fittings to be able to handle being in contact with an intentionally heated surface for long periods of time. Planes get rebuilt a lot, I'm not sure it would be that safe for a daily drive without increasing the cost by a few K.