Call me a crackpot but the fuel cooler (see related "fuel too hot" thread) i put in really works... I ran the car before the installation to see how hot everything gets. The conditions where at night when it was cool. The fuel lines (return as well as the feed line from the tank) themselves got pretty warm. Not so hot as to burn but enough to make them uncomfortable to the touch. The air cleaner as well as the manifold themselves where so damn hot that i cant touch or hold them for more then several seconds at a time. The manifold was probably around 210 or so. The tbi base itself was pretty hot as well. After the install, the fuel lines where nice and cool to the touch. The aircleaner and the manifold are still damn hot but the tbi base is nice and cool. The adapter plate below it was realativly cool as well, signifying that the air mixture there was significantly cooled by the chilled, evaporating fuel. Its like the stock airbox with the cold air intake without the fueling problems that i had when it got cold out. I was surprised at how well the air mixture cooled. I dont know how well it works at WOT but at part throttle driving its just like a cold air intake. All i did to do this was buy a 30 dollar 4 pass atf cooler and some fuel lines as well as fuel fittings and located the cooler out of harms way and ran the lines from the feed line to it.

Actually, I am a crackpot... but it still works...

 

I really think you got the placebo effect. I can tell you that the rate of heat transfer from the air to the fuel is so small that you would not feel anything. At WOT air is moving in and out very fast and the rate of conduction and convection doesn't happen that fast. Now if the fuel were cooled to sub zero temperatures than you may see some heat transfer but that type of cooling is not going to cool the fuel anything past ambient conditions. Not trying to discourage you from innovating but I am sceptical.

 

So, where did you mount the cooler?

Did you use the one from Jeg's?

What fittings were required?

Are you running elevated fuel pressures? If so, this may be a worthwhile mod for TBI users that are running at elevated pressures.

 

Actually elevated pressures would be worse and would decrease the amount of heat transfer because of its rapid displacment. Fuel in its liquid state will not compress so it will not get hot under pressure.

 

the ammount of heat transfer is the only thing that matters in my case. Since the fuel is continously circulating through the system the entire fuel supply will be cooled down to ambient temperature. Since my underhood temps are somewhere between blast furnace and the surface of the sun the fuel would get quite hot given enough time since it always goes through the engine compartment. This is a problem since i did away with the canister and its hardware, as well as the pressure relief valve. I now have just a breather. Now when the fuel heats up, all the volatiles escape out the breather and make a nice pungent cloud of fumes around the car after its been run for a while. Again, the thing that the cooler does is cool the entire fuel system to at most (least) near ambient air temperature. The thing the fuel does do is help cool the entire tbi as it a). cools the pod since it circulates through it and b). cools the walls of the tbi when it comes into contact with them. It also can absorb more heat from the incoming air as the fuel has to be heated as well as evaporate. The addition of needed to be heated before vaporization enables the fuel to soak up that extra ammount of heat in addition to that taken up by the fuel vaporizing. Again, the effect is probably small and not one of those "adds 30 hp mods" but in addition to cooling the fuel, it does help the lower the intake charge temperatures. I suppose if you really wanted to you could do an enthalpy balance to figure out how much the fuel could possibly lower the temperature of the mixture at each pressure in the manifold but its alot of work and its late and im tired. As for the other post, pressure/flowrate are irrelevent since the main governing factors are the mass of fuel present and the heat removed by the cooler per unit time. The flow rate would be relevent if the system was open but in our case its a closed system.

Oh, im using a Haydon 4 pass "tube" style finned cooler.
Mounted on the upper portion radiator in front of the fan. This should shield it from depris. Shielding from high speed front head on collisions is optional. I used barbed brass fuel fittings to join the connections.

 

one more thing before i log off... The way i determined the temps was by drivign around for around 20 mins or so each time and then pulling over and quickly getting out to, by hand, feel the temperatures of each component. The temperature scale goes as follows: cold enough to freeze a witch's tittie off < cold enough to freeze meat < kinda cold < kinda hot < ouch that burns < OMG call an ambulence!!!

 

hehehehehe I like that scale

 

I can assure you that you are not going to take enough heat out of the stuff under your engine to make a difference. The mass difference between your fuel lines and fuel and your engine is huge. The heat that you remove from your TBI unit the air around it is going have the same amount of heat entering into it as it is leaving. As long as thermal energy is being produced from the source you will not cool anything around it with something as small as fuel lines cooled to near ambient conditions. Not only that, you can only hope to cool the fuel to ambient conditions. When you have a heat source as hot as an engine you are going to need a compressed air/gas system to cool the charge anywhere near where you want it to be. You cannot do an enthalpy balance because enthalpy is a combination of properties that include total and specific enthalpy. Also as the fuel is burnt you have mass leaving the system so it is not a truly closed system. Try this. Take a pan and put it on a hot stove top. Put a couple drops of water on it and let it heat up and take it off, blow on it and put it back on. Keep doing this and see how cool you get the pan. As long as you have heat coming from a source you will not cool it unless the mass that you are cooling it with is greater. Like I said, the heat that enters the fuel is immediately being replaced from the heat source. You are amplifying the convection and conduction properties and that’s about it.

 

i think you misunderstood me...

First, i wasnt refferring to removing heat from the entire engine or other nearby components with just the fuel. Theres another device for that, namly the radiator. The intake charge is considerably cooled at part throttle loads where there is enough vaccuum in the manifold to lower the boiling point of the gas enough so that it flashes over to a vapor as soon as it crosses into the manifold. Obviously this effect is almost nil at WOT since the a good portion of the fuel possibly wont evaporate until its in the cylinders and under high heat from being compressed. It is useful for that other 99.5% of my engines operation, which cools the intake charge to help improve part throttle operation.

While any performance benifits may be strictly subjective, it does cool the charge down more then hot fuel thats already near its boiling point would. Theres no doubt about it. Its readily aparent in the cold tbi and realativly cooler upper portions of the intake. Obviously the lower portion of the intake will be hot since its in contact with the heads and coolant, which also explanes the 'air gap' technology from edelbrock to help isolate the intake runners from heat.

As for the enthalpy balance, i was reffering to the fue/air charge only after it enters the intake, not the whole engine. Its possible to get a simple estimate of how much the maximum cooling effect could be but to me its more work then its worth just to toss around some more theory.

Finally, i was reffering to the fuel system being closed since the fuel is just continously circulating. If it was open one way flow, such as a carb, then the ability of the condencer to remove heat would be more important since the mass flowing though it would only get to make one pass before it entered the carb. Again, the cooling efect is probably minimal at WOT but for part throttle loading, it does cool things off.

edit: hows that? Better?

 

People.

I'm begging ya.

Please use paragraphs.

Or at least complete thoughts.

I'm getting dizzy from the onslaught of words.

 

I understand what you are saying and it is well thought out but by the time you cool the fuel and send it on its way to the TBI it has already picked up lots of heat. That is what I meant by soaking it in from the engine. Where did you say the fuel radiator was located? What is your cooling medium? Outside air (changes with speed) or fan? It may make the intake charge slightly cooler but it is so small and don't see how it will yield more power. Even at part throttle air and fuel are moving very fast. You also have to realize that thermal radiation is completely transmitted through a gas. It does not heat it at all. So you have to really solely on conduction and convection. Convection is the more efficient way and that is why there is the "air gap" in certain intakes. It slightly limits 2 forms of heat transfer and leaves convection behind. Good idea and good technology. This is very interesting and I have a few people I am going to talk to here at school. One is Dr. Boehman and he is famous for his vehicle performace analysis with GM and SAE. We may be on to something. I am not going to say your wrong or right until we dig deeper. You are very knowledgable and I want to explore this more. I think your theory is correct but for fuel that is static at instantaneous intervals once it is dynamically moving that the end result of any heat transfer is negligable.

 

*starts crying out of frustration*

 

I dont have any Kawlledge credentials or anything but last I heard, liquid under pressure requires more heat than something at atmospheric to boil and vaporize. This is why our cooling systems are under like 15 psi.

Vapor lock is just that too, fuel that has gotten hot enough in the fuel lines to vaporize.

I would suggest (if you can burn chips to compensate) increasing the pressure. Dont know where you are at now but i would guess near stock. Try 20 psi

 

Why would you want to cool the fuel in the first place other than because you are experiencing vapor lock? You want the fuel to be kind of hot so that it can atomize inside the intake better. Cold fuel would simply puddle.

 

not when the engine is pulling 400 some odd degree air right off the headers. I actually had a nice air box that i made myself but all the plastic bits and rubber had a nuclear meltdown because of the heat.
The 'real' solution to my problem would be to get a fancy aftermarket hood,replace the heavily damaged underskirt and airdam, and get some ceramic coated headers so it doesnt get so damn hot under there. The problem is I dont have that kinda dough not to mention the fact that the airdam would be ripped off again.

Pablo,
Like I always say, the only thing the college degrees seem to give people is just some fancy letters after their names and the license to use big words... Im off to grad school soon so i wont be a 'real' engineer for a while.

 

oh, id like to try a higher pressure but my fuel pump would probably die long before it ever made it to 20 psi. maybe 14 but even then the pump would be close to not flowing at all.

 

btw why is your car getting so hot? it should not be.. it sounds to me like you have a problem with retarded timing which will tend to make your headers "omg call an ambulance" hot

 

The fuel temps at the feed and return lines are both cold to the touch.

Of coarse, now that winter is coming, ill never get to know how mcuh it helps in the heat untill summer rolls back around. The fuel would already be cold even without it since its going to be really cold outside soon.

 

been through that one before... Theyre now just 'ouch that burns hot', lol... ive been through that already. They where hot enough to melt the plug wires and glow from sucky timing but now the timing is pretty good and the primaries are aparenly at normal temps.

 

Well you guys has to remember that your fuel doesn't vaporize in the intake. It atomizes but not vaporizes. It takes the the heat from the combustion stroke to vaporize it. When it is in your intake it is still in its liquid state just spread out into tiny tiny particles. Kinda like a fog. That is why GM had that stupid charcoal canister. It takes that atomized fuel when you shut off your car and sorta makes it "rain" fuel back into your return line. Gimmicky at best. If your fuel vaporizes before it enters the cylinder than you have vapor lock. Any liquid takes less atmophseris pressure top boil the higher it is. That is why water boils at the top of a mountain at like 190*. At sea level or close to it your fuel should still maitain its liquid state. What is the boiling point of fuel?

 

Actually, the tbi can get very cold if you have an engine that pulls a decent ammount of vacuum. The best example of this can be seen on initial startup. The tbi will get very cold after just a few seonds of operation. I would assume that most of this chilling effect comes from the fuel literally boiling when it enters the low vacuum of the manifold. I suppose it could also come from the air suddenly expanding as it enters the manifold but i dont think it could fully account for this. Try it... The first time i observed it i was amazed at how cold it could get.

 

actually it does vaporize, thats why manifolds have heat going under them. Its so that the fuel that hits the bottom vaporizes. Vapor lock is not when its vaporized in the manifolds but rather vaporized in the fuel line which would send your metering all to hell.


Dimented also brought up a good point in that the temp of the TBI drops significantly on startup and you dont get temp drops unless you are vaporizing some fuel (i.e. as it travels from high to low pressure in the manifold past the edges of the throttle blades).

 

College is good for a degree, working at a "Center for Automotive Research" facility that has lots of goodies and smarter guys makes for a better vocab. Anybody up for a game of scrable .

The fuel vaporizing from high pressure to low pressure pulls out a lot of heat. By evaporating at a high rate the fuel is effectively absorbing as much heat as possible (why fuel stays vaporized until cooled down or pressurized). It's all about the surface area! If you're having a hard time understanding just take notice that football teams use misting fans to cool down there players and ever wonder why your swet.

I think Pablo is getting the same feeling I originally had.... that it isn't your fuel that's the problem. There is something else wrong with your car. Maybe it's the thermostat, or a collapsed lower hose (happens when you modify the cooling system and forget a bypass), or you're running too much coolant and not enough water. Or there is something wrong in your tune like retarded timing resulting in hot headers/engine.

Oh, and to be more specific about the whole vaporize vs atomize, vaporize contains the word vapor, just like evaporate. Atomize is when something is broken down into smaller particles but still in liquid form, vapor is a gas state. There is probably a good reason why gasoline has the word gas in it, my thoughts is because it's usefulness is only practical when in it's gas form (vapors).
Gasoline in an intake manifold only takes but 120 degrees or so for it to vaporize, it all depends on pressure or the lack there of.
http://www.afdc.doe.gov/pdfs/fueltable.pdf

 

I think most of you have made good points but have also forgotten why a lot of drag racers use cool cans in their cars. Cooler fuel can absorb more heat. The cooler the intake charge the more HP. This in conjunction with a cold air intake system might be of some benefit on a street car on a hot day by keeping the engine out of detonation, allowing the engine to see max advance at all times. If you know how to burn chips and have the smarts to take advantage of the cooler air temps then I would say your system would be very helpfull in acheiving higher performance from your car. Have you thought about taking a temp reading before and after the fuel goes thru the cooler?

Steve

 

cold air intake is a project for the summer. Itll be problematic for the winter time. The temps are about the same at the inlet and the outlet. Probably around 75-80 degrees to the touch. I have to box off the corners around the radiator, though before itll get cooler. W/o the a/c condenser, there are large gaps between teh radiator and the support on each side that are allowing hot air from the engine compartment to circulate around to the front of the radiator, and through the cooler when the car is at a stop with the fan on. After i close those off, ill take some readings with a thermometer.

 

Engine temps are fine. Never goes above 200, even in the heat. But, however, the fan supplies most of the cooling since the airdam isnt in place. Without that, theres nothing to generate a region of high pressure infront of the radiator. The only air in is from the fan itself. It may not be as hot as i describe it, but to me, even though the engine runs cool, it just seems like its darn hot under there. I know it has enough time. Ive already been through not enough timing and glowing headers before when i first put it together. Thats no longer an issue. Im 99.999% sure about that.

 

actually, now that winter is on its way in, the temps are much more reasonable. When it was topping off at 90, and sometimes 100 outside over the summer is when it got hot. The engine itself still managed to keep its cool.