lemonade

someone said fuel will cool when its looseing pressure. so im wondering, if there is a way to get colder fuel in a drawthrough turbo, but using a 40psi fuel pump, then a 4 psi pressure regulater......

Moonchopper

Hrm... if you had colder fuel, wouldn't that HURT performance? I was under the impression that fuel was 'ignited'/'combusted' because the mixture in between the spark plug gap absorbed so much heat/energy that it raised its igniting temperature (lack of a better term >.<).

I know that cooler air means denser mixture, but would this be the same case?

I don't think that a lower pressure regulator or anything would actually affect the fuel at all. The pressure is only present when the fuel is in the lines being pumped, am I right? (I could be wrong.) So, when the fuel enters the chamber, it would equalize with the pressure inside the chamber.

I would also think that fuel has a higher specific heat than air molecules, and as such would be harder to lower the temperature.

P.S. Sorry, just trying to make sure I understand how everything works. Correct me if I'm wrong on something, or all of it.

[edit] Gay-Lussac's law states: "The Pressure of a fixed mass of an ideal gas is directly proportional to its temperature measured upon the absolute scale, provided its volume remains constant"

Think of if this way: When pressure increases, temperature also increases (directly proportional.) When pressure decreases, temperature also decreases (directly proportional as well.)

And, as everyone knows, less temperature = denser molecules, so less pressure = denser molecules as well. But when you draw the mixture into the chamber, the volume changes. So how would that affect it?

Brent_F

The one thing I've noticed about cars with fuel coolers is that frequently they run an external fuel pump and or multiple external fuel pumps. Normally the pump would be cooled internally and externally by the gas in and around it (in tank). My only thought is that the high temp of the gas (caused by multiple uncooled pumps) causes some pre-ignition.

I was talking with a drag racer earlier this year about this very topic. His goal with the device he was talking about was I believe to get the fuel temp BELOW ambient temp in order to achieve some cooling of the intake air. But at best that gain is about 1 horse per 10F.

Perhaps if you put the regulator in the back of the car with the filter? Then after the preassure drop the fuel will have time to cool back down. Also you avoid heat soak on the reg from under hood temps.

Brianhsval

CryO2 makes a cold fuel system. It has a fuel bar that attaches just before the fuel rail and cools the fuel to -80 IIRC. It also has one for the air intake and an intercooler. System starts around $320.

Brent_F

By the name I'm guessing it may be CO2 based? -80 seems a bit excessive in my opinion, but that would defintely cool the intake air mixture.

Does this not cause the carb/ injectors to "freeze over" due to moisture in the air?

DAVID GRIMES

Colder is atoms closer together which gives you more air/fuel in the same space/time.

But that is the principle of nitrous doing the same thing by giving you 2 oxygen to every one nitrogen atoms by volume instead of 2 oxygen atoms 20% by volume in the normally aspired "air". In other words, the air has only 20% oxygen while NO2 is greater than 60% oxygen.

I'd have a small wet nitrous system before I'd pay all that for chilled air.

Brianhsval

It isn't just for cold air, It also has a add on to the fuel rail, ( tube). Yes same princible as Nitrous only considered safer for your engine is all. BTW, I only know of this system from reading I know of NO ONE using it at this time. The biggest difference that I can see is the price. Cheaper than re-filling the nitrous bottle.

Moonchopper

It would seem to me that -80*F would be kind of dangerous and would cause something to become brittle/shatter. (Of course, we are talking about metal/steel, so that might not be the same thing.)

Sort of like washing a drinking glass with an industrial washer (ones that use REALLY hot water) and then putting ice in it immediately. Would this be the same case? And would it lower thermal efficiency?

If not, then I would think that would produce quiet a bit of power, would it not?

And wouldn't it make the fuel harder to ignite, or do spark plugs provide so much energy that it would ignite it easily? After the mixture between the plugs is ignited, then wouldn't the "flame travel speed" be reduced since the colder fuel droplets are able to absorb more heat before they combust/ignite?

P.S. Playing a little devil's advocate here, somewhat unintentionally.

zyounker

2 words: Liquid propane.

On desiels it shows 50-90whp gains by just injecting it.. Then the fact that it is 118 octain lets you boost even more.


I am working on a rotary kit. Will post results when i have test results.. prolly next spring.

851stgen12a

A friend of mine used to drag race her Nova with a 455 buick in it.
They had what they called a "cold can". The fuel lines ran in a spiral through the box and they filled it with dry ice.
They did this supposedly because it make for a denser fuel mixture, and it was supposed to help quite a bit with consistancy.

Brent_F

Moonchopper I'm with you I think that severe a temperature swing would make for shall we say a steep developemental curve. I forsee a lot of problems with any rubber gaskets/ seals in the fuel system based on what I have seen with painball guns that run CO2 eating seals

rotor vs. piston

If you're looking for that .01 sec improvement on the track you can worry about this, but for a daily driver or a road course car it will have no "set of the pants" benefit. The best and most cost effective thing to do is to insulate the fuel lines in your engine bay and get a heat shield for your carb bowls. My .02c