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DRIVER said:
what about using compressed CO2, from a bottle something like what is used on a paintball gun. Extremely cold, but shouldn't damage anything...any opinions?
The reason I thought of liquid nitrogen (bad idea) in the first place was to avoid CO2 being near the intake. N2O would work as well

Any pressurized gas sprayed onto the IC could cool it, it's just a matter of satey and cost, or at least cost. ;)

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Jeff
 

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I wouldn't worry about screwing up the mixure when using dry ice. Even though the air becomes denser when it gets colder, the mass of air present doesn't change. In other words, the total amount of air that is present doesn't change. This mass of air has been metered and now the ECU knows that it's there. You can expand it, contract it, heat or cool it and it won't matter because the mass stays the same. The only problem I would have with dry ice is that it's expensive. Like Jim said, regular ice is practically free, and easy to use. It also doesn't have to be handled carefully like dry ice does.

Overcooling the intake charge can also make you lose boost. As air get colder, it also contracts. If that air is under pressure, then the contraction translates into a loss of pressure(boost).

Alin
 

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Superfluid SS said:
What about liquid nitrogen?

It's colder than dry ice so you wouldn't have to use as much.
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Jeff
WooHoo! I love liquid nitrogen, cool stuff (badump bump <--suppose to be a drum sound to indicate really cheesy pun). Anyway, liquid nitrogen is around -200C (or -328F), so to say it's colder is actually quite an understatement. Of course, in the application of it, you no doubt would never reach that type of temperature, but you could definitely see around -100C (or -148F), so you would definitely need to miss any hosing as it would definitely get brittle and crack. Over time, I'm sure the IC would end up cracking as well, but I'm not sure how long that would take. The other major problem is handling it. There isn't really any practical way to "carry" it since it boils at room temp. I can see the tech guys having a hayday with this one when you try to get it "passed".

BTW, ProdriveMS, I think that you sort of contradicted yourself in saying that the ratio (air/fuel) wouldn't be effected by the cooling, but then saying that the air would be compressed. I think that was the original point as to why it would screw up the air/fuel ratio and cause you to run lean. If the air is compressed, you can cram more in the piston chamber than what the computer is assuming would be there, thus you'd create a lean condition.

As an aside, Snicker bars frozen in liquid nitrogen are INCREDIBLE! uh...if I were to do something like that, I mean, I think it would be good.....:p
 

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WRXed said:


...The other major problem is handling it. There isn't really any practical way to "carry" it since it boils at room temp. I can see the tech guys having a hayday with this one when you try to get it "passed"....
I thought of that too at first, but I've seen my physics prof. throw some on the chalk board to clean it off (it worked but only where it actually hit the board), I think this would give you enough time to pour it onto the IC.

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Superfluid SS said:
The air cooled IC couldn't cool the air more than the outside air temp.

Right?

If so, why would in need this extra sensor?
Jeff
the sensor is the MAF, and it's judging the amount of intake air based on atmoshperic conditions. once that air is compressed, then cooled to some rediculously low temp, it is even more compressed, therefore, you WOULD run lean, b/c the computer is expecting a certain amount of air, when in fact you've compressed it beyond that. regular ice would lean you out a little, giving you a little more power, but when you start talking about inducing cooling with something so cold it boils at room tempurature, you're compressing that intake charge significantly more, and you could (theoretically) approach a dangerously lean condition.

feel free to contradict, but i think that negative 150 degrees F is REALLY going to make a difference in the mass of air in the mix, never mind you'll be freezing any free water molecules in the air into an immediate solid.

dR
 

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i think just putting some chunks of dry ice in the intercooler would work well, not all over it just some crushed. F1 cars put it in their radiator cages on the start line, or used to, i hav seen on some first corners it just coming out all over the track.
 

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dark_rex said:
feel free to contradict, but i think that negative 150 degrees F is REALLY going to make a difference in the mass of air in the mix, never mind you'll be freezing any free water molecules in the air into an immediate solid.

dR
Mike, Law of conservation of mass. In a closed system, the mass can't change.

Once the air enters, it stays the same mass. The density of the air charge entering the cylinders is the issue. The air would become ridiculously "thick" or "heavy" for lack of a better word.

Furthermore, cold air doesn't take fuel well. Everyone remember carbuerators in winter? Bad.

-Jim
 

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Discussion Starter · #32 ·
whoa - I started something here - went to a meeting and then there are 2 pages worth of discussion!

Liquid N2 - handling issues would suck.

dry ice - a pair of leather gloves are fine to avoid injury. Storage is also the same as water ice - just a beer cooler will do.

I was interested if there were any negatives when compared to ice in terms of performance.

The condensing of water in the I/C may be an issue when the engine is stopped, but if applied when running - the flow of air through the I/C would stop that ( I think).

Maybe the best solution would be a combination of ice and dry ice.

Ice when sitting still with the engine off, change to dry ice when you start again and hence still get the cooling but do not have the issue of dripping on the track and pissing off the officials???

Andrew


PS: which grocery stores sell dry ice??? I have only been in the US 9 months and haven't seen that yet.
 

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Discussion Starter · #33 ·
Trypsin said:
i think just putting some chunks of dry ice in the intercooler would work well, not all over it just some crushed. F1 cars put it in their radiator cages on the start line, or used to, i hav seen on some first corners it just coming out all over the track.
That was what I was thinking ;-)

Andrew
 

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PlatinumWRX said:


Mike, Law of conservation of mass. In a closed system, the mass can't change.

Once the air enters, it stays the same mass. The density of the air charge entering the cylinders is the issue. The air would become ridiculously "thick" or "heavy" for lack of a better word.

Furthermore, cold air doesn't take fuel well. Everyone remember carbuerators in winter? Bad.

-Jim
:)

nice try jim, but the valves open and close at a fixed rate, so more dense air means that you can fit more into the same space at that fixed interval.

dR
 

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dark_rex said:


:)

nice try jim, but the valves open and close at a fixed rate, so more dense air means that you can fit more into the same space at that fixed interval. this equates to more mass at the colder temp, not b/c the temp is creating mass out of nowhere, but b/c more can fit due to the colder/denser charge.

dR
You're right. At an intercooler and manifold level, I am correct, at a cylinder level, however, the closed system ends, you would be packing more mass in the cylinder. This is only true as time approaches zero however, which means we need (OH DEAR GOD) CALCULUS!!!

Damn, this is fun. :D

-Jim
 

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man i miss calculus

PlatinumWRX said:


You're right. At an intercooler and manifold level, I am correct, at a cylinder level, however, the closed system ends, you would be packing more mass in the cylinder. This is only true as time approaches zero however, which means we need (OH DEAR GOD) CALCULUS!!!

Damn, this is fun. :D

-Jim
how long are the valve intervals? is this timing the same as the injector timing? i would assume so....

once i have that number, i'll start with the logarithms. :D

dR

ps: I beat Jim!
 

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I don't believe I've contradicted myself. Look at it this way. Lets say we freeze time for a second and look at whats happening inside the motor. Let's say the motor just ingested 1 lb of air. That 1 lb of air has been metered and the ECU knows that it's there. It will then inject the proper amount of fuel. Remember that A/F ratio is always based on mass and not volume.(14.7lbs of air to 1lb of fuel at stoich) Now whether you heat the air or cool it, you will still have that same 1lb of air. Now because we have a turbo helping to cram the air in, we have to deal with pressure as well. Because air's mass doesn't change but its volume decreases the air pressure must drop.

It is true that the valves open and close over a certain time interval and the cylinder will be filled with a certain volume of air. The argument was then made that since the air is denser and the same volume will occupy the cylinder that more air mass will fill the cylinder. The problem with that argument is that it assumes that pressure stays the same which it doesn't. While the air is denser, the pressure will decrease, therefore you will get roughly the same amount of air mass entering the cylinder as with a hotter charge. See it all balances out because the air mass never changes, only it's volume does.

Btw, this doesn't apply to NA engines. Colder air means you need to add more fuel.

Another potential problem might be poor fuel atomization from the colder air charge. The fuel needs tp be in vapor form since liquid wont combust and heat is used to vaporize it. This shouldn't be a problem though since in all modern FI engines, fuel is squirted on the back of a hot intake valve sometime during the compression stroke. The hot valve helps the fuel vaporize and by the time the valve opens for the next intake event, most of the fuel should be vaporized.

Alin
 

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ProdriveMS said:
I don't believe I've contradicted myself. Look at it this way. Lets say we freeze time for a second and look at whats happening inside the motor. ...

Btw, this doesn't apply to NA engines. Colder air means you need to add more fuel.

Another potential problem might be poor fuel atomization from the colder air charge. The fuel needs tp be in vapor form since liquid wont combust and heat is used to vaporize it. This shouldn't be a problem though since in all modern FI engines, fuel is squirted on the back of a hot intake valve sometime during the compression stroke. The hot valve helps the fuel vaporize and by the time the valve opens for the next intake event, most of the fuel should be vaporized.

Alin
Alin,

Who said you contradicted yourself? We're just mulling this over.

Good call on the fuel vaporization, I hadn't thought of that.

-Jim
 
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