Buyer beware!

[Grayghostcoyote]

sorry I meant Fiat ..

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[TexasRebel]

I can feel it just sitting parked.

That's just it though. They don't do anything if you aren't moving.

Also, if you aren't moving, why is your engine under load?

 

[TexasRebel]

Water vapor is plenty compressible.

Saturated air is compressible. The water that makes the air saturated is not.

For example, at 75F air can contain 1/3 oz of water per pound of air. Unless you are drying your intake air, those are molecules that don't burn while taking up volume.

 

[Scruffy]

Saturated air is compressible. The water that makes the air saturated is not.

For example, at 75F air can contain 1/3 oz of water per pound of air. Unless you are drying your intake air, those are molecules that don't burn while taking up volume.

I spent many years working in the chemical process and power generation business with high pressure steam (water vapor) systems. Water vapor is indeed compressible

 

[Grayghostcoyote]

why is this in conversation to the originality of my post? lol sheesh

 

[TexasRebel]

I spent many years working in the chemical process and power generation business with high pressure steam (water vapor) systems. Water vapor is indeed compressible

yes, the air that holds the water is compressible.
the water is not. Unless your engine is pulling in steam for combustion... (it's not)

you're talking about saturated or superheated steam. The atmosphere is neither.

 

[Scruffy]

yes, the air that holds the water is compressible.
the water is not. Unless your engine is pulling in steam for combustion... (it's not)

you're talking about saturated or superheated steam. The atmosphere is neither.

Are you referring to liquid water droplets, or evaporated water in the gas state when talking about water in the air? Liquid water droplets are not compressible, but evaporated water in the gas state (humidity) is compressible.

 

[Paul McWhiskey]

If I recall correctly the extra power supplied by water injection (which also helps to keep combustion temps lower and reduce detonation) is due to the change of state from liquid to a gas state. This increases cylinder pressure which creates power. I can't show my math here, but perhaps there is an engineer among us who can? It is somewhat like steam power except that it is not injected steam but created from the burning of gasoline in the cylinder.

The B-17 utilized water injection on takeoff to reduce CHT, the potential of detonation, cool the engines, and increase the HP. All of which were critical for getting the machine into the air with a full bomb load. I am not part of the Greatest Generation, but it was part of the training in order to get an A&P license when I was in school.

 

[shogun32]

B17 water injection would have been at the intake. The liquid droplets would phase change when hitting the hot intake parts, and this lower the metal temp. If the intake charge was sufficiently warm it too would cause the droplets to become gas and so doing reduce the fuel air mixture temp and also make it slight more dense. Any dropets still unconverted and now in the cylinder would become steam when meeting the flame front. And therefore absorb combustion heat and lower the exiting gases while also lending extra psi to the chamber by turning into a fgaseus state. Which would impart more piston force on the crank.

 

[codemanstang]

Gotta love the vague titles

 

[TexasRebel]

If I recall correctly the extra power supplied by water injection (which also helps to keep combustion temps lower and reduce detonation) is due to the change of state from liquid to a gas state. This increases cylinder pressure which creates power. I can't show my math here, but perhaps there is an engineer among us who can? It is somewhat like steam power except that it is not injected steam but created from the burning of gasoline in the cylinder.

The B-17 utilized water injection on takeoff to reduce CHT, the potential of detonation, cool the engines, and increase the HP. All of which were critical for getting the machine into the air with a full bomb load. I am not part of the Greatest Generation, but it was part of the training in order to get an A&P license when I was in school.

You're referring to the latent heat of vaporization.

Yes, that keeps temperatures down, as heat is required to move between phases, but temperature does not change. It's why water can exist at two (or three) phases simultaneously at certain temperatures and pressures.

As the piston reduces volume in the cylinder, temperature rises (P1V1=P2V2 compression is not 100% efficient and PV=nRT). Since liquid water can only exist up to a certain temperature, the water will pull some heat from the a/f mixture to change phases to a vapor and become saturated steam. The atmosphere does this, too, but to a much lesser effect.

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