Top alcohol staging (1 Viewer)

[flapjack]

What are they spraying on the butterflies when a top alcohol funny car is staging?

 

[none]

De-icer, when the alcohol is introduced in the injector above the blower it is so cold that it can form frost on the throttle blades and shaft, a quick spray of de-icer and the throttle will continue to work smoothly.
Alan

 

[flapjack]

De-icer, when the alcohol is introduced in the injector above the blower it is so cold that it can form frost on the throttle blades and shaft, a quick spray of de-icer and the throttle will continue to work smoothly.
Alan

Thanks Alan. Didn't realize methanol got that cold when it vaporizes.

 

[flapjack]

I asked my nephew about this. He's a chemical engineering major. This is what he had to say:

"It's an enthalpy thing called Joule-Thomson expansion. When something goes from high pressure in a nozzle to low pressure outside there isn't sufficient time for the system to equilibrate isothermally, so it equilibrates enthalpicly. Vaporizing a liquid requires energy, and for the system to vaporize isenthalpicly that energy is taken from the enthalpy of the liquid. Since the liquid's energy goes down, temperature goes down. Compressed air cans do the same thing, it happens for all fluids"

I get the general gist of this, but man has it been a long time since I studied chemistry and physics and what not. Sorry for the mind bender, I was just humored by his response. He's a smart kid, sometimes too much for his own good, lol

 

[stitcherbob]

What are they spraying on the butterflies when a top alcohol funny car is staging?

De-icer, when the alcohol is introduced in the injector above the blower it is so cold that it can form frost on the throttle blades and shaft, a quick spray of de-icer and the throttle will continue to work smoothly.
Alan

it's not Febreeze Essence of Nitro????

 

[Justin@NRE]

I asked my nephew about this. He's a chemical engineering major. This is what he had to say:

"It's an enthalpy thing called Joule-Thomson expansion. When something goes from high pressure in a nozzle to low pressure outside there isn't sufficient time for the system to equilibrate isothermally, so it equilibrates enthalpicly. Vaporizing a liquid requires energy, and for the system to vaporize isenthalpicly that energy is taken from the enthalpy of the liquid. Since the liquid's energy goes down, temperature goes down. Compressed air cans do the same thing, it happens for all fluids"

I get the general gist of this, but man has it been a long time since I studied chemistry and physics and what not. Sorry for the mind bender, I was just humored by his response. He's a smart kid, sometimes too much for his own good, lol

Combined with the extreme low pressure area of the injector hat as the supercharger sucks air, it creates a perfect storm. Some injectors handle it better than others too, like roots and taller dragster scoops where there is a little more volume to the injector itself and you typically don't have to spray in lower humidity conditions. If you watch the TAFC's warm up on a humid day, the whole injector hat will be covered in frost just idling, especially if they're still using a metal bodied injector. Harder to see on the carbon fiber stuff and it is a better insulator.

 

[stitcherbob]

 

[flapjack]

LOL

 

[Tumbleweed]

If you have a Carbon hat, you don't need de-icing. Its only for the Magnesium and Aluminum hats.

 

[stitcherbob]

and the tin foil hats....

 

[turbo ken]

In the late 1980's I seen alky FC's stage with icicles hanging off the injector hat.

 

[FABMAN]

Thi isn't related to subject so to speak but shows how air flow affects fuel. In early seventies i had a drag boat with big block tunnel ram with 2 4 bbl holleys and when running down the lake the plenium under carbs would freeze while temps were in the 90's so i can imagine how quick alcohol could freeze.

 

[Justin@NRE]

The biggest reason it happens is the low pressure/vacuum created. Pressure helps keep things liquid. The low pressure area or vacuum created in the manifold allows the fuel to evaporate to a gas much more easily and the evaporation is what causes the chilling effect. Just like how sweating helps cool your body, or why alcohol swabs on your skin feel cold.

 

[Randy]

I've used my temp gun on the injector and butterflies in high humidity situations when it was icing up on a warm up in my pit. IIRC, it read somewhere in the low 20 degree range on an 80 degree day. The ice is the condensing moisture in the air (just like an ice cold Coke bottle will get wet on the outside) and then freezing against the cold surfaces. Alcohol evaporates at a fast rate which cools the interior surfaces of the magnesium injector and aluminum butterflies transferring the cold to the outside surfaces to below freezing temps. Carbon fiber does not conduct heat or cold like metals do so it doesn't readily transfer the cold temperatures to the outside surfaces, so icing is less likely. The reason for spraying is to liquify the ice because the ice gets into the butterfly shaft area including the needle bearings, and can freeze the butterflies to the injector housing.