Fuel atomization (1 Viewer)

[Ryan S.]

I've heard two conflictiong theories on this. First is that warm fuel promotes atomization and therefore more efficient burning of the fuel. This makes sense to me in that the stock exhaust manifold bolts under the carb on the intake manifold, to heat that fuel up. And MAF sells the heat riser kit to make up for some of this heat loss if headers are installed.

Another theory came from a local stock car racer. He says cooler fuel atomizes better, and drivers even install cooling boxes to cool the fuel before combustion.
Which one is it?

 

[FJ40Jim]

Hot air does a more effective job of boiling liquid gasoline into vapor.

Liquid gasoline is unflammable.
Gasoline vapor is highly inflammable.

 

[2mbb]

Cooler gases (air and vaporized gasoline) are more dense when cold--you get more molecules per cubic inch, which means more oxygen and more fuel which should mean more power. But it's a trade off, because as Jim says you need some heat to do effective vaporiztion. I think your hot-rod-friends cooling box is to make the gaseous fuel-air mixture more dense to get more potential power into the cylinder.

 

[Mark W]

"Cool Cans" are an old hotrodders trick The goal is to get the densest posible fuel in the carb so that more fuel is sucked into the engine. But once it is in the intake tract it needs to atomize, and warm fuel does so more effeciently.

I've used cool cans in the distant past. Basically a coffee can full of ice with a coiled fuel line running through it before reaching the carb. It's a drag race thing, not an all day system.
Make sure you don't locate the can where a leak can dump water in front of your drag slick so that you hit it a few feet into you full power launch. I came off of a wheels in the air start, headed for the rail on night when that happened to me back in the days when dinosaurs ruled the streets. Not fun!

Your buddy is wrong when he says that cool fuel atomizes better. A racer is not looking for most effecient. Just most powerful. Unburnt fuel out the tailpipe dosn't bother him if he can gain a little power in exchange.

For your Cruiser you want the coolest air and fuel you can reasonably get going into an engine which has a warm intake tract (fluid exhange heater installed on the intake if you don't have a factory exhaust manifold.


Mark...