18/03/2025
Atomization: Fuel Atomization can be broadly grouped into 3 categories, listed from worst to best:
1. Spray
2. Mist
3. Fog
The quality is mainly determined by the nozzle body type, although fuel pressure plays a part as well.
#1 in the photo is a common Enderle deflector style that relies on a jet of fuel hitting an angled surface. These provide mainly a fuel Spray. Aerated bodies atomize a little better, especially at low pressure.
#2 Produces better atomization and a different spray pattern.. and tends more toward a Mist of fuel. Use where suitable, which for me is in the hat.
#3 Are impingement nozzles with a pin located very close to the exit of the fuel. These produce the best atomization and quite a lot of Fog. Commonly used in spray bar setups where they provide maximum cooling of the incoming air.
The earlier you introduce fuel into the intake air, the more time it has to affect temperature and density, and this is where you'll get the most benefit from better nozzles.
There's not much room, time or area to do much with fuel in the ports.. and remember it will accumulate on the back of the intake valve during overlap. I tend to use the Enderle deflector type here to direct the fuel in the port.
When the intake valve opens, air velocity, heat of compression, and combustion dynamics take care of fuel atomization.
Some droplets are too large to be burnt during the resident time in the cylinder, and these will exit the exhaust as unburnt fuel.
I've added video of the different types in the Comments.
