Carb fuel "atomization"

["Storhok, Eric (E.M.)" <estorhok@domain.elided>]

Its in quotes for a good reason.  I've seen a couple of videos of carburetors at work, and I wouldn't exactly call it atomization... more like dribbling.  The only way carbs can vaporize the fuel better is if they had a LONG heated manifold with forces the fuel to atomize.

Think about it- the pressure change between the venturi and the float bowls can be measured in single inches of mercury, less than 5 psi, whereas most electronic fuel injections inject at 39 psi across the injector, some modern now even inject at 65psi.  SPICA is an entirely different animal- it injects at a whopping 140psi (that's what you get when starting with a diesel pump).  Probably the Bosch direct injection runs near the 1500-2000 psi range when running.

The thing that ices it for me is that I can have a 40mm port without ANY venturi restriction in it (or whatever port size).

Some of my classes even tried to convince us that the port injection does a good job at charge cooling, but from the dyno data I've seen, its only when you do the injection when the valve is open (which opens a whole nother can of worms).

Of course, injection is not perfect, either- while the system is still cold, the atomization isn't that great, but as the manifold warms up, and the valve gets hotter, for the most part, it works well.

Eric Storhok
Core Emissions and Fuel Economy Team
Advanced Powertrain Engineering
(313)33x75011
MD 35, FPC-B
Ford Motor Company

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