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Old 12-21-2012, 09:30 PM   #3205
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Originally Posted by roger 04 rt View Post

--My fuel pressure increase is to improve atomization at the injectors . . .
Here's some information relating to fuel injector atomization and fuel pressure, and how they relate to fuel vaporization.

Atomization doesn't much change the fuel vaporization rate within the atmosphere of the intake tract. But the increased fuel pressure likely creates a somewhat larger spray pattern, and that would make a difference.

The sequence of events goes sort of like this. Fuel leaves the injector, flies through the air, and lands on the intake port wall where it begins to vaporize. That waiting-to-vaporize fuel is often referred to as 'port wall fuel'. That 'puddle' of fuel if you will, covers some amount of surface area on the intake port wall. The vaporization rate of the 'port wall fuel' is primarily based on the surface temperature of the wall.

After spraying from the injector nozzle, some of the sprayed fuel vaporizes due to the low pressure of the intake manifold. The low pressure vaporization rate is based on manifold pressure and is not significantly dependent on fuel droplet size (aka atomization.)

The remaining bulk of the sprayed fuel vaporizes after coming into contact with the warm inside walls of the throttle body and intake port. That particular vaporization rate is based on a few things. Manifold pressure continues to be a minor factor in fuel vaporization rate, but there are three other larger factors. 1. The temperature of the inside walls of the throttle body and intake port. 2. The the total area of the injector spray pattern. 3. The velocity of the intake air across the 'port wall fuel puddle'.


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Poolside screwed with this post 12-21-2012 at 10:01 PM Reason: Clarity
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