[Tom Vaught]

Now that you have a handle on the difference between a Enclosure and a Bonnet I will tell you the advantages and dis-advantages of each.

Enclosure First.

The Enclosure fits over the carb, just like if you had a engine in a pressurized dyno test cell.

The carb linkage from the gas pedal goes thru the "Box" and attaches to the Holley carb linkage.

The Fuel Line from the Fuel Pressure Regulator goes thru the "Box" and hooks up to the carb fuel bowls.
A Boost Gage nipple allows a remote Boost Gage in the car.
The lid seals the carb inside the "Box" so there are no adjustments that you can make to the carb without removing the carb from the "Box" so the carb has to be dialed in pretty well naturally aspirated before you decide to run boosted.
But you do not need to make a lot of carb adjustments once you figure out the jetting needed to support the boost pressure/ mass air flow you are adding to the "Box".

Since we are talking about fuel pressure regulators you need a "Boost Referenced" Regulator. You also need a fuel pump capable of more fuel pressure and flow to support the higher HP. The "Boost Referenced" Regulator has a nipple on it that connects to the "box" so that if the pressure in the box goes up by 2 psi the fuel pressure also goes up by 2 psi.
So if you want the normal 6 psi to the Holley Carb Fuel Bowls then when you have 2 psi of boost, the fuel pressure from the fuel pump will actually be 8 psi but the fuel bowl vent/fuel bowl will be fighting that 8 psi with 2 psi of Boost Pressure so the Holley carb will actually still have 6 psi of fuel pressure setting the fuel level in the bowls. Right where you wanted it to be.
So if the boost pressure goes to 10 psi the box pressure will be 10 psi and the fuel pump will supply 16 psi of fuel pressure to the "Box".

Pretty simple, just like putting the carb in a pressurized room with the only real mods to the carb being bigger jets so the air fuel ratio is correct. No real air bleed changes, no big mods to the carb. You just want to use black floats as they will not crush under boost pressure.

Later we can talk about Holley Bonnet Systems.

Tom V.