Unlike most other carburetors which are adapted for aircraft use, the EFS-2 throttle
body injector was designed specifically for the converted VW aircraft engine. Other
carburetors used with this engine may utilize "add on" mixture controls and
require constant mixture control adjustment whenever the throttle setting is changed.
The EFS-2 incorporates a mixture control designed into the unit, not added on.
Changes in throttle setting do not significantly affect fuel air ratio.
The EFS-2 also has a diaphragm controlled regulator in place of a float bowl, allowing
side draft, up or down draft orientations. The unit is not subject to changes in fuel
metering due to G loads and therefore will operate in all flight attitudes.
Many VW installations suffer from poor fuel distribution resulting from poor manifold
design. With the EFS-2 a more efficient manifold can be installed, allowing the throttle
body to mount on the top of the engine. A sketch of this type of manifold is presented
For VW engines with displacements greater than 3000 cc the EFS-3A should be used.
Those who have installed this manifold have reported greatly improved performance. If
you wish to mount the throttle body under or in back of the engine, the Great Plains
Aircraft supply dual port manifold is one of the better designs.
See comments related to carburetor heat,
fuel filtration, and
suggestions when planning a TBI installation on a VW engine.