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Ellison Throttle Body Injector

Long-Eze Installations

Most Long-Eze builders consider fuel economy to be a very important feature of their unique aircraft. Installation of the Ellison Throttle Body Injector can increase fuel mileage by as much as 10% over the stock Marvel carburetor. The efficiency of the Ellison Throttle Body Injector was proven every year that the CAFE 400 comparative aircraft flight efficiency competition was held.  In its last five years, the winning aircraft in the 2 seat experimental category were equipped with Ellison Throttle Body Injectors.

Airbox Design and Airframe Modifications

Careful planning of your throttle body injector installation will result in maximum performance and economy. The original intake air plumbing called out by the Long Eze plans is quite restrictive. Dynamometer tests have shown the original intake plumbing to reduce the 0-235 engine power output by 8 horsepower. Re-designing the air intake system increases engine power output by reducing flow losses and allows the installation of a more aerodynamic cowl. Click on inlet airbox for specific information relating to the design of this important induction system component.

When updating a Marvel Schebler equipped aircraft with the Ellison Throttle Body Injector a few changes to the airframe are necessary.  First, because the throttle friction of the Throttle Body Injector is substantially higher than that of the Marvel carburetor, the pull wire and spring type throttle and mixture cables must be replaced with push pull type cables.  Also, the elbow which is normally used on the air inlet flange of the Marvel carburetor is not compatible with the Throttle Body Injector. This is because the TBI requires smooth, uniform air, flowing past the fuel metering tube, which is not available when the air is forced through a right angle turn by the plans specified elbow. This results in rough engine operation at wide open throttle. The solution to this problem is to design an airbox which allows air to enter the TBI from all sides. When the throttle body draws its air from a large volume of still air, good fuel metering results.  Click on inlet airbox for information on the design of this important induction system component.

If you have a Long Eze with the "male" cooling air intake, there is plenty of room for a good airbox design. If you have a NACA Scoop for the cooling air intake, there may be little room for a good air inlet to the throttle body. To gain much needed cowl clearance, Ellison Fluid Systems, Inc. has designed a plenum box which mounts to the standard Lycoming updraft sump and allows the TBI to be mounted in a side draft configuration. This plenum box gives excellent fuel distribution resulting in maximum fuel economy. The use of the plenum box provides about 3 inches more cowl clearance than a standard Throttle Body/airbox combination.  Also, intake airbox design is now simplified because the induction air no longer has to make a 90 degree turn before entering the TBI. The use of the TBI and the plenum box allows for the installation of a tighter, more aerodynamic, cowl which would not be possible with the standard Marvel carburetor installed. There are however, disadvantages to using the plenum box which can be reviewed by clicking plenum box.

Plenum box configuration 1

Plenum box configuration 2

TBI Orientation

On Long Eze aircraft, TBI orientation that activates the throttle in a spanwise direction will generally yield better performance than one in which the slide moves fore and aft.

Fuel System

See comments related to fuel filtration and primer suggestions when planning a TBI installation on an Long Eze aircraft.

Although it is always important to design the fuel system to minimize the chance of vapor formation, the Long Eze with its up draft cooling makes this job very easy because all of the fuel system components in the engine compartment are surrounded by cold air. 

Up draft cooling exacerbates the potential for carburetor and induction ice, making the requirement for a well designed carburetor heat system even more critical.

Ordering Information


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