AeroInjector Frequently Asked Questions

 
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Read AeroVee Frequently Asked Questions



I see you now offer an "AeroInjector." Is this an electronic fuel injection system?

No. A new version of the AeroCarb, the AeroInjector, has now been introduced to replace the AeroCarb line of throttle body injectors. The AeroInjector is essentially identical to the AeroCarb in function, however, the body has been lightened by approximately 9 ounces, and is more compact in size. We've named the new product AeroInjector to drive-home the point that this device is a throttle body injector and not a carburetor by true definition, and therefore does not require carb heat.



What are the differences between the AeroInjector and AeroCarb?

The AeroCarb was already the lightest and simplest fuel injection device available in the aviation market. The AeroInjector is simply a lighter and more compact version of the AeroCarb weighing 9 ounces less.



What kind of throttle control do you recommend using the the AeroInjector?

Since the AeroInjector does not have the push-to-open functions of the AeroCarb, we highly recommend using one of the AeroConversions Throttle Quadrants on the AeroInjector. They were designed to complement each other with a conventional and proportional throttle feel. Read More about Throttle and Mixture Cable Selection.



I only see two sizes of the new AeroInjector? Will the 29mm and 38mm AeroCarbs still be available?

No. As-of January, 2011, the 29mm ACV-C02 AeroCarb has been discontinued, and engines from 30-65 hp are now being serviced by the 32mm AeroInjector 32. As-of April, 2011, the 38mm ACV-C05 AeroCarb has also been discontinued. The vast majority of AeroCarb/AeroInjector sales have been in the 32mm and 35mm sizes, and AeroConversions is focusing on servicing only the 30-125 hp range of four-stroke engines with the new AeroInjector product line.



I noticed that the 29mm ACV-C02 AeroCarb is now missing from your sizing chart and the 32mm AeroInjector 32 is now servicing an expanded range of engines (30-90 hp). Why did you make this change?

The reason for this discontinuation is because sales demand for AeroCarbs servicing the 30-65 hp range is relatively very low. The good news is, we are still serving customers with engines in this power range using our larger, 32mm AeroInjector 32. The 32mm AeroInjector can service 30-65 hp engines by simply restricting maximum throttle opening to 29mm so that your engine will not be overcarbureted at wide-open throttle. This simple throttle restriction procedure is fully covered in the AeroInjector Owner’s Manual.



How do I Choose an AeroInjector that is Suitable for My Engine?

AeroInjectors are selected according to the horsepower rating of your engine, in your particular aircraft installation. Two different AeroInjector sizes are available to service engines ranging from 30 to 125 hp. If your engine's hp rating is right on the line between two AeroCarb/AeroInjector sizes, we recommend going with the larger size (particularly if there's a chance your engine can produce more hp than expected in your installation). If your engine turns-out to be overcarburated at WOT with the larger AeroInjector, you can restrict maximum throttle travel at WOT to make the AeroInjector behave like a slightly smaller injector (This procedure is also used when installing the AeroInjector 32 on engines producing less-than 65hp).

You also need to select a method of mounting the AeroInjector to your engine's intake manifold. An intake manifold mount comes with your AeroInjector purchase and we have three different mounts available, two different sizes of spigot mounts, and a flange mount meeting common aircraft engine flange specifications.

You can find the AeroInjector horsepower/sizing chart and intake manifold mounting options on the main AeroInjector page. For a quick and easy way of selecting your AeroInjector, mount, and popular options and accessories, use our javascript AeroInjector Selection Wizard!



Don't I Need to Consider Displacement and CFM Specs for My Specific Engine?

No. We do not size the AeroInjector according to CFM calculations as there are far too many variables to use CFM calculations reliably. The AeroInjector has plenty of flow within the horsepower range specified for each size, and we size the AeroInjector according to hp rating alone. Every unit of horsepower requires a set amount of air/fuel mixture or "flow." An aircraft with a 6 cylinder engine flying next an identical aircraft with a 4 cylinder engine at the same speed will be using an identical flow of air and fuel in a perfectly controlled test environment.



Why do Your Recommended Throat Sizes Appear to be Too Small for my Engine?

Because the AeroInjector has what hydraulic and pneumatic engineers call a "perfect flow passage" in its throat design, AeroInjector throat diameter requirements typically run slightly smaller than throat requirements of other carbs on engines with equivalent horsepower. This is a fairly common point of confusion about the AeroInjector as all of our recommendations for specific, known engines have slightly smaller throat diameter than required when using other carbs on those same engines.



Where can I find a Fuel Pressure Regulator for my AeroInjector installation?

Many automotive suppliers have several different fuel pressure regulators that are adjustable and restrict flow down to the 1-2 psi range, although most regulators deal with much higher pressures. Our customers have reported much success with the Holley Standard Fuel Pressure Regulator, which can be found at http://www.jegs.com

Be sure to see our Compatible Fuel Systems diagram on the main AeroInjector page to see if you need a fuel pressure regulator. Whenever possible, we recommend eliminating fuel pumps and the need for regulators in favor of gravity feed. Gravity has never failed us. In all cases, aircraft builders should strive to make aircraft engine and AeroInjector installations as simple as possible, eliminating all unneccesary equipment wherever possible.



What kind of Throttle/Mixture Cables do I need for my AeroInjector installation?

The following information is also detailed in the AeroInjector Owners Manual:

Throttle Cable: Use of a reversing throttle quadrant is required for all AeroInjectors. You can choose between three types of “pull” throttle cables:

  • Flexible Cable with Attached Ball End
  • Flexible Cable with a Cable Stop
  • Solid Piano Wire

If you use the AeroConversions Throttle Quadrants, a Flexible Cable with Attached Ball End is already included with the quadrant.

Mixture Cable: You must use a push-pull boden wire style cable for mixture control. We highly recommend use of mixture cable assemblies with a friction or button lock, such as Wicks Aircraft Supply PN# A700-RED.



What Kind of Fuel Burn Rates will I see with my AeroInjector?

With its fixed-orientation mixture needle holder/adjuster, the AeroInjector is infinitely adjustible in mixture tuning and, in concert with in-cockpit mixture control, you will see outstanding fuel economy with your AeroInjector throughout the entire throttle setting range. With its extremely simple design and construction, AeroInjector can be quickly and easily tuned using the procedure published in the AeroInjector Owners Manual.

See fuel-burn rates for AeroVee, Jabiru 2200 and Jabiru 3300 engines.

Read "The $35 Hamburger"



Can I Install the AeroInjector on a Two-Stroke Engine?

The AeroInjector is not a good fit for Two-Stroke engines because of their reliance on oil mixed in the fuel for lubrication, and we do not sell the AeroInjector for Two-Stroke Installation. Back in the 1970’s and 80’s our company used similar Lake Injector carbs with much success on the Monnett Moni and Monerai’s two-stroke powerplants, but there is significant danger of instantly seizing-up the engine if the mixture is leaned too much, and we've seen less-experienced builders do just that. Even setting-up the AeroInjector to run a two-stroke engine for the first time is very perilous, and once running, an instant of over-leaning will immediately ruin a two-stroke engine.



Should I use an AeroInjector on my 2200 or 3300 Jabiru engine?

Absolutely. The overwhelming majority of the thousands of Sonex Aircraft Fleet hours with the Jabiru 3300 engines have been flown with either the AeroCarb/AeroInjector or Ellison. The Sonex pilots using these combinations have seen remarkable performance. These alternative carbs allow Jabiru engines to turn up higher and produce more power.

The AeroInjector exists (and has become a great option for many a homebuilder on a wide range of engines) because of the Bing Carburetor supplied with Jabiru engines. We encountered many troubles and needless complications when installing Bing Carbs in our own factory Sonex Aircraft. While it has been claimed by Jabiru that "all of these issues have been fixed" we continue to see these surface as new builders complete and fly their Jabiru powered aircraft. Note that the most recent issues reported did have Bing Carbs with the newer "Economy Tuning Kits" installed.

With over 30 years of experience using throttle-body type carbs, we knew there was a better way and that we were just the design team that could introduce a better Carb for the Jabiru engine. The result of our extensive R&D and flight testing is the AeroInjector line of throttle body injectors.

The AeroInjector represents the better carburetor option for your Jabiru engine in every measurable way, including but not limited to:

  1. Increased Flight Performance
  2. Better Fuel Economy
  3. Lower Cylinder Head Temps
  4. Lower Exhaust Gas Temps
  5. Lower Oil Temps
  6. Simpler Installation due to the elimination of the fuel pump
  7. Simpler Installation due to built-in control cable mounts
  8. Allows for Aerobatics
  9. Simpler Starting (no primer or choke required)
  10. Impervious to Carb Ice
  11. Lower Maintenance and Less Prone to Clogging
  12. Weight Savings

Some flight performance and test numbers to back up each of our claims:

While almost all of the Sonex Pilots with the 3300 Jabiru Engine are flying with an AeroCarb/AeroInjector (including Sonex Prototype Serial Number 0001, Xenos Prototype Serial Number 0001, and Sonex employee Kerry Fores' Serial Number 0009), there are some Sonex Pilots who insist on using the Bing carb. The reported performance and temperature data reported by these pilots has served as the control group as we compare them to those flying with the AeroInjector. This data was compiled using the same prop on the same airplane with the only difference being the carburetors/injectors.

1. Increased flight performance:

All Jabiru Engines powered by alternative carbs perform better than the standard Bing. (Note that the Ellison Carb costs twice as much as the AeroInjector and still requires the use of a fuel pump.)

In an impromptu comparison flight, Kerry Fores in his AeroCarb equipped, 3300-powered tailwheel Sonex was able to catch up with a Bing-equipped 3300-powered tailwheel Sonex in a shallow climb and, once level, was able to easily pull away. Both aircraft have the same propeller. While this is "unscientific" data, it is the only head-to-head comparison we know of to date. While we're confident the pilot of the other aircraft would not mind being identified, we will not identify him without his permission. This flight was witnessed from the cockpit by another builder, who is now flying his own AeroCarb equipped Jabiru 3300-powered Sonex.

2. Better Fuel Economy:

The AeroInjector provides better fuel economy because of two primary features. An infinitely adjustable main needle jet along with cockpit adjustible mixture control.

During initial tuning the fuel metering needle is set for optimum performance with the cockpit mixture control in the full-rich position, as detailed in the AeroInjector Owners Manual. Once in the air, the pilot can pull the mixture control until the engine just begins to run rough, then richen until it smooths out. This means the engine is always running at or near peak fuel efficiency. The AeroInjector saves between 3 and 4 gph vs. the standard Bing Carb in climb-out conditions and a little over 1 gph in an economy cruise over the Bing Carb. At $4 per gallon or more, the AeroInjector will pay for itself in much less than 100 hours of flying....then it's just more money in your pocket.

On Kerry's cross-country from Oshkosh to Sun and Fun and back (with his 3300 Jabiru powered Sonex) he had the opportunity to collect extended data on fuel consumption, particularly during the 1190 SM flight home which he was able to fly almost entirely at or near 8500 feet and 2950 rpm. With a fuel flow gauge fitted, which has proven extremely accurate over the past year of flying, cruise fuel burn rates ranged from 5.2 to 5.7 gph. Over the course of the entire flight fuel burn averaged 5.55 gph for time spent flying (fuel used/flight timer time), and 5.16 gph average for all time spent with the engine running (fuel used/hobbs meter time). Specifically, 88.76 gallons of gas were consumed, 17.2 hours were recorded on the Hobbs, and approximately 2400 miles were flown. The round trip flight included 8 stops (5 for fuel, 1 to wait for Lakeland airport to re-open after the airshow, and, of course, 1 each at arrival in Lakeland and back home in Oshkosh.

3. Lower Cylinder Head Temps:

Sonex Aircraft, LLC and AeroConversions created its own laser-cut and pre-bent cooling baffle system for use with either the 2200 or 3300 Jabiru. We have been running these successfully in our factory aircraft with AeroInjectors with all temps well within the green. We had two very recent reports of "high cylinder head temps with your laser-cut metal cooling baffles". Both of these reports were from pilots who insisted on using the Bing Carb, who were running up to 350 degrees on the center and aft cylinders.

Kerry has been flying the aluminum cooling baffles on his aircraft for all of the airplane's 190 hours (at the time of this writing). He developed the aluminum baffles after struggling with the Jabiru-provided fiberglass baffles. The hottest cylinder is cylinder #6 which in cruise at 2950 rpm and with an OAT of 55 degrees would top off at 320 degrees, but would quickly drop below 295 at 2800 rpm or less. The next hottest cylinder was #5, which never went over 287 and averaged 278. It must be pointed out here that in local flights around the patch when the engine is not being operated almost continuously for over 8 hours, #6 cylinder seldom tops 300 degrees. Cooling for #6 cylinder, with the metal baffles, can be dramatically improved by replacing a large cowl seal over #6 cylinder with a piece of aluminum which will add two or three minutes to the time it takes to remove/install the baffle.

4. Lower Exhaust Gas Temps:

EGT is the primary indicator of optimum fuel consumption and power output. The AeroInjector puts that control in the pilot's hand. By being able to pull the mixture lean in flight, power output is optimized and fuel consumption minimized. Without this control a pilot is at the mercy of a properly tuned Bing carb, a properly profiled needle, and the ill effects that come when the carburetor is no longer operating as efficiently as "new". The actual temperature to which you can lean changes from day to day, but with the AeroInjector the range is about 1285 degrees to 1425 degrees before engine performance diminishes from lack of fuel.

The Bottom line is that the pilot is in control of this most critical component of engine operation whether operating at full throttle in a zoom climb or cruising at altitude.

5. Lower Oil Temps:

Due to lower cylinder head and overall lower engine temperatures by running with the AeroInjector, oil temps have been observed 20 to 30 degrees lower than those running with the Bing. We also observed the elimination of the big heat-generating muffler and instead run the current standard straight-pipe Jabiru 3300 exhaust on Sonex Aircraft with no muffler, which was also one of the reasons for these lower oil temps.

Oil temps with the Sonex/Jabiru 3300 oil cooler installation ranged from a low of 168 degrees on Kerry's flight to Florida, to a high of 185 degrees. Oil pressure in cruising flight ranged from 49 psi to 54 psi. On a hot day of playing around the oil temperature will climb to 220 degrees, but will fall off quickly when flight attitude is stabilized or the throttle is brought back from the firewall. When the temperature falls below 40 degrees, the air inlet for the oil cooler can be closed off entirely. Oil temps should be allowed to climb high enough to burn out the moisture in the engine, but not so high as to impede proper cooling and lubrication.

6. Simpler Installation due to the elimination of the fuel pump. Also eliminates vapor lock:

Anytime we can eliminate another mechanical system on an aircraft that can fail, we jump at the chance. The variable fuel pressures delivered by the fuel pump can also result in vapor lock, which is eliminated when the AeroInjector is used.

7. Simpler Installation due to built-in control cable mounts:

Those of you who have accomplished a Bing Carb installation know exactly what we're talking about. Most Bing Carb installers fashion their own custom brackets and modify the Bing Carb throttle control to make the installation somewhat workable. The AeroInjector has a built-in Throttle Cable Mount and Mixture Mount, greatly simplifying your cable routing. The new "pull-type" throttle cable installation of the AeroInjector offers an even cleaner and simpler installation along with more flexibility in control cable routing.

8. Allows for Aerobatics:

Because the AeroInjector lacks a float bowl and delivers fuel largely based on the suction of the engine, it is the perfect carb for those intending to do positive G aerobatics and limited-duration* inverted and negative G manuevers. *A reverse fuel and oil system would have to be added to do longer duration inverted flight.

9. Simpler Starting (no primer or choke required):

A properly tuned AeroInjector will have your Jabiru starting on the first or second blade every time. We have never installed a primer and have never required a choke.

10. Impervious to Carb Ice:

Due to its design with no venturi and no butterfly, no factory AeroCarb/AeroInjector installations have ever used carb heat. There has also never been a documented case of carb ice in any AeroCarb/AeroInjector installation or any of the injectors in the same family including the Lake Injector and POSA carbs which are well into the tens of thousands of flight hours.

11. Lower Maintenance and Less Prone to Clogging:

Due to its minimal part count and simple design, the AeroInjector represents a quantum leap in reduced maintenance compared to the Bing Carb. Also due to the AeroInjector's clean, straight-through fuel orifice and as long as standard aircraft fuel filtration is used, fuel clogging due to debris or water in the fuel system are non-existent.

12. Weight Savings:

The AeroInjector itself weighs just over one pound, nine ounces less than the Bing Carb. There is additional weight savings in the simpler installation of approx 3 or 4 lbs with the deletion of the fuel pump (for those aircraft that can use gravity feed), carb heat box, and associated scat hose and clamps.

The AeroInjector has emerged as the preferred choice for a wide range of engine types. Hundreds of AeroCarb/AeroInjectors are currently being flown on Continentals, Lycomings, VW's, Subaru's, Corvairs, and virtually every other aircraft powerplant under 160 hp (30-125 hp engines currently served by the AeroInjector line). The AeroInjector is for those who love simplicity and want to maximize the performance of their engine.

There is an excellent article on this subject: "The $35 Hamburger" by Kerry Fores (Fuel Burn on the AeroCarb-equipped 3300 Jabiru)



How does the use of the AeroInjector affect my Jabiru Engine Warranty?

Sonex Aircraft knows of no instance where a warranty claim has been denied because an AeroInjector has been fitted. To our knowledge, they have honored all engine warranty issues brought to their attention regardless of AeroInjector use. That said, if you "cook" your Jabiru Engine using an AeroInjector because you weren't monitoring temperatures or didn't have your AeroInjector tuned properly, then you will be paying for the repairs to your engine. Follow the detailed instructions in your AeroInjector Owners Manual and your Jabiru engine will have better performance, will run cool, and will burn less fuel, virtually eliminating carburetor maintenance to boot.



The Bing Carb has been flying on Jabiru Engines all over the world for years. Why are you trying to reinvent the wheel by going to an AeroInjector?

Our best comparison to the modifications we make to the Jabiru Engine to make it better is the automobile aftermarket. There are many thousands of catalog and web site pages filled with different versions of carbs, manifolds, exhausts, fuel injectors, ignition systems, and misc. accessories for just about every automobile on the road. These different versions make various claims as to increased performance, weight savings, better cooling, and better fuel economy just to name a few.... All the same things that the AeroInjector offers Jabiru engine pilots. Our question is, once you learn all of the advantages the AeroInjector brings with it, why would anyone fly with a Bing carburetor?

 
 
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